LCOV - code coverage report
Current view: top level - gcore - overview.cpp (source / functions) Hit Total Coverage
Test: gdal_filtered.info Lines: 2722 3097 87.9 %
Date: 2026-02-21 16:21:44 Functions: 168 176 95.5 %

          Line data    Source code
       1             : 
       2             : /******************************************************************************
       3             :  *
       4             :  * Project:  GDAL Core
       5             :  * Purpose:  Helper code to implement overview support in different drivers.
       6             :  * Author:   Frank Warmerdam, warmerdam@pobox.com
       7             :  *
       8             :  ******************************************************************************
       9             :  * Copyright (c) 2000, Frank Warmerdam
      10             :  * Copyright (c) 2007-2010, Even Rouault <even dot rouault at spatialys.com>
      11             :  *
      12             :  * SPDX-License-Identifier: MIT
      13             :  ****************************************************************************/
      14             : 
      15             : #include "cpl_port.h"
      16             : #include "gdal_priv.h"
      17             : 
      18             : #include <cmath>
      19             : #include <cstddef>
      20             : #include <cstdlib>
      21             : 
      22             : #include <algorithm>
      23             : #include <complex>
      24             : #include <condition_variable>
      25             : #include <limits>
      26             : #include <list>
      27             : #include <memory>
      28             : #include <mutex>
      29             : #include <vector>
      30             : 
      31             : #include "cpl_conv.h"
      32             : #include "cpl_error.h"
      33             : #include "cpl_float.h"
      34             : #include "cpl_progress.h"
      35             : #include "cpl_vsi.h"
      36             : #include "cpl_worker_thread_pool.h"
      37             : #include "gdal.h"
      38             : #include "gdal_thread_pool.h"
      39             : #include "gdalwarper.h"
      40             : #include "gdal_vrt.h"
      41             : #include "vrtdataset.h"
      42             : 
      43             : #ifdef USE_NEON_OPTIMIZATIONS
      44             : #include "include_sse2neon.h"
      45             : 
      46             : #if (!defined(__aarch64__) && !defined(_M_ARM64))
      47             : #define ARM_V7
      48             : #endif
      49             : 
      50             : #define USE_SSE2
      51             : 
      52             : #include "gdalsse_priv.h"
      53             : 
      54             : // Restrict to 64bit processors because they are guaranteed to have SSE2,
      55             : // or if __AVX2__ is defined.
      56             : #elif defined(__x86_64) || defined(_M_X64) || defined(__AVX2__)
      57             : #define USE_SSE2
      58             : 
      59             : #include "gdalsse_priv.h"
      60             : 
      61             : #ifdef __SSE3__
      62             : #include <pmmintrin.h>
      63             : #endif
      64             : #ifdef __SSSE3__
      65             : #include <tmmintrin.h>
      66             : #endif
      67             : #ifdef __SSE4_1__
      68             : #include <smmintrin.h>
      69             : #endif
      70             : #ifdef __AVX2__
      71             : #include <immintrin.h>
      72             : #endif
      73             : 
      74             : #endif
      75             : 
      76             : // To be included after above USE_SSE2 and include gdalsse_priv.h
      77             : // to avoid build issue on Windows x86
      78             : #include "gdal_priv_templates.hpp"
      79             : 
      80             : /************************************************************************/
      81             : /*                       GDALResampleChunk_Near()                       */
      82             : /************************************************************************/
      83             : 
      84             : template <class T>
      85        1237 : static CPLErr GDALResampleChunk_NearT(const GDALOverviewResampleArgs &args,
      86             :                                       const T *pChunk, T **ppDstBuffer)
      87             : 
      88             : {
      89        1237 :     const double dfXRatioDstToSrc = args.dfXRatioDstToSrc;
      90        1237 :     const double dfYRatioDstToSrc = args.dfYRatioDstToSrc;
      91        1237 :     const GDALDataType eWrkDataType = args.eWrkDataType;
      92        1237 :     const int nChunkXOff = args.nChunkXOff;
      93        1237 :     const int nChunkXSize = args.nChunkXSize;
      94        1237 :     const int nChunkYOff = args.nChunkYOff;
      95        1237 :     const int nDstXOff = args.nDstXOff;
      96        1237 :     const int nDstXOff2 = args.nDstXOff2;
      97        1237 :     const int nDstYOff = args.nDstYOff;
      98        1237 :     const int nDstYOff2 = args.nDstYOff2;
      99        1237 :     const int nDstXWidth = nDstXOff2 - nDstXOff;
     100             : 
     101             :     /* -------------------------------------------------------------------- */
     102             :     /*      Allocate buffers.                                               */
     103             :     /* -------------------------------------------------------------------- */
     104        1237 :     *ppDstBuffer = static_cast<T *>(
     105        1237 :         VSI_MALLOC3_VERBOSE(nDstXWidth, nDstYOff2 - nDstYOff,
     106             :                             GDALGetDataTypeSizeBytes(eWrkDataType)));
     107        1237 :     if (*ppDstBuffer == nullptr)
     108             :     {
     109           0 :         return CE_Failure;
     110             :     }
     111        1237 :     T *const pDstBuffer = *ppDstBuffer;
     112             : 
     113             :     int *panSrcXOff =
     114        1237 :         static_cast<int *>(VSI_MALLOC2_VERBOSE(nDstXWidth, sizeof(int)));
     115             : 
     116        1237 :     if (panSrcXOff == nullptr)
     117             :     {
     118           0 :         return CE_Failure;
     119             :     }
     120             : 
     121             :     /* ==================================================================== */
     122             :     /*      Precompute inner loop constants.                                */
     123             :     /* ==================================================================== */
     124      840463 :     for (int iDstPixel = nDstXOff; iDstPixel < nDstXOff2; ++iDstPixel)
     125             :     {
     126      839226 :         int nSrcXOff = static_cast<int>(0.5 + iDstPixel * dfXRatioDstToSrc);
     127      839226 :         if (nSrcXOff < nChunkXOff)
     128           0 :             nSrcXOff = nChunkXOff;
     129             : 
     130      839226 :         panSrcXOff[iDstPixel - nDstXOff] = nSrcXOff;
     131             :     }
     132             : 
     133             :     /* ==================================================================== */
     134             :     /*      Loop over destination scanlines.                                */
     135             :     /* ==================================================================== */
     136      142070 :     for (int iDstLine = nDstYOff; iDstLine < nDstYOff2; ++iDstLine)
     137             :     {
     138      140833 :         int nSrcYOff = static_cast<int>(0.5 + iDstLine * dfYRatioDstToSrc);
     139      140833 :         if (nSrcYOff < nChunkYOff)
     140           0 :             nSrcYOff = nChunkYOff;
     141             : 
     142      140833 :         const T *const pSrcScanline =
     143             :             pChunk +
     144      140833 :             (static_cast<size_t>(nSrcYOff - nChunkYOff) * nChunkXSize) -
     145      137799 :             nChunkXOff;
     146             : 
     147             :         /* --------------------------------------------------------------------
     148             :          */
     149             :         /*      Loop over destination pixels */
     150             :         /* --------------------------------------------------------------------
     151             :          */
     152      140833 :         T *pDstScanline =
     153      140833 :             pDstBuffer + static_cast<size_t>(iDstLine - nDstYOff) * nDstXWidth;
     154   120237794 :         for (int iDstPixel = 0; iDstPixel < nDstXWidth; ++iDstPixel)
     155             :         {
     156   120096760 :             pDstScanline[iDstPixel] = pSrcScanline[panSrcXOff[iDstPixel]];
     157             :         }
     158             :     }
     159             : 
     160        1237 :     CPLFree(panSrcXOff);
     161             : 
     162        1237 :     return CE_None;
     163             : }
     164             : 
     165        1237 : static CPLErr GDALResampleChunk_Near(const GDALOverviewResampleArgs &args,
     166             :                                      const void *pChunk, void **ppDstBuffer,
     167             :                                      GDALDataType *peDstBufferDataType)
     168             : {
     169        1237 :     *peDstBufferDataType = args.eWrkDataType;
     170        1237 :     switch (args.eWrkDataType)
     171             :     {
     172             :         // For nearest resampling, as no computation is done, only the
     173             :         // size of the data type matters.
     174        1080 :         case GDT_UInt8:
     175             :         case GDT_Int8:
     176             :         {
     177        1080 :             CPLAssert(GDALGetDataTypeSizeBytes(args.eWrkDataType) == 1);
     178        1080 :             return GDALResampleChunk_NearT(
     179             :                 args, static_cast<const uint8_t *>(pChunk),
     180        1080 :                 reinterpret_cast<uint8_t **>(ppDstBuffer));
     181             :         }
     182             : 
     183          52 :         case GDT_Int16:
     184             :         case GDT_UInt16:
     185             :         case GDT_Float16:
     186             :         {
     187          52 :             CPLAssert(GDALGetDataTypeSizeBytes(args.eWrkDataType) == 2);
     188          52 :             return GDALResampleChunk_NearT(
     189             :                 args, static_cast<const uint16_t *>(pChunk),
     190          52 :                 reinterpret_cast<uint16_t **>(ppDstBuffer));
     191             :         }
     192             : 
     193          57 :         case GDT_CInt16:
     194             :         case GDT_CFloat16:
     195             :         case GDT_Int32:
     196             :         case GDT_UInt32:
     197             :         case GDT_Float32:
     198             :         {
     199          57 :             CPLAssert(GDALGetDataTypeSizeBytes(args.eWrkDataType) == 4);
     200          57 :             return GDALResampleChunk_NearT(
     201             :                 args, static_cast<const uint32_t *>(pChunk),
     202          57 :                 reinterpret_cast<uint32_t **>(ppDstBuffer));
     203             :         }
     204             : 
     205          44 :         case GDT_CInt32:
     206             :         case GDT_CFloat32:
     207             :         case GDT_Int64:
     208             :         case GDT_UInt64:
     209             :         case GDT_Float64:
     210             :         {
     211          44 :             CPLAssert(GDALGetDataTypeSizeBytes(args.eWrkDataType) == 8);
     212          44 :             return GDALResampleChunk_NearT(
     213             :                 args, static_cast<const uint64_t *>(pChunk),
     214          44 :                 reinterpret_cast<uint64_t **>(ppDstBuffer));
     215             :         }
     216             : 
     217           4 :         case GDT_CFloat64:
     218             :         {
     219           4 :             return GDALResampleChunk_NearT(
     220             :                 args, static_cast<const std::complex<double> *>(pChunk),
     221           4 :                 reinterpret_cast<std::complex<double> **>(ppDstBuffer));
     222             :         }
     223             : 
     224           0 :         case GDT_Unknown:
     225             :         case GDT_TypeCount:
     226           0 :             break;
     227             :     }
     228           0 :     CPLAssert(false);
     229             :     return CE_Failure;
     230             : }
     231             : 
     232             : namespace
     233             : {
     234             : 
     235             : // Find in the color table the entry whose RGB value is the closest
     236             : // (using quadratic distance) to the test color, ignoring transparent entries.
     237        3837 : int BestColorEntry(const std::vector<GDALColorEntry> &entries,
     238             :                    const GDALColorEntry &test)
     239             : {
     240        3837 :     int nMinDist = std::numeric_limits<int>::max();
     241        3837 :     size_t bestEntry = 0;
     242      986109 :     for (size_t i = 0; i < entries.size(); ++i)
     243             :     {
     244      982272 :         const GDALColorEntry &entry = entries[i];
     245             :         // Ignore transparent entries
     246      982272 :         if (entry.c4 == 0)
     247        3237 :             continue;
     248             : 
     249      979035 :         int nDist = ((test.c1 - entry.c1) * (test.c1 - entry.c1)) +
     250      979035 :                     ((test.c2 - entry.c2) * (test.c2 - entry.c2)) +
     251      979035 :                     ((test.c3 - entry.c3) * (test.c3 - entry.c3));
     252      979035 :         if (nDist < nMinDist)
     253             :         {
     254       15847 :             nMinDist = nDist;
     255       15847 :             bestEntry = i;
     256             :         }
     257             :     }
     258        3837 :     return static_cast<int>(bestEntry);
     259             : }
     260             : 
     261           7 : std::vector<GDALColorEntry> ReadColorTable(const GDALColorTable &table,
     262             :                                            int &transparentIdx)
     263             : {
     264           7 :     std::vector<GDALColorEntry> entries(table.GetColorEntryCount());
     265             : 
     266           7 :     transparentIdx = -1;
     267           7 :     int i = 0;
     268        1799 :     for (auto &entry : entries)
     269             :     {
     270        1792 :         table.GetColorEntryAsRGB(i, &entry);
     271        1792 :         if (transparentIdx < 0 && entry.c4 == 0)
     272           1 :             transparentIdx = i;
     273        1792 :         ++i;
     274             :     }
     275           7 :     return entries;
     276             : }
     277             : 
     278             : }  // unnamed  namespace
     279             : 
     280             : /************************************************************************/
     281             : /*                               SQUARE()                               */
     282             : /************************************************************************/
     283             : 
     284        4897 : template <class T, class Tsquare = T> inline Tsquare SQUARE(T val)
     285             : {
     286        4897 :     return static_cast<Tsquare>(val) * val;
     287             : }
     288             : 
     289             : /************************************************************************/
     290             : /*                         ComputeIntegerRMS()                          */
     291             : /************************************************************************/
     292             : // Compute rms = sqrt(sumSquares / weight) in such a way that it is the
     293             : // integer that minimizes abs(rms**2 - sumSquares / weight)
     294             : template <class T, class Twork>
     295          42 : inline T ComputeIntegerRMS(double sumSquares, double weight)
     296             : {
     297          42 :     const double sumDivWeight = sumSquares / weight;
     298          42 :     T rms = static_cast<T>(sqrt(sumDivWeight));
     299             : 
     300             :     // Is rms**2 or (rms+1)**2 closest to sumSquares / weight ?
     301             :     // Naive version:
     302             :     // if( weight * (rms+1)**2 - sumSquares < sumSquares - weight * rms**2 )
     303          42 :     if (static_cast<double>(static_cast<Twork>(2) * rms * (rms + 1) + 1) <
     304          42 :         2 * sumDivWeight)
     305           6 :         rms += 1;
     306          42 :     return rms;
     307             : }
     308             : 
     309             : template <class T, class Tsum> inline T ComputeIntegerRMS_4values(Tsum)
     310             : {
     311             :     CPLAssert(false);
     312             :     return 0;
     313             : }
     314             : 
     315          28 : template <> inline GByte ComputeIntegerRMS_4values<GByte, int>(int sumSquares)
     316             : {
     317             :     // It has been verified that given the correction on rms below, using
     318             :     // sqrt((float)((sumSquares + 1)/ 4)) or sqrt((float)sumSquares * 0.25f)
     319             :     // is equivalent, so use the former as it is used twice.
     320          28 :     const int sumSquaresPlusOneDiv4 = (sumSquares + 1) / 4;
     321          28 :     const float sumDivWeight = static_cast<float>(sumSquaresPlusOneDiv4);
     322          28 :     GByte rms = static_cast<GByte>(std::sqrt(sumDivWeight));
     323             : 
     324             :     // Is rms**2 or (rms+1)**2 closest to sumSquares / weight ?
     325             :     // Naive version:
     326             :     // if( weight * (rms+1)**2 - sumSquares < sumSquares - weight * rms**2 )
     327             :     // Optimized version for integer case and weight == 4
     328          28 :     if (static_cast<int>(rms) * (rms + 1) < sumSquaresPlusOneDiv4)
     329           5 :         rms += 1;
     330          28 :     return rms;
     331             : }
     332             : 
     333             : template <>
     334          24 : inline GUInt16 ComputeIntegerRMS_4values<GUInt16, double>(double sumSquares)
     335             : {
     336          24 :     const double sumDivWeight = sumSquares * 0.25;
     337          24 :     GUInt16 rms = static_cast<GUInt16>(std::sqrt(sumDivWeight));
     338             : 
     339             :     // Is rms**2 or (rms+1)**2 closest to sumSquares / weight ?
     340             :     // Naive version:
     341             :     // if( weight * (rms+1)**2 - sumSquares < sumSquares - weight * rms**2 )
     342             :     // Optimized version for integer case and weight == 4
     343          24 :     if (static_cast<GUInt32>(rms) * (rms + 1) <
     344          24 :         static_cast<GUInt32>(sumDivWeight + 0.25))
     345           4 :         rms += 1;
     346          24 :     return rms;
     347             : }
     348             : 
     349             : #ifdef USE_SSE2
     350             : 
     351             : /************************************************************************/
     352             : /*                    QuadraticMeanByteSSE2OrAVX2()                     */
     353             : /************************************************************************/
     354             : 
     355             : #if defined(__SSE4_1__) || defined(__AVX__) || defined(USE_NEON_OPTIMIZATIONS)
     356             : #define sse2_packus_epi32 _mm_packus_epi32
     357             : #else
     358      516139 : inline __m128i sse2_packus_epi32(__m128i a, __m128i b)
     359             : {
     360      516139 :     const auto minus32768_32 = _mm_set1_epi32(-32768);
     361      516139 :     const auto minus32768_16 = _mm_set1_epi16(-32768);
     362      516139 :     a = _mm_add_epi32(a, minus32768_32);
     363      516139 :     b = _mm_add_epi32(b, minus32768_32);
     364      516139 :     a = _mm_packs_epi32(a, b);
     365      516139 :     a = _mm_sub_epi16(a, minus32768_16);
     366      516139 :     return a;
     367             : }
     368             : #endif
     369             : 
     370             : #if defined(__SSSE3__) || defined(USE_NEON_OPTIMIZATIONS)
     371             : #define sse2_hadd_epi16 _mm_hadd_epi16
     372             : #else
     373     4715530 : inline __m128i sse2_hadd_epi16(__m128i a, __m128i b)
     374             : {
     375             :     // Horizontal addition of adjacent pairs
     376     4715530 :     const auto mask = _mm_set1_epi32(0xFFFF);
     377             :     const auto horizLo =
     378    14146600 :         _mm_add_epi32(_mm_and_si128(a, mask), _mm_srli_epi32(a, 16));
     379             :     const auto horizHi =
     380    14146600 :         _mm_add_epi32(_mm_and_si128(b, mask), _mm_srli_epi32(b, 16));
     381             : 
     382             :     // Recombine low and high parts
     383     4715530 :     return _mm_packs_epi32(horizLo, horizHi);
     384             : }
     385             : #endif
     386             : 
     387             : #ifdef __AVX2__
     388             : 
     389             : #define set1_epi16 _mm256_set1_epi16
     390             : #define set1_epi32 _mm256_set1_epi32
     391             : #define setzero _mm256_setzero_si256
     392             : #define set1_ps _mm256_set1_ps
     393             : #define loadu_int(x) _mm256_loadu_si256(reinterpret_cast<__m256i const *>(x))
     394             : #define unpacklo_epi8 _mm256_unpacklo_epi8
     395             : #define unpackhi_epi8 _mm256_unpackhi_epi8
     396             : #define madd_epi16 _mm256_madd_epi16
     397             : #define add_epi32 _mm256_add_epi32
     398             : #define mul_ps _mm256_mul_ps
     399             : #define cvtepi32_ps _mm256_cvtepi32_ps
     400             : #define sqrt_ps _mm256_sqrt_ps
     401             : #define cvttps_epi32 _mm256_cvttps_epi32
     402             : #define packs_epi32 _mm256_packs_epi32
     403             : #define packus_epi32 _mm256_packus_epi32
     404             : #define srli_epi32 _mm256_srli_epi32
     405             : #define mullo_epi16 _mm256_mullo_epi16
     406             : #define srli_epi16 _mm256_srli_epi16
     407             : #define cmpgt_epi16 _mm256_cmpgt_epi16
     408             : #define add_epi16 _mm256_add_epi16
     409             : #define sub_epi16 _mm256_sub_epi16
     410             : #define packus_epi16 _mm256_packus_epi16
     411             : 
     412             : /* AVX2 operates on 2 separate 128-bit lanes, so we have to do shuffling */
     413             : /* to get the lower 128-bit bits of what would be a true 256-bit vector register
     414             :  */
     415             : 
     416             : inline __m256i FIXUP_LANES(__m256i x)
     417             : {
     418             :     return _mm256_permute4x64_epi64(x, _MM_SHUFFLE(3, 1, 2, 0));
     419             : }
     420             : 
     421             : #define store_lo(x, y)                                                         \
     422             :     _mm_storeu_si128(reinterpret_cast<__m128i *>(x),                           \
     423             :                      _mm256_extracti128_si256(FIXUP_LANES(y), 0))
     424             : #define storeu_int(x, y)                                                       \
     425             :     _mm256_storeu_si256(reinterpret_cast<__m256i *>(x), FIXUP_LANES(y))
     426             : #define hadd_epi16 _mm256_hadd_epi16
     427             : #else
     428             : #define set1_epi16 _mm_set1_epi16
     429             : #define set1_epi32 _mm_set1_epi32
     430             : #define setzero _mm_setzero_si128
     431             : #define set1_ps _mm_set1_ps
     432             : #define loadu_int(x) _mm_loadu_si128(reinterpret_cast<__m128i const *>(x))
     433             : #define unpacklo_epi8 _mm_unpacklo_epi8
     434             : #define unpackhi_epi8 _mm_unpackhi_epi8
     435             : #define madd_epi16 _mm_madd_epi16
     436             : #define add_epi32 _mm_add_epi32
     437             : #define mul_ps _mm_mul_ps
     438             : #define cvtepi32_ps _mm_cvtepi32_ps
     439             : #define sqrt_ps _mm_sqrt_ps
     440             : #define cvttps_epi32 _mm_cvttps_epi32
     441             : #define packs_epi32 _mm_packs_epi32
     442             : #define packus_epi32 sse2_packus_epi32
     443             : #define srli_epi32 _mm_srli_epi32
     444             : #define mullo_epi16 _mm_mullo_epi16
     445             : #define srli_epi16 _mm_srli_epi16
     446             : #define cmpgt_epi16 _mm_cmpgt_epi16
     447             : #define add_epi16 _mm_add_epi16
     448             : #define sub_epi16 _mm_sub_epi16
     449             : #define packus_epi16 _mm_packus_epi16
     450             : #define store_lo(x, y) _mm_storel_epi64(reinterpret_cast<__m128i *>(x), (y))
     451             : #define storeu_int(x, y) _mm_storeu_si128(reinterpret_cast<__m128i *>(x), (y))
     452             : #define hadd_epi16 sse2_hadd_epi16
     453             : #endif
     454             : 
     455             : template <class T>
     456             : static int
     457             : #if defined(__GNUC__)
     458             :     __attribute__((noinline))
     459             : #endif
     460        5389 :     QuadraticMeanByteSSE2OrAVX2(int nDstXWidth, int nChunkXSize,
     461             :                                 const T *&CPL_RESTRICT pSrcScanlineShiftedInOut,
     462             :                                 T *CPL_RESTRICT pDstScanline)
     463             : {
     464             :     // Optimized implementation for RMS on Byte by
     465             :     // processing by group of 8 output pixels, so as to use
     466             :     // a single _mm_sqrt_ps() call for 4 output pixels
     467        5389 :     const T *CPL_RESTRICT pSrcScanlineShifted = pSrcScanlineShiftedInOut;
     468             : 
     469        5389 :     int iDstPixel = 0;
     470        5389 :     const auto one16 = set1_epi16(1);
     471        5389 :     const auto one32 = set1_epi32(1);
     472        5389 :     const auto zero = setzero();
     473        5389 :     const auto minus32768 = set1_epi16(-32768);
     474             : 
     475        5389 :     constexpr int DEST_ELTS = static_cast<int>(sizeof(zero)) / 2;
     476      521504 :     for (; iDstPixel < nDstXWidth - (DEST_ELTS - 1); iDstPixel += DEST_ELTS)
     477             :     {
     478             :         // Load 2 * DEST_ELTS bytes from each line
     479      516115 :         auto firstLine = loadu_int(pSrcScanlineShifted);
     480     1032230 :         auto secondLine = loadu_int(pSrcScanlineShifted + nChunkXSize);
     481             :         // Extend those Bytes as UInt16s
     482      516115 :         auto firstLineLo = unpacklo_epi8(firstLine, zero);
     483      516115 :         auto firstLineHi = unpackhi_epi8(firstLine, zero);
     484      516115 :         auto secondLineLo = unpacklo_epi8(secondLine, zero);
     485      516115 :         auto secondLineHi = unpackhi_epi8(secondLine, zero);
     486             : 
     487             :         // Multiplication of 16 bit values and horizontal
     488             :         // addition of 32 bit results
     489             :         // [ src[2*i+0]^2 + src[2*i+1]^2 for i in range(4) ]
     490      516115 :         firstLineLo = madd_epi16(firstLineLo, firstLineLo);
     491      516115 :         firstLineHi = madd_epi16(firstLineHi, firstLineHi);
     492      516115 :         secondLineLo = madd_epi16(secondLineLo, secondLineLo);
     493      516115 :         secondLineHi = madd_epi16(secondLineHi, secondLineHi);
     494             : 
     495             :         // Vertical addition
     496      516115 :         const auto sumSquaresLo = add_epi32(firstLineLo, secondLineLo);
     497      516115 :         const auto sumSquaresHi = add_epi32(firstLineHi, secondLineHi);
     498             : 
     499             :         const auto sumSquaresPlusOneDiv4Lo =
     500     1032230 :             srli_epi32(add_epi32(sumSquaresLo, one32), 2);
     501             :         const auto sumSquaresPlusOneDiv4Hi =
     502     1032230 :             srli_epi32(add_epi32(sumSquaresHi, one32), 2);
     503             : 
     504             :         // Take square root and truncate/floor to int32
     505             :         const auto rmsLo =
     506     1548340 :             cvttps_epi32(sqrt_ps(cvtepi32_ps(sumSquaresPlusOneDiv4Lo)));
     507             :         const auto rmsHi =
     508     1548340 :             cvttps_epi32(sqrt_ps(cvtepi32_ps(sumSquaresPlusOneDiv4Hi)));
     509             : 
     510             :         // Merge back low and high registers with each RMS value
     511             :         // as a 16 bit value.
     512      516115 :         auto rms = packs_epi32(rmsLo, rmsHi);
     513             : 
     514             :         // Round to upper value if it minimizes the
     515             :         // error |rms^2 - sumSquares/4|
     516             :         // if( 2 * (2 * rms * (rms + 1) + 1) < sumSquares )
     517             :         //    rms += 1;
     518             :         // which is equivalent to:
     519             :         // if( rms * (rms + 1) < (sumSquares+1) / 4 )
     520             :         //    rms += 1;
     521             :         // And both left and right parts fit on 16 (unsigned) bits
     522             :         const auto sumSquaresPlusOneDiv4 =
     523      516115 :             packus_epi32(sumSquaresPlusOneDiv4Lo, sumSquaresPlusOneDiv4Hi);
     524             :         // cmpgt_epi16 operates on signed int16, but here
     525             :         // we have unsigned values, so shift them by -32768 before
     526     2580580 :         const auto mask = cmpgt_epi16(
     527             :             add_epi16(sumSquaresPlusOneDiv4, minus32768),
     528             :             add_epi16(mullo_epi16(rms, add_epi16(rms, one16)), minus32768));
     529             :         // The value of the mask will be -1 when the correction needs to be
     530             :         // applied
     531      516115 :         rms = sub_epi16(rms, mask);
     532             : 
     533             :         // Pack each 16 bit RMS value to 8 bits
     534      516115 :         rms = packus_epi16(rms, rms /* could be anything */);
     535      516115 :         store_lo(&pDstScanline[iDstPixel], rms);
     536      516115 :         pSrcScanlineShifted += 2 * DEST_ELTS;
     537             :     }
     538             : 
     539        5389 :     pSrcScanlineShiftedInOut = pSrcScanlineShifted;
     540        5389 :     return iDstPixel;
     541             : }
     542             : 
     543             : /************************************************************************/
     544             : /*                       AverageByteSSE2OrAVX2()                        */
     545             : /************************************************************************/
     546             : 
     547             : static int
     548      111734 : AverageByteSSE2OrAVX2(int nDstXWidth, int nChunkXSize,
     549             :                       const GByte *&CPL_RESTRICT pSrcScanlineShiftedInOut,
     550             :                       GByte *CPL_RESTRICT pDstScanline)
     551             : {
     552             :     // Optimized implementation for average on Byte by
     553             :     // processing by group of 16 output pixels for SSE2, or 32 for AVX2
     554             : 
     555      111734 :     const auto zero = setzero();
     556      111734 :     const auto two16 = set1_epi16(2);
     557      111734 :     const GByte *CPL_RESTRICT pSrcScanlineShifted = pSrcScanlineShiftedInOut;
     558             : 
     559      111734 :     constexpr int DEST_ELTS = static_cast<int>(sizeof(zero)) / 2;
     560      111734 :     int iDstPixel = 0;
     561     2469500 :     for (; iDstPixel < nDstXWidth - (2 * DEST_ELTS - 1);
     562     2357770 :          iDstPixel += 2 * DEST_ELTS)
     563             :     {
     564             :         decltype(setzero()) average0;
     565             :         {
     566             :             // Load 2 * DEST_ELTS bytes from each line
     567     2357770 :             const auto firstLine = loadu_int(pSrcScanlineShifted);
     568             :             const auto secondLine =
     569     4715530 :                 loadu_int(pSrcScanlineShifted + nChunkXSize);
     570             :             // Extend those Bytes as UInt16s
     571     2357770 :             const auto firstLineLo = unpacklo_epi8(firstLine, zero);
     572     2357770 :             const auto firstLineHi = unpackhi_epi8(firstLine, zero);
     573     2357770 :             const auto secondLineLo = unpacklo_epi8(secondLine, zero);
     574     2357770 :             const auto secondLineHi = unpackhi_epi8(secondLine, zero);
     575             : 
     576             :             // Vertical addition
     577     2357770 :             const auto sumLo = add_epi16(firstLineLo, secondLineLo);
     578     2357770 :             const auto sumHi = add_epi16(firstLineHi, secondLineHi);
     579             : 
     580             :             // Horizontal addition of adjacent pairs, and recombine low and high
     581             :             // parts
     582     2357770 :             const auto sum = hadd_epi16(sumLo, sumHi);
     583             : 
     584             :             // average = (sum + 2) / 4
     585     2357770 :             average0 = srli_epi16(add_epi16(sum, two16), 2);
     586             : 
     587     2357770 :             pSrcScanlineShifted += 2 * DEST_ELTS;
     588             :         }
     589             : 
     590             :         decltype(setzero()) average1;
     591             :         {
     592             :             // Load 2 * DEST_ELTS bytes from each line
     593     2357770 :             const auto firstLine = loadu_int(pSrcScanlineShifted);
     594             :             const auto secondLine =
     595     4715530 :                 loadu_int(pSrcScanlineShifted + nChunkXSize);
     596             :             // Extend those Bytes as UInt16s
     597     2357770 :             const auto firstLineLo = unpacklo_epi8(firstLine, zero);
     598     2357770 :             const auto firstLineHi = unpackhi_epi8(firstLine, zero);
     599     2357770 :             const auto secondLineLo = unpacklo_epi8(secondLine, zero);
     600     2357770 :             const auto secondLineHi = unpackhi_epi8(secondLine, zero);
     601             : 
     602             :             // Vertical addition
     603     2357770 :             const auto sumLo = add_epi16(firstLineLo, secondLineLo);
     604     2357770 :             const auto sumHi = add_epi16(firstLineHi, secondLineHi);
     605             : 
     606             :             // Horizontal addition of adjacent pairs, and recombine low and high
     607             :             // parts
     608     2357770 :             const auto sum = hadd_epi16(sumLo, sumHi);
     609             : 
     610             :             // average = (sum + 2) / 4
     611     2357770 :             average1 = srli_epi16(add_epi16(sum, two16), 2);
     612             : 
     613     2357770 :             pSrcScanlineShifted += 2 * DEST_ELTS;
     614             :         }
     615             : 
     616             :         // Pack each 16 bit average value to 8 bits
     617     2357770 :         const auto average = packus_epi16(average0, average1);
     618     2357770 :         storeu_int(&pDstScanline[iDstPixel], average);
     619             :     }
     620             : 
     621      111734 :     pSrcScanlineShiftedInOut = pSrcScanlineShifted;
     622      111734 :     return iDstPixel;
     623             : }
     624             : 
     625             : /************************************************************************/
     626             : /*                      QuadraticMeanUInt16SSE2()                       */
     627             : /************************************************************************/
     628             : 
     629             : #ifdef __SSE3__
     630             : #define sse2_hadd_pd _mm_hadd_pd
     631             : #else
     632         185 : inline __m128d sse2_hadd_pd(__m128d a, __m128d b)
     633             : {
     634             :     auto aLo_bLo =
     635         740 :         _mm_castps_pd(_mm_movelh_ps(_mm_castpd_ps(a), _mm_castpd_ps(b)));
     636             :     auto aHi_bHi =
     637         740 :         _mm_castps_pd(_mm_movehl_ps(_mm_castpd_ps(b), _mm_castpd_ps(a)));
     638         185 :     return _mm_add_pd(aLo_bLo, aHi_bHi);  // (aLo + aHi, bLo + bHi)
     639             : }
     640             : #endif
     641             : 
     642         120 : inline __m128d SQUARE_PD(__m128d x)
     643             : {
     644         120 :     return _mm_mul_pd(x, x);
     645             : }
     646             : 
     647             : #ifdef __AVX2__
     648             : 
     649             : inline __m256d SQUARE_PD(__m256d x)
     650             : {
     651             :     return _mm256_mul_pd(x, x);
     652             : }
     653             : 
     654             : inline __m256d FIXUP_LANES(__m256d x)
     655             : {
     656             :     return _mm256_permute4x64_pd(x, _MM_SHUFFLE(3, 1, 2, 0));
     657             : }
     658             : 
     659             : inline __m256 FIXUP_LANES(__m256 x)
     660             : {
     661             :     return _mm256_castpd_ps(FIXUP_LANES(_mm256_castps_pd(x)));
     662             : }
     663             : 
     664             : #endif
     665             : 
     666             : static int
     667          14 : QuadraticMeanUInt16SSE2(int nDstXWidth, int nChunkXSize,
     668             :                         const uint16_t *&CPL_RESTRICT pSrcScanlineShiftedInOut,
     669             :                         uint16_t *CPL_RESTRICT pDstScanline)
     670             : {
     671             :     // Optimized implementation for RMS on UInt16 by
     672             :     // processing by group of 4 output pixels.
     673          14 :     const uint16_t *CPL_RESTRICT pSrcScanlineShifted = pSrcScanlineShiftedInOut;
     674             : 
     675          14 :     int iDstPixel = 0;
     676          14 :     const auto zero = _mm_setzero_si128();
     677             : 
     678             : #ifdef __AVX2__
     679             :     const auto zeroDot25 = _mm256_set1_pd(0.25);
     680             :     const auto zeroDot5 = _mm256_set1_pd(0.5);
     681             : 
     682             :     // The first four 0's could be anything, as we only take the bottom
     683             :     // 128 bits.
     684             :     const auto permutation = _mm256_set_epi32(0, 0, 0, 0, 6, 4, 2, 0);
     685             : #else
     686          14 :     const auto zeroDot25 = _mm_set1_pd(0.25);
     687          14 :     const auto zeroDot5 = _mm_set1_pd(0.5);
     688             : #endif
     689             : 
     690          14 :     constexpr int DEST_ELTS =
     691             :         static_cast<int>(sizeof(zero) / sizeof(uint16_t)) / 2;
     692          52 :     for (; iDstPixel < nDstXWidth - (DEST_ELTS - 1); iDstPixel += DEST_ELTS)
     693             :     {
     694             :         // Load 8 UInt16 from each line
     695          38 :         const auto firstLine = _mm_loadu_si128(
     696             :             reinterpret_cast<__m128i const *>(pSrcScanlineShifted));
     697             :         const auto secondLine =
     698          38 :             _mm_loadu_si128(reinterpret_cast<__m128i const *>(
     699          38 :                 pSrcScanlineShifted + nChunkXSize));
     700             : 
     701             :         // Detect if all of the source values fit in 14 bits.
     702             :         // because if x < 2^14, then 4 * x^2 < 2^30 which fits in a signed int32
     703             :         // and we can do a much faster implementation.
     704             :         const auto maskTmp =
     705          76 :             _mm_srli_epi16(_mm_or_si128(firstLine, secondLine), 14);
     706             : #if defined(__i386__) || defined(_M_IX86)
     707             :         uint64_t nMaskFitsIn14Bits = 0;
     708             :         _mm_storel_epi64(
     709             :             reinterpret_cast<__m128i *>(&nMaskFitsIn14Bits),
     710             :             _mm_packus_epi16(maskTmp, maskTmp /* could be anything */));
     711             : #else
     712          38 :         const auto nMaskFitsIn14Bits = _mm_cvtsi128_si64(
     713             :             _mm_packus_epi16(maskTmp, maskTmp /* could be anything */));
     714             : #endif
     715          38 :         if (nMaskFitsIn14Bits == 0)
     716             :         {
     717             :             // Multiplication of 16 bit values and horizontal
     718             :             // addition of 32 bit results
     719             :             const auto firstLineHSumSquare =
     720          26 :                 _mm_madd_epi16(firstLine, firstLine);
     721             :             const auto secondLineHSumSquare =
     722          26 :                 _mm_madd_epi16(secondLine, secondLine);
     723             :             // Vertical addition
     724             :             const auto sumSquares =
     725          26 :                 _mm_add_epi32(firstLineHSumSquare, secondLineHSumSquare);
     726             :             // In theory we should take sqrt(sumSquares * 0.25f)
     727             :             // but given the rounding we do, this is equivalent to
     728             :             // sqrt((sumSquares + 1)/4). This has been verified exhaustively for
     729             :             // sumSquares <= 4 * 16383^2
     730          26 :             const auto one32 = _mm_set1_epi32(1);
     731             :             const auto sumSquaresPlusOneDiv4 =
     732          52 :                 _mm_srli_epi32(_mm_add_epi32(sumSquares, one32), 2);
     733             :             // Take square root and truncate/floor to int32
     734          78 :             auto rms = _mm_cvttps_epi32(
     735             :                 _mm_sqrt_ps(_mm_cvtepi32_ps(sumSquaresPlusOneDiv4)));
     736             : 
     737             :             // Round to upper value if it minimizes the
     738             :             // error |rms^2 - sumSquares/4|
     739             :             // if( 2 * (2 * rms * (rms + 1) + 1) < sumSquares )
     740             :             //    rms += 1;
     741             :             // which is equivalent to:
     742             :             // if( rms * rms + rms < (sumSquares+1) / 4 )
     743             :             //    rms += 1;
     744             :             auto mask =
     745          78 :                 _mm_cmpgt_epi32(sumSquaresPlusOneDiv4,
     746             :                                 _mm_add_epi32(_mm_madd_epi16(rms, rms), rms));
     747          26 :             rms = _mm_sub_epi32(rms, mask);
     748             :             // Pack each 32 bit RMS value to 16 bits
     749          26 :             rms = _mm_packs_epi32(rms, rms /* could be anything */);
     750             :             _mm_storel_epi64(
     751          26 :                 reinterpret_cast<__m128i *>(&pDstScanline[iDstPixel]), rms);
     752          26 :             pSrcScanlineShifted += 2 * DEST_ELTS;
     753          26 :             continue;
     754             :         }
     755             : 
     756             :         // An approach using _mm_mullo_epi16, _mm_mulhi_epu16 before extending
     757             :         // to 32 bit would result in 4 multiplications instead of 8, but
     758             :         // mullo/mulhi have a worse throughput than mul_pd.
     759             : 
     760             :         // Extend those UInt16s as UInt32s
     761          12 :         const auto firstLineLo = _mm_unpacklo_epi16(firstLine, zero);
     762          12 :         const auto firstLineHi = _mm_unpackhi_epi16(firstLine, zero);
     763          12 :         const auto secondLineLo = _mm_unpacklo_epi16(secondLine, zero);
     764          12 :         const auto secondLineHi = _mm_unpackhi_epi16(secondLine, zero);
     765             : 
     766             : #ifdef __AVX2__
     767             :         // Multiplication of 32 bit values previously converted to 64 bit double
     768             :         const auto firstLineLoDbl = SQUARE_PD(_mm256_cvtepi32_pd(firstLineLo));
     769             :         const auto firstLineHiDbl = SQUARE_PD(_mm256_cvtepi32_pd(firstLineHi));
     770             :         const auto secondLineLoDbl =
     771             :             SQUARE_PD(_mm256_cvtepi32_pd(secondLineLo));
     772             :         const auto secondLineHiDbl =
     773             :             SQUARE_PD(_mm256_cvtepi32_pd(secondLineHi));
     774             : 
     775             :         // Vertical addition of squares
     776             :         const auto sumSquaresLo =
     777             :             _mm256_add_pd(firstLineLoDbl, secondLineLoDbl);
     778             :         const auto sumSquaresHi =
     779             :             _mm256_add_pd(firstLineHiDbl, secondLineHiDbl);
     780             : 
     781             :         // Horizontal addition of squares
     782             :         const auto sumSquares =
     783             :             FIXUP_LANES(_mm256_hadd_pd(sumSquaresLo, sumSquaresHi));
     784             : 
     785             :         const auto sumDivWeight = _mm256_mul_pd(sumSquares, zeroDot25);
     786             : 
     787             :         // Take square root and truncate/floor to int32
     788             :         auto rms = _mm256_cvttpd_epi32(_mm256_sqrt_pd(sumDivWeight));
     789             :         const auto rmsDouble = _mm256_cvtepi32_pd(rms);
     790             :         const auto right = _mm256_sub_pd(
     791             :             sumDivWeight, _mm256_add_pd(SQUARE_PD(rmsDouble), rmsDouble));
     792             : 
     793             :         auto mask =
     794             :             _mm256_castpd_ps(_mm256_cmp_pd(zeroDot5, right, _CMP_LT_OS));
     795             :         // Extract 32-bit from each of the 4 64-bit masks
     796             :         // mask = FIXUP_LANES(_mm256_shuffle_ps(mask, mask,
     797             :         // _MM_SHUFFLE(2,0,2,0)));
     798             :         mask = _mm256_permutevar8x32_ps(mask, permutation);
     799             :         const auto maskI = _mm_castps_si128(_mm256_extractf128_ps(mask, 0));
     800             : 
     801             :         // Apply the correction
     802             :         rms = _mm_sub_epi32(rms, maskI);
     803             : 
     804             :         // Pack each 32 bit RMS value to 16 bits
     805             :         rms = _mm_packus_epi32(rms, rms /* could be anything */);
     806             : #else
     807             :         // Multiplication of 32 bit values previously converted to 64 bit double
     808          12 :         const auto firstLineLoLo = SQUARE_PD(_mm_cvtepi32_pd(firstLineLo));
     809             :         const auto firstLineLoHi =
     810          24 :             SQUARE_PD(_mm_cvtepi32_pd(_mm_srli_si128(firstLineLo, 8)));
     811          12 :         const auto firstLineHiLo = SQUARE_PD(_mm_cvtepi32_pd(firstLineHi));
     812             :         const auto firstLineHiHi =
     813          24 :             SQUARE_PD(_mm_cvtepi32_pd(_mm_srli_si128(firstLineHi, 8)));
     814             : 
     815          12 :         const auto secondLineLoLo = SQUARE_PD(_mm_cvtepi32_pd(secondLineLo));
     816             :         const auto secondLineLoHi =
     817          24 :             SQUARE_PD(_mm_cvtepi32_pd(_mm_srli_si128(secondLineLo, 8)));
     818          12 :         const auto secondLineHiLo = SQUARE_PD(_mm_cvtepi32_pd(secondLineHi));
     819             :         const auto secondLineHiHi =
     820          24 :             SQUARE_PD(_mm_cvtepi32_pd(_mm_srli_si128(secondLineHi, 8)));
     821             : 
     822             :         // Vertical addition of squares
     823          12 :         const auto sumSquaresLoLo = _mm_add_pd(firstLineLoLo, secondLineLoLo);
     824          12 :         const auto sumSquaresLoHi = _mm_add_pd(firstLineLoHi, secondLineLoHi);
     825          12 :         const auto sumSquaresHiLo = _mm_add_pd(firstLineHiLo, secondLineHiLo);
     826          12 :         const auto sumSquaresHiHi = _mm_add_pd(firstLineHiHi, secondLineHiHi);
     827             : 
     828             :         // Horizontal addition of squares
     829          12 :         const auto sumSquaresLo = sse2_hadd_pd(sumSquaresLoLo, sumSquaresLoHi);
     830          12 :         const auto sumSquaresHi = sse2_hadd_pd(sumSquaresHiLo, sumSquaresHiHi);
     831             : 
     832          12 :         const auto sumDivWeightLo = _mm_mul_pd(sumSquaresLo, zeroDot25);
     833          12 :         const auto sumDivWeightHi = _mm_mul_pd(sumSquaresHi, zeroDot25);
     834             :         // Take square root and truncate/floor to int32
     835          24 :         const auto rmsLo = _mm_cvttpd_epi32(_mm_sqrt_pd(sumDivWeightLo));
     836          24 :         const auto rmsHi = _mm_cvttpd_epi32(_mm_sqrt_pd(sumDivWeightHi));
     837             : 
     838             :         // Correctly round rms to minimize | rms^2 - sumSquares / 4 |
     839             :         // if( 0.5 < sumDivWeight - (rms * rms + rms) )
     840             :         //     rms += 1;
     841          12 :         const auto rmsLoDouble = _mm_cvtepi32_pd(rmsLo);
     842          12 :         const auto rmsHiDouble = _mm_cvtepi32_pd(rmsHi);
     843          24 :         const auto rightLo = _mm_sub_pd(
     844             :             sumDivWeightLo, _mm_add_pd(SQUARE_PD(rmsLoDouble), rmsLoDouble));
     845          36 :         const auto rightHi = _mm_sub_pd(
     846             :             sumDivWeightHi, _mm_add_pd(SQUARE_PD(rmsHiDouble), rmsHiDouble));
     847             : 
     848          24 :         const auto maskLo = _mm_castpd_ps(_mm_cmplt_pd(zeroDot5, rightLo));
     849          12 :         const auto maskHi = _mm_castpd_ps(_mm_cmplt_pd(zeroDot5, rightHi));
     850             :         // The value of the mask will be -1 when the correction needs to be
     851             :         // applied
     852          24 :         const auto mask = _mm_castps_si128(_mm_shuffle_ps(
     853             :             maskLo, maskHi, (0 << 0) | (2 << 2) | (0 << 4) | (2 << 6)));
     854             : 
     855          48 :         auto rms = _mm_castps_si128(
     856             :             _mm_movelh_ps(_mm_castsi128_ps(rmsLo), _mm_castsi128_ps(rmsHi)));
     857             :         // Apply the correction
     858          12 :         rms = _mm_sub_epi32(rms, mask);
     859             : 
     860             :         // Pack each 32 bit RMS value to 16 bits
     861          12 :         rms = sse2_packus_epi32(rms, rms /* could be anything */);
     862             : #endif
     863             : 
     864          12 :         _mm_storel_epi64(reinterpret_cast<__m128i *>(&pDstScanline[iDstPixel]),
     865             :                          rms);
     866          12 :         pSrcScanlineShifted += 2 * DEST_ELTS;
     867             :     }
     868             : 
     869          14 :     pSrcScanlineShiftedInOut = pSrcScanlineShifted;
     870          14 :     return iDstPixel;
     871             : }
     872             : 
     873             : /************************************************************************/
     874             : /*                         AverageUInt16SSE2()                          */
     875             : /************************************************************************/
     876             : 
     877             : static int
     878          13 : AverageUInt16SSE2(int nDstXWidth, int nChunkXSize,
     879             :                   const uint16_t *&CPL_RESTRICT pSrcScanlineShiftedInOut,
     880             :                   uint16_t *CPL_RESTRICT pDstScanline)
     881             : {
     882             :     // Optimized implementation for average on UInt16 by
     883             :     // processing by group of 8 output pixels.
     884             : 
     885          13 :     const auto mask = _mm_set1_epi32(0xFFFF);
     886          13 :     const auto two = _mm_set1_epi32(2);
     887          13 :     const uint16_t *CPL_RESTRICT pSrcScanlineShifted = pSrcScanlineShiftedInOut;
     888             : 
     889          13 :     int iDstPixel = 0;
     890          13 :     constexpr int DEST_ELTS = static_cast<int>(sizeof(mask) / sizeof(uint16_t));
     891          25 :     for (; iDstPixel < nDstXWidth - (DEST_ELTS - 1); iDstPixel += DEST_ELTS)
     892             :     {
     893             :         __m128i averageLow;
     894             :         // Load 8 UInt16 from each line
     895             :         {
     896          12 :             const auto firstLine = _mm_loadu_si128(
     897             :                 reinterpret_cast<__m128i const *>(pSrcScanlineShifted));
     898             :             const auto secondLine =
     899          12 :                 _mm_loadu_si128(reinterpret_cast<__m128i const *>(
     900          12 :                     pSrcScanlineShifted + nChunkXSize));
     901             : 
     902             :             // Horizontal addition and extension to 32 bit
     903          36 :             const auto horizAddFirstLine = _mm_add_epi32(
     904             :                 _mm_and_si128(firstLine, mask), _mm_srli_epi32(firstLine, 16));
     905             :             const auto horizAddSecondLine =
     906          36 :                 _mm_add_epi32(_mm_and_si128(secondLine, mask),
     907             :                               _mm_srli_epi32(secondLine, 16));
     908             : 
     909             :             // Vertical addition and average computation
     910             :             // average = (sum + 2) >> 2
     911          24 :             const auto sum = _mm_add_epi32(
     912             :                 _mm_add_epi32(horizAddFirstLine, horizAddSecondLine), two);
     913          12 :             averageLow = _mm_srli_epi32(sum, 2);
     914             :         }
     915             :         // Load 8 UInt16 from each line
     916             :         __m128i averageHigh;
     917             :         {
     918             :             const auto firstLine =
     919          12 :                 _mm_loadu_si128(reinterpret_cast<__m128i const *>(
     920          12 :                     pSrcScanlineShifted + DEST_ELTS));
     921             :             const auto secondLine =
     922          12 :                 _mm_loadu_si128(reinterpret_cast<__m128i const *>(
     923          12 :                     pSrcScanlineShifted + DEST_ELTS + nChunkXSize));
     924             : 
     925             :             // Horizontal addition and extension to 32 bit
     926          36 :             const auto horizAddFirstLine = _mm_add_epi32(
     927             :                 _mm_and_si128(firstLine, mask), _mm_srli_epi32(firstLine, 16));
     928             :             const auto horizAddSecondLine =
     929          36 :                 _mm_add_epi32(_mm_and_si128(secondLine, mask),
     930             :                               _mm_srli_epi32(secondLine, 16));
     931             : 
     932             :             // Vertical addition and average computation
     933             :             // average = (sum + 2) >> 2
     934          24 :             const auto sum = _mm_add_epi32(
     935             :                 _mm_add_epi32(horizAddFirstLine, horizAddSecondLine), two);
     936          12 :             averageHigh = _mm_srli_epi32(sum, 2);
     937             :         }
     938             : 
     939             :         // Pack each 32 bit average value to 16 bits
     940          12 :         auto average = sse2_packus_epi32(averageLow, averageHigh);
     941          12 :         _mm_storeu_si128(reinterpret_cast<__m128i *>(&pDstScanline[iDstPixel]),
     942             :                          average);
     943          12 :         pSrcScanlineShifted += 2 * DEST_ELTS;
     944             :     }
     945             : 
     946          13 :     pSrcScanlineShiftedInOut = pSrcScanlineShifted;
     947          13 :     return iDstPixel;
     948             : }
     949             : 
     950             : /************************************************************************/
     951             : /*                       QuadraticMeanFloatSSE2()                       */
     952             : /************************************************************************/
     953             : 
     954             : #if !defined(ARM_V7)
     955             : 
     956             : #ifdef __SSE3__
     957             : #define sse2_hadd_ps _mm_hadd_ps
     958             : #else
     959          82 : inline __m128 sse2_hadd_ps(__m128 a, __m128 b)
     960             : {
     961          82 :     auto aEven_bEven = _mm_shuffle_ps(a, b, _MM_SHUFFLE(2, 0, 2, 0));
     962          82 :     auto aOdd_bOdd = _mm_shuffle_ps(a, b, _MM_SHUFFLE(3, 1, 3, 1));
     963          82 :     return _mm_add_ps(aEven_bEven, aOdd_bOdd);  // (aEven + aOdd, bEven + bOdd)
     964             : }
     965             : #endif
     966             : 
     967             : #ifdef __AVX2__
     968             : #define set1_ps _mm256_set1_ps
     969             : #define loadu_ps _mm256_loadu_ps
     970             : #define andnot_ps _mm256_andnot_ps
     971             : #define and_ps _mm256_and_ps
     972             : #define max_ps _mm256_max_ps
     973             : #define shuffle_ps _mm256_shuffle_ps
     974             : #define div_ps _mm256_div_ps
     975             : #define cmpeq_ps(x, y) _mm256_cmp_ps((x), (y), _CMP_EQ_OQ)
     976             : #define mul_ps _mm256_mul_ps
     977             : #define add_ps _mm256_add_ps
     978             : #define hadd_ps _mm256_hadd_ps
     979             : #define sqrt_ps _mm256_sqrt_ps
     980             : #define or_ps _mm256_or_ps
     981             : #define unpacklo_ps _mm256_unpacklo_ps
     982             : #define unpackhi_ps _mm256_unpackhi_ps
     983             : #define storeu_ps _mm256_storeu_ps
     984             : #define blendv_ps _mm256_blendv_ps
     985             : 
     986             : inline __m256 SQUARE_PS(__m256 x)
     987             : {
     988             :     return _mm256_mul_ps(x, x);
     989             : }
     990             : 
     991             : #else
     992             : 
     993             : #define set1_ps _mm_set1_ps
     994             : #define loadu_ps _mm_loadu_ps
     995             : #define andnot_ps _mm_andnot_ps
     996             : #define and_ps _mm_and_ps
     997             : #define max_ps _mm_max_ps
     998             : #define shuffle_ps _mm_shuffle_ps
     999             : #define div_ps _mm_div_ps
    1000             : #define cmpeq_ps _mm_cmpeq_ps
    1001             : #define mul_ps _mm_mul_ps
    1002             : #define add_ps _mm_add_ps
    1003             : #define hadd_ps sse2_hadd_ps
    1004             : #define sqrt_ps _mm_sqrt_ps
    1005             : #define or_ps _mm_or_ps
    1006             : #define unpacklo_ps _mm_unpacklo_ps
    1007             : #define unpackhi_ps _mm_unpackhi_ps
    1008             : #define storeu_ps _mm_storeu_ps
    1009             : 
    1010         132 : inline __m128 blendv_ps(__m128 a, __m128 b, __m128 mask)
    1011             : {
    1012             : #if defined(__SSE4_1__) || defined(__AVX__) || defined(USE_NEON_OPTIMIZATIONS)
    1013             :     return _mm_blendv_ps(a, b, mask);
    1014             : #else
    1015         396 :     return _mm_or_ps(_mm_andnot_ps(mask, a), _mm_and_ps(mask, b));
    1016             : #endif
    1017             : }
    1018             : 
    1019         528 : inline __m128 SQUARE_PS(__m128 x)
    1020             : {
    1021         528 :     return _mm_mul_ps(x, x);
    1022             : }
    1023             : 
    1024         132 : inline __m128 FIXUP_LANES(__m128 x)
    1025             : {
    1026         132 :     return x;
    1027             : }
    1028             : 
    1029             : #endif
    1030             : 
    1031             : static int
    1032             : #if defined(__GNUC__)
    1033             :     __attribute__((noinline))
    1034             : #endif
    1035          66 :     QuadraticMeanFloatSSE2(int nDstXWidth, int nChunkXSize,
    1036             :                            const float *&CPL_RESTRICT pSrcScanlineShiftedInOut,
    1037             :                            float *CPL_RESTRICT pDstScanline)
    1038             : {
    1039             :     // Optimized implementation for RMS on Float32 by
    1040             :     // processing by group of output pixels.
    1041          66 :     const float *CPL_RESTRICT pSrcScanlineShifted = pSrcScanlineShiftedInOut;
    1042             : 
    1043          66 :     int iDstPixel = 0;
    1044          66 :     const auto minus_zero = set1_ps(-0.0f);
    1045          66 :     const auto zeroDot25 = set1_ps(0.25f);
    1046          66 :     const auto one = set1_ps(1.0f);
    1047          66 :     const auto infv = set1_ps(std::numeric_limits<float>::infinity());
    1048          66 :     constexpr int DEST_ELTS = static_cast<int>(sizeof(one) / sizeof(float));
    1049             : 
    1050         198 :     for (; iDstPixel < nDstXWidth - (DEST_ELTS - 1); iDstPixel += DEST_ELTS)
    1051             :     {
    1052             :         // Load 2*DEST_ELTS Float32 from each line
    1053         132 :         auto firstLineLo = loadu_ps(pSrcScanlineShifted);
    1054         132 :         auto firstLineHi = loadu_ps(pSrcScanlineShifted + DEST_ELTS);
    1055         132 :         auto secondLineLo = loadu_ps(pSrcScanlineShifted + nChunkXSize);
    1056             :         auto secondLineHi =
    1057         264 :             loadu_ps(pSrcScanlineShifted + DEST_ELTS + nChunkXSize);
    1058             : 
    1059             :         // Take the absolute value
    1060         132 :         firstLineLo = andnot_ps(minus_zero, firstLineLo);
    1061         132 :         firstLineHi = andnot_ps(minus_zero, firstLineHi);
    1062         132 :         secondLineLo = andnot_ps(minus_zero, secondLineLo);
    1063         132 :         secondLineHi = andnot_ps(minus_zero, secondLineHi);
    1064             : 
    1065             :         auto firstLineEven =
    1066         132 :             shuffle_ps(firstLineLo, firstLineHi, _MM_SHUFFLE(2, 0, 2, 0));
    1067             :         auto firstLineOdd =
    1068         132 :             shuffle_ps(firstLineLo, firstLineHi, _MM_SHUFFLE(3, 1, 3, 1));
    1069             :         auto secondLineEven =
    1070         132 :             shuffle_ps(secondLineLo, secondLineHi, _MM_SHUFFLE(2, 0, 2, 0));
    1071             :         auto secondLineOdd =
    1072         132 :             shuffle_ps(secondLineLo, secondLineHi, _MM_SHUFFLE(3, 1, 3, 1));
    1073             : 
    1074             :         // Compute the maximum of each DEST_ELTS value to RMS-average
    1075         396 :         const auto maxV = max_ps(max_ps(firstLineEven, firstLineOdd),
    1076             :                                  max_ps(secondLineEven, secondLineEven));
    1077             : 
    1078             :         // Normalize each value by the maximum of the DEST_ELTS ones.
    1079             :         // This step is important to avoid that the square evaluates to infinity
    1080             :         // for sufficiently big input.
    1081         132 :         auto invMax = div_ps(one, maxV);
    1082             :         // Deal with 0 being the maximum to correct division by zero
    1083             :         // note: comparing to -0 leads to identical results as to comparing with
    1084             :         // 0
    1085         264 :         invMax = andnot_ps(cmpeq_ps(maxV, minus_zero), invMax);
    1086             : 
    1087         132 :         firstLineEven = mul_ps(firstLineEven, invMax);
    1088         132 :         firstLineOdd = mul_ps(firstLineOdd, invMax);
    1089         132 :         secondLineEven = mul_ps(secondLineEven, invMax);
    1090         132 :         secondLineOdd = mul_ps(secondLineOdd, invMax);
    1091             : 
    1092             :         // Compute squares
    1093         132 :         firstLineEven = SQUARE_PS(firstLineEven);
    1094         132 :         firstLineOdd = SQUARE_PS(firstLineOdd);
    1095         132 :         secondLineEven = SQUARE_PS(secondLineEven);
    1096         132 :         secondLineOdd = SQUARE_PS(secondLineOdd);
    1097             : 
    1098         396 :         const auto sumSquares = add_ps(add_ps(firstLineEven, firstLineOdd),
    1099             :                                        add_ps(secondLineEven, secondLineOdd));
    1100             : 
    1101         396 :         auto rms = mul_ps(maxV, sqrt_ps(mul_ps(sumSquares, zeroDot25)));
    1102             : 
    1103             :         // Deal with infinity being the maximum
    1104         132 :         const auto maskIsInf = cmpeq_ps(maxV, infv);
    1105         132 :         rms = blendv_ps(rms, infv, maskIsInf);
    1106             : 
    1107         132 :         rms = FIXUP_LANES(rms);
    1108             : 
    1109         132 :         storeu_ps(&pDstScanline[iDstPixel], rms);
    1110         132 :         pSrcScanlineShifted += DEST_ELTS * 2;
    1111             :     }
    1112             : 
    1113          66 :     pSrcScanlineShiftedInOut = pSrcScanlineShifted;
    1114          66 :     return iDstPixel;
    1115             : }
    1116             : 
    1117             : /************************************************************************/
    1118             : /*                          AverageFloatSSE2()                          */
    1119             : /************************************************************************/
    1120             : 
    1121          50 : static int AverageFloatSSE2(int nDstXWidth, int nChunkXSize,
    1122             :                             const float *&CPL_RESTRICT pSrcScanlineShiftedInOut,
    1123             :                             float *CPL_RESTRICT pDstScanline)
    1124             : {
    1125             :     // Optimized implementation for average on Float32 by
    1126             :     // processing by group of output pixels.
    1127          50 :     const float *CPL_RESTRICT pSrcScanlineShifted = pSrcScanlineShiftedInOut;
    1128             : 
    1129          50 :     int iDstPixel = 0;
    1130          50 :     const auto zeroDot25 = _mm_set1_ps(0.25f);
    1131          50 :     constexpr int DEST_ELTS =
    1132             :         static_cast<int>(sizeof(zeroDot25) / sizeof(float));
    1133             : 
    1134         132 :     for (; iDstPixel < nDstXWidth - (DEST_ELTS - 1); iDstPixel += DEST_ELTS)
    1135             :     {
    1136             :         // Load 2 * DEST_ELTS Float32 from each line
    1137             :         const auto firstLineLo =
    1138          82 :             _mm_mul_ps(_mm_loadu_ps(pSrcScanlineShifted), zeroDot25);
    1139         164 :         const auto firstLineHi = _mm_mul_ps(
    1140             :             _mm_loadu_ps(pSrcScanlineShifted + DEST_ELTS), zeroDot25);
    1141          82 :         const auto secondLineLo = _mm_mul_ps(
    1142          82 :             _mm_loadu_ps(pSrcScanlineShifted + nChunkXSize), zeroDot25);
    1143         164 :         const auto secondLineHi = _mm_mul_ps(
    1144          82 :             _mm_loadu_ps(pSrcScanlineShifted + DEST_ELTS + nChunkXSize),
    1145             :             zeroDot25);
    1146             : 
    1147             :         // Vertical addition
    1148          82 :         const auto tmpLo = _mm_add_ps(firstLineLo, secondLineLo);
    1149          82 :         const auto tmpHi = _mm_add_ps(firstLineHi, secondLineHi);
    1150             : 
    1151             :         // Horizontal addition
    1152          82 :         const auto average = sse2_hadd_ps(tmpLo, tmpHi);
    1153             : 
    1154          82 :         _mm_storeu_ps(&pDstScanline[iDstPixel], average);
    1155          82 :         pSrcScanlineShifted += DEST_ELTS * 2;
    1156             :     }
    1157             : 
    1158          50 :     pSrcScanlineShiftedInOut = pSrcScanlineShifted;
    1159          50 :     return iDstPixel;
    1160             : }
    1161             : 
    1162             : /************************************************************************/
    1163             : /*                         AverageDoubleSSE2()                          */
    1164             : /************************************************************************/
    1165             : 
    1166             : static int
    1167          50 : AverageDoubleSSE2(int nDstXWidth, int nChunkXSize,
    1168             :                   const double *&CPL_RESTRICT pSrcScanlineShiftedInOut,
    1169             :                   double *CPL_RESTRICT pDstScanline)
    1170             : {
    1171             :     // Optimized implementation for average on Float64 by
    1172             :     // processing by group of output pixels.
    1173          50 :     const double *CPL_RESTRICT pSrcScanlineShifted = pSrcScanlineShiftedInOut;
    1174             : 
    1175          50 :     int iDstPixel = 0;
    1176          50 :     const auto zeroDot25 = _mm_set1_pd(0.25);
    1177          50 :     constexpr int DEST_ELTS =
    1178             :         static_cast<int>(sizeof(zeroDot25) / sizeof(double));
    1179             : 
    1180         211 :     for (; iDstPixel < nDstXWidth - (DEST_ELTS - 1); iDstPixel += DEST_ELTS)
    1181             :     {
    1182             :         // Load 4 * DEST_ELTS Float64 from each line
    1183         161 :         const auto firstLine0 = _mm_mul_pd(
    1184             :             _mm_loadu_pd(pSrcScanlineShifted + 0 * DEST_ELTS), zeroDot25);
    1185         322 :         const auto firstLine1 = _mm_mul_pd(
    1186             :             _mm_loadu_pd(pSrcScanlineShifted + 1 * DEST_ELTS), zeroDot25);
    1187         161 :         const auto secondLine0 = _mm_mul_pd(
    1188         161 :             _mm_loadu_pd(pSrcScanlineShifted + 0 * DEST_ELTS + nChunkXSize),
    1189             :             zeroDot25);
    1190         322 :         const auto secondLine1 = _mm_mul_pd(
    1191         161 :             _mm_loadu_pd(pSrcScanlineShifted + 1 * DEST_ELTS + nChunkXSize),
    1192             :             zeroDot25);
    1193             : 
    1194             :         // Vertical addition
    1195         161 :         const auto tmp0 = _mm_add_pd(firstLine0, secondLine0);
    1196         161 :         const auto tmp1 = _mm_add_pd(firstLine1, secondLine1);
    1197             : 
    1198             :         // Horizontal addition
    1199         161 :         const auto average0 = sse2_hadd_pd(tmp0, tmp1);
    1200             : 
    1201         161 :         _mm_storeu_pd(&pDstScanline[iDstPixel + 0], average0);
    1202         161 :         pSrcScanlineShifted += DEST_ELTS * 2;
    1203             :     }
    1204             : 
    1205          50 :     pSrcScanlineShiftedInOut = pSrcScanlineShifted;
    1206          50 :     return iDstPixel;
    1207             : }
    1208             : 
    1209             : #endif
    1210             : 
    1211             : #endif
    1212             : 
    1213             : /************************************************************************/
    1214             : /*                   GDALResampleChunk_AverageOrRMS()                   */
    1215             : /************************************************************************/
    1216             : 
    1217             : template <class T, class Tsum, GDALDataType eWrkDataType, bool bQuadraticMean>
    1218             : static CPLErr
    1219        2394 : GDALResampleChunk_AverageOrRMS_T(const GDALOverviewResampleArgs &args,
    1220             :                                  const T *pChunk, void **ppDstBuffer)
    1221             : {
    1222        2394 :     const double dfXRatioDstToSrc = args.dfXRatioDstToSrc;
    1223        2394 :     const double dfYRatioDstToSrc = args.dfYRatioDstToSrc;
    1224        2394 :     const double dfSrcXDelta = args.dfSrcXDelta;
    1225        2394 :     const double dfSrcYDelta = args.dfSrcYDelta;
    1226        2394 :     const GByte *pabyChunkNodataMask = args.pabyChunkNodataMask;
    1227        2394 :     const int nChunkXOff = args.nChunkXOff;
    1228        2394 :     const int nChunkYOff = args.nChunkYOff;
    1229        2394 :     const int nChunkXSize = args.nChunkXSize;
    1230        2394 :     const int nChunkYSize = args.nChunkYSize;
    1231        2394 :     const int nDstXOff = args.nDstXOff;
    1232        2394 :     const int nDstXOff2 = args.nDstXOff2;
    1233        2394 :     const int nDstYOff = args.nDstYOff;
    1234        2394 :     const int nDstYOff2 = args.nDstYOff2;
    1235        2394 :     const char *pszResampling = args.pszResampling;
    1236        2394 :     bool bHasNoData = args.bHasNoData;
    1237        2394 :     const double dfNoDataValue = args.dfNoDataValue;
    1238        2394 :     const GDALColorTable *const poColorTable =
    1239             :         !bQuadraticMean &&
    1240             :                 // AVERAGE_BIT2GRAYSCALE
    1241        2317 :                 CPL_TO_BOOL(STARTS_WITH_CI(pszResampling, "AVERAGE_BIT2G"))
    1242             :             ? nullptr
    1243             :             : args.poColorTable;
    1244        2394 :     const bool bPropagateNoData = args.bPropagateNoData;
    1245             : 
    1246        2394 :     T tNoDataValue = (!bHasNoData) ? 0 : static_cast<T>(dfNoDataValue);
    1247        2394 :     const T tReplacementVal =
    1248         178 :         bHasNoData ? static_cast<T>(GDALGetNoDataReplacementValue(
    1249          58 :                          args.eOvrDataType, dfNoDataValue))
    1250             :                    : 0;
    1251             : 
    1252        2394 :     const int nChunkRightXOff = nChunkXOff + nChunkXSize;
    1253        2394 :     const int nChunkBottomYOff = nChunkYOff + nChunkYSize;
    1254        2394 :     const int nDstXWidth = nDstXOff2 - nDstXOff;
    1255             : 
    1256             :     /* -------------------------------------------------------------------- */
    1257             :     /*      Allocate buffers.                                               */
    1258             :     /* -------------------------------------------------------------------- */
    1259        2394 :     *ppDstBuffer = static_cast<T *>(
    1260        2394 :         VSI_MALLOC3_VERBOSE(nDstXWidth, nDstYOff2 - nDstYOff,
    1261             :                             GDALGetDataTypeSizeBytes(eWrkDataType)));
    1262        2394 :     if (*ppDstBuffer == nullptr)
    1263             :     {
    1264           0 :         return CE_Failure;
    1265             :     }
    1266        2394 :     T *const pDstBuffer = static_cast<T *>(*ppDstBuffer);
    1267             : 
    1268             :     struct PrecomputedXValue
    1269             :     {
    1270             :         int nLeftXOffShifted;
    1271             :         int nRightXOffShifted;
    1272             :         double dfLeftWeight;
    1273             :         double dfRightWeight;
    1274             :         double dfTotalWeightFullLine;
    1275             :     };
    1276             : 
    1277             :     PrecomputedXValue *pasSrcX = static_cast<PrecomputedXValue *>(
    1278        2394 :         VSI_MALLOC2_VERBOSE(nDstXWidth, sizeof(PrecomputedXValue)));
    1279             : 
    1280        2394 :     if (pasSrcX == nullptr)
    1281             :     {
    1282           0 :         return CE_Failure;
    1283             :     }
    1284             : 
    1285        2394 :     std::vector<GDALColorEntry> colorEntries;
    1286             : 
    1287        2394 :     if (poColorTable)
    1288             :     {
    1289           5 :         int nTransparentIdx = -1;
    1290           5 :         colorEntries = ReadColorTable(*poColorTable, nTransparentIdx);
    1291             : 
    1292             :         // Force c4 of nodata entry to 0 so that GDALFindBestEntry() identifies
    1293             :         // it as nodata value
    1294           6 :         if (bHasNoData && dfNoDataValue >= 0.0 &&
    1295           1 :             tNoDataValue < colorEntries.size())
    1296           1 :             colorEntries[static_cast<int>(tNoDataValue)].c4 = 0;
    1297             : 
    1298             :         // Or if we have no explicit nodata, but a color table entry that is
    1299             :         // transparent, consider it as the nodata value
    1300           4 :         else if (!bHasNoData && nTransparentIdx >= 0)
    1301             :         {
    1302           0 :             bHasNoData = true;
    1303           0 :             tNoDataValue = static_cast<T>(nTransparentIdx);
    1304             :         }
    1305             :     }
    1306             : 
    1307             :     /* ==================================================================== */
    1308             :     /*      Precompute inner loop constants.                                */
    1309             :     /* ==================================================================== */
    1310        2394 :     bool bSrcXSpacingIsTwo = true;
    1311        2394 :     int nLastSrcXOff2 = -1;
    1312      856928 :     for (int iDstPixel = nDstXOff; iDstPixel < nDstXOff2; ++iDstPixel)
    1313             :     {
    1314      854534 :         const double dfSrcXOff = dfSrcXDelta + iDstPixel * dfXRatioDstToSrc;
    1315             :         // Apply some epsilon to avoid numerical precision issues
    1316      854534 :         int nSrcXOff = static_cast<int>(dfSrcXOff + 1e-8);
    1317      854534 :         const double dfSrcXOff2 =
    1318      854534 :             dfSrcXDelta + (iDstPixel + 1) * dfXRatioDstToSrc;
    1319      854534 :         int nSrcXOff2 = static_cast<int>(ceil(dfSrcXOff2 - 1e-8));
    1320             : 
    1321      854534 :         if (nSrcXOff < nChunkXOff)
    1322           0 :             nSrcXOff = nChunkXOff;
    1323      854534 :         if (nSrcXOff2 == nSrcXOff)
    1324           0 :             nSrcXOff2++;
    1325      854534 :         if (nSrcXOff2 > nChunkRightXOff)
    1326           1 :             nSrcXOff2 = nChunkRightXOff;
    1327             : 
    1328      854534 :         pasSrcX[iDstPixel - nDstXOff].nLeftXOffShifted = nSrcXOff - nChunkXOff;
    1329      854534 :         pasSrcX[iDstPixel - nDstXOff].nRightXOffShifted =
    1330      854534 :             nSrcXOff2 - nChunkXOff;
    1331          21 :         pasSrcX[iDstPixel - nDstXOff].dfLeftWeight =
    1332      854534 :             (nSrcXOff2 == nSrcXOff + 1) ? 1.0 : 1 - (dfSrcXOff - nSrcXOff);
    1333      854534 :         pasSrcX[iDstPixel - nDstXOff].dfRightWeight =
    1334      854534 :             1 - (nSrcXOff2 - dfSrcXOff2);
    1335      854534 :         pasSrcX[iDstPixel - nDstXOff].dfTotalWeightFullLine =
    1336      854534 :             pasSrcX[iDstPixel - nDstXOff].dfLeftWeight;
    1337      854534 :         if (nSrcXOff + 1 < nSrcXOff2)
    1338             :         {
    1339      854513 :             pasSrcX[iDstPixel - nDstXOff].dfTotalWeightFullLine +=
    1340      854513 :                 nSrcXOff2 - nSrcXOff - 2;
    1341      854513 :             pasSrcX[iDstPixel - nDstXOff].dfTotalWeightFullLine +=
    1342      854513 :                 pasSrcX[iDstPixel - nDstXOff].dfRightWeight;
    1343             :         }
    1344             : 
    1345      854534 :         if (nSrcXOff2 - nSrcXOff != 2 ||
    1346      733041 :             (nLastSrcXOff2 >= 0 && nLastSrcXOff2 != nSrcXOff))
    1347             :         {
    1348      120637 :             bSrcXSpacingIsTwo = false;
    1349             :         }
    1350      854534 :         nLastSrcXOff2 = nSrcXOff2;
    1351             :     }
    1352             : 
    1353             :     /* ==================================================================== */
    1354             :     /*      Loop over destination scanlines.                                */
    1355             :     /* ==================================================================== */
    1356      722579 :     for (int iDstLine = nDstYOff; iDstLine < nDstYOff2; ++iDstLine)
    1357             :     {
    1358      720185 :         const double dfSrcYOff = dfSrcYDelta + iDstLine * dfYRatioDstToSrc;
    1359      720185 :         int nSrcYOff = static_cast<int>(dfSrcYOff + 1e-8);
    1360      720185 :         if (nSrcYOff < nChunkYOff)
    1361           0 :             nSrcYOff = nChunkYOff;
    1362             : 
    1363      720185 :         const double dfSrcYOff2 =
    1364      720185 :             dfSrcYDelta + (iDstLine + 1) * dfYRatioDstToSrc;
    1365      720185 :         int nSrcYOff2 = static_cast<int>(ceil(dfSrcYOff2 - 1e-8));
    1366      720185 :         if (nSrcYOff2 == nSrcYOff)
    1367           0 :             ++nSrcYOff2;
    1368      720185 :         if (nSrcYOff2 > nChunkBottomYOff)
    1369           3 :             nSrcYOff2 = nChunkBottomYOff;
    1370             : 
    1371      720185 :         T *const pDstScanline =
    1372      720185 :             pDstBuffer + static_cast<size_t>(iDstLine - nDstYOff) * nDstXWidth;
    1373             : 
    1374             :         /* --------------------------------------------------------------------
    1375             :          */
    1376             :         /*      Loop over destination pixels */
    1377             :         /* --------------------------------------------------------------------
    1378             :          */
    1379      720185 :         if (poColorTable == nullptr)
    1380             :         {
    1381      720070 :             if (bSrcXSpacingIsTwo && nSrcYOff2 == nSrcYOff + 2 &&
    1382             :                 pabyChunkNodataMask == nullptr)
    1383             :             {
    1384             :                 if constexpr (eWrkDataType == GDT_UInt8 ||
    1385             :                               eWrkDataType == GDT_UInt16)
    1386             :                 {
    1387             :                     // Optimized case : no nodata, overview by a factor of 2 and
    1388             :                     // regular x and y src spacing.
    1389      117150 :                     const T *pSrcScanlineShifted =
    1390      117150 :                         pChunk + pasSrcX[0].nLeftXOffShifted +
    1391      117150 :                         static_cast<size_t>(nSrcYOff - nChunkYOff) *
    1392      117150 :                             nChunkXSize;
    1393      117150 :                     int iDstPixel = 0;
    1394             : #ifdef USE_SSE2
    1395             :                     if constexpr (eWrkDataType == GDT_UInt8)
    1396             :                     {
    1397             :                         if constexpr (bQuadraticMean)
    1398             :                         {
    1399        5389 :                             iDstPixel = QuadraticMeanByteSSE2OrAVX2(
    1400             :                                 nDstXWidth, nChunkXSize, pSrcScanlineShifted,
    1401             :                                 pDstScanline);
    1402             :                         }
    1403             :                         else
    1404             :                         {
    1405      111734 :                             iDstPixel = AverageByteSSE2OrAVX2(
    1406             :                                 nDstXWidth, nChunkXSize, pSrcScanlineShifted,
    1407             :                                 pDstScanline);
    1408             :                         }
    1409             :                     }
    1410             :                     else
    1411             :                     {
    1412             :                         static_assert(eWrkDataType == GDT_UInt16);
    1413             :                         if constexpr (bQuadraticMean)
    1414             :                         {
    1415          14 :                             iDstPixel = QuadraticMeanUInt16SSE2(
    1416             :                                 nDstXWidth, nChunkXSize, pSrcScanlineShifted,
    1417             :                                 pDstScanline);
    1418             :                         }
    1419             :                         else
    1420             :                         {
    1421          13 :                             iDstPixel = AverageUInt16SSE2(
    1422             :                                 nDstXWidth, nChunkXSize, pSrcScanlineShifted,
    1423             :                                 pDstScanline);
    1424             :                         }
    1425             :                     }
    1426             : #endif
    1427      291609 :                     for (; iDstPixel < nDstXWidth; ++iDstPixel)
    1428             :                     {
    1429      174459 :                         Tsum nTotal = 0;
    1430             :                         T nVal;
    1431             :                         if constexpr (bQuadraticMean)
    1432          52 :                             nTotal =
    1433          52 :                                 SQUARE<Tsum>(pSrcScanlineShifted[0]) +
    1434          52 :                                 SQUARE<Tsum>(pSrcScanlineShifted[1]) +
    1435          52 :                                 SQUARE<Tsum>(pSrcScanlineShifted[nChunkXSize]) +
    1436          52 :                                 SQUARE<Tsum>(
    1437          52 :                                     pSrcScanlineShifted[1 + nChunkXSize]);
    1438             :                         else
    1439      174407 :                             nTotal = pSrcScanlineShifted[0] +
    1440      174407 :                                      pSrcScanlineShifted[1] +
    1441      174407 :                                      pSrcScanlineShifted[nChunkXSize] +
    1442      174407 :                                      pSrcScanlineShifted[1 + nChunkXSize];
    1443             : 
    1444      174459 :                         constexpr int nTotalWeight = 4;
    1445             :                         if constexpr (bQuadraticMean)
    1446          52 :                             nVal = ComputeIntegerRMS_4values<T>(nTotal);
    1447             :                         else
    1448      174407 :                             nVal = static_cast<T>((nTotal + nTotalWeight / 2) /
    1449             :                                                   nTotalWeight);
    1450             : 
    1451             :                         // No need to compare nVal against tNoDataValue as we
    1452             :                         // are in a case where pabyChunkNodataMask == nullptr
    1453             :                         // implies the absence of nodata value.
    1454      174459 :                         pDstScanline[iDstPixel] = nVal;
    1455      174459 :                         pSrcScanlineShifted += 2;
    1456             :                     }
    1457             :                 }
    1458             :                 else
    1459             :                 {
    1460             :                     static_assert(eWrkDataType == GDT_Float32 ||
    1461             :                                   eWrkDataType == GDT_Float64);
    1462         202 :                     const T *pSrcScanlineShifted =
    1463         202 :                         pChunk + pasSrcX[0].nLeftXOffShifted +
    1464         202 :                         static_cast<size_t>(nSrcYOff - nChunkYOff) *
    1465         202 :                             nChunkXSize;
    1466         202 :                     int iDstPixel = 0;
    1467             : #if defined(USE_SSE2) && !defined(ARM_V7)
    1468             :                     if constexpr (eWrkDataType == GDT_Float32)
    1469             :                     {
    1470             :                         static_assert(std::is_same_v<T, float>);
    1471             :                         if constexpr (bQuadraticMean)
    1472             :                         {
    1473          66 :                             iDstPixel = QuadraticMeanFloatSSE2(
    1474             :                                 nDstXWidth, nChunkXSize, pSrcScanlineShifted,
    1475             :                                 pDstScanline);
    1476             :                         }
    1477             :                         else
    1478             :                         {
    1479          50 :                             iDstPixel = AverageFloatSSE2(
    1480             :                                 nDstXWidth, nChunkXSize, pSrcScanlineShifted,
    1481             :                                 pDstScanline);
    1482             :                         }
    1483             :                     }
    1484             :                     else
    1485             :                     {
    1486             :                         if constexpr (!bQuadraticMean)
    1487             :                         {
    1488          50 :                             iDstPixel = AverageDoubleSSE2(
    1489             :                                 nDstXWidth, nChunkXSize, pSrcScanlineShifted,
    1490             :                                 pDstScanline);
    1491             :                         }
    1492             :                     }
    1493             : #endif
    1494             : 
    1495         726 :                     for (; iDstPixel < nDstXWidth; ++iDstPixel)
    1496             :                     {
    1497             :                         T nVal;
    1498             : 
    1499             :                         if constexpr (bQuadraticMean)
    1500             :                         {
    1501             :                             // Avoid issues with large values by renormalizing
    1502          96 :                             const auto max = std::max(
    1503         420 :                                 {std::fabs(pSrcScanlineShifted[0]),
    1504         420 :                                  std::fabs(pSrcScanlineShifted[1]),
    1505         420 :                                  std::fabs(pSrcScanlineShifted[nChunkXSize]),
    1506         420 :                                  std::fabs(
    1507         420 :                                      pSrcScanlineShifted[1 + nChunkXSize])});
    1508         420 :                             if (max == 0)
    1509             :                             {
    1510           8 :                                 nVal = 0;
    1511             :                             }
    1512         412 :                             else if (std::isinf(max))
    1513             :                             {
    1514             :                                 // If there is at least one infinity value,
    1515             :                                 // then just summing, and taking the abs
    1516             :                                 // value will give the expected result:
    1517             :                                 // * +inf if all values are +inf
    1518             :                                 // * +inf if all values are -inf
    1519             :                                 // * NaN otherwise
    1520          82 :                                 nVal = std::fabs(
    1521          82 :                                     pSrcScanlineShifted[0] +
    1522          82 :                                     pSrcScanlineShifted[1] +
    1523          82 :                                     pSrcScanlineShifted[nChunkXSize] +
    1524          82 :                                     pSrcScanlineShifted[1 + nChunkXSize]);
    1525             :                             }
    1526             :                             else
    1527             :                             {
    1528         330 :                                 const auto inv_max = static_cast<T>(1.0) / max;
    1529         330 :                                 nVal =
    1530             :                                     max *
    1531         330 :                                     std::sqrt(
    1532             :                                         static_cast<T>(0.25) *
    1533         330 :                                         (SQUARE(pSrcScanlineShifted[0] *
    1534         330 :                                                 inv_max) +
    1535         330 :                                          SQUARE(pSrcScanlineShifted[1] *
    1536         330 :                                                 inv_max) +
    1537         330 :                                          SQUARE(
    1538         330 :                                              pSrcScanlineShifted[nChunkXSize] *
    1539         330 :                                              inv_max) +
    1540         330 :                                          SQUARE(
    1541         330 :                                              pSrcScanlineShifted[1 +
    1542             :                                                                  nChunkXSize] *
    1543             :                                              inv_max)));
    1544             :                             }
    1545             :                         }
    1546             :                         else
    1547             :                         {
    1548         104 :                             constexpr auto weight = static_cast<T>(0.25);
    1549             :                             // Multiply each value by weight to avoid
    1550             :                             // potential overflow
    1551         104 :                             nVal =
    1552         104 :                                 (weight * pSrcScanlineShifted[0] +
    1553         104 :                                  weight * pSrcScanlineShifted[1] +
    1554         104 :                                  weight * pSrcScanlineShifted[nChunkXSize] +
    1555         104 :                                  weight * pSrcScanlineShifted[1 + nChunkXSize]);
    1556             :                         }
    1557             : 
    1558             :                         // No need to compare nVal against tNoDataValue as we
    1559             :                         // are in a case where pabyChunkNodataMask == nullptr
    1560             :                         // implies the absence of nodata value.
    1561         524 :                         pDstScanline[iDstPixel] = nVal;
    1562         524 :                         pSrcScanlineShifted += 2;
    1563             :                     }
    1564      117352 :                 }
    1565             :             }
    1566             :             else
    1567             :             {
    1568          17 :                 const double dfBottomWeight =
    1569      602718 :                     (nSrcYOff + 1 == nSrcYOff2) ? 1.0
    1570      602701 :                                                 : 1.0 - (dfSrcYOff - nSrcYOff);
    1571      602718 :                 const double dfTopWeight = 1.0 - (nSrcYOff2 - dfSrcYOff2);
    1572      602718 :                 nSrcYOff -= nChunkYOff;
    1573      602718 :                 nSrcYOff2 -= nChunkYOff;
    1574             : 
    1575      602718 :                 double dfTotalWeightFullColumn = dfBottomWeight;
    1576      602718 :                 if (nSrcYOff + 1 < nSrcYOff2)
    1577             :                 {
    1578      602701 :                     dfTotalWeightFullColumn += nSrcYOff2 - nSrcYOff - 2;
    1579      602701 :                     dfTotalWeightFullColumn += dfTopWeight;
    1580             :                 }
    1581             : 
    1582    18759673 :                 for (int iDstPixel = 0; iDstPixel < nDstXWidth; ++iDstPixel)
    1583             :                 {
    1584    18156933 :                     const int nSrcXOff = pasSrcX[iDstPixel].nLeftXOffShifted;
    1585    18156933 :                     const int nSrcXOff2 = pasSrcX[iDstPixel].nRightXOffShifted;
    1586             : 
    1587    18156933 :                     double dfTotal = 0;
    1588    18156933 :                     double dfTotalWeight = 0;
    1589    18156933 :                     [[maybe_unused]] double dfMulFactor = 1.0;
    1590    18156933 :                     [[maybe_unused]] double dfInvMulFactor = 1.0;
    1591    18156933 :                     constexpr bool bUseMulFactor =
    1592             :                         (eWrkDataType == GDT_Float32 ||
    1593             :                          eWrkDataType == GDT_Float64);
    1594    18156933 :                     if (pabyChunkNodataMask == nullptr)
    1595             :                     {
    1596             :                         if constexpr (bUseMulFactor)
    1597             :                         {
    1598             :                             if constexpr (bQuadraticMean)
    1599             :                             {
    1600          80 :                                 T mulFactor = 0;
    1601          80 :                                 auto pChunkShifted =
    1602          80 :                                     pChunk +
    1603          80 :                                     static_cast<size_t>(nSrcYOff) * nChunkXSize;
    1604             : 
    1605         240 :                                 for (int iY = nSrcYOff; iY < nSrcYOff2;
    1606         160 :                                      ++iY, pChunkShifted += nChunkXSize)
    1607             :                                 {
    1608         480 :                                     for (int iX = nSrcXOff; iX < nSrcXOff2;
    1609             :                                          ++iX)
    1610         640 :                                         mulFactor = std::max(
    1611             :                                             mulFactor,
    1612         320 :                                             std::fabs(pChunkShifted[iX]));
    1613             :                                 }
    1614          80 :                                 dfMulFactor = double(mulFactor);
    1615         142 :                                 dfInvMulFactor =
    1616          62 :                                     dfMulFactor > 0 &&
    1617          62 :                                             std::isfinite(dfMulFactor)
    1618             :                                         ? 1.0 / dfMulFactor
    1619             :                                         : 1.0;
    1620             :                             }
    1621             :                             else
    1622             :                             {
    1623         139 :                                 dfMulFactor = (nSrcYOff2 - nSrcYOff) *
    1624         139 :                                               (nSrcXOff2 - nSrcXOff);
    1625         139 :                                 dfInvMulFactor = 1.0 / dfMulFactor;
    1626             :                             }
    1627             :                         }
    1628             : 
    1629     1746545 :                         auto pChunkShifted =
    1630         227 :                             pChunk +
    1631     1746545 :                             static_cast<size_t>(nSrcYOff) * nChunkXSize;
    1632     1746545 :                         int nCounterY = nSrcYOff2 - nSrcYOff - 1;
    1633     1746545 :                         double dfWeightY = dfBottomWeight;
    1634     3493539 :                         while (true)
    1635             :                         {
    1636             :                             double dfTotalLine;
    1637             :                             if constexpr (bQuadraticMean)
    1638             :                             {
    1639             :                                 // Left pixel
    1640             :                                 {
    1641         216 :                                     const T val = pChunkShifted[nSrcXOff];
    1642         216 :                                     dfTotalLine =
    1643         216 :                                         SQUARE(double(val) * dfInvMulFactor) *
    1644         216 :                                         pasSrcX[iDstPixel].dfLeftWeight;
    1645             :                                 }
    1646             : 
    1647         216 :                                 if (nSrcXOff + 1 < nSrcXOff2)
    1648             :                                 {
    1649             :                                     // Middle pixels
    1650         216 :                                     for (int iX = nSrcXOff + 1;
    1651         536 :                                          iX < nSrcXOff2 - 1; ++iX)
    1652             :                                     {
    1653         320 :                                         const T val = pChunkShifted[iX];
    1654         320 :                                         dfTotalLine += SQUARE(double(val) *
    1655             :                                                               dfInvMulFactor);
    1656             :                                     }
    1657             : 
    1658             :                                     // Right pixel
    1659             :                                     {
    1660         216 :                                         const T val =
    1661         216 :                                             pChunkShifted[nSrcXOff2 - 1];
    1662         216 :                                         dfTotalLine +=
    1663         216 :                                             SQUARE(double(val) *
    1664         216 :                                                    dfInvMulFactor) *
    1665         216 :                                             pasSrcX[iDstPixel].dfRightWeight;
    1666             :                                     }
    1667             :                                 }
    1668             :                             }
    1669             :                             else
    1670             :                             {
    1671             :                                 // Left pixel
    1672             :                                 {
    1673     5239868 :                                     const T val = pChunkShifted[nSrcXOff];
    1674     5239868 :                                     dfTotalLine =
    1675     5239868 :                                         double(val) * dfInvMulFactor *
    1676     5239868 :                                         pasSrcX[iDstPixel].dfLeftWeight;
    1677             :                                 }
    1678             : 
    1679     5239868 :                                 if (nSrcXOff + 1 < nSrcXOff2)
    1680             :                                 {
    1681             :                                     // Middle pixels
    1682     4239442 :                                     for (int iX = nSrcXOff + 1;
    1683    64183238 :                                          iX < nSrcXOff2 - 1; ++iX)
    1684             :                                     {
    1685    59943836 :                                         const T val = pChunkShifted[iX];
    1686    59943836 :                                         dfTotalLine +=
    1687    59943836 :                                             double(val) * dfInvMulFactor;
    1688             :                                     }
    1689             : 
    1690             :                                     // Right pixel
    1691             :                                     {
    1692     4239442 :                                         const T val =
    1693     4239442 :                                             pChunkShifted[nSrcXOff2 - 1];
    1694     4239442 :                                         dfTotalLine +=
    1695     4239442 :                                             double(val) * dfInvMulFactor *
    1696     4239442 :                                             pasSrcX[iDstPixel].dfRightWeight;
    1697             :                                     }
    1698             :                                 }
    1699             :                             }
    1700             : 
    1701     5240084 :                             dfTotal += dfTotalLine * dfWeightY;
    1702     5240084 :                             --nCounterY;
    1703     5240084 :                             if (nCounterY < 0)
    1704     1746545 :                                 break;
    1705     3493539 :                             pChunkShifted += nChunkXSize;
    1706     3493539 :                             dfWeightY = (nCounterY == 0) ? dfTopWeight : 1.0;
    1707             :                         }
    1708             : 
    1709     1746545 :                         dfTotalWeight =
    1710     1746545 :                             pasSrcX[iDstPixel].dfTotalWeightFullLine *
    1711             :                             dfTotalWeightFullColumn;
    1712             :                     }
    1713             :                     else
    1714             :                     {
    1715    16410398 :                         size_t nCount = 0;
    1716    71788794 :                         for (int iY = nSrcYOff; iY < nSrcYOff2; ++iY)
    1717             :                         {
    1718    55378396 :                             const auto pChunkShifted =
    1719    55378396 :                                 pChunk + static_cast<size_t>(iY) * nChunkXSize;
    1720             : 
    1721    55378396 :                             double dfTotalLine = 0;
    1722    55378396 :                             double dfTotalWeightLine = 0;
    1723             :                             // Left pixel
    1724             :                             {
    1725    55378396 :                                 const int iX = nSrcXOff;
    1726    55378396 :                                 const T val = pChunkShifted[iX];
    1727    55378396 :                                 if (pabyChunkNodataMask
    1728    55378396 :                                         [iX +
    1729    55378396 :                                          static_cast<size_t>(iY) * nChunkXSize])
    1730             :                                 {
    1731    23518643 :                                     nCount++;
    1732    23518643 :                                     const double dfWeightX =
    1733    23518643 :                                         pasSrcX[iDstPixel].dfLeftWeight;
    1734    23518643 :                                     dfTotalWeightLine = dfWeightX;
    1735             :                                     if constexpr (bQuadraticMean)
    1736          60 :                                         dfTotalLine =
    1737          60 :                                             SQUARE(double(val)) * dfWeightX;
    1738             :                                     else
    1739    23518583 :                                         dfTotalLine = double(val) * dfWeightX;
    1740             :                                 }
    1741             :                             }
    1742             : 
    1743    55378396 :                             if (nSrcXOff < nSrcXOff2 - 1)
    1744             :                             {
    1745             :                                 // Middle pixels
    1746   152899196 :                                 for (int iX = nSrcXOff + 1; iX < nSrcXOff2 - 1;
    1747             :                                      ++iX)
    1748             :                                 {
    1749    97521100 :                                     const T val = pChunkShifted[iX];
    1750    97521100 :                                     if (pabyChunkNodataMask
    1751    97521100 :                                             [iX + static_cast<size_t>(iY) *
    1752    97521100 :                                                       nChunkXSize])
    1753             :                                     {
    1754    39728400 :                                         nCount++;
    1755    39728400 :                                         dfTotalWeightLine += 1;
    1756             :                                         if constexpr (bQuadraticMean)
    1757           0 :                                             dfTotalLine += SQUARE(double(val));
    1758             :                                         else
    1759    39728400 :                                             dfTotalLine += double(val);
    1760             :                                     }
    1761             :                                 }
    1762             : 
    1763             :                                 // Right pixel
    1764             :                                 {
    1765    55378396 :                                     const int iX = nSrcXOff2 - 1;
    1766    55378396 :                                     const T val = pChunkShifted[iX];
    1767    55378396 :                                     if (pabyChunkNodataMask
    1768    55378396 :                                             [iX + static_cast<size_t>(iY) *
    1769    55378396 :                                                       nChunkXSize])
    1770             :                                     {
    1771    23517911 :                                         nCount++;
    1772    23517911 :                                         const double dfWeightX =
    1773    23517911 :                                             pasSrcX[iDstPixel].dfRightWeight;
    1774    23517911 :                                         dfTotalWeightLine += dfWeightX;
    1775             :                                         if constexpr (bQuadraticMean)
    1776          61 :                                             dfTotalLine +=
    1777          61 :                                                 SQUARE(double(val)) * dfWeightX;
    1778             :                                         else
    1779    23517850 :                                             dfTotalLine +=
    1780    23517850 :                                                 double(val) * dfWeightX;
    1781             :                                     }
    1782             :                                 }
    1783             :                             }
    1784             : 
    1785    94346294 :                             const double dfWeightY =
    1786             :                                 (iY == nSrcYOff)        ? dfBottomWeight
    1787    38967998 :                                 : (iY + 1 == nSrcYOff2) ? dfTopWeight
    1788             :                                                         : 1.0;
    1789    55378396 :                             dfTotal += dfTotalLine * dfWeightY;
    1790    55378396 :                             dfTotalWeight += dfTotalWeightLine * dfWeightY;
    1791             :                         }
    1792             : 
    1793    16410398 :                         if (nCount == 0 ||
    1794           8 :                             (bPropagateNoData &&
    1795             :                              nCount <
    1796           8 :                                  static_cast<size_t>(nSrcYOff2 - nSrcYOff) *
    1797           8 :                                      (nSrcXOff2 - nSrcXOff)))
    1798             :                         {
    1799     9609422 :                             pDstScanline[iDstPixel] = tNoDataValue;
    1800     9609422 :                             continue;
    1801             :                         }
    1802             :                     }
    1803             :                     if constexpr (eWrkDataType == GDT_UInt8)
    1804             :                     {
    1805             :                         T nVal;
    1806             :                         if constexpr (bQuadraticMean)
    1807          38 :                             nVal = ComputeIntegerRMS<T, int>(dfTotal,
    1808             :                                                              dfTotalWeight);
    1809             :                         else
    1810     8547230 :                             nVal =
    1811     8547230 :                                 static_cast<T>(dfTotal / dfTotalWeight + 0.5);
    1812     8547268 :                         if (bHasNoData && nVal == tNoDataValue)
    1813           0 :                             nVal = tReplacementVal;
    1814     8547268 :                         pDstScanline[iDstPixel] = nVal;
    1815             :                     }
    1816             :                     else if constexpr (eWrkDataType == GDT_UInt16)
    1817             :                     {
    1818             :                         T nVal;
    1819             :                         if constexpr (bQuadraticMean)
    1820           4 :                             nVal = ComputeIntegerRMS<T, uint64_t>(
    1821             :                                 dfTotal, dfTotalWeight);
    1822             :                         else
    1823           4 :                             nVal =
    1824           4 :                                 static_cast<T>(dfTotal / dfTotalWeight + 0.5);
    1825           8 :                         if (bHasNoData && nVal == tNoDataValue)
    1826           0 :                             nVal = tReplacementVal;
    1827           8 :                         pDstScanline[iDstPixel] = nVal;
    1828             :                     }
    1829             :                     else
    1830             :                     {
    1831             :                         T nVal;
    1832             :                         if constexpr (bQuadraticMean)
    1833             :                         {
    1834             :                             if constexpr (bUseMulFactor)
    1835          81 :                                 nVal = static_cast<T>(
    1836          48 :                                     dfMulFactor *
    1837          81 :                                     sqrt(dfTotal / dfTotalWeight));
    1838             :                             else
    1839             :                                 nVal = static_cast<T>(
    1840             :                                     sqrt(dfTotal / dfTotalWeight));
    1841             :                         }
    1842             :                         else
    1843             :                         {
    1844             :                             if constexpr (bUseMulFactor)
    1845         184 :                                 nVal = static_cast<T>(
    1846         184 :                                     dfMulFactor * (dfTotal / dfTotalWeight));
    1847             :                             else
    1848             :                                 nVal = static_cast<T>(dfTotal / dfTotalWeight);
    1849             :                         }
    1850         265 :                         if (bHasNoData && nVal == tNoDataValue)
    1851           2 :                             nVal = tReplacementVal;
    1852         265 :                         pDstScanline[iDstPixel] = nVal;
    1853             :                     }
    1854             :                 }
    1855             :             }
    1856             :         }
    1857             :         else
    1858             :         {
    1859         115 :             nSrcYOff -= nChunkYOff;
    1860         115 :             nSrcYOff2 -= nChunkYOff;
    1861             : 
    1862        6590 :             for (int iDstPixel = 0; iDstPixel < nDstXWidth; ++iDstPixel)
    1863             :             {
    1864        6475 :                 const int nSrcXOff = pasSrcX[iDstPixel].nLeftXOffShifted;
    1865        6475 :                 const int nSrcXOff2 = pasSrcX[iDstPixel].nRightXOffShifted;
    1866             : 
    1867        6475 :                 uint64_t nTotalR = 0;
    1868        6475 :                 uint64_t nTotalG = 0;
    1869        6475 :                 uint64_t nTotalB = 0;
    1870        6475 :                 size_t nCount = 0;
    1871             : 
    1872       19425 :                 for (int iY = nSrcYOff; iY < nSrcYOff2; ++iY)
    1873             :                 {
    1874       38850 :                     for (int iX = nSrcXOff; iX < nSrcXOff2; ++iX)
    1875             :                     {
    1876       25900 :                         const T val =
    1877       25900 :                             pChunk[iX + static_cast<size_t>(iY) * nChunkXSize];
    1878             :                         // cppcheck-suppress unsignedLessThanZero
    1879       25900 :                         if (val < 0 || val >= colorEntries.size())
    1880           0 :                             continue;
    1881       25900 :                         const size_t idx = static_cast<size_t>(val);
    1882       25900 :                         const auto &entry = colorEntries[idx];
    1883       25900 :                         if (entry.c4)
    1884             :                         {
    1885             :                             if constexpr (bQuadraticMean)
    1886             :                             {
    1887         800 :                                 nTotalR += SQUARE<int>(entry.c1);
    1888         800 :                                 nTotalG += SQUARE<int>(entry.c2);
    1889         800 :                                 nTotalB += SQUARE<int>(entry.c3);
    1890         800 :                                 ++nCount;
    1891             :                             }
    1892             :                             else
    1893             :                             {
    1894       13328 :                                 nTotalR += entry.c1;
    1895       13328 :                                 nTotalG += entry.c2;
    1896       13328 :                                 nTotalB += entry.c3;
    1897       13328 :                                 ++nCount;
    1898             :                             }
    1899             :                         }
    1900             :                     }
    1901             :                 }
    1902             : 
    1903        6475 :                 if (nCount == 0 ||
    1904           0 :                     (bPropagateNoData &&
    1905           0 :                      nCount < static_cast<size_t>(nSrcYOff2 - nSrcYOff) *
    1906           0 :                                   (nSrcXOff2 - nSrcXOff)))
    1907             :                 {
    1908        2838 :                     pDstScanline[iDstPixel] = tNoDataValue;
    1909             :                 }
    1910             :                 else
    1911             :                 {
    1912             :                     GDALColorEntry color;
    1913             :                     if constexpr (bQuadraticMean)
    1914             :                     {
    1915         200 :                         color.c1 =
    1916         200 :                             static_cast<short>(sqrt(nTotalR / nCount) + 0.5);
    1917         200 :                         color.c2 =
    1918         200 :                             static_cast<short>(sqrt(nTotalG / nCount) + 0.5);
    1919         200 :                         color.c3 =
    1920         200 :                             static_cast<short>(sqrt(nTotalB / nCount) + 0.5);
    1921             :                     }
    1922             :                     else
    1923             :                     {
    1924        3437 :                         color.c1 =
    1925        3437 :                             static_cast<short>((nTotalR + nCount / 2) / nCount);
    1926        3437 :                         color.c2 =
    1927        3437 :                             static_cast<short>((nTotalG + nCount / 2) / nCount);
    1928        3437 :                         color.c3 =
    1929        3437 :                             static_cast<short>((nTotalB + nCount / 2) / nCount);
    1930             :                     }
    1931        3637 :                     pDstScanline[iDstPixel] =
    1932        3637 :                         static_cast<T>(BestColorEntry(colorEntries, color));
    1933             :                 }
    1934             :             }
    1935             :         }
    1936             :     }
    1937             : 
    1938        2394 :     CPLFree(pasSrcX);
    1939             : 
    1940        2394 :     return CE_None;
    1941             : }
    1942             : 
    1943             : template <bool bQuadraticMean>
    1944             : static CPLErr
    1945        2394 : GDALResampleChunk_AverageOrRMSInternal(const GDALOverviewResampleArgs &args,
    1946             :                                        const void *pChunk, void **ppDstBuffer,
    1947             :                                        GDALDataType *peDstBufferDataType)
    1948             : {
    1949        2394 :     *peDstBufferDataType = args.eWrkDataType;
    1950        2394 :     switch (args.eWrkDataType)
    1951             :     {
    1952        2263 :         case GDT_UInt8:
    1953             :         {
    1954             :             return GDALResampleChunk_AverageOrRMS_T<GByte, int, GDT_UInt8,
    1955        2263 :                                                     bQuadraticMean>(
    1956        2263 :                 args, static_cast<const GByte *>(pChunk), ppDstBuffer);
    1957             :         }
    1958             : 
    1959          11 :         case GDT_UInt16:
    1960             :         {
    1961             :             if constexpr (bQuadraticMean)
    1962             :             {
    1963             :                 // Use double as accumulation type, because UInt32 could overflow
    1964             :                 return GDALResampleChunk_AverageOrRMS_T<
    1965           6 :                     GUInt16, double, GDT_UInt16, bQuadraticMean>(
    1966           6 :                     args, static_cast<const GUInt16 *>(pChunk), ppDstBuffer);
    1967             :             }
    1968             :             else
    1969             :             {
    1970             :                 return GDALResampleChunk_AverageOrRMS_T<
    1971           5 :                     GUInt16, GUInt32, GDT_UInt16, bQuadraticMean>(
    1972           5 :                     args, static_cast<const GUInt16 *>(pChunk), ppDstBuffer);
    1973             :             }
    1974             :         }
    1975             : 
    1976          73 :         case GDT_Float32:
    1977             :         {
    1978             :             return GDALResampleChunk_AverageOrRMS_T<float, double, GDT_Float32,
    1979          73 :                                                     bQuadraticMean>(
    1980          73 :                 args, static_cast<const float *>(pChunk), ppDstBuffer);
    1981             :         }
    1982             : 
    1983          47 :         case GDT_Float64:
    1984             :         {
    1985             :             return GDALResampleChunk_AverageOrRMS_T<double, double, GDT_Float64,
    1986          47 :                                                     bQuadraticMean>(
    1987          47 :                 args, static_cast<const double *>(pChunk), ppDstBuffer);
    1988             :         }
    1989             : 
    1990           0 :         default:
    1991           0 :             break;
    1992             :     }
    1993             : 
    1994           0 :     CPLAssert(false);
    1995             :     return CE_Failure;
    1996             : }
    1997             : 
    1998             : static CPLErr
    1999        2394 : GDALResampleChunk_AverageOrRMS(const GDALOverviewResampleArgs &args,
    2000             :                                const void *pChunk, void **ppDstBuffer,
    2001             :                                GDALDataType *peDstBufferDataType)
    2002             : {
    2003        2394 :     if (EQUAL(args.pszResampling, "RMS"))
    2004          77 :         return GDALResampleChunk_AverageOrRMSInternal<true>(
    2005          77 :             args, pChunk, ppDstBuffer, peDstBufferDataType);
    2006             :     else
    2007        2317 :         return GDALResampleChunk_AverageOrRMSInternal<false>(
    2008        2317 :             args, pChunk, ppDstBuffer, peDstBufferDataType);
    2009             : }
    2010             : 
    2011             : /************************************************************************/
    2012             : /*                      GDALResampleChunk_Gauss()                       */
    2013             : /************************************************************************/
    2014             : 
    2015          86 : static CPLErr GDALResampleChunk_Gauss(const GDALOverviewResampleArgs &args,
    2016             :                                       const void *pChunk, void **ppDstBuffer,
    2017             :                                       GDALDataType *peDstBufferDataType)
    2018             : 
    2019             : {
    2020          86 :     const double dfXRatioDstToSrc = args.dfXRatioDstToSrc;
    2021          86 :     const double dfYRatioDstToSrc = args.dfYRatioDstToSrc;
    2022          86 :     const GByte *pabyChunkNodataMask = args.pabyChunkNodataMask;
    2023          86 :     const int nChunkXOff = args.nChunkXOff;
    2024          86 :     const int nChunkXSize = args.nChunkXSize;
    2025          86 :     const int nChunkYOff = args.nChunkYOff;
    2026          86 :     const int nChunkYSize = args.nChunkYSize;
    2027          86 :     const int nDstXOff = args.nDstXOff;
    2028          86 :     const int nDstXOff2 = args.nDstXOff2;
    2029          86 :     const int nDstYOff = args.nDstYOff;
    2030          86 :     const int nDstYOff2 = args.nDstYOff2;
    2031          86 :     const bool bHasNoData = args.bHasNoData;
    2032          86 :     double dfNoDataValue = args.dfNoDataValue;
    2033          86 :     const GDALColorTable *poColorTable = args.poColorTable;
    2034             : 
    2035          86 :     const double *const padfChunk = static_cast<const double *>(pChunk);
    2036             : 
    2037          86 :     *ppDstBuffer =
    2038          86 :         VSI_MALLOC3_VERBOSE(nDstXOff2 - nDstXOff, nDstYOff2 - nDstYOff,
    2039             :                             GDALGetDataTypeSizeBytes(GDT_Float64));
    2040          86 :     if (*ppDstBuffer == nullptr)
    2041             :     {
    2042           0 :         return CE_Failure;
    2043             :     }
    2044          86 :     *peDstBufferDataType = GDT_Float64;
    2045          86 :     double *const padfDstBuffer = static_cast<double *>(*ppDstBuffer);
    2046             : 
    2047             :     /* -------------------------------------------------------------------- */
    2048             :     /*      Create the filter kernel and allocate scanline buffer.          */
    2049             :     /* -------------------------------------------------------------------- */
    2050          86 :     int nGaussMatrixDim = 3;
    2051             :     const int *panGaussMatrix;
    2052          86 :     constexpr int anGaussMatrix3x3[] = {1, 2, 1, 2, 4, 2, 1, 2, 1};
    2053          86 :     constexpr int anGaussMatrix5x5[] = {1,  4, 6,  4,  1,  4, 16, 24, 16,
    2054             :                                         4,  6, 24, 36, 24, 6, 4,  16, 24,
    2055             :                                         16, 4, 1,  4,  6,  4, 1};
    2056          86 :     constexpr int anGaussMatrix7x7[] = {
    2057             :         1,   6,  15, 20,  15,  6,   1,   6,  36, 90,  120, 90,  36,
    2058             :         6,   15, 90, 225, 300, 225, 90,  15, 20, 120, 300, 400, 300,
    2059             :         120, 20, 15, 90,  225, 300, 225, 90, 15, 6,   36,  90,  120,
    2060             :         90,  36, 6,  1,   6,   15,  20,  15, 6,  1};
    2061             : 
    2062          86 :     const int nOXSize = args.nOvrXSize;
    2063          86 :     const int nOYSize = args.nOvrYSize;
    2064          86 :     const int nResYFactor = static_cast<int>(0.5 + dfYRatioDstToSrc);
    2065             : 
    2066             :     // matrix for gauss filter
    2067          86 :     if (nResYFactor <= 2)
    2068             :     {
    2069          85 :         panGaussMatrix = anGaussMatrix3x3;
    2070          85 :         nGaussMatrixDim = 3;
    2071             :     }
    2072           1 :     else if (nResYFactor <= 4)
    2073             :     {
    2074           0 :         panGaussMatrix = anGaussMatrix5x5;
    2075           0 :         nGaussMatrixDim = 5;
    2076             :     }
    2077             :     else
    2078             :     {
    2079           1 :         panGaussMatrix = anGaussMatrix7x7;
    2080           1 :         nGaussMatrixDim = 7;
    2081             :     }
    2082             : 
    2083             : #ifdef DEBUG_OUT_OF_BOUND_ACCESS
    2084             :     int *panGaussMatrixDup = static_cast<int *>(
    2085             :         CPLMalloc(sizeof(int) * nGaussMatrixDim * nGaussMatrixDim));
    2086             :     memcpy(panGaussMatrixDup, panGaussMatrix,
    2087             :            sizeof(int) * nGaussMatrixDim * nGaussMatrixDim);
    2088             :     panGaussMatrix = panGaussMatrixDup;
    2089             : #endif
    2090             : 
    2091          86 :     if (!bHasNoData)
    2092          79 :         dfNoDataValue = 0.0;
    2093             : 
    2094          86 :     std::vector<GDALColorEntry> colorEntries;
    2095          86 :     int nTransparentIdx = -1;
    2096          86 :     if (poColorTable)
    2097           2 :         colorEntries = ReadColorTable(*poColorTable, nTransparentIdx);
    2098             : 
    2099             :     // Force c4 of nodata entry to 0 so that GDALFindBestEntry() identifies
    2100             :     // it as nodata value.
    2101          92 :     if (bHasNoData && dfNoDataValue >= 0.0 &&
    2102           6 :         dfNoDataValue < colorEntries.size())
    2103           0 :         colorEntries[static_cast<int>(dfNoDataValue)].c4 = 0;
    2104             : 
    2105             :     // Or if we have no explicit nodata, but a color table entry that is
    2106             :     // transparent, consider it as the nodata value.
    2107          86 :     else if (!bHasNoData && nTransparentIdx >= 0)
    2108             :     {
    2109           0 :         dfNoDataValue = nTransparentIdx;
    2110             :     }
    2111             : 
    2112          86 :     const int nChunkRightXOff = nChunkXOff + nChunkXSize;
    2113          86 :     const int nChunkBottomYOff = nChunkYOff + nChunkYSize;
    2114          86 :     const int nDstXWidth = nDstXOff2 - nDstXOff;
    2115             : 
    2116             :     /* ==================================================================== */
    2117             :     /*      Loop over destination scanlines.                                */
    2118             :     /* ==================================================================== */
    2119       16488 :     for (int iDstLine = nDstYOff; iDstLine < nDstYOff2; ++iDstLine)
    2120             :     {
    2121       16402 :         int nSrcYOff = static_cast<int>(0.5 + iDstLine * dfYRatioDstToSrc);
    2122       16402 :         int nSrcYOff2 =
    2123       16402 :             static_cast<int>(0.5 + (iDstLine + 1) * dfYRatioDstToSrc) + 1;
    2124             : 
    2125       16402 :         if (nSrcYOff < nChunkYOff)
    2126             :         {
    2127           0 :             nSrcYOff = nChunkYOff;
    2128           0 :             nSrcYOff2++;
    2129             :         }
    2130             : 
    2131       16402 :         const int iSizeY = nSrcYOff2 - nSrcYOff;
    2132       16402 :         nSrcYOff = nSrcYOff + iSizeY / 2 - nGaussMatrixDim / 2;
    2133       16402 :         nSrcYOff2 = nSrcYOff + nGaussMatrixDim;
    2134             : 
    2135       16402 :         if (nSrcYOff2 > nChunkBottomYOff ||
    2136       16359 :             (dfYRatioDstToSrc > 1 && iDstLine == nOYSize - 1))
    2137             :         {
    2138          44 :             nSrcYOff2 = std::min(nChunkBottomYOff, nSrcYOff + nGaussMatrixDim);
    2139             :         }
    2140             : 
    2141       16402 :         int nYShiftGaussMatrix = 0;
    2142       16402 :         if (nSrcYOff < nChunkYOff)
    2143             :         {
    2144           0 :             nYShiftGaussMatrix = -(nSrcYOff - nChunkYOff);
    2145           0 :             nSrcYOff = nChunkYOff;
    2146             :         }
    2147             : 
    2148       16402 :         const double *const padfSrcScanline =
    2149       16402 :             padfChunk + ((nSrcYOff - nChunkYOff) * nChunkXSize);
    2150       16402 :         const GByte *pabySrcScanlineNodataMask = nullptr;
    2151       16402 :         if (pabyChunkNodataMask != nullptr)
    2152         152 :             pabySrcScanlineNodataMask =
    2153         152 :                 pabyChunkNodataMask + ((nSrcYOff - nChunkYOff) * nChunkXSize);
    2154             : 
    2155             :         /* --------------------------------------------------------------------
    2156             :          */
    2157             :         /*      Loop over destination pixels */
    2158             :         /* --------------------------------------------------------------------
    2159             :          */
    2160       16402 :         double *const padfDstScanline =
    2161       16402 :             padfDstBuffer + (iDstLine - nDstYOff) * nDstXWidth;
    2162     4149980 :         for (int iDstPixel = nDstXOff; iDstPixel < nDstXOff2; ++iDstPixel)
    2163             :         {
    2164     4133580 :             int nSrcXOff = static_cast<int>(0.5 + iDstPixel * dfXRatioDstToSrc);
    2165     4133580 :             int nSrcXOff2 =
    2166     4133580 :                 static_cast<int>(0.5 + (iDstPixel + 1) * dfXRatioDstToSrc) + 1;
    2167             : 
    2168     4133580 :             if (nSrcXOff < nChunkXOff)
    2169             :             {
    2170           0 :                 nSrcXOff = nChunkXOff;
    2171           0 :                 nSrcXOff2++;
    2172             :             }
    2173             : 
    2174     4133580 :             const int iSizeX = nSrcXOff2 - nSrcXOff;
    2175     4133580 :             nSrcXOff = nSrcXOff + iSizeX / 2 - nGaussMatrixDim / 2;
    2176     4133580 :             nSrcXOff2 = nSrcXOff + nGaussMatrixDim;
    2177             : 
    2178     4133580 :             if (nSrcXOff2 > nChunkRightXOff ||
    2179     4127930 :                 (dfXRatioDstToSrc > 1 && iDstPixel == nOXSize - 1))
    2180             :             {
    2181        5650 :                 nSrcXOff2 =
    2182        5650 :                     std::min(nChunkRightXOff, nSrcXOff + nGaussMatrixDim);
    2183             :             }
    2184             : 
    2185     4133580 :             int nXShiftGaussMatrix = 0;
    2186     4133580 :             if (nSrcXOff < nChunkXOff)
    2187             :             {
    2188           0 :                 nXShiftGaussMatrix = -(nSrcXOff - nChunkXOff);
    2189           0 :                 nSrcXOff = nChunkXOff;
    2190             :             }
    2191             : 
    2192     4133580 :             if (poColorTable == nullptr)
    2193             :             {
    2194     4133380 :                 double dfTotal = 0.0;
    2195     4133380 :                 GInt64 nCount = 0;
    2196     4133380 :                 const int *panLineWeight =
    2197     4133380 :                     panGaussMatrix + nYShiftGaussMatrix * nGaussMatrixDim +
    2198             :                     nXShiftGaussMatrix;
    2199             : 
    2200    16527900 :                 for (int j = 0, iY = nSrcYOff; iY < nSrcYOff2;
    2201    12394500 :                      ++iY, ++j, panLineWeight += nGaussMatrixDim)
    2202             :                 {
    2203    49561300 :                     for (int i = 0, iX = nSrcXOff; iX < nSrcXOff2; ++iX, ++i)
    2204             :                     {
    2205    37166800 :                         const double val =
    2206    37166800 :                             padfSrcScanline[iX - nChunkXOff +
    2207    37166800 :                                             static_cast<GPtrDiff_t>(iY -
    2208    37166800 :                                                                     nSrcYOff) *
    2209    37166800 :                                                 nChunkXSize];
    2210    37166800 :                         if (pabySrcScanlineNodataMask == nullptr ||
    2211       32872 :                             pabySrcScanlineNodataMask[iX - nChunkXOff +
    2212       32872 :                                                       static_cast<GPtrDiff_t>(
    2213       32872 :                                                           iY - nSrcYOff) *
    2214       32872 :                                                           nChunkXSize])
    2215             :                         {
    2216    37146100 :                             const int nWeight = panLineWeight[i];
    2217    37146100 :                             dfTotal += val * nWeight;
    2218    37146100 :                             nCount += nWeight;
    2219             :                         }
    2220             :                     }
    2221             :                 }
    2222             : 
    2223     4133380 :                 if (nCount == 0)
    2224             :                 {
    2225        2217 :                     padfDstScanline[iDstPixel - nDstXOff] = dfNoDataValue;
    2226             :                 }
    2227             :                 else
    2228             :                 {
    2229     4131160 :                     padfDstScanline[iDstPixel - nDstXOff] = dfTotal / nCount;
    2230             :                 }
    2231             :             }
    2232             :             else
    2233             :             {
    2234         200 :                 GInt64 nTotalR = 0;
    2235         200 :                 GInt64 nTotalG = 0;
    2236         200 :                 GInt64 nTotalB = 0;
    2237         200 :                 GInt64 nTotalWeight = 0;
    2238         200 :                 const int *panLineWeight =
    2239         200 :                     panGaussMatrix + nYShiftGaussMatrix * nGaussMatrixDim +
    2240             :                     nXShiftGaussMatrix;
    2241             : 
    2242         780 :                 for (int j = 0, iY = nSrcYOff; iY < nSrcYOff2;
    2243         580 :                      ++iY, ++j, panLineWeight += nGaussMatrixDim)
    2244             :                 {
    2245        2262 :                     for (int i = 0, iX = nSrcXOff; iX < nSrcXOff2; ++iX, ++i)
    2246             :                     {
    2247        1682 :                         const double val =
    2248        1682 :                             padfSrcScanline[iX - nChunkXOff +
    2249        1682 :                                             static_cast<GPtrDiff_t>(iY -
    2250        1682 :                                                                     nSrcYOff) *
    2251        1682 :                                                 nChunkXSize];
    2252        1682 :                         if (val < 0 || val >= colorEntries.size())
    2253           0 :                             continue;
    2254             : 
    2255        1682 :                         size_t idx = static_cast<size_t>(val);
    2256        1682 :                         if (colorEntries[idx].c4)
    2257             :                         {
    2258        1682 :                             const int nWeight = panLineWeight[i];
    2259        1682 :                             nTotalR +=
    2260        1682 :                                 static_cast<GInt64>(colorEntries[idx].c1) *
    2261        1682 :                                 nWeight;
    2262        1682 :                             nTotalG +=
    2263        1682 :                                 static_cast<GInt64>(colorEntries[idx].c2) *
    2264        1682 :                                 nWeight;
    2265        1682 :                             nTotalB +=
    2266        1682 :                                 static_cast<GInt64>(colorEntries[idx].c3) *
    2267        1682 :                                 nWeight;
    2268        1682 :                             nTotalWeight += nWeight;
    2269             :                         }
    2270             :                     }
    2271             :                 }
    2272             : 
    2273         200 :                 if (nTotalWeight == 0)
    2274             :                 {
    2275           0 :                     padfDstScanline[iDstPixel - nDstXOff] = dfNoDataValue;
    2276             :                 }
    2277             :                 else
    2278             :                 {
    2279             :                     GDALColorEntry color;
    2280             : 
    2281         200 :                     color.c1 = static_cast<short>((nTotalR + nTotalWeight / 2) /
    2282             :                                                   nTotalWeight);
    2283         200 :                     color.c2 = static_cast<short>((nTotalG + nTotalWeight / 2) /
    2284             :                                                   nTotalWeight);
    2285         200 :                     color.c3 = static_cast<short>((nTotalB + nTotalWeight / 2) /
    2286             :                                                   nTotalWeight);
    2287         200 :                     padfDstScanline[iDstPixel - nDstXOff] =
    2288         200 :                         BestColorEntry(colorEntries, color);
    2289             :                 }
    2290             :             }
    2291             :         }
    2292             :     }
    2293             : 
    2294             : #ifdef DEBUG_OUT_OF_BOUND_ACCESS
    2295             :     CPLFree(panGaussMatrixDup);
    2296             : #endif
    2297             : 
    2298          86 :     return CE_None;
    2299             : }
    2300             : 
    2301             : /************************************************************************/
    2302             : /*                       GDALResampleChunk_Mode()                       */
    2303             : /************************************************************************/
    2304             : 
    2305         688 : template <class T> static inline bool IsSame(T a, T b)
    2306             : {
    2307         688 :     return a == b;
    2308             : }
    2309             : 
    2310          60 : template <> bool IsSame<GFloat16>(GFloat16 a, GFloat16 b)
    2311             : {
    2312          60 :     return a == b || (CPLIsNan(a) && CPLIsNan(b));
    2313             : }
    2314             : 
    2315        4902 : template <> bool IsSame<float>(float a, float b)
    2316             : {
    2317        4902 :     return a == b || (std::isnan(a) && std::isnan(b));
    2318             : }
    2319             : 
    2320        1020 : template <> bool IsSame<double>(double a, double b)
    2321             : {
    2322        1020 :     return a == b || (std::isnan(a) && std::isnan(b));
    2323             : }
    2324             : 
    2325             : namespace
    2326             : {
    2327             : struct ComplexFloat16
    2328             : {
    2329             :     GFloat16 r;
    2330             :     GFloat16 i;
    2331             : };
    2332             : }  // namespace
    2333             : 
    2334          60 : template <> bool IsSame<ComplexFloat16>(ComplexFloat16 a, ComplexFloat16 b)
    2335             : {
    2336          90 :     return (a.r == b.r && a.i == b.i) ||
    2337          90 :            (CPLIsNan(a.r) && CPLIsNan(a.i) && CPLIsNan(b.r) && CPLIsNan(b.i));
    2338             : }
    2339             : 
    2340             : template <>
    2341          60 : bool IsSame<std::complex<float>>(std::complex<float> a, std::complex<float> b)
    2342             : {
    2343         120 :     return a == b || (std::isnan(a.real()) && std::isnan(a.imag()) &&
    2344         120 :                       std::isnan(b.real()) && std::isnan(b.imag()));
    2345             : }
    2346             : 
    2347             : template <>
    2348          60 : bool IsSame<std::complex<double>>(std::complex<double> a,
    2349             :                                   std::complex<double> b)
    2350             : {
    2351         120 :     return a == b || (std::isnan(a.real()) && std::isnan(a.imag()) &&
    2352         120 :                       std::isnan(b.real()) && std::isnan(b.imag()));
    2353             : }
    2354             : 
    2355             : template <class T>
    2356         176 : static CPLErr GDALResampleChunk_ModeT(const GDALOverviewResampleArgs &args,
    2357             :                                       const T *pChunk, T *const pDstBuffer)
    2358             : 
    2359             : {
    2360         176 :     const double dfXRatioDstToSrc = args.dfXRatioDstToSrc;
    2361         176 :     const double dfYRatioDstToSrc = args.dfYRatioDstToSrc;
    2362         176 :     const double dfSrcXDelta = args.dfSrcXDelta;
    2363         176 :     const double dfSrcYDelta = args.dfSrcYDelta;
    2364         176 :     const GByte *pabyChunkNodataMask = args.pabyChunkNodataMask;
    2365         176 :     const int nChunkXOff = args.nChunkXOff;
    2366         176 :     const int nChunkXSize = args.nChunkXSize;
    2367         176 :     const int nChunkYOff = args.nChunkYOff;
    2368         176 :     const int nChunkYSize = args.nChunkYSize;
    2369         176 :     const int nDstXOff = args.nDstXOff;
    2370         176 :     const int nDstXOff2 = args.nDstXOff2;
    2371         176 :     const int nDstYOff = args.nDstYOff;
    2372         176 :     const int nDstYOff2 = args.nDstYOff2;
    2373         176 :     const bool bHasNoData = args.bHasNoData;
    2374         176 :     const GDALColorTable *poColorTable = args.poColorTable;
    2375         176 :     const int nDstXSize = nDstXOff2 - nDstXOff;
    2376             : 
    2377           8 :     T tNoDataValue;
    2378             :     if constexpr (std::is_same<T, ComplexFloat16>::value)
    2379             :     {
    2380           4 :         tNoDataValue.r = cpl::NumericLimits<GFloat16>::quiet_NaN();
    2381           4 :         tNoDataValue.i = cpl::NumericLimits<GFloat16>::quiet_NaN();
    2382             :     }
    2383             :     else if constexpr (std::is_same<T, std::complex<float>>::value ||
    2384             :                        std::is_same<T, std::complex<double>>::value)
    2385             :     {
    2386             :         using BaseT = typename T::value_type;
    2387           8 :         tNoDataValue =
    2388             :             std::complex<BaseT>(std::numeric_limits<BaseT>::quiet_NaN(),
    2389             :                                 std::numeric_limits<BaseT>::quiet_NaN());
    2390             :     }
    2391         164 :     else if (!bHasNoData || !GDALIsValueInRange<T>(args.dfNoDataValue))
    2392         163 :         tNoDataValue = 0;
    2393             :     else
    2394           1 :         tNoDataValue = static_cast<T>(args.dfNoDataValue);
    2395             : 
    2396             :     using CountType = uint32_t;
    2397         176 :     CountType nMaxNumPx = 0;
    2398         176 :     T *paVals = nullptr;
    2399         176 :     CountType *panCounts = nullptr;
    2400             : 
    2401         176 :     const int nChunkRightXOff = nChunkXOff + nChunkXSize;
    2402         176 :     const int nChunkBottomYOff = nChunkYOff + nChunkYSize;
    2403         352 :     std::vector<int> anVals(256, 0);
    2404             : 
    2405             :     /* ==================================================================== */
    2406             :     /*      Loop over destination scanlines.                                */
    2407             :     /* ==================================================================== */
    2408        7679 :     for (int iDstLine = nDstYOff; iDstLine < nDstYOff2; ++iDstLine)
    2409             :     {
    2410        7503 :         const double dfSrcYOff = dfSrcYDelta + iDstLine * dfYRatioDstToSrc;
    2411        7503 :         int nSrcYOff = static_cast<int>(dfSrcYOff + 1e-8);
    2412             : #ifdef only_pixels_with_more_than_10_pct_participation
    2413             :         // When oversampling, don't take into account pixels that have a tiny
    2414             :         // participation in the resulting pixel
    2415             :         if (dfYRatioDstToSrc > 1 && dfSrcYOff - nSrcYOff > 0.9 &&
    2416             :             nSrcYOff < nChunkBottomYOff)
    2417             :             nSrcYOff++;
    2418             : #endif
    2419        7503 :         if (nSrcYOff < nChunkYOff)
    2420           0 :             nSrcYOff = nChunkYOff;
    2421             : 
    2422        7503 :         const double dfSrcYOff2 =
    2423        7503 :             dfSrcYDelta + (iDstLine + 1) * dfYRatioDstToSrc;
    2424        7503 :         int nSrcYOff2 = static_cast<int>(ceil(dfSrcYOff2 - 1e-8));
    2425             : #ifdef only_pixels_with_more_than_10_pct_participation
    2426             :         // When oversampling, don't take into account pixels that have a tiny
    2427             :         // participation in the resulting pixel
    2428             :         if (dfYRatioDstToSrc > 1 && nSrcYOff2 - dfSrcYOff2 > 0.9 &&
    2429             :             nSrcYOff2 > nChunkYOff)
    2430             :             nSrcYOff2--;
    2431             : #endif
    2432        7503 :         if (nSrcYOff2 == nSrcYOff)
    2433           0 :             ++nSrcYOff2;
    2434        7503 :         if (nSrcYOff2 > nChunkBottomYOff)
    2435           0 :             nSrcYOff2 = nChunkBottomYOff;
    2436             : 
    2437        7503 :         const T *const paSrcScanline =
    2438         253 :             pChunk +
    2439        7503 :             (static_cast<GPtrDiff_t>(nSrcYOff - nChunkYOff) * nChunkXSize);
    2440        7503 :         const GByte *pabySrcScanlineNodataMask = nullptr;
    2441        7503 :         if (pabyChunkNodataMask != nullptr)
    2442        1810 :             pabySrcScanlineNodataMask =
    2443             :                 pabyChunkNodataMask +
    2444        1810 :                 static_cast<GPtrDiff_t>(nSrcYOff - nChunkYOff) * nChunkXSize;
    2445             : 
    2446        7503 :         T *const paDstScanline = pDstBuffer + (iDstLine - nDstYOff) * nDstXSize;
    2447             :         /* --------------------------------------------------------------------
    2448             :          */
    2449             :         /*      Loop over destination pixels */
    2450             :         /* --------------------------------------------------------------------
    2451             :          */
    2452     4260400 :         for (int iDstPixel = nDstXOff; iDstPixel < nDstXOff2; ++iDstPixel)
    2453             :         {
    2454     4252893 :             const double dfSrcXOff = dfSrcXDelta + iDstPixel * dfXRatioDstToSrc;
    2455             :             // Apply some epsilon to avoid numerical precision issues
    2456     4252893 :             int nSrcXOff = static_cast<int>(dfSrcXOff + 1e-8);
    2457             : #ifdef only_pixels_with_more_than_10_pct_participation
    2458             :             // When oversampling, don't take into account pixels that have a
    2459             :             // tiny participation in the resulting pixel
    2460             :             if (dfXRatioDstToSrc > 1 && dfSrcXOff - nSrcXOff > 0.9 &&
    2461             :                 nSrcXOff < nChunkRightXOff)
    2462             :                 nSrcXOff++;
    2463             : #endif
    2464     4252893 :             if (nSrcXOff < nChunkXOff)
    2465           0 :                 nSrcXOff = nChunkXOff;
    2466             : 
    2467     4252893 :             const double dfSrcXOff2 =
    2468     4252893 :                 dfSrcXDelta + (iDstPixel + 1) * dfXRatioDstToSrc;
    2469     4252893 :             int nSrcXOff2 = static_cast<int>(ceil(dfSrcXOff2 - 1e-8));
    2470             : #ifdef only_pixels_with_more_than_10_pct_participation
    2471             :             // When oversampling, don't take into account pixels that have a
    2472             :             // tiny participation in the resulting pixel
    2473             :             if (dfXRatioDstToSrc > 1 && nSrcXOff2 - dfSrcXOff2 > 0.9 &&
    2474             :                 nSrcXOff2 > nChunkXOff)
    2475             :                 nSrcXOff2--;
    2476             : #endif
    2477     4252893 :             if (nSrcXOff2 == nSrcXOff)
    2478           0 :                 nSrcXOff2++;
    2479     4252893 :             if (nSrcXOff2 > nChunkRightXOff)
    2480           0 :                 nSrcXOff2 = nChunkRightXOff;
    2481             : 
    2482     4252893 :             bool bRegularProcessing = false;
    2483             :             if constexpr (!std::is_same<T, GByte>::value)
    2484        1503 :                 bRegularProcessing = true;
    2485     4251390 :             else if (poColorTable && poColorTable->GetColorEntryCount() > 256)
    2486           0 :                 bRegularProcessing = true;
    2487             : 
    2488     4252893 :             if (bRegularProcessing)
    2489             :             {
    2490             :                 // Sanity check to make sure the allocation of paVals and
    2491             :                 // panCounts don't overflow.
    2492             :                 static_assert(sizeof(CountType) <= sizeof(size_t));
    2493        3006 :                 if (nSrcYOff2 - nSrcYOff <= 0 || nSrcXOff2 - nSrcXOff <= 0 ||
    2494        1503 :                     static_cast<CountType>(nSrcYOff2 - nSrcYOff) >
    2495        1503 :                         (std::numeric_limits<CountType>::max() /
    2496        3006 :                          std::max(sizeof(T), sizeof(CountType))) /
    2497        1503 :                             static_cast<CountType>(nSrcXOff2 - nSrcXOff))
    2498             :                 {
    2499           0 :                     CPLError(CE_Failure, CPLE_NotSupported,
    2500             :                              "Too big downsampling factor");
    2501           0 :                     CPLFree(paVals);
    2502           0 :                     CPLFree(panCounts);
    2503           0 :                     return CE_Failure;
    2504             :                 }
    2505        1503 :                 const CountType nNumPx =
    2506        1503 :                     static_cast<CountType>(nSrcYOff2 - nSrcYOff) *
    2507        1503 :                     (nSrcXOff2 - nSrcXOff);
    2508        1503 :                 CountType iMaxInd = 0;
    2509        1503 :                 CountType iMaxVal = 0;
    2510             : 
    2511        1503 :                 if (paVals == nullptr || nNumPx > nMaxNumPx)
    2512             :                 {
    2513             :                     T *paValsNew = static_cast<T *>(
    2514         110 :                         VSI_REALLOC_VERBOSE(paVals, nNumPx * sizeof(T)));
    2515             :                     CountType *panCountsNew =
    2516         110 :                         static_cast<CountType *>(VSI_REALLOC_VERBOSE(
    2517             :                             panCounts, nNumPx * sizeof(CountType)));
    2518         110 :                     if (paValsNew != nullptr)
    2519         110 :                         paVals = paValsNew;
    2520         110 :                     if (panCountsNew != nullptr)
    2521         110 :                         panCounts = panCountsNew;
    2522         110 :                     if (paValsNew == nullptr || panCountsNew == nullptr)
    2523             :                     {
    2524           0 :                         CPLFree(paVals);
    2525           0 :                         CPLFree(panCounts);
    2526           0 :                         return CE_Failure;
    2527             :                     }
    2528         110 :                     nMaxNumPx = nNumPx;
    2529             :                 }
    2530             : 
    2531        4629 :                 for (int iY = nSrcYOff; iY < nSrcYOff2; ++iY)
    2532             :                 {
    2533        3126 :                     const GPtrDiff_t iTotYOff =
    2534        3126 :                         static_cast<GPtrDiff_t>(iY - nSrcYOff) * nChunkXSize -
    2535        3126 :                         nChunkXOff;
    2536        9858 :                     for (int iX = nSrcXOff; iX < nSrcXOff2; ++iX)
    2537             :                     {
    2538        6732 :                         if (pabySrcScanlineNodataMask == nullptr ||
    2539          16 :                             pabySrcScanlineNodataMask[iX + iTotYOff])
    2540             :                         {
    2541        6717 :                             const T val = paSrcScanline[iX + iTotYOff];
    2542        6717 :                             CountType i = 0;  // Used after for.
    2543             : 
    2544             :                             // Check array for existing entry.
    2545       10081 :                             for (; i < iMaxInd; ++i)
    2546             :                             {
    2547        6850 :                                 if (IsSame(paVals[i], val))
    2548             :                                 {
    2549        3486 :                                     if (++panCounts[i] > panCounts[iMaxVal])
    2550             :                                     {
    2551         246 :                                         iMaxVal = i;
    2552             :                                     }
    2553        3486 :                                     break;
    2554             :                                 }
    2555             :                             }
    2556             : 
    2557             :                             // Add to arr if entry not already there.
    2558        6717 :                             if (i == iMaxInd)
    2559             :                             {
    2560        3231 :                                 paVals[iMaxInd] = val;
    2561        3231 :                                 panCounts[iMaxInd] = 1;
    2562             : 
    2563        3231 :                                 if (iMaxInd == 0)
    2564             :                                 {
    2565        1500 :                                     iMaxVal = iMaxInd;
    2566             :                                 }
    2567             : 
    2568        3231 :                                 ++iMaxInd;
    2569             :                             }
    2570             :                         }
    2571             :                     }
    2572             :                 }
    2573             : 
    2574        1503 :                 if (iMaxInd == 0)
    2575           3 :                     paDstScanline[iDstPixel - nDstXOff] = tNoDataValue;
    2576             :                 else
    2577        1500 :                     paDstScanline[iDstPixel - nDstXOff] = paVals[iMaxVal];
    2578             :             }
    2579             :             else if constexpr (std::is_same<T, GByte>::value)
    2580             :             // ( eSrcDataType == GDT_UInt8 && nEntryCount < 256 )
    2581             :             {
    2582             :                 // So we go here for a paletted or non-paletted byte band.
    2583             :                 // The input values are then between 0 and 255.
    2584     4251390 :                 int nMaxVal = 0;
    2585     4251390 :                 int iMaxInd = -1;
    2586             : 
    2587             :                 // The cost of this zeroing might be high. Perhaps we should
    2588             :                 // just use the above generic case, and go to this one if the
    2589             :                 // number of source pixels is large enough
    2590     4251390 :                 std::fill(anVals.begin(), anVals.end(), 0);
    2591             : 
    2592    12777800 :                 for (int iY = nSrcYOff; iY < nSrcYOff2; ++iY)
    2593             :                 {
    2594     8526440 :                     const GPtrDiff_t iTotYOff =
    2595     8526440 :                         static_cast<GPtrDiff_t>(iY - nSrcYOff) * nChunkXSize -
    2596     8526440 :                         nChunkXOff;
    2597    25649600 :                     for (int iX = nSrcXOff; iX < nSrcXOff2; ++iX)
    2598             :                     {
    2599    17123100 :                         const T val = paSrcScanline[iX + iTotYOff];
    2600    17123100 :                         if (!bHasNoData || val != tNoDataValue)
    2601             :                         {
    2602    17123100 :                             int nVal = static_cast<int>(val);
    2603    17123100 :                             if (++anVals[nVal] > nMaxVal)
    2604             :                             {
    2605             :                                 // Sum the density.
    2606             :                                 // Is it the most common value so far?
    2607    17006400 :                                 iMaxInd = nVal;
    2608    17006400 :                                 nMaxVal = anVals[nVal];
    2609             :                             }
    2610             :                         }
    2611             :                     }
    2612             :                 }
    2613             : 
    2614     4251390 :                 if (iMaxInd == -1)
    2615           0 :                     paDstScanline[iDstPixel - nDstXOff] = tNoDataValue;
    2616             :                 else
    2617     4251390 :                     paDstScanline[iDstPixel - nDstXOff] =
    2618             :                         static_cast<T>(iMaxInd);
    2619             :             }
    2620             :         }
    2621             :     }
    2622             : 
    2623         176 :     CPLFree(paVals);
    2624         176 :     CPLFree(panCounts);
    2625             : 
    2626         176 :     return CE_None;
    2627             : }
    2628             : 
    2629         176 : static CPLErr GDALResampleChunk_Mode(const GDALOverviewResampleArgs &args,
    2630             :                                      const void *pChunk, void **ppDstBuffer,
    2631             :                                      GDALDataType *peDstBufferDataType)
    2632             : {
    2633         176 :     *ppDstBuffer = VSI_MALLOC3_VERBOSE(
    2634             :         args.nDstXOff2 - args.nDstXOff, args.nDstYOff2 - args.nDstYOff,
    2635             :         GDALGetDataTypeSizeBytes(args.eWrkDataType));
    2636         176 :     if (*ppDstBuffer == nullptr)
    2637             :     {
    2638           0 :         return CE_Failure;
    2639             :     }
    2640             : 
    2641         176 :     CPLAssert(args.eSrcDataType == args.eWrkDataType);
    2642             : 
    2643         176 :     *peDstBufferDataType = args.eWrkDataType;
    2644         176 :     switch (args.eWrkDataType)
    2645             :     {
    2646             :         // For mode resampling, as no computation is done, only the
    2647             :         // size of the data type matters... except for Byte where we have
    2648             :         // special processing. And for floating point values
    2649          66 :         case GDT_UInt8:
    2650             :         {
    2651          66 :             return GDALResampleChunk_ModeT(args,
    2652             :                                            static_cast<const GByte *>(pChunk),
    2653          66 :                                            static_cast<GByte *>(*ppDstBuffer));
    2654             :         }
    2655             : 
    2656           4 :         case GDT_Int8:
    2657             :         {
    2658           4 :             return GDALResampleChunk_ModeT(args,
    2659             :                                            static_cast<const int8_t *>(pChunk),
    2660           4 :                                            static_cast<int8_t *>(*ppDstBuffer));
    2661             :         }
    2662             : 
    2663          10 :         case GDT_Int16:
    2664             :         case GDT_UInt16:
    2665             :         {
    2666          10 :             CPLAssert(GDALGetDataTypeSizeBytes(args.eWrkDataType) == 2);
    2667          10 :             return GDALResampleChunk_ModeT(
    2668             :                 args, static_cast<const uint16_t *>(pChunk),
    2669          10 :                 static_cast<uint16_t *>(*ppDstBuffer));
    2670             :         }
    2671             : 
    2672          15 :         case GDT_CInt16:
    2673             :         case GDT_Int32:
    2674             :         case GDT_UInt32:
    2675             :         {
    2676          15 :             CPLAssert(GDALGetDataTypeSizeBytes(args.eWrkDataType) == 4);
    2677          15 :             return GDALResampleChunk_ModeT(
    2678             :                 args, static_cast<const uint32_t *>(pChunk),
    2679          15 :                 static_cast<uint32_t *>(*ppDstBuffer));
    2680             :         }
    2681             : 
    2682          12 :         case GDT_CInt32:
    2683             :         case GDT_Int64:
    2684             :         case GDT_UInt64:
    2685             :         {
    2686          12 :             CPLAssert(GDALGetDataTypeSizeBytes(args.eWrkDataType) == 8);
    2687          12 :             return GDALResampleChunk_ModeT(
    2688             :                 args, static_cast<const uint64_t *>(pChunk),
    2689          12 :                 static_cast<uint64_t *>(*ppDstBuffer));
    2690             :         }
    2691             : 
    2692           4 :         case GDT_Float16:
    2693             :         {
    2694           4 :             return GDALResampleChunk_ModeT(
    2695             :                 args, static_cast<const GFloat16 *>(pChunk),
    2696           4 :                 static_cast<GFloat16 *>(*ppDstBuffer));
    2697             :         }
    2698             : 
    2699          32 :         case GDT_Float32:
    2700             :         {
    2701          32 :             return GDALResampleChunk_ModeT(args,
    2702             :                                            static_cast<const float *>(pChunk),
    2703          32 :                                            static_cast<float *>(*ppDstBuffer));
    2704             :         }
    2705             : 
    2706          21 :         case GDT_Float64:
    2707             :         {
    2708          21 :             return GDALResampleChunk_ModeT(args,
    2709             :                                            static_cast<const double *>(pChunk),
    2710          21 :                                            static_cast<double *>(*ppDstBuffer));
    2711             :         }
    2712             : 
    2713           4 :         case GDT_CFloat16:
    2714             :         {
    2715           4 :             return GDALResampleChunk_ModeT(
    2716             :                 args, static_cast<const ComplexFloat16 *>(pChunk),
    2717           4 :                 static_cast<ComplexFloat16 *>(*ppDstBuffer));
    2718             :         }
    2719             : 
    2720           4 :         case GDT_CFloat32:
    2721             :         {
    2722           4 :             return GDALResampleChunk_ModeT(
    2723             :                 args, static_cast<const std::complex<float> *>(pChunk),
    2724           4 :                 static_cast<std::complex<float> *>(*ppDstBuffer));
    2725             :         }
    2726             : 
    2727           4 :         case GDT_CFloat64:
    2728             :         {
    2729           4 :             return GDALResampleChunk_ModeT(
    2730             :                 args, static_cast<const std::complex<double> *>(pChunk),
    2731           4 :                 static_cast<std::complex<double> *>(*ppDstBuffer));
    2732             :         }
    2733             : 
    2734           0 :         case GDT_Unknown:
    2735             :         case GDT_TypeCount:
    2736           0 :             break;
    2737             :     }
    2738             : 
    2739           0 :     CPLAssert(false);
    2740             :     return CE_Failure;
    2741             : }
    2742             : 
    2743             : /************************************************************************/
    2744             : /*                 GDALResampleConvolutionHorizontal()                  */
    2745             : /************************************************************************/
    2746             : 
    2747             : template <class T>
    2748             : static inline double
    2749       46038 : GDALResampleConvolutionHorizontal(const T *pChunk, const double *padfWeights,
    2750             :                                   int nSrcPixelCount)
    2751             : {
    2752       46038 :     double dfVal1 = 0.0;
    2753       46038 :     double dfVal2 = 0.0;
    2754       46038 :     int i = 0;  // Used after for.
    2755             :     // Intel Compiler 2024.0.2.29 (maybe other versions?) crashes on this
    2756             :     // manually (untypical) unrolled loop in -O2 and -O3:
    2757             :     // https://github.com/OSGeo/gdal/issues/9508
    2758             : #if !defined(__INTEL_CLANG_COMPILER)
    2759       92396 :     for (; i < nSrcPixelCount - 3; i += 4)
    2760             :     {
    2761       46358 :         dfVal1 += double(pChunk[i + 0]) * padfWeights[i];
    2762       46358 :         dfVal1 += double(pChunk[i + 1]) * padfWeights[i + 1];
    2763       46358 :         dfVal2 += double(pChunk[i + 2]) * padfWeights[i + 2];
    2764       46358 :         dfVal2 += double(pChunk[i + 3]) * padfWeights[i + 3];
    2765             :     }
    2766             : #endif
    2767       48662 :     for (; i < nSrcPixelCount; ++i)
    2768             :     {
    2769        2624 :         dfVal1 += double(pChunk[i]) * padfWeights[i];
    2770             :     }
    2771       46038 :     return dfVal1 + dfVal2;
    2772             : }
    2773             : 
    2774             : template <class T>
    2775       44576 : static inline void GDALResampleConvolutionHorizontalWithMask(
    2776             :     const T *pChunk, const GByte *pabyMask, const double *padfWeights,
    2777             :     int nSrcPixelCount, double &dfVal, double &dfWeightSum)
    2778             : {
    2779       44576 :     dfVal = 0;
    2780       44576 :     dfWeightSum = 0;
    2781       44576 :     int i = 0;
    2782       98300 :     for (; i < nSrcPixelCount - 3; i += 4)
    2783             :     {
    2784       53724 :         const double dfWeight0 = padfWeights[i] * pabyMask[i];
    2785       53724 :         const double dfWeight1 = padfWeights[i + 1] * pabyMask[i + 1];
    2786       53724 :         const double dfWeight2 = padfWeights[i + 2] * pabyMask[i + 2];
    2787       53724 :         const double dfWeight3 = padfWeights[i + 3] * pabyMask[i + 3];
    2788       53724 :         dfVal += double(pChunk[i + 0]) * dfWeight0;
    2789       53724 :         dfVal += double(pChunk[i + 1]) * dfWeight1;
    2790       53724 :         dfVal += double(pChunk[i + 2]) * dfWeight2;
    2791       53724 :         dfVal += double(pChunk[i + 3]) * dfWeight3;
    2792       53724 :         dfWeightSum += dfWeight0 + dfWeight1 + dfWeight2 + dfWeight3;
    2793             :     }
    2794       61162 :     for (; i < nSrcPixelCount; ++i)
    2795             :     {
    2796       16586 :         const double dfWeight = padfWeights[i] * pabyMask[i];
    2797       16586 :         dfVal += double(pChunk[i]) * dfWeight;
    2798       16586 :         dfWeightSum += dfWeight;
    2799             :     }
    2800       44576 : }
    2801             : 
    2802             : template <class T>
    2803     1341366 : static inline void GDALResampleConvolutionHorizontal_3rows(
    2804             :     const T *pChunkRow1, const T *pChunkRow2, const T *pChunkRow3,
    2805             :     const double *padfWeights, int nSrcPixelCount, double &dfRes1,
    2806             :     double &dfRes2, double &dfRes3)
    2807             : {
    2808     1341366 :     double dfVal1 = 0.0;
    2809     1341366 :     double dfVal2 = 0.0;
    2810     1341366 :     double dfVal3 = 0.0;
    2811     1341366 :     double dfVal4 = 0.0;
    2812     1341366 :     double dfVal5 = 0.0;
    2813     1341366 :     double dfVal6 = 0.0;
    2814     1341366 :     int i = 0;  // Used after for.
    2815     2736937 :     for (; i < nSrcPixelCount - 3; i += 4)
    2816             :     {
    2817     1395570 :         dfVal1 += double(pChunkRow1[i + 0]) * padfWeights[i + 0];
    2818     1395570 :         dfVal1 += double(pChunkRow1[i + 1]) * padfWeights[i + 1];
    2819     1395570 :         dfVal2 += double(pChunkRow1[i + 2]) * padfWeights[i + 2];
    2820     1395570 :         dfVal2 += double(pChunkRow1[i + 3]) * padfWeights[i + 3];
    2821     1395570 :         dfVal3 += double(pChunkRow2[i + 0]) * padfWeights[i + 0];
    2822     1395570 :         dfVal3 += double(pChunkRow2[i + 1]) * padfWeights[i + 1];
    2823     1395570 :         dfVal4 += double(pChunkRow2[i + 2]) * padfWeights[i + 2];
    2824     1395570 :         dfVal4 += double(pChunkRow2[i + 3]) * padfWeights[i + 3];
    2825     1395570 :         dfVal5 += double(pChunkRow3[i + 0]) * padfWeights[i + 0];
    2826     1395570 :         dfVal5 += double(pChunkRow3[i + 1]) * padfWeights[i + 1];
    2827     1395570 :         dfVal6 += double(pChunkRow3[i + 2]) * padfWeights[i + 2];
    2828     1395570 :         dfVal6 += double(pChunkRow3[i + 3]) * padfWeights[i + 3];
    2829             :     }
    2830     1381377 :     for (; i < nSrcPixelCount; ++i)
    2831             :     {
    2832       40011 :         dfVal1 += double(pChunkRow1[i]) * padfWeights[i];
    2833       40011 :         dfVal3 += double(pChunkRow2[i]) * padfWeights[i];
    2834       40011 :         dfVal5 += double(pChunkRow3[i]) * padfWeights[i];
    2835             :     }
    2836     1341366 :     dfRes1 = dfVal1 + dfVal2;
    2837     1341366 :     dfRes2 = dfVal3 + dfVal4;
    2838     1341366 :     dfRes3 = dfVal5 + dfVal6;
    2839     1341366 : }
    2840             : 
    2841             : template <class T>
    2842       18980 : static inline void GDALResampleConvolutionHorizontalPixelCountLess8_3rows(
    2843             :     const T *pChunkRow1, const T *pChunkRow2, const T *pChunkRow3,
    2844             :     const double *padfWeights, int nSrcPixelCount, double &dfRes1,
    2845             :     double &dfRes2, double &dfRes3)
    2846             : {
    2847       18980 :     GDALResampleConvolutionHorizontal_3rows(pChunkRow1, pChunkRow2, pChunkRow3,
    2848             :                                             padfWeights, nSrcPixelCount, dfRes1,
    2849             :                                             dfRes2, dfRes3);
    2850       18980 : }
    2851             : 
    2852             : template <class T>
    2853     1256690 : static inline void GDALResampleConvolutionHorizontalPixelCount4_3rows(
    2854             :     const T *pChunkRow1, const T *pChunkRow2, const T *pChunkRow3,
    2855             :     const double *padfWeights, double &dfRes1, double &dfRes2, double &dfRes3)
    2856             : {
    2857     1256690 :     GDALResampleConvolutionHorizontal_3rows(pChunkRow1, pChunkRow2, pChunkRow3,
    2858             :                                             padfWeights, 4, dfRes1, dfRes2,
    2859             :                                             dfRes3);
    2860     1256690 : }
    2861             : 
    2862             : /************************************************************************/
    2863             : /*                  GDALResampleConvolutionVertical()                   */
    2864             : /************************************************************************/
    2865             : 
    2866             : template <class T>
    2867             : static inline double
    2868      465678 : GDALResampleConvolutionVertical(const T *pChunk, size_t nStride,
    2869             :                                 const double *padfWeights, int nSrcLineCount)
    2870             : {
    2871      465678 :     double dfVal1 = 0.0;
    2872      465678 :     double dfVal2 = 0.0;
    2873      465678 :     int i = 0;
    2874      465678 :     size_t j = 0;
    2875      916919 :     for (; i < nSrcLineCount - 3; i += 4, j += 4 * nStride)
    2876             :     {
    2877      451241 :         dfVal1 += pChunk[j + 0 * nStride] * padfWeights[i + 0];
    2878      451241 :         dfVal1 += pChunk[j + 1 * nStride] * padfWeights[i + 1];
    2879      451241 :         dfVal2 += pChunk[j + 2 * nStride] * padfWeights[i + 2];
    2880      451241 :         dfVal2 += pChunk[j + 3 * nStride] * padfWeights[i + 3];
    2881             :     }
    2882      519809 :     for (; i < nSrcLineCount; ++i, j += nStride)
    2883             :     {
    2884       54131 :         dfVal1 += pChunk[j] * padfWeights[i];
    2885             :     }
    2886      465678 :     return dfVal1 + dfVal2;
    2887             : }
    2888             : 
    2889             : template <class T>
    2890     2930610 : static inline void GDALResampleConvolutionVertical_2cols(
    2891             :     const T *pChunk, size_t nStride, const double *padfWeights,
    2892             :     int nSrcLineCount, double &dfRes1, double &dfRes2)
    2893             : {
    2894     2930610 :     double dfVal1 = 0.0;
    2895     2930610 :     double dfVal2 = 0.0;
    2896     2930610 :     double dfVal3 = 0.0;
    2897     2930610 :     double dfVal4 = 0.0;
    2898     2930610 :     int i = 0;
    2899     2930610 :     size_t j = 0;
    2900     5863170 :     for (; i < nSrcLineCount - 3; i += 4, j += 4 * nStride)
    2901             :     {
    2902     2932560 :         dfVal1 += pChunk[j + 0 + 0 * nStride] * padfWeights[i + 0];
    2903     2932560 :         dfVal3 += pChunk[j + 1 + 0 * nStride] * padfWeights[i + 0];
    2904     2932560 :         dfVal1 += pChunk[j + 0 + 1 * nStride] * padfWeights[i + 1];
    2905     2932560 :         dfVal3 += pChunk[j + 1 + 1 * nStride] * padfWeights[i + 1];
    2906     2932560 :         dfVal2 += pChunk[j + 0 + 2 * nStride] * padfWeights[i + 2];
    2907     2932560 :         dfVal4 += pChunk[j + 1 + 2 * nStride] * padfWeights[i + 2];
    2908     2932560 :         dfVal2 += pChunk[j + 0 + 3 * nStride] * padfWeights[i + 3];
    2909     2932560 :         dfVal4 += pChunk[j + 1 + 3 * nStride] * padfWeights[i + 3];
    2910             :     }
    2911     3053490 :     for (; i < nSrcLineCount; ++i, j += nStride)
    2912             :     {
    2913      122880 :         dfVal1 += pChunk[j + 0] * padfWeights[i];
    2914      122880 :         dfVal3 += pChunk[j + 1] * padfWeights[i];
    2915             :     }
    2916     2930610 :     dfRes1 = dfVal1 + dfVal2;
    2917     2930610 :     dfRes2 = dfVal3 + dfVal4;
    2918     2930610 : }
    2919             : 
    2920             : #ifdef USE_SSE2
    2921             : 
    2922             : #ifdef __AVX__
    2923             : /************************************************************************/
    2924             : /*              GDALResampleConvolutionVertical_16cols<T>               */
    2925             : /************************************************************************/
    2926             : 
    2927             : template <class T>
    2928             : static inline void
    2929             : GDALResampleConvolutionVertical_16cols(const T *pChunk, size_t nStride,
    2930             :                                        const double *padfWeights,
    2931             :                                        int nSrcLineCount, float *afDest)
    2932             : {
    2933             :     int i = 0;
    2934             :     size_t j = 0;
    2935             :     XMMReg4Double v_acc0 = XMMReg4Double::Zero();
    2936             :     XMMReg4Double v_acc1 = XMMReg4Double::Zero();
    2937             :     XMMReg4Double v_acc2 = XMMReg4Double::Zero();
    2938             :     XMMReg4Double v_acc3 = XMMReg4Double::Zero();
    2939             :     for (; i < nSrcLineCount - 3; i += 4, j += 4 * nStride)
    2940             :     {
    2941             :         XMMReg4Double w0 =
    2942             :             XMMReg4Double::Load1ValHighAndLow(padfWeights + i + 0);
    2943             :         XMMReg4Double w1 =
    2944             :             XMMReg4Double::Load1ValHighAndLow(padfWeights + i + 1);
    2945             :         XMMReg4Double w2 =
    2946             :             XMMReg4Double::Load1ValHighAndLow(padfWeights + i + 2);
    2947             :         XMMReg4Double w3 =
    2948             :             XMMReg4Double::Load1ValHighAndLow(padfWeights + i + 3);
    2949             :         v_acc0 += XMMReg4Double::Load4Val(pChunk + j + 0 + 0 * nStride) * w0;
    2950             :         v_acc1 += XMMReg4Double::Load4Val(pChunk + j + 4 + 0 * nStride) * w0;
    2951             :         v_acc2 += XMMReg4Double::Load4Val(pChunk + j + 8 + 0 * nStride) * w0;
    2952             :         v_acc3 += XMMReg4Double::Load4Val(pChunk + j + 12 + 0 * nStride) * w0;
    2953             :         v_acc0 += XMMReg4Double::Load4Val(pChunk + j + 0 + 1 * nStride) * w1;
    2954             :         v_acc1 += XMMReg4Double::Load4Val(pChunk + j + 4 + 1 * nStride) * w1;
    2955             :         v_acc2 += XMMReg4Double::Load4Val(pChunk + j + 8 + 1 * nStride) * w1;
    2956             :         v_acc3 += XMMReg4Double::Load4Val(pChunk + j + 12 + 1 * nStride) * w1;
    2957             :         v_acc0 += XMMReg4Double::Load4Val(pChunk + j + 0 + 2 * nStride) * w2;
    2958             :         v_acc1 += XMMReg4Double::Load4Val(pChunk + j + 4 + 2 * nStride) * w2;
    2959             :         v_acc2 += XMMReg4Double::Load4Val(pChunk + j + 8 + 2 * nStride) * w2;
    2960             :         v_acc3 += XMMReg4Double::Load4Val(pChunk + j + 12 + 2 * nStride) * w2;
    2961             :         v_acc0 += XMMReg4Double::Load4Val(pChunk + j + 0 + 3 * nStride) * w3;
    2962             :         v_acc1 += XMMReg4Double::Load4Val(pChunk + j + 4 + 3 * nStride) * w3;
    2963             :         v_acc2 += XMMReg4Double::Load4Val(pChunk + j + 8 + 3 * nStride) * w3;
    2964             :         v_acc3 += XMMReg4Double::Load4Val(pChunk + j + 12 + 3 * nStride) * w3;
    2965             :     }
    2966             :     for (; i < nSrcLineCount; ++i, j += nStride)
    2967             :     {
    2968             :         XMMReg4Double w = XMMReg4Double::Load1ValHighAndLow(padfWeights + i);
    2969             :         v_acc0 += XMMReg4Double::Load4Val(pChunk + j + 0) * w;
    2970             :         v_acc1 += XMMReg4Double::Load4Val(pChunk + j + 4) * w;
    2971             :         v_acc2 += XMMReg4Double::Load4Val(pChunk + j + 8) * w;
    2972             :         v_acc3 += XMMReg4Double::Load4Val(pChunk + j + 12) * w;
    2973             :     }
    2974             :     v_acc0.Store4Val(afDest);
    2975             :     v_acc1.Store4Val(afDest + 4);
    2976             :     v_acc2.Store4Val(afDest + 8);
    2977             :     v_acc3.Store4Val(afDest + 12);
    2978             : }
    2979             : 
    2980             : template <class T>
    2981             : static inline void GDALResampleConvolutionVertical_16cols(const T *, int,
    2982             :                                                           const double *, int,
    2983             :                                                           double *)
    2984             : {
    2985             :     // Cannot be reached
    2986             :     CPLAssert(false);
    2987             : }
    2988             : 
    2989             : #else
    2990             : 
    2991             : /************************************************************************/
    2992             : /*               GDALResampleConvolutionVertical_8cols<T>               */
    2993             : /************************************************************************/
    2994             : 
    2995             : template <class T>
    2996             : static inline void
    2997    25609800 : GDALResampleConvolutionVertical_8cols(const T *pChunk, size_t nStride,
    2998             :                                       const double *padfWeights,
    2999             :                                       int nSrcLineCount, float *afDest)
    3000             : {
    3001    25609800 :     int i = 0;
    3002    25609800 :     size_t j = 0;
    3003    25609800 :     XMMReg4Double v_acc0 = XMMReg4Double::Zero();
    3004    25609800 :     XMMReg4Double v_acc1 = XMMReg4Double::Zero();
    3005    53417600 :     for (; i < nSrcLineCount - 3; i += 4, j += 4 * nStride)
    3006             :     {
    3007    27807800 :         XMMReg4Double w0 =
    3008    27807800 :             XMMReg4Double::Load1ValHighAndLow(padfWeights + i + 0);
    3009    27807800 :         XMMReg4Double w1 =
    3010    27807800 :             XMMReg4Double::Load1ValHighAndLow(padfWeights + i + 1);
    3011    27807800 :         XMMReg4Double w2 =
    3012    27807800 :             XMMReg4Double::Load1ValHighAndLow(padfWeights + i + 2);
    3013    27807800 :         XMMReg4Double w3 =
    3014    27807800 :             XMMReg4Double::Load1ValHighAndLow(padfWeights + i + 3);
    3015    27807800 :         v_acc0 += XMMReg4Double::Load4Val(pChunk + j + 0 + 0 * nStride) * w0;
    3016    27807800 :         v_acc1 += XMMReg4Double::Load4Val(pChunk + j + 4 + 0 * nStride) * w0;
    3017    27807800 :         v_acc0 += XMMReg4Double::Load4Val(pChunk + j + 0 + 1 * nStride) * w1;
    3018    27807800 :         v_acc1 += XMMReg4Double::Load4Val(pChunk + j + 4 + 1 * nStride) * w1;
    3019    27807800 :         v_acc0 += XMMReg4Double::Load4Val(pChunk + j + 0 + 2 * nStride) * w2;
    3020    27807800 :         v_acc1 += XMMReg4Double::Load4Val(pChunk + j + 4 + 2 * nStride) * w2;
    3021    27807800 :         v_acc0 += XMMReg4Double::Load4Val(pChunk + j + 0 + 3 * nStride) * w3;
    3022    27807800 :         v_acc1 += XMMReg4Double::Load4Val(pChunk + j + 4 + 3 * nStride) * w3;
    3023             :     }
    3024    37176700 :     for (; i < nSrcLineCount; ++i, j += nStride)
    3025             :     {
    3026    11566800 :         XMMReg4Double w = XMMReg4Double::Load1ValHighAndLow(padfWeights + i);
    3027    11566800 :         v_acc0 += XMMReg4Double::Load4Val(pChunk + j + 0) * w;
    3028    11566800 :         v_acc1 += XMMReg4Double::Load4Val(pChunk + j + 4) * w;
    3029             :     }
    3030    25609800 :     v_acc0.Store4Val(afDest);
    3031    25609800 :     v_acc1.Store4Val(afDest + 4);
    3032    25609800 : }
    3033             : 
    3034             : template <class T>
    3035             : static inline void GDALResampleConvolutionVertical_8cols(const T *, int,
    3036             :                                                          const double *, int,
    3037             :                                                          double *)
    3038             : {
    3039             :     // Cannot be reached
    3040             :     CPLAssert(false);
    3041             : }
    3042             : 
    3043             : #endif  // __AVX__
    3044             : 
    3045             : /************************************************************************/
    3046             : /*               GDALResampleConvolutionHorizontalSSE2<T>               */
    3047             : /************************************************************************/
    3048             : 
    3049             : template <class T>
    3050     3137782 : static inline double GDALResampleConvolutionHorizontalSSE2(
    3051             :     const T *pChunk, const double *padfWeightsAligned, int nSrcPixelCount)
    3052             : {
    3053     3137782 :     XMMReg4Double v_acc1 = XMMReg4Double::Zero();
    3054     3137782 :     XMMReg4Double v_acc2 = XMMReg4Double::Zero();
    3055     3137782 :     int i = 0;  // Used after for.
    3056     3513158 :     for (; i < nSrcPixelCount - 7; i += 8)
    3057             :     {
    3058             :         // Retrieve the pixel & accumulate
    3059      375371 :         const XMMReg4Double v_pixels1 = XMMReg4Double::Load4Val(pChunk + i);
    3060      375371 :         const XMMReg4Double v_pixels2 = XMMReg4Double::Load4Val(pChunk + i + 4);
    3061      375371 :         const XMMReg4Double v_weight1 =
    3062      375371 :             XMMReg4Double::Load4ValAligned(padfWeightsAligned + i);
    3063      375371 :         const XMMReg4Double v_weight2 =
    3064      375371 :             XMMReg4Double::Load4ValAligned(padfWeightsAligned + i + 4);
    3065             : 
    3066      375371 :         v_acc1 += v_pixels1 * v_weight1;
    3067      375371 :         v_acc2 += v_pixels2 * v_weight2;
    3068             :     }
    3069             : 
    3070     3137782 :     v_acc1 += v_acc2;
    3071             : 
    3072     3137782 :     double dfVal = v_acc1.GetHorizSum();
    3073    10317730 :     for (; i < nSrcPixelCount; ++i)
    3074             :     {
    3075     7179950 :         dfVal += pChunk[i] * padfWeightsAligned[i];
    3076             :     }
    3077     3137782 :     return dfVal;
    3078             : }
    3079             : 
    3080             : /************************************************************************/
    3081             : /*               GDALResampleConvolutionHorizontal<GByte>               */
    3082             : /************************************************************************/
    3083             : 
    3084             : template <>
    3085     2588620 : inline double GDALResampleConvolutionHorizontal<GByte>(
    3086             :     const GByte *pChunk, const double *padfWeightsAligned, int nSrcPixelCount)
    3087             : {
    3088     2588620 :     return GDALResampleConvolutionHorizontalSSE2(pChunk, padfWeightsAligned,
    3089     2588620 :                                                  nSrcPixelCount);
    3090             : }
    3091             : 
    3092             : template <>
    3093      549162 : inline double GDALResampleConvolutionHorizontal<GUInt16>(
    3094             :     const GUInt16 *pChunk, const double *padfWeightsAligned, int nSrcPixelCount)
    3095             : {
    3096      549162 :     return GDALResampleConvolutionHorizontalSSE2(pChunk, padfWeightsAligned,
    3097      549162 :                                                  nSrcPixelCount);
    3098             : }
    3099             : 
    3100             : /************************************************************************/
    3101             : /*           GDALResampleConvolutionHorizontalWithMaskSSE2<T>           */
    3102             : /************************************************************************/
    3103             : 
    3104             : template <class T>
    3105     6408653 : static inline void GDALResampleConvolutionHorizontalWithMaskSSE2(
    3106             :     const T *pChunk, const GByte *pabyMask, const double *padfWeightsAligned,
    3107             :     int nSrcPixelCount, double &dfVal, double &dfWeightSum)
    3108             : {
    3109     6408653 :     int i = 0;  // Used after for.
    3110     6408653 :     XMMReg4Double v_acc = XMMReg4Double::Zero();
    3111     6408653 :     XMMReg4Double v_acc_weight = XMMReg4Double::Zero();
    3112    17785121 :     for (; i < nSrcPixelCount - 3; i += 4)
    3113             :     {
    3114    11376458 :         const XMMReg4Double v_pixels = XMMReg4Double::Load4Val(pChunk + i);
    3115    11376458 :         const XMMReg4Double v_mask = XMMReg4Double::Load4Val(pabyMask + i);
    3116    11376458 :         XMMReg4Double v_weight =
    3117    11376458 :             XMMReg4Double::Load4ValAligned(padfWeightsAligned + i);
    3118    11376458 :         v_weight *= v_mask;
    3119    11376458 :         v_acc += v_pixels * v_weight;
    3120    11376458 :         v_acc_weight += v_weight;
    3121             :     }
    3122             : 
    3123     6408653 :     dfVal = v_acc.GetHorizSum();
    3124     6408653 :     dfWeightSum = v_acc_weight.GetHorizSum();
    3125     6614913 :     for (; i < nSrcPixelCount; ++i)
    3126             :     {
    3127      206258 :         const double dfWeight = padfWeightsAligned[i] * pabyMask[i];
    3128      206258 :         dfVal += pChunk[i] * dfWeight;
    3129      206258 :         dfWeightSum += dfWeight;
    3130             :     }
    3131     6408653 : }
    3132             : 
    3133             : /************************************************************************/
    3134             : /*           GDALResampleConvolutionHorizontalWithMask<GByte>           */
    3135             : /************************************************************************/
    3136             : 
    3137             : template <>
    3138     6408590 : inline void GDALResampleConvolutionHorizontalWithMask<GByte>(
    3139             :     const GByte *pChunk, const GByte *pabyMask,
    3140             :     const double *padfWeightsAligned, int nSrcPixelCount, double &dfVal,
    3141             :     double &dfWeightSum)
    3142             : {
    3143     6408590 :     GDALResampleConvolutionHorizontalWithMaskSSE2(
    3144             :         pChunk, pabyMask, padfWeightsAligned, nSrcPixelCount, dfVal,
    3145             :         dfWeightSum);
    3146     6408590 : }
    3147             : 
    3148             : template <>
    3149          63 : inline void GDALResampleConvolutionHorizontalWithMask<GUInt16>(
    3150             :     const GUInt16 *pChunk, const GByte *pabyMask,
    3151             :     const double *padfWeightsAligned, int nSrcPixelCount, double &dfVal,
    3152             :     double &dfWeightSum)
    3153             : {
    3154          63 :     GDALResampleConvolutionHorizontalWithMaskSSE2(
    3155             :         pChunk, pabyMask, padfWeightsAligned, nSrcPixelCount, dfVal,
    3156             :         dfWeightSum);
    3157          63 : }
    3158             : 
    3159             : /************************************************************************/
    3160             : /*           GDALResampleConvolutionHorizontal_3rows_SSE2<T>            */
    3161             : /************************************************************************/
    3162             : 
    3163             : template <class T>
    3164    35128386 : static inline void GDALResampleConvolutionHorizontal_3rows_SSE2(
    3165             :     const T *pChunkRow1, const T *pChunkRow2, const T *pChunkRow3,
    3166             :     const double *padfWeightsAligned, int nSrcPixelCount, double &dfRes1,
    3167             :     double &dfRes2, double &dfRes3)
    3168             : {
    3169    35128386 :     XMMReg4Double v_acc1 = XMMReg4Double::Zero(),
    3170    35128386 :                   v_acc2 = XMMReg4Double::Zero(),
    3171    35128386 :                   v_acc3 = XMMReg4Double::Zero();
    3172    35128386 :     int i = 0;
    3173    70070156 :     for (; i < nSrcPixelCount - 7; i += 8)
    3174             :     {
    3175             :         // Retrieve the pixel & accumulate.
    3176    34941870 :         XMMReg4Double v_pixels1 = XMMReg4Double::Load4Val(pChunkRow1 + i);
    3177    34941870 :         XMMReg4Double v_pixels2 = XMMReg4Double::Load4Val(pChunkRow1 + i + 4);
    3178    34941870 :         const XMMReg4Double v_weight1 =
    3179    34941870 :             XMMReg4Double::Load4ValAligned(padfWeightsAligned + i);
    3180    34941870 :         const XMMReg4Double v_weight2 =
    3181    34941870 :             XMMReg4Double::Load4ValAligned(padfWeightsAligned + i + 4);
    3182             : 
    3183    34941870 :         v_acc1 += v_pixels1 * v_weight1;
    3184    34941870 :         v_acc1 += v_pixels2 * v_weight2;
    3185             : 
    3186    34941870 :         v_pixels1 = XMMReg4Double::Load4Val(pChunkRow2 + i);
    3187    34941870 :         v_pixels2 = XMMReg4Double::Load4Val(pChunkRow2 + i + 4);
    3188    34941870 :         v_acc2 += v_pixels1 * v_weight1;
    3189    34941870 :         v_acc2 += v_pixels2 * v_weight2;
    3190             : 
    3191    34941870 :         v_pixels1 = XMMReg4Double::Load4Val(pChunkRow3 + i);
    3192    34941870 :         v_pixels2 = XMMReg4Double::Load4Val(pChunkRow3 + i + 4);
    3193    34941870 :         v_acc3 += v_pixels1 * v_weight1;
    3194    34941870 :         v_acc3 += v_pixels2 * v_weight2;
    3195             :     }
    3196             : 
    3197    35128386 :     dfRes1 = v_acc1.GetHorizSum();
    3198    35128386 :     dfRes2 = v_acc2.GetHorizSum();
    3199    35128386 :     dfRes3 = v_acc3.GetHorizSum();
    3200    47367852 :     for (; i < nSrcPixelCount; ++i)
    3201             :     {
    3202    12239466 :         dfRes1 += pChunkRow1[i] * padfWeightsAligned[i];
    3203    12239466 :         dfRes2 += pChunkRow2[i] * padfWeightsAligned[i];
    3204    12239466 :         dfRes3 += pChunkRow3[i] * padfWeightsAligned[i];
    3205             :     }
    3206    35128386 : }
    3207             : 
    3208             : /************************************************************************/
    3209             : /*            GDALResampleConvolutionHorizontal_3rows<GByte>            */
    3210             : /************************************************************************/
    3211             : 
    3212             : template <>
    3213    35128300 : inline void GDALResampleConvolutionHorizontal_3rows<GByte>(
    3214             :     const GByte *pChunkRow1, const GByte *pChunkRow2, const GByte *pChunkRow3,
    3215             :     const double *padfWeightsAligned, int nSrcPixelCount, double &dfRes1,
    3216             :     double &dfRes2, double &dfRes3)
    3217             : {
    3218    35128300 :     GDALResampleConvolutionHorizontal_3rows_SSE2(
    3219             :         pChunkRow1, pChunkRow2, pChunkRow3, padfWeightsAligned, nSrcPixelCount,
    3220             :         dfRes1, dfRes2, dfRes3);
    3221    35128300 : }
    3222             : 
    3223             : template <>
    3224          86 : inline void GDALResampleConvolutionHorizontal_3rows<GUInt16>(
    3225             :     const GUInt16 *pChunkRow1, const GUInt16 *pChunkRow2,
    3226             :     const GUInt16 *pChunkRow3, const double *padfWeightsAligned,
    3227             :     int nSrcPixelCount, double &dfRes1, double &dfRes2, double &dfRes3)
    3228             : {
    3229          86 :     GDALResampleConvolutionHorizontal_3rows_SSE2(
    3230             :         pChunkRow1, pChunkRow2, pChunkRow3, padfWeightsAligned, nSrcPixelCount,
    3231             :         dfRes1, dfRes2, dfRes3);
    3232          86 : }
    3233             : 
    3234             : /************************************************************************/
    3235             : /*    GDALResampleConvolutionHorizontalPixelCountLess8_3rows_SSE2<T>    */
    3236             : /************************************************************************/
    3237             : 
    3238             : template <class T>
    3239     7840250 : static inline void GDALResampleConvolutionHorizontalPixelCountLess8_3rows_SSE2(
    3240             :     const T *pChunkRow1, const T *pChunkRow2, const T *pChunkRow3,
    3241             :     const double *padfWeightsAligned, int nSrcPixelCount, double &dfRes1,
    3242             :     double &dfRes2, double &dfRes3)
    3243             : {
    3244     7840250 :     XMMReg4Double v_acc1 = XMMReg4Double::Zero();
    3245     7840250 :     XMMReg4Double v_acc2 = XMMReg4Double::Zero();
    3246     7840250 :     XMMReg4Double v_acc3 = XMMReg4Double::Zero();
    3247     7840250 :     int i = 0;  // Use after for.
    3248    19104350 :     for (; i < nSrcPixelCount - 3; i += 4)
    3249             :     {
    3250             :         // Retrieve the pixel & accumulate.
    3251    11264100 :         const XMMReg4Double v_pixels1 = XMMReg4Double::Load4Val(pChunkRow1 + i);
    3252    11264100 :         const XMMReg4Double v_pixels2 = XMMReg4Double::Load4Val(pChunkRow2 + i);
    3253    11264100 :         const XMMReg4Double v_pixels3 = XMMReg4Double::Load4Val(pChunkRow3 + i);
    3254    11264100 :         const XMMReg4Double v_weight =
    3255    11264100 :             XMMReg4Double::Load4ValAligned(padfWeightsAligned + i);
    3256             : 
    3257    11264100 :         v_acc1 += v_pixels1 * v_weight;
    3258    11264100 :         v_acc2 += v_pixels2 * v_weight;
    3259    11264100 :         v_acc3 += v_pixels3 * v_weight;
    3260             :     }
    3261             : 
    3262     7840250 :     dfRes1 = v_acc1.GetHorizSum();
    3263     7840250 :     dfRes2 = v_acc2.GetHorizSum();
    3264     7840250 :     dfRes3 = v_acc3.GetHorizSum();
    3265             : 
    3266    12290222 :     for (; i < nSrcPixelCount; ++i)
    3267             :     {
    3268     4449942 :         dfRes1 += pChunkRow1[i] * padfWeightsAligned[i];
    3269     4449942 :         dfRes2 += pChunkRow2[i] * padfWeightsAligned[i];
    3270     4449942 :         dfRes3 += pChunkRow3[i] * padfWeightsAligned[i];
    3271             :     }
    3272     7840250 : }
    3273             : 
    3274             : /************************************************************************/
    3275             : /*    GDALResampleConvolutionHorizontalPixelCountLess8_3rows<GByte>     */
    3276             : /************************************************************************/
    3277             : 
    3278             : template <>
    3279     7773100 : inline void GDALResampleConvolutionHorizontalPixelCountLess8_3rows<GByte>(
    3280             :     const GByte *pChunkRow1, const GByte *pChunkRow2, const GByte *pChunkRow3,
    3281             :     const double *padfWeightsAligned, int nSrcPixelCount, double &dfRes1,
    3282             :     double &dfRes2, double &dfRes3)
    3283             : {
    3284     7773100 :     GDALResampleConvolutionHorizontalPixelCountLess8_3rows_SSE2(
    3285             :         pChunkRow1, pChunkRow2, pChunkRow3, padfWeightsAligned, nSrcPixelCount,
    3286             :         dfRes1, dfRes2, dfRes3);
    3287     7773100 : }
    3288             : 
    3289             : template <>
    3290       67150 : inline void GDALResampleConvolutionHorizontalPixelCountLess8_3rows<GUInt16>(
    3291             :     const GUInt16 *pChunkRow1, const GUInt16 *pChunkRow2,
    3292             :     const GUInt16 *pChunkRow3, const double *padfWeightsAligned,
    3293             :     int nSrcPixelCount, double &dfRes1, double &dfRes2, double &dfRes3)
    3294             : {
    3295       67150 :     GDALResampleConvolutionHorizontalPixelCountLess8_3rows_SSE2(
    3296             :         pChunkRow1, pChunkRow2, pChunkRow3, padfWeightsAligned, nSrcPixelCount,
    3297             :         dfRes1, dfRes2, dfRes3);
    3298       67150 : }
    3299             : 
    3300             : /************************************************************************/
    3301             : /*      GDALResampleConvolutionHorizontalPixelCount4_3rows_SSE2<T>      */
    3302             : /************************************************************************/
    3303             : 
    3304             : template <class T>
    3305    13996690 : static inline void GDALResampleConvolutionHorizontalPixelCount4_3rows_SSE2(
    3306             :     const T *pChunkRow1, const T *pChunkRow2, const T *pChunkRow3,
    3307             :     const double *padfWeightsAligned, double &dfRes1, double &dfRes2,
    3308             :     double &dfRes3)
    3309             : {
    3310    13996690 :     const XMMReg4Double v_weight =
    3311             :         XMMReg4Double::Load4ValAligned(padfWeightsAligned);
    3312             : 
    3313             :     // Retrieve the pixel & accumulate.
    3314    13996690 :     const XMMReg4Double v_pixels1 = XMMReg4Double::Load4Val(pChunkRow1);
    3315    13996690 :     const XMMReg4Double v_pixels2 = XMMReg4Double::Load4Val(pChunkRow2);
    3316    13996690 :     const XMMReg4Double v_pixels3 = XMMReg4Double::Load4Val(pChunkRow3);
    3317             : 
    3318    13996690 :     XMMReg4Double v_acc1 = v_pixels1 * v_weight;
    3319    13996690 :     XMMReg4Double v_acc2 = v_pixels2 * v_weight;
    3320    13996690 :     XMMReg4Double v_acc3 = v_pixels3 * v_weight;
    3321             : 
    3322    13996690 :     dfRes1 = v_acc1.GetHorizSum();
    3323    13996690 :     dfRes2 = v_acc2.GetHorizSum();
    3324    13996690 :     dfRes3 = v_acc3.GetHorizSum();
    3325    13996690 : }
    3326             : 
    3327             : /************************************************************************/
    3328             : /*      GDALResampleConvolutionHorizontalPixelCount4_3rows<GByte>       */
    3329             : /************************************************************************/
    3330             : 
    3331             : template <>
    3332     8283970 : inline void GDALResampleConvolutionHorizontalPixelCount4_3rows<GByte>(
    3333             :     const GByte *pChunkRow1, const GByte *pChunkRow2, const GByte *pChunkRow3,
    3334             :     const double *padfWeightsAligned, double &dfRes1, double &dfRes2,
    3335             :     double &dfRes3)
    3336             : {
    3337     8283970 :     GDALResampleConvolutionHorizontalPixelCount4_3rows_SSE2(
    3338             :         pChunkRow1, pChunkRow2, pChunkRow3, padfWeightsAligned, dfRes1, dfRes2,
    3339             :         dfRes3);
    3340     8283970 : }
    3341             : 
    3342             : template <>
    3343     5712720 : inline void GDALResampleConvolutionHorizontalPixelCount4_3rows<GUInt16>(
    3344             :     const GUInt16 *pChunkRow1, const GUInt16 *pChunkRow2,
    3345             :     const GUInt16 *pChunkRow3, const double *padfWeightsAligned, double &dfRes1,
    3346             :     double &dfRes2, double &dfRes3)
    3347             : {
    3348     5712720 :     GDALResampleConvolutionHorizontalPixelCount4_3rows_SSE2(
    3349             :         pChunkRow1, pChunkRow2, pChunkRow3, padfWeightsAligned, dfRes1, dfRes2,
    3350             :         dfRes3);
    3351     5712720 : }
    3352             : 
    3353             : #endif  // USE_SSE2
    3354             : 
    3355             : /************************************************************************/
    3356             : /*                   GDALResampleChunk_Convolution()                    */
    3357             : /************************************************************************/
    3358             : 
    3359             : template <class T, class Twork, GDALDataType eWrkDataType,
    3360             :           bool bKernelWithNegativeWeights, bool bNeedRescale>
    3361        5093 : static CPLErr GDALResampleChunk_ConvolutionT(
    3362             :     const GDALOverviewResampleArgs &args, const T *pChunk, void *pDstBuffer,
    3363             :     FilterFuncType pfnFilterFunc, FilterFunc4ValuesType pfnFilterFunc4Values,
    3364             :     int nKernelRadius, float fMaxVal)
    3365             : 
    3366             : {
    3367        5093 :     const double dfXRatioDstToSrc = args.dfXRatioDstToSrc;
    3368        5093 :     const double dfYRatioDstToSrc = args.dfYRatioDstToSrc;
    3369        5093 :     const double dfSrcXDelta = args.dfSrcXDelta;
    3370        5093 :     const double dfSrcYDelta = args.dfSrcYDelta;
    3371        5093 :     constexpr int nBands = 1;
    3372        5093 :     const GByte *pabyChunkNodataMask = args.pabyChunkNodataMask;
    3373        5093 :     const int nChunkXOff = args.nChunkXOff;
    3374        5093 :     const int nChunkXSize = args.nChunkXSize;
    3375        5093 :     const int nChunkYOff = args.nChunkYOff;
    3376        5093 :     const int nChunkYSize = args.nChunkYSize;
    3377        5093 :     const int nDstXOff = args.nDstXOff;
    3378        5093 :     const int nDstXOff2 = args.nDstXOff2;
    3379        5093 :     const int nDstYOff = args.nDstYOff;
    3380        5093 :     const int nDstYOff2 = args.nDstYOff2;
    3381        5093 :     const bool bHasNoData = args.bHasNoData;
    3382        5093 :     double dfNoDataValue = args.dfNoDataValue;
    3383             : 
    3384        5093 :     if (!bHasNoData)
    3385        5018 :         dfNoDataValue = 0.0;
    3386        5093 :     const auto dstDataType = args.eOvrDataType;
    3387        5093 :     const int nDstDataTypeSize = GDALGetDataTypeSizeBytes(dstDataType);
    3388        5093 :     const double dfReplacementVal =
    3389          75 :         bHasNoData ? GDALGetNoDataReplacementValue(dstDataType, dfNoDataValue)
    3390             :                    : dfNoDataValue;
    3391             :     // cppcheck-suppress unreadVariable
    3392        5093 :     const int isIntegerDT = GDALDataTypeIsInteger(dstDataType);
    3393        5093 :     const bool bNoDataValueInt64Valid =
    3394        5093 :         isIntegerDT && GDALIsValueExactAs<GInt64>(dfNoDataValue);
    3395        5093 :     const auto nNodataValueInt64 =
    3396             :         bNoDataValueInt64Valid ? static_cast<GInt64>(dfNoDataValue) : 0;
    3397        5093 :     constexpr int nWrkDataTypeSize = static_cast<int>(sizeof(Twork));
    3398             : 
    3399             :     // TODO: we should have some generic function to do this.
    3400        5093 :     Twork fDstMin = cpl::NumericLimits<Twork>::lowest();
    3401        5093 :     Twork fDstMax = cpl::NumericLimits<Twork>::max();
    3402        5093 :     if (dstDataType == GDT_UInt8)
    3403             :     {
    3404        4225 :         fDstMin = std::numeric_limits<GByte>::min();
    3405        4225 :         fDstMax = std::numeric_limits<GByte>::max();
    3406             :     }
    3407         868 :     else if (dstDataType == GDT_Int8)
    3408             :     {
    3409           1 :         fDstMin = std::numeric_limits<GInt8>::min();
    3410           1 :         fDstMax = std::numeric_limits<GInt8>::max();
    3411             :     }
    3412         867 :     else if (dstDataType == GDT_UInt16)
    3413             :     {
    3414         402 :         fDstMin = std::numeric_limits<GUInt16>::min();
    3415         402 :         fDstMax = std::numeric_limits<GUInt16>::max();
    3416             :     }
    3417         465 :     else if (dstDataType == GDT_Int16)
    3418             :     {
    3419         291 :         fDstMin = std::numeric_limits<GInt16>::min();
    3420         291 :         fDstMax = std::numeric_limits<GInt16>::max();
    3421             :     }
    3422         174 :     else if (dstDataType == GDT_UInt32)
    3423             :     {
    3424           1 :         fDstMin = static_cast<Twork>(std::numeric_limits<GUInt32>::min());
    3425           1 :         fDstMax = static_cast<Twork>(std::numeric_limits<GUInt32>::max());
    3426             :     }
    3427         173 :     else if (dstDataType == GDT_Int32)
    3428             :     {
    3429             :         // cppcheck-suppress unreadVariable
    3430           2 :         fDstMin = static_cast<Twork>(std::numeric_limits<GInt32>::min());
    3431             :         // cppcheck-suppress unreadVariable
    3432           2 :         fDstMax = static_cast<Twork>(std::numeric_limits<GInt32>::max());
    3433             :     }
    3434         171 :     else if (dstDataType == GDT_UInt64)
    3435             :     {
    3436             :         // cppcheck-suppress unreadVariable
    3437           1 :         fDstMin = static_cast<Twork>(std::numeric_limits<uint64_t>::min());
    3438             :         // cppcheck-suppress unreadVariable
    3439             :         // (1 << 64) - 2048: largest uint64 value a double can hold
    3440           1 :         fDstMax = static_cast<Twork>(18446744073709549568ULL);
    3441             :     }
    3442         170 :     else if (dstDataType == GDT_Int64)
    3443             :     {
    3444             :         // cppcheck-suppress unreadVariable
    3445           1 :         fDstMin = static_cast<Twork>(std::numeric_limits<int64_t>::min());
    3446             :         // cppcheck-suppress unreadVariable
    3447             :         // (1 << 63) - 1024: largest int64 that a double can hold
    3448           1 :         fDstMax = static_cast<Twork>(9223372036854774784LL);
    3449             :     }
    3450             : 
    3451    36939169 :     auto replaceValIfNodata = [bHasNoData, isIntegerDT, fDstMin, fDstMax,
    3452             :                                bNoDataValueInt64Valid, nNodataValueInt64,
    3453             :                                dfNoDataValue, dfReplacementVal](Twork fVal)
    3454             :     {
    3455    15833200 :         if (!bHasNoData)
    3456    11612800 :             return fVal;
    3457             : 
    3458             :         // Clamp value before comparing to nodata: this is only needed for
    3459             :         // kernels with negative weights (Lanczos)
    3460     4220490 :         Twork fClamped = fVal;
    3461     4220490 :         if (fClamped < fDstMin)
    3462       15998 :             fClamped = fDstMin;
    3463     4204490 :         else if (fClamped > fDstMax)
    3464       16406 :             fClamped = fDstMax;
    3465     4220490 :         if (isIntegerDT)
    3466             :         {
    3467     4220480 :             if (bNoDataValueInt64Valid)
    3468             :             {
    3469     4220470 :                 const double fClampedRounded = double(std::round(fClamped));
    3470     8440960 :                 if (fClampedRounded >=
    3471             :                         static_cast<double>(static_cast<Twork>(
    3472     8440960 :                             std::numeric_limits<int64_t>::min())) &&
    3473             :                     fClampedRounded <= static_cast<double>(static_cast<Twork>(
    3474     8440960 :                                            9223372036854774784LL)) &&
    3475     4220470 :                     nNodataValueInt64 ==
    3476     4220480 :                         static_cast<GInt64>(std::round(fClamped)))
    3477             :                 {
    3478             :                     // Do not use the nodata value
    3479       14435 :                     return static_cast<Twork>(dfReplacementVal);
    3480             :                 }
    3481             :             }
    3482             :         }
    3483           7 :         else if (dfNoDataValue == static_cast<double>(fClamped))
    3484             :         {
    3485             :             // Do not use the nodata value
    3486           1 :             return static_cast<Twork>(dfReplacementVal);
    3487             :         }
    3488     4206050 :         return fClamped;
    3489             :     };
    3490             : 
    3491             :     /* -------------------------------------------------------------------- */
    3492             :     /*      Allocate work buffers.                                          */
    3493             :     /* -------------------------------------------------------------------- */
    3494        5093 :     const int nDstXSize = nDstXOff2 - nDstXOff;
    3495        5093 :     Twork *pafWrkScanline = nullptr;
    3496        5093 :     if (dstDataType != eWrkDataType)
    3497             :     {
    3498             :         pafWrkScanline =
    3499        4924 :             static_cast<Twork *>(VSI_MALLOC2_VERBOSE(nDstXSize, sizeof(Twork)));
    3500        4924 :         if (pafWrkScanline == nullptr)
    3501           0 :             return CE_Failure;
    3502             :     }
    3503             : 
    3504        5093 :     const double dfXScale = 1.0 / dfXRatioDstToSrc;
    3505        5093 :     const double dfXScaleWeight = (dfXScale >= 1.0) ? 1.0 : dfXScale;
    3506        5093 :     const double dfXScaledRadius = nKernelRadius / dfXScaleWeight;
    3507        5093 :     const double dfYScale = 1.0 / dfYRatioDstToSrc;
    3508        5093 :     const double dfYScaleWeight = (dfYScale >= 1.0) ? 1.0 : dfYScale;
    3509        5093 :     const double dfYScaledRadius = nKernelRadius / dfYScaleWeight;
    3510             : 
    3511             :     // Temporary array to store result of horizontal filter.
    3512             :     double *const padfHorizontalFiltered = static_cast<double *>(
    3513        5093 :         VSI_MALLOC3_VERBOSE(nChunkYSize, nDstXSize, sizeof(double) * nBands));
    3514             : 
    3515             :     // To store convolution coefficients.
    3516             :     double *const padfWeights =
    3517        5093 :         static_cast<double *>(VSI_MALLOC_ALIGNED_AUTO_VERBOSE(
    3518             :             static_cast<int>(
    3519             :                 2 + 2 * std::max(dfXScaledRadius, dfYScaledRadius) + 0.5) *
    3520             :             sizeof(double)));
    3521             : 
    3522        5093 :     GByte *pabyChunkNodataMaskHorizontalFiltered = nullptr;
    3523        5093 :     if (pabyChunkNodataMask)
    3524             :         pabyChunkNodataMaskHorizontalFiltered =
    3525         438 :             static_cast<GByte *>(VSI_MALLOC2_VERBOSE(nChunkYSize, nDstXSize));
    3526        5093 :     if (padfHorizontalFiltered == nullptr || padfWeights == nullptr ||
    3527         438 :         (pabyChunkNodataMask != nullptr &&
    3528             :          pabyChunkNodataMaskHorizontalFiltered == nullptr))
    3529             :     {
    3530           0 :         VSIFree(pafWrkScanline);
    3531           0 :         VSIFree(padfHorizontalFiltered);
    3532           0 :         VSIFreeAligned(padfWeights);
    3533           0 :         VSIFree(pabyChunkNodataMaskHorizontalFiltered);
    3534           0 :         return CE_Failure;
    3535             :     }
    3536             : 
    3537             :     /* ==================================================================== */
    3538             :     /*      First pass: horizontal filter                                   */
    3539             :     /* ==================================================================== */
    3540        5093 :     const int nChunkRightXOff = nChunkXOff + nChunkXSize;
    3541             : #ifdef USE_SSE2
    3542        5093 :     const bool bSrcPixelCountLess8 = dfXScaledRadius < 4;
    3543             : #endif
    3544     3042748 :     for (int iDstPixel = nDstXOff; iDstPixel < nDstXOff2; ++iDstPixel)
    3545             :     {
    3546     3037659 :         const double dfSrcPixel =
    3547     3037659 :             (iDstPixel + 0.5) * dfXRatioDstToSrc + dfSrcXDelta;
    3548     3037659 :         int nSrcPixelStart =
    3549     3037659 :             static_cast<int>(floor(dfSrcPixel - dfXScaledRadius + 0.5));
    3550     3037659 :         if (nSrcPixelStart < nChunkXOff)
    3551       57253 :             nSrcPixelStart = nChunkXOff;
    3552     3037659 :         int nSrcPixelStop =
    3553     3037659 :             static_cast<int>(dfSrcPixel + dfXScaledRadius + 0.5);
    3554     3037659 :         if (nSrcPixelStop > nChunkRightXOff)
    3555       57268 :             nSrcPixelStop = nChunkRightXOff;
    3556             : #if 0
    3557             :         if( nSrcPixelStart < nChunkXOff && nChunkXOff > 0 )
    3558             :         {
    3559             :             printf( "truncated iDstPixel = %d\n", iDstPixel );/*ok*/
    3560             :         }
    3561             :         if( nSrcPixelStop > nChunkRightXOff && nChunkRightXOff < nSrcWidth )
    3562             :         {
    3563             :             printf( "truncated iDstPixel = %d\n", iDstPixel );/*ok*/
    3564             :         }
    3565             : #endif
    3566     3037659 :         const int nSrcPixelCount = nSrcPixelStop - nSrcPixelStart;
    3567     3037659 :         double dfWeightSum = 0.0;
    3568             : 
    3569             :         // Compute convolution coefficients.
    3570     3037659 :         int nSrcPixel = nSrcPixelStart;
    3571     3037659 :         double dfX = dfXScaleWeight * (nSrcPixel - dfSrcPixel + 0.5);
    3572     4424858 :         for (; nSrcPixel < nSrcPixelStop - 3; nSrcPixel += 4)
    3573             :         {
    3574     1387200 :             padfWeights[nSrcPixel - nSrcPixelStart] = dfX;
    3575     1387200 :             dfX += dfXScaleWeight;
    3576     1387200 :             padfWeights[nSrcPixel + 1 - nSrcPixelStart] = dfX;
    3577     1387200 :             dfX += dfXScaleWeight;
    3578     1387200 :             padfWeights[nSrcPixel + 2 - nSrcPixelStart] = dfX;
    3579     1387200 :             dfX += dfXScaleWeight;
    3580     1387200 :             padfWeights[nSrcPixel + 3 - nSrcPixelStart] = dfX;
    3581     1387200 :             dfX += dfXScaleWeight;
    3582     1387200 :             dfWeightSum +=
    3583     1387200 :                 pfnFilterFunc4Values(padfWeights + nSrcPixel - nSrcPixelStart);
    3584             :         }
    3585     7028459 :         for (; nSrcPixel < nSrcPixelStop; ++nSrcPixel, dfX += dfXScaleWeight)
    3586             :         {
    3587     3990800 :             const double dfWeight = pfnFilterFunc(dfX);
    3588     3990800 :             padfWeights[nSrcPixel - nSrcPixelStart] = dfWeight;
    3589     3990800 :             dfWeightSum += dfWeight;
    3590             :         }
    3591             : 
    3592     3037659 :         const int nHeight = nChunkYSize * nBands;
    3593     3037659 :         if (pabyChunkNodataMask == nullptr)
    3594             :         {
    3595             :             // For floating-point data types, we must scale down a bit values
    3596             :             // if input values are close to +/- std::numeric_limits<T>::max()
    3597             : #ifdef OLD_CPPCHECK
    3598             :             constexpr double mulFactor = 1;
    3599             : #else
    3600     2954736 :             constexpr double mulFactor =
    3601             :                 (bNeedRescale &&
    3602             :                  (std::is_same_v<T, float> || std::is_same_v<T, double>))
    3603             :                     ? 2
    3604             :                     : 1;
    3605             : #endif
    3606             : 
    3607     2954736 :             if (dfWeightSum != 0)
    3608             :             {
    3609     2954736 :                 const double dfInvWeightSum = 1.0 / (mulFactor * dfWeightSum);
    3610    11886984 :                 for (int i = 0; i < nSrcPixelCount; ++i)
    3611             :                 {
    3612     8932253 :                     padfWeights[i] *= dfInvWeightSum;
    3613             :                 }
    3614             :             }
    3615             : 
    3616   178104060 :             const auto ScaleValue = [
    3617             : #ifdef _MSC_VER
    3618             :                                         mulFactor
    3619             : #endif
    3620             :             ](double dfVal, [[maybe_unused]] const T *inputValues,
    3621             :                                     [[maybe_unused]] int nInputValues)
    3622             :             {
    3623   178104000 :                 constexpr bool isFloat =
    3624             :                     std::is_same_v<T, float> || std::is_same_v<T, double>;
    3625             :                 if constexpr (isFloat)
    3626             :                 {
    3627     4070140 :                     if (std::isfinite(dfVal))
    3628             :                     {
    3629             :                         return std::clamp(dfVal,
    3630    12204800 :                                           -std::numeric_limits<double>::max() /
    3631             :                                               mulFactor,
    3632     4068260 :                                           std::numeric_limits<double>::max() /
    3633     4068260 :                                               mulFactor) *
    3634     4068260 :                                mulFactor;
    3635             :                     }
    3636             :                     else if constexpr (bKernelWithNegativeWeights)
    3637             :                     {
    3638         936 :                         if (std::isnan(dfVal))
    3639             :                         {
    3640             :                             // Either one of the input value is NaN or they are +/-Inf
    3641         936 :                             const bool isPositive = inputValues[0] >= 0;
    3642        6008 :                             for (int i = 0; i < nInputValues; ++i)
    3643             :                             {
    3644        5384 :                                 if (std::isnan(inputValues[i]))
    3645         312 :                                     return dfVal;
    3646             :                                 // cppcheck-suppress knownConditionTrueFalse
    3647        5072 :                                 if ((inputValues[i] >= 0) != isPositive)
    3648           0 :                                     return dfVal;
    3649             :                             }
    3650             :                             // All values are positive or negative infinity
    3651         624 :                             return static_cast<double>(inputValues[0]);
    3652             :                         }
    3653             :                     }
    3654             :                 }
    3655   174035000 :                 return dfVal;
    3656             :             };
    3657             : 
    3658     2954736 :             int iSrcLineOff = 0;
    3659             : #ifdef USE_SSE2
    3660     2954736 :             if (nSrcPixelCount == 4)
    3661             :             {
    3662    15867185 :                 for (; iSrcLineOff < nHeight - 2; iSrcLineOff += 3)
    3663             :                 {
    3664    15253386 :                     const size_t j =
    3665    15253386 :                         static_cast<size_t>(iSrcLineOff) * nChunkXSize +
    3666    15253386 :                         (nSrcPixelStart - nChunkXOff);
    3667    15253386 :                     double dfVal1 = 0.0;
    3668    15253386 :                     double dfVal2 = 0.0;
    3669    15253386 :                     double dfVal3 = 0.0;
    3670    15253386 :                     GDALResampleConvolutionHorizontalPixelCount4_3rows(
    3671    15253386 :                         pChunk + j, pChunk + j + nChunkXSize,
    3672    15253386 :                         pChunk + j + 2 * nChunkXSize, padfWeights, dfVal1,
    3673             :                         dfVal2, dfVal3);
    3674    30506746 :                     padfHorizontalFiltered[static_cast<size_t>(iSrcLineOff) *
    3675    15253386 :                                                nDstXSize +
    3676    15253386 :                                            iDstPixel - nDstXOff] =
    3677    15253386 :                         ScaleValue(dfVal1, pChunk + j, 4);
    3678    30506746 :                     padfHorizontalFiltered[(static_cast<size_t>(iSrcLineOff) +
    3679    15253386 :                                             1) *
    3680    15253386 :                                                nDstXSize +
    3681    15253386 :                                            iDstPixel - nDstXOff] =
    3682    15253386 :                         ScaleValue(dfVal2, pChunk + j + nChunkXSize, 4);
    3683    15253795 :                     padfHorizontalFiltered[(static_cast<size_t>(iSrcLineOff) +
    3684    15253386 :                                             2) *
    3685    15253386 :                                                nDstXSize +
    3686    15253386 :                                            iDstPixel - nDstXOff] =
    3687    15253386 :                         ScaleValue(dfVal3, pChunk + j + 2 * nChunkXSize, 4);
    3688             :                 }
    3689             :             }
    3690     2340929 :             else if (bSrcPixelCountLess8)
    3691             :             {
    3692     9927838 :                 for (; iSrcLineOff < nHeight - 2; iSrcLineOff += 3)
    3693             :                 {
    3694     7859228 :                     const size_t j =
    3695     7859228 :                         static_cast<size_t>(iSrcLineOff) * nChunkXSize +
    3696     7859228 :                         (nSrcPixelStart - nChunkXOff);
    3697     7859228 :                     double dfVal1 = 0.0;
    3698     7859228 :                     double dfVal2 = 0.0;
    3699     7859228 :                     double dfVal3 = 0.0;
    3700     7859228 :                     GDALResampleConvolutionHorizontalPixelCountLess8_3rows(
    3701     7859228 :                         pChunk + j, pChunk + j + nChunkXSize,
    3702     7859228 :                         pChunk + j + 2 * nChunkXSize, padfWeights,
    3703             :                         nSrcPixelCount, dfVal1, dfVal2, dfVal3);
    3704    15718416 :                     padfHorizontalFiltered[static_cast<size_t>(iSrcLineOff) *
    3705     7859228 :                                                nDstXSize +
    3706     7859228 :                                            iDstPixel - nDstXOff] =
    3707     7859228 :                         ScaleValue(dfVal1, pChunk + j, nSrcPixelCount);
    3708    15718416 :                     padfHorizontalFiltered[(static_cast<size_t>(iSrcLineOff) +
    3709     7859228 :                                             1) *
    3710     7859228 :                                                nDstXSize +
    3711     7859228 :                                            iDstPixel - nDstXOff] =
    3712     7859228 :                         ScaleValue(dfVal2, pChunk + j + nChunkXSize,
    3713             :                                    nSrcPixelCount);
    3714     7859316 :                     padfHorizontalFiltered[(static_cast<size_t>(iSrcLineOff) +
    3715     7859228 :                                             2) *
    3716     7859228 :                                                nDstXSize +
    3717     7859228 :                                            iDstPixel - nDstXOff] =
    3718     7859228 :                         ScaleValue(dfVal3, pChunk + j + 2 * nChunkXSize,
    3719             :                                    nSrcPixelCount);
    3720             :                 }
    3721             :             }
    3722             :             else
    3723             : #endif
    3724             :             {
    3725    35466358 :                 for (; iSrcLineOff < nHeight - 2; iSrcLineOff += 3)
    3726             :                 {
    3727    35194044 :                     const size_t j =
    3728    35194044 :                         static_cast<size_t>(iSrcLineOff) * nChunkXSize +
    3729    35194044 :                         (nSrcPixelStart - nChunkXOff);
    3730    35194044 :                     double dfVal1 = 0.0;
    3731    35194044 :                     double dfVal2 = 0.0;
    3732    35194044 :                     double dfVal3 = 0.0;
    3733    35194044 :                     GDALResampleConvolutionHorizontal_3rows(
    3734    35194044 :                         pChunk + j, pChunk + j + nChunkXSize,
    3735    35194044 :                         pChunk + j + 2 * nChunkXSize, padfWeights,
    3736             :                         nSrcPixelCount, dfVal1, dfVal2, dfVal3);
    3737    70388098 :                     padfHorizontalFiltered[static_cast<size_t>(iSrcLineOff) *
    3738    35194044 :                                                nDstXSize +
    3739    35194044 :                                            iDstPixel - nDstXOff] =
    3740    35194044 :                         ScaleValue(dfVal1, pChunk + j, nSrcPixelCount);
    3741    70388098 :                     padfHorizontalFiltered[(static_cast<size_t>(iSrcLineOff) +
    3742    35194044 :                                             1) *
    3743    35194044 :                                                nDstXSize +
    3744    35194044 :                                            iDstPixel - nDstXOff] =
    3745    35194044 :                         ScaleValue(dfVal2, pChunk + j + nChunkXSize,
    3746             :                                    nSrcPixelCount);
    3747    35259148 :                     padfHorizontalFiltered[(static_cast<size_t>(iSrcLineOff) +
    3748    35194044 :                                             2) *
    3749    35194044 :                                                nDstXSize +
    3750    35194044 :                                            iDstPixel - nDstXOff] =
    3751    35194044 :                         ScaleValue(dfVal3, pChunk + j + 2 * nChunkXSize,
    3752             :                                    nSrcPixelCount);
    3753             :                 }
    3754             :             }
    3755     6138566 :             for (; iSrcLineOff < nHeight; ++iSrcLineOff)
    3756             :             {
    3757     3183826 :                 const size_t j =
    3758     3183826 :                     static_cast<size_t>(iSrcLineOff) * nChunkXSize +
    3759     3183826 :                     (nSrcPixelStart - nChunkXOff);
    3760     3732986 :                 const double dfVal = GDALResampleConvolutionHorizontal(
    3761      595200 :                     pChunk + j, padfWeights, nSrcPixelCount);
    3762     3184275 :                 padfHorizontalFiltered[static_cast<size_t>(iSrcLineOff) *
    3763     3183826 :                                            nDstXSize +
    3764     3183826 :                                        iDstPixel - nDstXOff] =
    3765     3183826 :                     ScaleValue(dfVal, pChunk + j, nSrcPixelCount);
    3766             :             }
    3767             :         }
    3768             :         else
    3769             :         {
    3770    19187467 :             for (int iSrcLineOff = 0; iSrcLineOff < nHeight; ++iSrcLineOff)
    3771             :             {
    3772    19104530 :                 const size_t j =
    3773    19104530 :                     static_cast<size_t>(iSrcLineOff) * nChunkXSize +
    3774    19104530 :                     (nSrcPixelStart - nChunkXOff);
    3775             : 
    3776             :                 if (bKernelWithNegativeWeights)
    3777             :                 {
    3778    18579412 :                     int nConsecutiveValid = 0;
    3779    18579412 :                     int nMaxConsecutiveValid = 0;
    3780   170140458 :                     for (int k = 0; k < nSrcPixelCount; k++)
    3781             :                     {
    3782   151560146 :                         if (pabyChunkNodataMask[j + k])
    3783    43672053 :                             nConsecutiveValid++;
    3784   107888793 :                         else if (nConsecutiveValid)
    3785             :                         {
    3786      107790 :                             nMaxConsecutiveValid = std::max(
    3787      107790 :                                 nMaxConsecutiveValid, nConsecutiveValid);
    3788      107790 :                             nConsecutiveValid = 0;
    3789             :                         }
    3790             :                     }
    3791    18579412 :                     nMaxConsecutiveValid =
    3792    18579412 :                         std::max(nMaxConsecutiveValid, nConsecutiveValid);
    3793    18579412 :                     if (nMaxConsecutiveValid < nSrcPixelCount / 2)
    3794             :                     {
    3795    12651307 :                         const size_t nTempOffset =
    3796    12651307 :                             static_cast<size_t>(iSrcLineOff) * nDstXSize +
    3797    12651307 :                             iDstPixel - nDstXOff;
    3798    12651307 :                         padfHorizontalFiltered[nTempOffset] = 0.0;
    3799    12651307 :                         pabyChunkNodataMaskHorizontalFiltered[nTempOffset] = 0;
    3800    12651307 :                         continue;
    3801             :                     }
    3802             :                 }
    3803             : 
    3804     6453233 :                 double dfVal = 0.0;
    3805     6453233 :                 GDALResampleConvolutionHorizontalWithMask(
    3806       44639 :                     pChunk + j, pabyChunkNodataMask + j, padfWeights,
    3807             :                     nSrcPixelCount, dfVal, dfWeightSum);
    3808     6453233 :                 const size_t nTempOffset =
    3809     6453233 :                     static_cast<size_t>(iSrcLineOff) * nDstXSize + iDstPixel -
    3810     6453233 :                     nDstXOff;
    3811     6453233 :                 if (dfWeightSum > 0.0)
    3812             :                 {
    3813     6408568 :                     padfHorizontalFiltered[nTempOffset] = dfVal / dfWeightSum;
    3814     6408568 :                     pabyChunkNodataMaskHorizontalFiltered[nTempOffset] = 1;
    3815             :                 }
    3816             :                 else
    3817             :                 {
    3818       44663 :                     padfHorizontalFiltered[nTempOffset] = 0.0;
    3819       44663 :                     pabyChunkNodataMaskHorizontalFiltered[nTempOffset] = 0;
    3820             :                 }
    3821             :             }
    3822             :         }
    3823             :     }
    3824             : 
    3825             :     /* ==================================================================== */
    3826             :     /*      Second pass: vertical filter                                    */
    3827             :     /* ==================================================================== */
    3828        5093 :     const int nChunkBottomYOff = nChunkYOff + nChunkYSize;
    3829             : 
    3830      394928 :     for (int iDstLine = nDstYOff; iDstLine < nDstYOff2; ++iDstLine)
    3831             :     {
    3832      389835 :         Twork *const pafDstScanline =
    3833             :             pafWrkScanline
    3834      389835 :                 ? pafWrkScanline
    3835        8797 :                 : static_cast<Twork *>(pDstBuffer) +
    3836        8797 :                       static_cast<size_t>(iDstLine - nDstYOff) * nDstXSize;
    3837             : 
    3838      389835 :         const double dfSrcLine =
    3839      389835 :             (iDstLine + 0.5) * dfYRatioDstToSrc + dfSrcYDelta;
    3840      389835 :         int nSrcLineStart =
    3841      389835 :             static_cast<int>(floor(dfSrcLine - dfYScaledRadius + 0.5));
    3842      389835 :         int nSrcLineStop = static_cast<int>(dfSrcLine + dfYScaledRadius + 0.5);
    3843      389835 :         if (nSrcLineStart < nChunkYOff)
    3844        3388 :             nSrcLineStart = nChunkYOff;
    3845      389835 :         if (nSrcLineStop > nChunkBottomYOff)
    3846        3432 :             nSrcLineStop = nChunkBottomYOff;
    3847             : #if 0
    3848             :         if( nSrcLineStart < nChunkYOff &&
    3849             :             nChunkYOff > 0 )
    3850             :         {
    3851             :             printf( "truncated iDstLine = %d\n", iDstLine );/*ok*/
    3852             :         }
    3853             :         if( nSrcLineStop > nChunkBottomYOff && nChunkBottomYOff < nSrcHeight )
    3854             :         {
    3855             :             printf( "truncated iDstLine = %d\n", iDstLine );/*ok*/
    3856             :         }
    3857             : #endif
    3858      389835 :         const int nSrcLineCount = nSrcLineStop - nSrcLineStart;
    3859      389835 :         double dfWeightSum = 0.0;
    3860             : 
    3861             :         // Compute convolution coefficients.
    3862      389835 :         int nSrcLine = nSrcLineStart;  // Used after for.
    3863      389835 :         double dfY = dfYScaleWeight * (nSrcLine - dfSrcLine + 0.5);
    3864      998892 :         for (; nSrcLine < nSrcLineStop - 3;
    3865      609057 :              nSrcLine += 4, dfY += 4 * dfYScaleWeight)
    3866             :         {
    3867      609057 :             padfWeights[nSrcLine - nSrcLineStart] = dfY;
    3868      609057 :             padfWeights[nSrcLine + 1 - nSrcLineStart] = dfY + dfYScaleWeight;
    3869      609057 :             padfWeights[nSrcLine + 2 - nSrcLineStart] =
    3870      609057 :                 dfY + 2 * dfYScaleWeight;
    3871      609057 :             padfWeights[nSrcLine + 3 - nSrcLineStart] =
    3872      609057 :                 dfY + 3 * dfYScaleWeight;
    3873      609057 :             dfWeightSum +=
    3874      609057 :                 pfnFilterFunc4Values(padfWeights + nSrcLine - nSrcLineStart);
    3875             :         }
    3876      427653 :         for (; nSrcLine < nSrcLineStop; ++nSrcLine, dfY += dfYScaleWeight)
    3877             :         {
    3878       37818 :             const double dfWeight = pfnFilterFunc(dfY);
    3879       37818 :             padfWeights[nSrcLine - nSrcLineStart] = dfWeight;
    3880       37818 :             dfWeightSum += dfWeight;
    3881             :         }
    3882             : 
    3883      389835 :         if (pabyChunkNodataMask == nullptr)
    3884             :         {
    3885             :             // For floating-point data types, we must scale down a bit values
    3886             :             // if input values are close to +/- std::numeric_limits<T>::max()
    3887             : #ifdef OLD_CPPCHECK
    3888             :             constexpr double mulFactor = 1;
    3889             : #else
    3890      353911 :             constexpr double mulFactor =
    3891             :                 (bNeedRescale &&
    3892             :                  (std::is_same_v<T, float> || std::is_same_v<T, double>))
    3893             :                     ? 2
    3894             :                     : 1;
    3895             : #endif
    3896             : 
    3897      353911 :             if (dfWeightSum != 0)
    3898             :             {
    3899      353911 :                 const double dfInvWeightSum = 1.0 / (mulFactor * dfWeightSum);
    3900     2579837 :                 for (int i = 0; i < nSrcLineCount; ++i)
    3901     2225927 :                     padfWeights[i] *= dfInvWeightSum;
    3902             :             }
    3903             : 
    3904      353911 :             int iFilteredPixelOff = 0;  // Used after for.
    3905             :             // j used after for.
    3906      353911 :             size_t j =
    3907      353911 :                 (nSrcLineStart - nChunkYOff) * static_cast<size_t>(nDstXSize);
    3908             : #ifdef USE_SSE2
    3909             :             if constexpr ((!bNeedRescale || !std::is_same_v<T, float>) &&
    3910             :                           eWrkDataType == GDT_Float32)
    3911             :             {
    3912             : #ifdef __AVX__
    3913             :                 for (; iFilteredPixelOff < nDstXSize - 15;
    3914             :                      iFilteredPixelOff += 16, j += 16)
    3915             :                 {
    3916             :                     GDALResampleConvolutionVertical_16cols(
    3917             :                         padfHorizontalFiltered + j, nDstXSize, padfWeights,
    3918             :                         nSrcLineCount, pafDstScanline + iFilteredPixelOff);
    3919             :                     if (bHasNoData)
    3920             :                     {
    3921             :                         for (int k = 0; k < 16; k++)
    3922             :                         {
    3923             :                             pafDstScanline[iFilteredPixelOff + k] =
    3924             :                                 replaceValIfNodata(
    3925             :                                     pafDstScanline[iFilteredPixelOff + k]);
    3926             :                         }
    3927             :                     }
    3928             :                 }
    3929             : #else
    3930    25954967 :                 for (; iFilteredPixelOff < nDstXSize - 7;
    3931             :                      iFilteredPixelOff += 8, j += 8)
    3932             :                 {
    3933    25609808 :                     GDALResampleConvolutionVertical_8cols(
    3934    25609808 :                         padfHorizontalFiltered + j, nDstXSize, padfWeights,
    3935    25609808 :                         nSrcLineCount, pafDstScanline + iFilteredPixelOff);
    3936    25609808 :                     if (bHasNoData)
    3937             :                     {
    3938      123192 :                         for (int k = 0; k < 8; k++)
    3939             :                         {
    3940      109504 :                             pafDstScanline[iFilteredPixelOff + k] =
    3941      109504 :                                 replaceValIfNodata(
    3942      109504 :                                     pafDstScanline[iFilteredPixelOff + k]);
    3943             :                         }
    3944             :                     }
    3945             :                 }
    3946             : #endif
    3947             : 
    3948      809343 :                 for (; iFilteredPixelOff < nDstXSize; iFilteredPixelOff++, j++)
    3949             :                 {
    3950      464251 :                     const Twork fVal =
    3951      464251 :                         static_cast<Twork>(GDALResampleConvolutionVertical(
    3952      464251 :                             padfHorizontalFiltered + j, nDstXSize, padfWeights,
    3953             :                             nSrcLineCount));
    3954      464251 :                     pafDstScanline[iFilteredPixelOff] =
    3955      464251 :                         replaceValIfNodata(fVal);
    3956             :                 }
    3957             :             }
    3958             :             else
    3959             : #endif
    3960             :             {
    3961     5862642 :                 const auto ScaleValue = [
    3962             : #ifdef _MSC_VER
    3963             :                                             mulFactor
    3964             : #endif
    3965             :                 ](double dfVal, [[maybe_unused]] const double *inputValues,
    3966             :                                         [[maybe_unused]] int nStride,
    3967             :                                         [[maybe_unused]] int nInputValues)
    3968             :                 {
    3969     5862640 :                     constexpr bool isFloat =
    3970             :                         std::is_same_v<T, float> || std::is_same_v<T, double>;
    3971             :                     if constexpr (isFloat)
    3972             :                     {
    3973     5862640 :                         if (std::isfinite(dfVal))
    3974             :                         {
    3975             :                             return std::clamp(
    3976             :                                        dfVal,
    3977             :                                        static_cast<double>(
    3978    17585400 :                                            -std::numeric_limits<Twork>::max()) /
    3979             :                                            mulFactor,
    3980             :                                        static_cast<double>(
    3981     5861800 :                                            std::numeric_limits<Twork>::max()) /
    3982     5861800 :                                            mulFactor) *
    3983     5861800 :                                    mulFactor;
    3984             :                         }
    3985             :                         else if constexpr (bKernelWithNegativeWeights)
    3986             :                         {
    3987         480 :                             if (std::isnan(dfVal))
    3988             :                             {
    3989             :                                 // Either one of the input value is NaN or they are +/-Inf
    3990         480 :                                 const bool isPositive = inputValues[0] >= 0;
    3991        2520 :                                 for (int i = 0; i < nInputValues; ++i)
    3992             :                                 {
    3993        2200 :                                     if (std::isnan(inputValues[i * nStride]))
    3994         160 :                                         return dfVal;
    3995             :                                     // cppcheck-suppress knownConditionTrueFalse
    3996        2040 :                                     if ((inputValues[i] >= 0) != isPositive)
    3997           0 :                                         return dfVal;
    3998             :                                 }
    3999             :                                 // All values are positive or negative infinity
    4000         320 :                                 return inputValues[0];
    4001             :                             }
    4002             :                         }
    4003             :                     }
    4004             : 
    4005         360 :                     return dfVal;
    4006             :                 };
    4007             : 
    4008     2939422 :                 for (; iFilteredPixelOff < nDstXSize - 1;
    4009             :                      iFilteredPixelOff += 2, j += 2)
    4010             :                 {
    4011     2930610 :                     double dfVal1 = 0.0;
    4012     2930610 :                     double dfVal2 = 0.0;
    4013     2930610 :                     GDALResampleConvolutionVertical_2cols(
    4014     2930610 :                         padfHorizontalFiltered + j, nDstXSize, padfWeights,
    4015             :                         nSrcLineCount, dfVal1, dfVal2);
    4016     5861220 :                     pafDstScanline[iFilteredPixelOff] =
    4017     2930610 :                         replaceValIfNodata(static_cast<Twork>(
    4018     2930610 :                             ScaleValue(dfVal1, padfHorizontalFiltered + j,
    4019             :                                        nDstXSize, nSrcLineCount)));
    4020     2930610 :                     pafDstScanline[iFilteredPixelOff + 1] =
    4021     2930610 :                         replaceValIfNodata(static_cast<Twork>(
    4022     2930610 :                             ScaleValue(dfVal2, padfHorizontalFiltered + j + 1,
    4023             :                                        nDstXSize, nSrcLineCount)));
    4024             :                 }
    4025        8819 :                 if (iFilteredPixelOff < nDstXSize)
    4026             :                 {
    4027        1427 :                     const double dfVal = GDALResampleConvolutionVertical(
    4028        1427 :                         padfHorizontalFiltered + j, nDstXSize, padfWeights,
    4029             :                         nSrcLineCount);
    4030        1427 :                     pafDstScanline[iFilteredPixelOff] =
    4031        1427 :                         replaceValIfNodata(static_cast<Twork>(
    4032        1427 :                             ScaleValue(dfVal, padfHorizontalFiltered + j,
    4033             :                                        nDstXSize, nSrcLineCount)));
    4034             :                 }
    4035             :             }
    4036             :         }
    4037             :         else
    4038             :         {
    4039    18367351 :             for (int iFilteredPixelOff = 0; iFilteredPixelOff < nDstXSize;
    4040             :                  ++iFilteredPixelOff)
    4041             :             {
    4042    18331457 :                 double dfVal = 0.0;
    4043    18331457 :                 dfWeightSum = 0.0;
    4044    18331457 :                 size_t j = (nSrcLineStart - nChunkYOff) *
    4045    18331457 :                                static_cast<size_t>(nDstXSize) +
    4046    18331457 :                            iFilteredPixelOff;
    4047             :                 if (bKernelWithNegativeWeights)
    4048             :                 {
    4049    18087901 :                     int nConsecutiveValid = 0;
    4050    18087901 :                     int nMaxConsecutiveValid = 0;
    4051   127256321 :                     for (int i = 0; i < nSrcLineCount; ++i, j += nDstXSize)
    4052             :                     {
    4053   109168020 :                         const double dfWeight =
    4054   109168020 :                             padfWeights[i] *
    4055             :                             pabyChunkNodataMaskHorizontalFiltered[j];
    4056   109168020 :                         if (pabyChunkNodataMaskHorizontalFiltered[j])
    4057             :                         {
    4058    46108037 :                             nConsecutiveValid++;
    4059             :                         }
    4060    63060183 :                         else if (nConsecutiveValid)
    4061             :                         {
    4062      204376 :                             nMaxConsecutiveValid = std::max(
    4063      204376 :                                 nMaxConsecutiveValid, nConsecutiveValid);
    4064      204376 :                             nConsecutiveValid = 0;
    4065             :                         }
    4066   109168020 :                         dfVal += padfHorizontalFiltered[j] * dfWeight;
    4067   109168020 :                         dfWeightSum += dfWeight;
    4068             :                     }
    4069    18087901 :                     nMaxConsecutiveValid =
    4070    18087901 :                         std::max(nMaxConsecutiveValid, nConsecutiveValid);
    4071    18087901 :                     if (nMaxConsecutiveValid < nSrcLineCount / 2)
    4072             :                     {
    4073     8918591 :                         pafDstScanline[iFilteredPixelOff] =
    4074     8918499 :                             static_cast<Twork>(dfNoDataValue);
    4075     8918591 :                         continue;
    4076             :                     }
    4077             :                 }
    4078             :                 else
    4079             :                 {
    4080     1237062 :                     for (int i = 0; i < nSrcLineCount; ++i, j += nDstXSize)
    4081             :                     {
    4082      993504 :                         const double dfWeight =
    4083      993504 :                             padfWeights[i] *
    4084             :                             pabyChunkNodataMaskHorizontalFiltered[j];
    4085      993504 :                         dfVal += padfHorizontalFiltered[j] * dfWeight;
    4086      993504 :                         dfWeightSum += dfWeight;
    4087             :                     }
    4088             :                 }
    4089     9412886 :                 if (dfWeightSum > 0.0)
    4090             :                 {
    4091     9396847 :                     pafDstScanline[iFilteredPixelOff] = replaceValIfNodata(
    4092     9396835 :                         static_cast<Twork>(dfVal / dfWeightSum));
    4093             :                 }
    4094             :                 else
    4095             :                 {
    4096       16045 :                     pafDstScanline[iFilteredPixelOff] =
    4097       16021 :                         static_cast<Twork>(dfNoDataValue);
    4098             :                 }
    4099             :             }
    4100             :         }
    4101             : 
    4102      389835 :         if (fMaxVal != 0.0f)
    4103             :         {
    4104             :             if constexpr (std::is_same_v<T, double>)
    4105             :             {
    4106           0 :                 for (int i = 0; i < nDstXSize; ++i)
    4107             :                 {
    4108           0 :                     if (pafDstScanline[i] > static_cast<double>(fMaxVal))
    4109           0 :                         pafDstScanline[i] = static_cast<double>(fMaxVal);
    4110             :                 }
    4111             :             }
    4112             :             else
    4113             :             {
    4114      192324 :                 for (int i = 0; i < nDstXSize; ++i)
    4115             :                 {
    4116      192088 :                     if (pafDstScanline[i] > fMaxVal)
    4117       96022 :                         pafDstScanline[i] = fMaxVal;
    4118             :                 }
    4119             :             }
    4120             :         }
    4121             : 
    4122      389835 :         if (pafWrkScanline)
    4123             :         {
    4124      381038 :             GDALCopyWords64(pafWrkScanline, eWrkDataType, nWrkDataTypeSize,
    4125             :                             static_cast<GByte *>(pDstBuffer) +
    4126      381038 :                                 static_cast<size_t>(iDstLine - nDstYOff) *
    4127      381038 :                                     nDstXSize * nDstDataTypeSize,
    4128             :                             dstDataType, nDstDataTypeSize, nDstXSize);
    4129             :         }
    4130             :     }
    4131             : 
    4132        5093 :     VSIFree(pafWrkScanline);
    4133        5093 :     VSIFreeAligned(padfWeights);
    4134        5093 :     VSIFree(padfHorizontalFiltered);
    4135        5093 :     VSIFree(pabyChunkNodataMaskHorizontalFiltered);
    4136             : 
    4137        5093 :     return CE_None;
    4138             : }
    4139             : 
    4140             : template <bool bKernelWithNegativeWeights, bool bNeedRescale>
    4141             : static CPLErr
    4142        5093 : GDALResampleChunk_ConvolutionInternal(const GDALOverviewResampleArgs &args,
    4143             :                                       const void *pChunk, void **ppDstBuffer,
    4144             :                                       GDALDataType *peDstBufferDataType)
    4145             : {
    4146             :     GDALResampleAlg eResample;
    4147        5093 :     if (EQUAL(args.pszResampling, "BILINEAR"))
    4148        2660 :         eResample = GRA_Bilinear;
    4149        2433 :     else if (EQUAL(args.pszResampling, "CUBIC"))
    4150        2284 :         eResample = GRA_Cubic;
    4151         149 :     else if (EQUAL(args.pszResampling, "CUBICSPLINE"))
    4152          59 :         eResample = GRA_CubicSpline;
    4153          90 :     else if (EQUAL(args.pszResampling, "LANCZOS"))
    4154          90 :         eResample = GRA_Lanczos;
    4155             :     else
    4156             :     {
    4157           0 :         CPLAssert(false);
    4158             :         return CE_Failure;
    4159             :     }
    4160        5093 :     const int nKernelRadius = GWKGetFilterRadius(eResample);
    4161        5093 :     FilterFuncType pfnFilterFunc = GWKGetFilterFunc(eResample);
    4162             :     const FilterFunc4ValuesType pfnFilterFunc4Values =
    4163        5093 :         GWKGetFilterFunc4Values(eResample);
    4164             : 
    4165        5093 :     float fMaxVal = 0.f;
    4166             :     // Cubic, etc... can have overshoots, so make sure we clamp values to the
    4167             :     // maximum value if NBITS is set.
    4168        5093 :     if (eResample != GRA_Bilinear && args.nOvrNBITS > 0 &&
    4169           8 :         (args.eOvrDataType == GDT_UInt8 || args.eOvrDataType == GDT_UInt16 ||
    4170           0 :          args.eOvrDataType == GDT_UInt32))
    4171             :     {
    4172           8 :         int nBits = args.nOvrNBITS;
    4173           8 :         if (nBits == GDALGetDataTypeSizeBits(args.eOvrDataType))
    4174           1 :             nBits = 0;
    4175           8 :         if (nBits > 0 && nBits < 32)
    4176           7 :             fMaxVal = static_cast<float>((1U << nBits) - 1);
    4177             :     }
    4178             : 
    4179        5093 :     *ppDstBuffer = VSI_MALLOC3_VERBOSE(
    4180             :         args.nDstXOff2 - args.nDstXOff, args.nDstYOff2 - args.nDstYOff,
    4181             :         GDALGetDataTypeSizeBytes(args.eOvrDataType));
    4182        5093 :     if (*ppDstBuffer == nullptr)
    4183             :     {
    4184           0 :         return CE_Failure;
    4185             :     }
    4186        5093 :     *peDstBufferDataType = args.eOvrDataType;
    4187             : 
    4188        5093 :     switch (args.eWrkDataType)
    4189             :     {
    4190        4225 :         case GDT_UInt8:
    4191             :         {
    4192             :             return GDALResampleChunk_ConvolutionT<GByte, float, GDT_Float32,
    4193             :                                                   bKernelWithNegativeWeights,
    4194        4225 :                                                   bNeedRescale>(
    4195             :                 args, static_cast<const GByte *>(pChunk), *ppDstBuffer,
    4196        4225 :                 pfnFilterFunc, pfnFilterFunc4Values, nKernelRadius, fMaxVal);
    4197             :         }
    4198             : 
    4199         402 :         case GDT_UInt16:
    4200             :         {
    4201             :             return GDALResampleChunk_ConvolutionT<GUInt16, float, GDT_Float32,
    4202             :                                                   bKernelWithNegativeWeights,
    4203         402 :                                                   bNeedRescale>(
    4204             :                 args, static_cast<const GUInt16 *>(pChunk), *ppDstBuffer,
    4205         402 :                 pfnFilterFunc, pfnFilterFunc4Values, nKernelRadius, fMaxVal);
    4206             :         }
    4207             : 
    4208         375 :         case GDT_Float32:
    4209             :         {
    4210             :             return GDALResampleChunk_ConvolutionT<float, float, GDT_Float32,
    4211             :                                                   bKernelWithNegativeWeights,
    4212         375 :                                                   bNeedRescale>(
    4213             :                 args, static_cast<const float *>(pChunk), *ppDstBuffer,
    4214         375 :                 pfnFilterFunc, pfnFilterFunc4Values, nKernelRadius, fMaxVal);
    4215             :         }
    4216             : 
    4217          91 :         case GDT_Float64:
    4218             :         {
    4219             :             return GDALResampleChunk_ConvolutionT<double, double, GDT_Float64,
    4220             :                                                   bKernelWithNegativeWeights,
    4221          91 :                                                   bNeedRescale>(
    4222             :                 args, static_cast<const double *>(pChunk), *ppDstBuffer,
    4223          91 :                 pfnFilterFunc, pfnFilterFunc4Values, nKernelRadius, fMaxVal);
    4224             :         }
    4225             : 
    4226           0 :         default:
    4227           0 :             break;
    4228             :     }
    4229             : 
    4230           0 :     CPLAssert(false);
    4231             :     return CE_Failure;
    4232             : }
    4233             : 
    4234             : static CPLErr
    4235        5093 : GDALResampleChunk_Convolution(const GDALOverviewResampleArgs &args,
    4236             :                               const void *pChunk, void **ppDstBuffer,
    4237             :                               GDALDataType *peDstBufferDataType)
    4238             : {
    4239        5093 :     if (EQUAL(args.pszResampling, "CUBIC") ||
    4240        2809 :         EQUAL(args.pszResampling, "LANCZOS"))
    4241             :         return GDALResampleChunk_ConvolutionInternal<
    4242        2374 :             /* bKernelWithNegativeWeights=*/true, /* bNeedRescale = */ true>(
    4243        2374 :             args, pChunk, ppDstBuffer, peDstBufferDataType);
    4244        2719 :     else if (EQUAL(args.pszResampling, "CUBICSPLINE"))
    4245          59 :         return GDALResampleChunk_ConvolutionInternal<false, true>(
    4246          59 :             args, pChunk, ppDstBuffer, peDstBufferDataType);
    4247             :     else
    4248        2660 :         return GDALResampleChunk_ConvolutionInternal<false, false>(
    4249        2660 :             args, pChunk, ppDstBuffer, peDstBufferDataType);
    4250             : }
    4251             : 
    4252             : /************************************************************************/
    4253             : /*                       GDALResampleChunkC32R()                        */
    4254             : /************************************************************************/
    4255             : 
    4256           2 : static CPLErr GDALResampleChunkC32R(const int nSrcWidth, const int nSrcHeight,
    4257             :                                     const float *pafChunk, const int nChunkYOff,
    4258             :                                     const int nChunkYSize, const int nDstYOff,
    4259             :                                     const int nDstYOff2, const int nOvrXSize,
    4260             :                                     const int nOvrYSize, void **ppDstBuffer,
    4261             :                                     GDALDataType *peDstBufferDataType,
    4262             :                                     const char *pszResampling)
    4263             : 
    4264             : {
    4265             :     enum Method
    4266             :     {
    4267             :         NEAR,
    4268             :         AVERAGE,
    4269             :         AVERAGE_MAGPHASE,
    4270             :         RMS,
    4271             :     };
    4272             : 
    4273           2 :     Method eMethod = NEAR;
    4274           2 :     if (STARTS_WITH_CI(pszResampling, "NEAR"))
    4275             :     {
    4276           0 :         eMethod = NEAR;
    4277             :     }
    4278           2 :     else if (EQUAL(pszResampling, "AVERAGE_MAGPHASE"))
    4279             :     {
    4280           0 :         eMethod = AVERAGE_MAGPHASE;
    4281             :     }
    4282           2 :     else if (EQUAL(pszResampling, "RMS"))
    4283             :     {
    4284           2 :         eMethod = RMS;
    4285             :     }
    4286           0 :     else if (STARTS_WITH_CI(pszResampling, "AVER"))
    4287             :     {
    4288           0 :         eMethod = AVERAGE;
    4289             :     }
    4290             :     else
    4291             :     {
    4292           0 :         CPLError(
    4293             :             CE_Failure, CPLE_NotSupported,
    4294             :             "Resampling method %s is not supported for complex data types. "
    4295             :             "Only NEAREST, AVERAGE, AVERAGE_MAGPHASE and RMS are supported",
    4296             :             pszResampling);
    4297           0 :         return CE_Failure;
    4298             :     }
    4299             : 
    4300           2 :     const int nOXSize = nOvrXSize;
    4301           2 :     *ppDstBuffer = VSI_MALLOC3_VERBOSE(nOXSize, nDstYOff2 - nDstYOff,
    4302             :                                        GDALGetDataTypeSizeBytes(GDT_CFloat32));
    4303           2 :     if (*ppDstBuffer == nullptr)
    4304             :     {
    4305           0 :         return CE_Failure;
    4306             :     }
    4307           2 :     float *const pafDstBuffer = static_cast<float *>(*ppDstBuffer);
    4308           2 :     *peDstBufferDataType = GDT_CFloat32;
    4309             : 
    4310           2 :     const int nOYSize = nOvrYSize;
    4311           2 :     const double dfXRatioDstToSrc = static_cast<double>(nSrcWidth) / nOXSize;
    4312           2 :     const double dfYRatioDstToSrc = static_cast<double>(nSrcHeight) / nOYSize;
    4313             : 
    4314             :     /* ==================================================================== */
    4315             :     /*      Loop over destination scanlines.                                */
    4316             :     /* ==================================================================== */
    4317           8 :     for (int iDstLine = nDstYOff; iDstLine < nDstYOff2; ++iDstLine)
    4318             :     {
    4319           6 :         int nSrcYOff = static_cast<int>(0.5 + iDstLine * dfYRatioDstToSrc);
    4320           6 :         if (nSrcYOff < nChunkYOff)
    4321           0 :             nSrcYOff = nChunkYOff;
    4322             : 
    4323           6 :         int nSrcYOff2 =
    4324           6 :             static_cast<int>(0.5 + (iDstLine + 1) * dfYRatioDstToSrc);
    4325           6 :         if (nSrcYOff2 == nSrcYOff)
    4326           0 :             nSrcYOff2++;
    4327             : 
    4328           6 :         if (nSrcYOff2 > nSrcHeight || iDstLine == nOYSize - 1)
    4329             :         {
    4330           2 :             if (nSrcYOff == nSrcHeight && nSrcHeight - 1 >= nChunkYOff)
    4331           0 :                 nSrcYOff = nSrcHeight - 1;
    4332           2 :             nSrcYOff2 = nSrcHeight;
    4333             :         }
    4334           6 :         if (nSrcYOff2 > nChunkYOff + nChunkYSize)
    4335           0 :             nSrcYOff2 = nChunkYOff + nChunkYSize;
    4336             : 
    4337           6 :         const float *const pafSrcScanline =
    4338           6 :             pafChunk +
    4339           6 :             (static_cast<size_t>(nSrcYOff - nChunkYOff) * nSrcWidth) * 2;
    4340           6 :         float *const pafDstScanline =
    4341           6 :             pafDstBuffer +
    4342           6 :             static_cast<size_t>(iDstLine - nDstYOff) * 2 * nOXSize;
    4343             : 
    4344             :         /* --------------------------------------------------------------------
    4345             :          */
    4346             :         /*      Loop over destination pixels */
    4347             :         /* --------------------------------------------------------------------
    4348             :          */
    4349          18 :         for (int iDstPixel = 0; iDstPixel < nOXSize; ++iDstPixel)
    4350             :         {
    4351          12 :             const size_t iDstPixelSZ = static_cast<size_t>(iDstPixel);
    4352          12 :             int nSrcXOff = static_cast<int>(0.5 + iDstPixel * dfXRatioDstToSrc);
    4353          12 :             int nSrcXOff2 =
    4354          12 :                 static_cast<int>(0.5 + (iDstPixel + 1) * dfXRatioDstToSrc);
    4355          12 :             if (nSrcXOff2 == nSrcXOff)
    4356           0 :                 nSrcXOff2++;
    4357          12 :             if (nSrcXOff2 > nSrcWidth || iDstPixel == nOXSize - 1)
    4358             :             {
    4359           6 :                 if (nSrcXOff == nSrcWidth && nSrcWidth - 1 >= 0)
    4360           0 :                     nSrcXOff = nSrcWidth - 1;
    4361           6 :                 nSrcXOff2 = nSrcWidth;
    4362             :             }
    4363          12 :             const size_t nSrcXOffSZ = static_cast<size_t>(nSrcXOff);
    4364             : 
    4365          12 :             if (eMethod == NEAR)
    4366             :             {
    4367           0 :                 pafDstScanline[iDstPixelSZ * 2] =
    4368           0 :                     pafSrcScanline[nSrcXOffSZ * 2];
    4369           0 :                 pafDstScanline[iDstPixelSZ * 2 + 1] =
    4370           0 :                     pafSrcScanline[nSrcXOffSZ * 2 + 1];
    4371             :             }
    4372          12 :             else if (eMethod == AVERAGE_MAGPHASE)
    4373             :             {
    4374           0 :                 double dfTotalR = 0.0;
    4375           0 :                 double dfTotalI = 0.0;
    4376           0 :                 double dfTotalM = 0.0;
    4377           0 :                 size_t nCount = 0;
    4378             : 
    4379           0 :                 for (int iY = nSrcYOff; iY < nSrcYOff2; ++iY)
    4380             :                 {
    4381           0 :                     for (int iX = nSrcXOff; iX < nSrcXOff2; ++iX)
    4382             :                     {
    4383           0 :                         const double dfR = double(
    4384           0 :                             pafSrcScanline[static_cast<size_t>(iX) * 2 +
    4385           0 :                                            static_cast<size_t>(iY - nSrcYOff) *
    4386           0 :                                                nSrcWidth * 2]);
    4387           0 :                         const double dfI = double(
    4388           0 :                             pafSrcScanline[static_cast<size_t>(iX) * 2 +
    4389           0 :                                            static_cast<size_t>(iY - nSrcYOff) *
    4390           0 :                                                nSrcWidth * 2 +
    4391           0 :                                            1]);
    4392           0 :                         dfTotalR += dfR;
    4393           0 :                         dfTotalI += dfI;
    4394           0 :                         dfTotalM += std::hypot(dfR, dfI);
    4395           0 :                         ++nCount;
    4396             :                     }
    4397             :                 }
    4398             : 
    4399           0 :                 CPLAssert(nCount > 0);
    4400           0 :                 if (nCount == 0)
    4401             :                 {
    4402           0 :                     pafDstScanline[iDstPixelSZ * 2] = 0.0;
    4403           0 :                     pafDstScanline[iDstPixelSZ * 2 + 1] = 0.0;
    4404             :                 }
    4405             :                 else
    4406             :                 {
    4407           0 :                     pafDstScanline[iDstPixelSZ * 2] = static_cast<float>(
    4408           0 :                         dfTotalR / static_cast<double>(nCount));
    4409           0 :                     pafDstScanline[iDstPixelSZ * 2 + 1] = static_cast<float>(
    4410           0 :                         dfTotalI / static_cast<double>(nCount));
    4411             :                     const double dfM =
    4412           0 :                         double(std::hypot(pafDstScanline[iDstPixelSZ * 2],
    4413           0 :                                           pafDstScanline[iDstPixelSZ * 2 + 1]));
    4414           0 :                     const double dfDesiredM =
    4415           0 :                         dfTotalM / static_cast<double>(nCount);
    4416           0 :                     double dfRatio = 1.0;
    4417           0 :                     if (dfM != 0.0)
    4418           0 :                         dfRatio = dfDesiredM / dfM;
    4419             : 
    4420           0 :                     pafDstScanline[iDstPixelSZ * 2] *=
    4421           0 :                         static_cast<float>(dfRatio);
    4422           0 :                     pafDstScanline[iDstPixelSZ * 2 + 1] *=
    4423           0 :                         static_cast<float>(dfRatio);
    4424             :                 }
    4425             :             }
    4426          12 :             else if (eMethod == RMS)
    4427             :             {
    4428          12 :                 double dfTotalR = 0.0;
    4429          12 :                 double dfTotalI = 0.0;
    4430          12 :                 size_t nCount = 0;
    4431             : 
    4432          36 :                 for (int iY = nSrcYOff; iY < nSrcYOff2; ++iY)
    4433             :                 {
    4434          72 :                     for (int iX = nSrcXOff; iX < nSrcXOff2; ++iX)
    4435             :                     {
    4436          48 :                         const double dfR = double(
    4437          48 :                             pafSrcScanline[static_cast<size_t>(iX) * 2 +
    4438          48 :                                            static_cast<size_t>(iY - nSrcYOff) *
    4439          48 :                                                nSrcWidth * 2]);
    4440          48 :                         const double dfI = double(
    4441          48 :                             pafSrcScanline[static_cast<size_t>(iX) * 2 +
    4442          48 :                                            static_cast<size_t>(iY - nSrcYOff) *
    4443          48 :                                                nSrcWidth * 2 +
    4444          48 :                                            1]);
    4445             : 
    4446          48 :                         dfTotalR += SQUARE(dfR);
    4447          48 :                         dfTotalI += SQUARE(dfI);
    4448             : 
    4449          48 :                         ++nCount;
    4450             :                     }
    4451             :                 }
    4452             : 
    4453          12 :                 CPLAssert(nCount > 0);
    4454          12 :                 if (nCount == 0)
    4455             :                 {
    4456           0 :                     pafDstScanline[iDstPixelSZ * 2] = 0.0;
    4457           0 :                     pafDstScanline[iDstPixelSZ * 2 + 1] = 0.0;
    4458             :                 }
    4459             :                 else
    4460             :                 {
    4461             :                     /* compute RMS */
    4462          12 :                     pafDstScanline[iDstPixelSZ * 2] = static_cast<float>(
    4463          12 :                         sqrt(dfTotalR / static_cast<double>(nCount)));
    4464          12 :                     pafDstScanline[iDstPixelSZ * 2 + 1] = static_cast<float>(
    4465          12 :                         sqrt(dfTotalI / static_cast<double>(nCount)));
    4466             :                 }
    4467             :             }
    4468           0 :             else if (eMethod == AVERAGE)
    4469             :             {
    4470           0 :                 double dfTotalR = 0.0;
    4471           0 :                 double dfTotalI = 0.0;
    4472           0 :                 size_t nCount = 0;
    4473             : 
    4474           0 :                 for (int iY = nSrcYOff; iY < nSrcYOff2; ++iY)
    4475             :                 {
    4476           0 :                     for (int iX = nSrcXOff; iX < nSrcXOff2; ++iX)
    4477             :                     {
    4478             :                         // TODO(schwehr): Maybe use std::complex?
    4479           0 :                         dfTotalR += double(
    4480           0 :                             pafSrcScanline[static_cast<size_t>(iX) * 2 +
    4481           0 :                                            static_cast<size_t>(iY - nSrcYOff) *
    4482           0 :                                                nSrcWidth * 2]);
    4483           0 :                         dfTotalI += double(
    4484           0 :                             pafSrcScanline[static_cast<size_t>(iX) * 2 +
    4485           0 :                                            static_cast<size_t>(iY - nSrcYOff) *
    4486           0 :                                                nSrcWidth * 2 +
    4487           0 :                                            1]);
    4488           0 :                         ++nCount;
    4489             :                     }
    4490             :                 }
    4491             : 
    4492           0 :                 CPLAssert(nCount > 0);
    4493           0 :                 if (nCount == 0)
    4494             :                 {
    4495           0 :                     pafDstScanline[iDstPixelSZ * 2] = 0.0;
    4496           0 :                     pafDstScanline[iDstPixelSZ * 2 + 1] = 0.0;
    4497             :                 }
    4498             :                 else
    4499             :                 {
    4500           0 :                     pafDstScanline[iDstPixelSZ * 2] = static_cast<float>(
    4501           0 :                         dfTotalR / static_cast<double>(nCount));
    4502           0 :                     pafDstScanline[iDstPixelSZ * 2 + 1] = static_cast<float>(
    4503           0 :                         dfTotalI / static_cast<double>(nCount));
    4504             :                 }
    4505             :             }
    4506             :         }
    4507             :     }
    4508             : 
    4509           2 :     return CE_None;
    4510             : }
    4511             : 
    4512             : /************************************************************************/
    4513             : /*                  GDALRegenerateCascadingOverviews()                  */
    4514             : /*                                                                      */
    4515             : /*      Generate a list of overviews in order from largest to           */
    4516             : /*      smallest, computing each from the next larger.                  */
    4517             : /************************************************************************/
    4518             : 
    4519          44 : static CPLErr GDALRegenerateCascadingOverviews(
    4520             :     GDALRasterBand *poSrcBand, int nOverviews, GDALRasterBand **papoOvrBands,
    4521             :     const char *pszResampling, GDALProgressFunc pfnProgress,
    4522             :     void *pProgressData, CSLConstList papszOptions)
    4523             : 
    4524             : {
    4525             :     /* -------------------------------------------------------------------- */
    4526             :     /*      First, we must put the overviews in order from largest to       */
    4527             :     /*      smallest.                                                       */
    4528             :     /* -------------------------------------------------------------------- */
    4529         127 :     for (int i = 0; i < nOverviews - 1; ++i)
    4530             :     {
    4531         292 :         for (int j = 0; j < nOverviews - i - 1; ++j)
    4532             :         {
    4533         209 :             if (papoOvrBands[j]->GetXSize() *
    4534         209 :                     static_cast<float>(papoOvrBands[j]->GetYSize()) <
    4535         209 :                 papoOvrBands[j + 1]->GetXSize() *
    4536         209 :                     static_cast<float>(papoOvrBands[j + 1]->GetYSize()))
    4537             :             {
    4538           0 :                 GDALRasterBand *poTempBand = papoOvrBands[j];
    4539           0 :                 papoOvrBands[j] = papoOvrBands[j + 1];
    4540           0 :                 papoOvrBands[j + 1] = poTempBand;
    4541             :             }
    4542             :         }
    4543             :     }
    4544             : 
    4545             :     /* -------------------------------------------------------------------- */
    4546             :     /*      Count total pixels so we can prepare appropriate scaled         */
    4547             :     /*      progress functions.                                             */
    4548             :     /* -------------------------------------------------------------------- */
    4549          44 :     double dfTotalPixels = 0.0;
    4550             : 
    4551         171 :     for (int i = 0; i < nOverviews; ++i)
    4552             :     {
    4553         127 :         dfTotalPixels += papoOvrBands[i]->GetXSize() *
    4554         127 :                          static_cast<double>(papoOvrBands[i]->GetYSize());
    4555             :     }
    4556             : 
    4557             :     /* -------------------------------------------------------------------- */
    4558             :     /*      Generate all the bands.                                         */
    4559             :     /* -------------------------------------------------------------------- */
    4560          44 :     double dfPixelsProcessed = 0.0;
    4561             : 
    4562          88 :     CPLStringList aosOptions(papszOptions);
    4563          44 :     aosOptions.SetNameValue("CASCADING", "YES");
    4564         171 :     for (int i = 0; i < nOverviews; ++i)
    4565             :     {
    4566         127 :         GDALRasterBand *poBaseBand = poSrcBand;
    4567         127 :         if (i != 0)
    4568          83 :             poBaseBand = papoOvrBands[i - 1];
    4569             : 
    4570         127 :         double dfPixels = papoOvrBands[i]->GetXSize() *
    4571         127 :                           static_cast<double>(papoOvrBands[i]->GetYSize());
    4572             : 
    4573         254 :         void *pScaledProgressData = GDALCreateScaledProgress(
    4574             :             dfPixelsProcessed / dfTotalPixels,
    4575         127 :             (dfPixelsProcessed + dfPixels) / dfTotalPixels, pfnProgress,
    4576             :             pProgressData);
    4577             : 
    4578         254 :         const CPLErr eErr = GDALRegenerateOverviewsEx(
    4579             :             poBaseBand, 1,
    4580         127 :             reinterpret_cast<GDALRasterBandH *>(papoOvrBands) + i,
    4581             :             pszResampling, GDALScaledProgress, pScaledProgressData,
    4582         127 :             aosOptions.List());
    4583         127 :         GDALDestroyScaledProgress(pScaledProgressData);
    4584             : 
    4585         127 :         if (eErr != CE_None)
    4586           0 :             return eErr;
    4587             : 
    4588         127 :         dfPixelsProcessed += dfPixels;
    4589             : 
    4590             :         // Only do the bit2grayscale promotion on the base band.
    4591         127 :         if (STARTS_WITH_CI(pszResampling,
    4592             :                            "AVERAGE_BIT2G" /* AVERAGE_BIT2GRAYSCALE */))
    4593           8 :             pszResampling = "AVERAGE";
    4594             :     }
    4595             : 
    4596          44 :     return CE_None;
    4597             : }
    4598             : 
    4599             : /************************************************************************/
    4600             : /*                      GDALGetResampleFunction()                       */
    4601             : /************************************************************************/
    4602             : 
    4603        5467 : GDALResampleFunction GDALGetResampleFunction(const char *pszResampling,
    4604             :                                              int *pnRadius)
    4605             : {
    4606        5467 :     if (pnRadius)
    4607        5467 :         *pnRadius = 0;
    4608        5467 :     if (STARTS_WITH_CI(pszResampling, "NEAR"))
    4609         519 :         return GDALResampleChunk_Near;
    4610        4948 :     else if (STARTS_WITH_CI(pszResampling, "AVER") ||
    4611        4373 :              EQUAL(pszResampling, "RMS"))
    4612         634 :         return GDALResampleChunk_AverageOrRMS;
    4613        4314 :     else if (EQUAL(pszResampling, "GAUSS"))
    4614             :     {
    4615          26 :         if (pnRadius)
    4616          26 :             *pnRadius = 1;
    4617          26 :         return GDALResampleChunk_Gauss;
    4618             :     }
    4619        4288 :     else if (EQUAL(pszResampling, "MODE"))
    4620         136 :         return GDALResampleChunk_Mode;
    4621        4152 :     else if (EQUAL(pszResampling, "CUBIC"))
    4622             :     {
    4623        1639 :         if (pnRadius)
    4624        1639 :             *pnRadius = GWKGetFilterRadius(GRA_Cubic);
    4625        1639 :         return GDALResampleChunk_Convolution;
    4626             :     }
    4627        2513 :     else if (EQUAL(pszResampling, "CUBICSPLINE"))
    4628             :     {
    4629          39 :         if (pnRadius)
    4630          39 :             *pnRadius = GWKGetFilterRadius(GRA_CubicSpline);
    4631          39 :         return GDALResampleChunk_Convolution;
    4632             :     }
    4633        2474 :     else if (EQUAL(pszResampling, "LANCZOS"))
    4634             :     {
    4635          44 :         if (pnRadius)
    4636          44 :             *pnRadius = GWKGetFilterRadius(GRA_Lanczos);
    4637          44 :         return GDALResampleChunk_Convolution;
    4638             :     }
    4639        2430 :     else if (EQUAL(pszResampling, "BILINEAR"))
    4640             :     {
    4641        2430 :         if (pnRadius)
    4642        2430 :             *pnRadius = GWKGetFilterRadius(GRA_Bilinear);
    4643        2430 :         return GDALResampleChunk_Convolution;
    4644             :     }
    4645             :     else
    4646             :     {
    4647           0 :         CPLError(
    4648             :             CE_Failure, CPLE_AppDefined,
    4649             :             "GDALGetResampleFunction: Unsupported resampling method \"%s\".",
    4650             :             pszResampling);
    4651           0 :         return nullptr;
    4652             :     }
    4653             : }
    4654             : 
    4655             : /************************************************************************/
    4656             : /*                       GDALGetOvrWorkDataType()                       */
    4657             : /************************************************************************/
    4658             : 
    4659        5349 : GDALDataType GDALGetOvrWorkDataType(const char *pszResampling,
    4660             :                                     GDALDataType eSrcDataType)
    4661             : {
    4662        5349 :     if (STARTS_WITH_CI(pszResampling, "NEAR") || EQUAL(pszResampling, "MODE"))
    4663             :     {
    4664         647 :         return eSrcDataType;
    4665             :     }
    4666        4702 :     else if (eSrcDataType == GDT_UInt8 &&
    4667        4167 :              (STARTS_WITH_CI(pszResampling, "AVER") ||
    4668        3682 :               EQUAL(pszResampling, "RMS") || EQUAL(pszResampling, "CUBIC") ||
    4669        2279 :               EQUAL(pszResampling, "CUBICSPLINE") ||
    4670        2274 :               EQUAL(pszResampling, "LANCZOS") ||
    4671        2267 :               EQUAL(pszResampling, "BILINEAR") || EQUAL(pszResampling, "MODE")))
    4672             :     {
    4673        4160 :         return GDT_UInt8;
    4674             :     }
    4675         542 :     else if (eSrcDataType == GDT_UInt16 &&
    4676         131 :              (STARTS_WITH_CI(pszResampling, "AVER") ||
    4677         126 :               EQUAL(pszResampling, "RMS") || EQUAL(pszResampling, "CUBIC") ||
    4678           8 :               EQUAL(pszResampling, "CUBICSPLINE") ||
    4679           6 :               EQUAL(pszResampling, "LANCZOS") ||
    4680           3 :               EQUAL(pszResampling, "BILINEAR") || EQUAL(pszResampling, "MODE")))
    4681             :     {
    4682         131 :         return GDT_UInt16;
    4683             :     }
    4684         411 :     else if (EQUAL(pszResampling, "GAUSS"))
    4685          20 :         return GDT_Float64;
    4686             : 
    4687         391 :     if (eSrcDataType == GDT_UInt8 || eSrcDataType == GDT_Int8 ||
    4688         390 :         eSrcDataType == GDT_UInt16 || eSrcDataType == GDT_Int16 ||
    4689             :         eSrcDataType == GDT_Float32)
    4690             :     {
    4691         257 :         return GDT_Float32;
    4692             :     }
    4693         134 :     return GDT_Float64;
    4694             : }
    4695             : 
    4696             : namespace
    4697             : {
    4698             : // Structure to hold a pointer to free with CPLFree()
    4699             : struct PointerHolder
    4700             : {
    4701             :     void *ptr = nullptr;
    4702             : 
    4703        4178 :     template <class T> explicit PointerHolder(T *&ptrIn) : ptr(ptrIn)
    4704             :     {
    4705        4178 :         ptrIn = nullptr;
    4706        4178 :     }
    4707             : 
    4708             :     template <class T>
    4709          32 :     explicit PointerHolder(std::unique_ptr<T, VSIFreeReleaser> ptrIn)
    4710          32 :         : ptr(ptrIn.release())
    4711             :     {
    4712          32 :     }
    4713             : 
    4714        4210 :     ~PointerHolder()
    4715        4210 :     {
    4716        4210 :         CPLFree(ptr);
    4717        4210 :     }
    4718             : 
    4719             :     PointerHolder(const PointerHolder &) = delete;
    4720             :     PointerHolder &operator=(const PointerHolder &) = delete;
    4721             : };
    4722             : }  // namespace
    4723             : 
    4724             : /************************************************************************/
    4725             : /*                      GDALRegenerateOverviews()                       */
    4726             : /************************************************************************/
    4727             : 
    4728             : /**
    4729             :  * \brief Generate downsampled overviews.
    4730             :  *
    4731             :  * This function will generate one or more overview images from a base image
    4732             :  * using the requested downsampling algorithm.  Its primary use is for
    4733             :  * generating overviews via GDALDataset::BuildOverviews(), but it can also be
    4734             :  * used to generate downsampled images in one file from another outside the
    4735             :  * overview architecture.
    4736             :  *
    4737             :  * The output bands need to exist in advance.
    4738             :  *
    4739             :  * The full set of resampling algorithms is documented in
    4740             :  * GDALDataset::BuildOverviews().
    4741             :  *
    4742             :  * This function will honour properly NODATA_VALUES tuples (special dataset
    4743             :  * metadata) so that only a given RGB triplet (in case of a RGB image) will be
    4744             :  * considered as the nodata value and not each value of the triplet
    4745             :  * independently per band.
    4746             :  *
    4747             :  * Starting with GDAL 3.2, the GDAL_NUM_THREADS configuration option can be set
    4748             :  * to "ALL_CPUS" or a integer value to specify the number of threads to use for
    4749             :  * overview computation.
    4750             :  *
    4751             :  * @param hSrcBand the source (base level) band.
    4752             :  * @param nOverviewCount the number of downsampled bands being generated.
    4753             :  * @param pahOvrBands the list of downsampled bands to be generated.
    4754             :  * @param pszResampling Resampling algorithm (e.g. "AVERAGE").
    4755             :  * @param pfnProgress progress report function.
    4756             :  * @param pProgressData progress function callback data.
    4757             :  * @return CE_None on success or CE_Failure on failure.
    4758             :  */
    4759         250 : CPLErr GDALRegenerateOverviews(GDALRasterBandH hSrcBand, int nOverviewCount,
    4760             :                                GDALRasterBandH *pahOvrBands,
    4761             :                                const char *pszResampling,
    4762             :                                GDALProgressFunc pfnProgress,
    4763             :                                void *pProgressData)
    4764             : 
    4765             : {
    4766         250 :     return GDALRegenerateOverviewsEx(hSrcBand, nOverviewCount, pahOvrBands,
    4767             :                                      pszResampling, pfnProgress, pProgressData,
    4768         250 :                                      nullptr);
    4769             : }
    4770             : 
    4771             : /************************************************************************/
    4772             : /*                     GDALRegenerateOverviewsEx()                      */
    4773             : /************************************************************************/
    4774             : 
    4775             : constexpr int RADIUS_TO_DIAMETER = 2;
    4776             : 
    4777             : /**
    4778             :  * \brief Generate downsampled overviews.
    4779             :  *
    4780             :  * This function will generate one or more overview images from a base image
    4781             :  * using the requested downsampling algorithm.  Its primary use is for
    4782             :  * generating overviews via GDALDataset::BuildOverviews(), but it can also be
    4783             :  * used to generate downsampled images in one file from another outside the
    4784             :  * overview architecture.
    4785             :  *
    4786             :  * The output bands need to exist in advance.
    4787             :  *
    4788             :  * The full set of resampling algorithms is documented in
    4789             :  * GDALDataset::BuildOverviews().
    4790             :  *
    4791             :  * This function will honour properly NODATA_VALUES tuples (special dataset
    4792             :  * metadata) so that only a given RGB triplet (in case of a RGB image) will be
    4793             :  * considered as the nodata value and not each value of the triplet
    4794             :  * independently per band.
    4795             :  *
    4796             :  * Starting with GDAL 3.2, the GDAL_NUM_THREADS configuration option can be set
    4797             :  * to "ALL_CPUS" or a integer value to specify the number of threads to use for
    4798             :  * overview computation.
    4799             :  *
    4800             :  * @param hSrcBand the source (base level) band.
    4801             :  * @param nOverviewCount the number of downsampled bands being generated.
    4802             :  * @param pahOvrBands the list of downsampled bands to be generated.
    4803             :  * @param pszResampling Resampling algorithm (e.g. "AVERAGE").
    4804             :  * @param pfnProgress progress report function.
    4805             :  * @param pProgressData progress function callback data.
    4806             :  * @param papszOptions NULL terminated list of options as key=value pairs, or
    4807             :  * NULL
    4808             :  * @return CE_None on success or CE_Failure on failure.
    4809             :  * @since GDAL 3.6
    4810             :  */
    4811         915 : CPLErr GDALRegenerateOverviewsEx(GDALRasterBandH hSrcBand, int nOverviewCount,
    4812             :                                  GDALRasterBandH *pahOvrBands,
    4813             :                                  const char *pszResampling,
    4814             :                                  GDALProgressFunc pfnProgress,
    4815             :                                  void *pProgressData, CSLConstList papszOptions)
    4816             : 
    4817             : {
    4818         915 :     GDALRasterBand *poSrcBand = GDALRasterBand::FromHandle(hSrcBand);
    4819         915 :     GDALRasterBand **papoOvrBands =
    4820             :         reinterpret_cast<GDALRasterBand **>(pahOvrBands);
    4821             : 
    4822         915 :     if (pfnProgress == nullptr)
    4823         252 :         pfnProgress = GDALDummyProgress;
    4824             : 
    4825         915 :     if (EQUAL(pszResampling, "NONE"))
    4826          49 :         return CE_None;
    4827             : 
    4828         866 :     int nKernelRadius = 0;
    4829             :     GDALResampleFunction pfnResampleFn =
    4830         866 :         GDALGetResampleFunction(pszResampling, &nKernelRadius);
    4831             : 
    4832         866 :     if (pfnResampleFn == nullptr)
    4833           0 :         return CE_Failure;
    4834             : 
    4835             :     /* -------------------------------------------------------------------- */
    4836             :     /*      Check color tables...                                           */
    4837             :     /* -------------------------------------------------------------------- */
    4838         866 :     GDALColorTable *poColorTable = nullptr;
    4839             : 
    4840         495 :     if ((STARTS_WITH_CI(pszResampling, "AVER") || EQUAL(pszResampling, "RMS") ||
    4841        1810 :          EQUAL(pszResampling, "MODE") || EQUAL(pszResampling, "GAUSS")) &&
    4842         460 :         poSrcBand->GetColorInterpretation() == GCI_PaletteIndex)
    4843             :     {
    4844           9 :         poColorTable = poSrcBand->GetColorTable();
    4845           9 :         if (poColorTable != nullptr)
    4846             :         {
    4847           9 :             if (poColorTable->GetPaletteInterpretation() != GPI_RGB)
    4848             :             {
    4849           0 :                 CPLError(CE_Warning, CPLE_AppDefined,
    4850             :                          "Computing overviews on palette index raster bands "
    4851             :                          "with a palette whose color interpretation is not RGB "
    4852             :                          "will probably lead to unexpected results.");
    4853           0 :                 poColorTable = nullptr;
    4854             :             }
    4855           9 :             else if (poColorTable->IsIdentity())
    4856             :             {
    4857           0 :                 poColorTable = nullptr;
    4858             :             }
    4859             :         }
    4860             :         else
    4861             :         {
    4862           0 :             CPLError(CE_Warning, CPLE_AppDefined,
    4863             :                      "Computing overviews on palette index raster bands "
    4864             :                      "without a palette will probably lead to unexpected "
    4865             :                      "results.");
    4866             :         }
    4867             :     }
    4868             :     // Not ready yet
    4869        2517 :     else if ((EQUAL(pszResampling, "CUBIC") ||
    4870         803 :               EQUAL(pszResampling, "CUBICSPLINE") ||
    4871         803 :               EQUAL(pszResampling, "LANCZOS") ||
    4872        1740 :               EQUAL(pszResampling, "BILINEAR")) &&
    4873          80 :              poSrcBand->GetColorInterpretation() == GCI_PaletteIndex)
    4874             :     {
    4875           0 :         CPLError(CE_Warning, CPLE_AppDefined,
    4876             :                  "Computing %s overviews on palette index raster bands "
    4877             :                  "will probably lead to unexpected results.",
    4878             :                  pszResampling);
    4879             :     }
    4880             : 
    4881             :     // If we have a nodata mask and we are doing something more complicated
    4882             :     // than nearest neighbouring, we have to fetch to nodata mask.
    4883             : 
    4884         866 :     GDALRasterBand *poMaskBand = nullptr;
    4885         866 :     bool bUseNoDataMask = false;
    4886         866 :     bool bCanUseCascaded = true;
    4887             : 
    4888         866 :     if (!STARTS_WITH_CI(pszResampling, "NEAR"))
    4889             :     {
    4890             :         // Special case if we are an alpha/mask band. We want it to be
    4891             :         // considered as the mask band to avoid alpha=0 to be taken into account
    4892             :         // in average computation.
    4893         540 :         if (poSrcBand->IsMaskBand())
    4894             :         {
    4895          93 :             poMaskBand = poSrcBand;
    4896          93 :             bUseNoDataMask = true;
    4897             :         }
    4898             :         else
    4899             :         {
    4900         447 :             poMaskBand = poSrcBand->GetMaskBand();
    4901         447 :             const int nMaskFlags = poSrcBand->GetMaskFlags();
    4902         447 :             bCanUseCascaded =
    4903         447 :                 (nMaskFlags == GMF_NODATA || nMaskFlags == GMF_ALL_VALID);
    4904         447 :             bUseNoDataMask = (nMaskFlags & GMF_ALL_VALID) == 0;
    4905             :         }
    4906             :     }
    4907             : 
    4908         866 :     int nHasNoData = 0;
    4909         866 :     const double dfNoDataValue = poSrcBand->GetNoDataValue(&nHasNoData);
    4910         866 :     const bool bHasNoData = CPL_TO_BOOL(nHasNoData);
    4911             :     const bool bPropagateNoData =
    4912         866 :         CPLTestBool(CPLGetConfigOption("GDAL_OVR_PROPAGATE_NODATA", "NO"));
    4913             : 
    4914         974 :     if (poSrcBand->GetBand() == 1 && bUseNoDataMask &&
    4915         108 :         CSLFetchNameValue(papszOptions, "CASCADING") == nullptr)
    4916             :     {
    4917         192 :         std::string osDetailMessage;
    4918          96 :         if (poSrcBand->HasConflictingMaskSources(&osDetailMessage, false))
    4919             :         {
    4920           2 :             CPLError(
    4921             :                 CE_Warning, CPLE_AppDefined, "%s%s", osDetailMessage.c_str(),
    4922             :                 bHasNoData
    4923             :                     ? "Only the nodata value will be taken into account."
    4924             :                     : "Only the first listed one will be taken into account.");
    4925             :         }
    4926             :     }
    4927             : 
    4928             :     /* -------------------------------------------------------------------- */
    4929             :     /*      If we are operating on multiple overviews, and using            */
    4930             :     /*      averaging, lets do them in cascading order to reduce the        */
    4931             :     /*      amount of computation.                                          */
    4932             :     /* -------------------------------------------------------------------- */
    4933             : 
    4934             :     // In case the mask made be computed from another band of the dataset,
    4935             :     // we can't use cascaded generation, as the computation of the overviews
    4936             :     // of the band used for the mask band may not have yet occurred (#3033).
    4937         866 :     if ((STARTS_WITH_CI(pszResampling, "AVER") ||
    4938         495 :          EQUAL(pszResampling, "GAUSS") || EQUAL(pszResampling, "RMS") ||
    4939         464 :          EQUAL(pszResampling, "CUBIC") || EQUAL(pszResampling, "CUBICSPLINE") ||
    4940         410 :          EQUAL(pszResampling, "LANCZOS") || EQUAL(pszResampling, "BILINEAR") ||
    4941         866 :          EQUAL(pszResampling, "MODE")) &&
    4942          44 :         nOverviewCount > 1 && bCanUseCascaded)
    4943          44 :         return GDALRegenerateCascadingOverviews(
    4944             :             poSrcBand, nOverviewCount, papoOvrBands, pszResampling, pfnProgress,
    4945          44 :             pProgressData, papszOptions);
    4946             : 
    4947             :     /* -------------------------------------------------------------------- */
    4948             :     /*      Setup one horizontal swath to read from the raw buffer.         */
    4949             :     /* -------------------------------------------------------------------- */
    4950         822 :     int nFRXBlockSize = 0;
    4951         822 :     int nFRYBlockSize = 0;
    4952         822 :     poSrcBand->GetBlockSize(&nFRXBlockSize, &nFRYBlockSize);
    4953             : 
    4954         822 :     const GDALDataType eSrcDataType = poSrcBand->GetRasterDataType();
    4955        1318 :     const bool bUseGenericResampleFn = STARTS_WITH_CI(pszResampling, "NEAR") ||
    4956        1268 :                                        EQUAL(pszResampling, "MODE") ||
    4957         446 :                                        !GDALDataTypeIsComplex(eSrcDataType);
    4958             :     const GDALDataType eWrkDataType =
    4959             :         bUseGenericResampleFn
    4960         822 :             ? GDALGetOvrWorkDataType(pszResampling, eSrcDataType)
    4961         822 :             : GDT_CFloat32;
    4962             : 
    4963         822 :     const int nWidth = poSrcBand->GetXSize();
    4964         822 :     const int nHeight = poSrcBand->GetYSize();
    4965             : 
    4966         822 :     int nMaxOvrFactor = 1;
    4967        1763 :     for (int iOverview = 0; iOverview < nOverviewCount; ++iOverview)
    4968             :     {
    4969         941 :         const int nDstWidth = papoOvrBands[iOverview]->GetXSize();
    4970         941 :         const int nDstHeight = papoOvrBands[iOverview]->GetYSize();
    4971         941 :         nMaxOvrFactor = std::max(
    4972             :             nMaxOvrFactor,
    4973         941 :             static_cast<int>(static_cast<double>(nWidth) / nDstWidth + 0.5));
    4974         941 :         nMaxOvrFactor = std::max(
    4975             :             nMaxOvrFactor,
    4976         941 :             static_cast<int>(static_cast<double>(nHeight) / nDstHeight + 0.5));
    4977             :     }
    4978             : 
    4979         822 :     int nFullResYChunk = nFRYBlockSize;
    4980         822 :     int nMaxChunkYSizeQueried = 0;
    4981             : 
    4982             :     const auto UpdateChunkHeightAndGetChunkSize =
    4983       10802 :         [&nFullResYChunk, &nMaxChunkYSizeQueried, nKernelRadius, nMaxOvrFactor,
    4984       87377 :          eWrkDataType, nWidth]()
    4985             :     {
    4986             :         // Make sure that round(nChunkYOff / nMaxOvrFactor) < round((nChunkYOff
    4987             :         // + nFullResYChunk) / nMaxOvrFactor)
    4988       10802 :         if (nMaxOvrFactor > INT_MAX / RADIUS_TO_DIAMETER)
    4989             :         {
    4990           1 :             return GINTBIG_MAX;
    4991             :         }
    4992       10801 :         nFullResYChunk =
    4993       10801 :             std::max(nFullResYChunk, RADIUS_TO_DIAMETER * nMaxOvrFactor);
    4994       10801 :         if ((nKernelRadius > 0 &&
    4995         970 :              nMaxOvrFactor > INT_MAX / (RADIUS_TO_DIAMETER * nKernelRadius)) ||
    4996       10801 :             nFullResYChunk >
    4997       10801 :                 INT_MAX - RADIUS_TO_DIAMETER * nKernelRadius * nMaxOvrFactor)
    4998             :         {
    4999           0 :             return GINTBIG_MAX;
    5000             :         }
    5001       10801 :         nMaxChunkYSizeQueried =
    5002       10801 :             nFullResYChunk + RADIUS_TO_DIAMETER * nKernelRadius * nMaxOvrFactor;
    5003       10801 :         if (GDALGetDataTypeSizeBytes(eWrkDataType) >
    5004       10801 :             std::numeric_limits<int64_t>::max() /
    5005       10801 :                 (static_cast<int64_t>(nMaxChunkYSizeQueried) * nWidth))
    5006             :         {
    5007           1 :             return GINTBIG_MAX;
    5008             :         }
    5009       10800 :         return static_cast<GIntBig>(GDALGetDataTypeSizeBytes(eWrkDataType)) *
    5010       10800 :                nMaxChunkYSizeQueried * nWidth;
    5011         822 :     };
    5012             : 
    5013             :     const char *pszChunkYSize =
    5014         822 :         CPLGetConfigOption("GDAL_OVR_CHUNKYSIZE", nullptr);
    5015             : #ifndef __COVERITY__
    5016             :     // Only configurable for debug / testing
    5017         822 :     if (pszChunkYSize)
    5018             :     {
    5019           0 :         nFullResYChunk = atoi(pszChunkYSize);
    5020             :     }
    5021             : #endif
    5022             : 
    5023             :     // Only configurable for debug / testing
    5024             :     const int nChunkMaxSize =
    5025         822 :         atoi(CPLGetConfigOption("GDAL_OVR_CHUNK_MAX_SIZE", "10485760"));
    5026             : 
    5027         822 :     auto nChunkSize = UpdateChunkHeightAndGetChunkSize();
    5028         822 :     if (nChunkSize > nChunkMaxSize)
    5029             :     {
    5030          15 :         if (poColorTable == nullptr && nFRXBlockSize < nWidth &&
    5031          44 :             !GDALDataTypeIsComplex(eSrcDataType) &&
    5032          14 :             (!STARTS_WITH_CI(pszResampling, "AVER") ||
    5033           2 :              EQUAL(pszResampling, "AVERAGE")))
    5034             :         {
    5035             :             // If this is tiled, then use GDALRegenerateOverviewsMultiBand()
    5036             :             // which use a block based strategy, which is much less memory
    5037             :             // hungry.
    5038          14 :             return GDALRegenerateOverviewsMultiBand(
    5039             :                 1, &poSrcBand, nOverviewCount, &papoOvrBands, pszResampling,
    5040          14 :                 pfnProgress, pProgressData, papszOptions);
    5041             :         }
    5042           1 :         else if (nOverviewCount > 1 && STARTS_WITH_CI(pszResampling, "NEAR"))
    5043             :         {
    5044           0 :             return GDALRegenerateCascadingOverviews(
    5045             :                 poSrcBand, nOverviewCount, papoOvrBands, pszResampling,
    5046           0 :                 pfnProgress, pProgressData, papszOptions);
    5047             :         }
    5048             :     }
    5049         807 :     else if (pszChunkYSize == nullptr)
    5050             :     {
    5051             :         // Try to get as close as possible to nChunkMaxSize
    5052       10787 :         while (nChunkSize < nChunkMaxSize / 2)
    5053             :         {
    5054        9980 :             nFullResYChunk *= 2;
    5055        9980 :             nChunkSize = UpdateChunkHeightAndGetChunkSize();
    5056             :         }
    5057             :     }
    5058             : 
    5059             :     // Structure describing a resampling job
    5060             :     struct OvrJob
    5061             :     {
    5062             :         // Buffers to free when job is finished
    5063             :         std::shared_ptr<PointerHolder> oSrcMaskBufferHolder{};
    5064             :         std::shared_ptr<PointerHolder> oSrcBufferHolder{};
    5065             :         std::unique_ptr<PointerHolder> oDstBufferHolder{};
    5066             : 
    5067             :         GDALRasterBand *poDstBand = nullptr;
    5068             : 
    5069             :         // Input parameters of pfnResampleFn
    5070             :         GDALResampleFunction pfnResampleFn = nullptr;
    5071             :         int nSrcWidth = 0;
    5072             :         int nSrcHeight = 0;
    5073             :         int nDstWidth = 0;
    5074             :         GDALOverviewResampleArgs args{};
    5075             :         const void *pChunk = nullptr;
    5076             :         bool bUseGenericResampleFn = false;
    5077             : 
    5078             :         // Output values of resampling function
    5079             :         CPLErr eErr = CE_Failure;
    5080             :         void *pDstBuffer = nullptr;
    5081             :         GDALDataType eDstBufferDataType = GDT_Unknown;
    5082             : 
    5083           0 :         void SetSrcMaskBufferHolder(
    5084             :             const std::shared_ptr<PointerHolder> &oSrcMaskBufferHolderIn)
    5085             :         {
    5086           0 :             oSrcMaskBufferHolder = oSrcMaskBufferHolderIn;
    5087           0 :         }
    5088             : 
    5089           0 :         void SetSrcBufferHolder(
    5090             :             const std::shared_ptr<PointerHolder> &oSrcBufferHolderIn)
    5091             :         {
    5092           0 :             oSrcBufferHolder = oSrcBufferHolderIn;
    5093           0 :         }
    5094             : 
    5095         910 :         void NotifyFinished()
    5096             :         {
    5097        1820 :             std::lock_guard guard(mutex);
    5098         910 :             bFinished = true;
    5099         910 :             cv.notify_one();
    5100         910 :         }
    5101             : 
    5102           0 :         bool IsFinished()
    5103             :         {
    5104           0 :             std::lock_guard guard(mutex);
    5105           0 :             return bFinished;
    5106             :         }
    5107             : 
    5108           0 :         void WaitFinished()
    5109             :         {
    5110           0 :             std::unique_lock oGuard(mutex);
    5111           0 :             while (!bFinished)
    5112             :             {
    5113           0 :                 cv.wait(oGuard);
    5114             :             }
    5115           0 :         }
    5116             : 
    5117             :       private:
    5118             :         // Synchronization
    5119             :         bool bFinished = false;
    5120             :         std::mutex mutex{};
    5121             :         std::condition_variable cv{};
    5122             :     };
    5123             : 
    5124             :     // Thread function to resample
    5125         910 :     const auto JobResampleFunc = [](void *pData)
    5126             :     {
    5127         910 :         OvrJob *poJob = static_cast<OvrJob *>(pData);
    5128             : 
    5129         910 :         if (poJob->bUseGenericResampleFn)
    5130             :         {
    5131         908 :             poJob->eErr = poJob->pfnResampleFn(poJob->args, poJob->pChunk,
    5132             :                                                &(poJob->pDstBuffer),
    5133             :                                                &(poJob->eDstBufferDataType));
    5134             :         }
    5135             :         else
    5136             :         {
    5137           2 :             poJob->eErr = GDALResampleChunkC32R(
    5138             :                 poJob->nSrcWidth, poJob->nSrcHeight,
    5139           2 :                 static_cast<const float *>(poJob->pChunk),
    5140             :                 poJob->args.nChunkYOff, poJob->args.nChunkYSize,
    5141             :                 poJob->args.nDstYOff, poJob->args.nDstYOff2,
    5142             :                 poJob->args.nOvrXSize, poJob->args.nOvrYSize,
    5143             :                 &(poJob->pDstBuffer), &(poJob->eDstBufferDataType),
    5144             :                 poJob->args.pszResampling);
    5145             :         }
    5146             : 
    5147         910 :         auto pDstBuffer = poJob->pDstBuffer;
    5148         910 :         poJob->oDstBufferHolder = std::make_unique<PointerHolder>(pDstBuffer);
    5149             : 
    5150         910 :         poJob->NotifyFinished();
    5151         910 :     };
    5152             : 
    5153             :     // Function to write resample data to target band
    5154         910 :     const auto WriteJobData = [](const OvrJob *poJob)
    5155             :     {
    5156        1820 :         return poJob->poDstBand->RasterIO(
    5157         910 :             GF_Write, 0, poJob->args.nDstYOff, poJob->nDstWidth,
    5158         910 :             poJob->args.nDstYOff2 - poJob->args.nDstYOff, poJob->pDstBuffer,
    5159         910 :             poJob->nDstWidth, poJob->args.nDstYOff2 - poJob->args.nDstYOff,
    5160         910 :             poJob->eDstBufferDataType, 0, 0, nullptr);
    5161             :     };
    5162             : 
    5163             :     // Wait for completion of oldest job and serialize it
    5164             :     const auto WaitAndFinalizeOldestJob =
    5165           0 :         [WriteJobData](std::list<std::unique_ptr<OvrJob>> &jobList)
    5166             :     {
    5167           0 :         auto poOldestJob = jobList.front().get();
    5168           0 :         poOldestJob->WaitFinished();
    5169           0 :         CPLErr l_eErr = poOldestJob->eErr;
    5170           0 :         if (l_eErr == CE_None)
    5171             :         {
    5172           0 :             l_eErr = WriteJobData(poOldestJob);
    5173             :         }
    5174             : 
    5175           0 :         jobList.pop_front();
    5176           0 :         return l_eErr;
    5177             :     };
    5178             : 
    5179             :     // Queue of jobs
    5180        1616 :     std::list<std::unique_ptr<OvrJob>> jobList;
    5181             : 
    5182         808 :     GByte *pabyChunkNodataMask = nullptr;
    5183         808 :     void *pChunk = nullptr;
    5184             : 
    5185         808 :     const int nThreads = GDALGetNumThreads(GDAL_DEFAULT_MAX_THREAD_COUNT,
    5186             :                                            /* bDefaultToAllCPUs=*/false);
    5187             :     auto poThreadPool =
    5188         808 :         nThreads > 1 ? GDALGetGlobalThreadPool(nThreads) : nullptr;
    5189             :     auto poJobQueue = poThreadPool ? poThreadPool->CreateJobQueue()
    5190        1616 :                                    : std::unique_ptr<CPLJobQueue>(nullptr);
    5191             : 
    5192             :     /* -------------------------------------------------------------------- */
    5193             :     /*      Loop over image operating on chunks.                            */
    5194             :     /* -------------------------------------------------------------------- */
    5195         808 :     int nChunkYOff = 0;
    5196         808 :     CPLErr eErr = CE_None;
    5197             : 
    5198        1621 :     for (nChunkYOff = 0; nChunkYOff < nHeight && eErr == CE_None;
    5199         813 :          nChunkYOff += nFullResYChunk)
    5200             :     {
    5201         813 :         if (!pfnProgress(nChunkYOff / static_cast<double>(nHeight), nullptr,
    5202             :                          pProgressData))
    5203             :         {
    5204           0 :             CPLError(CE_Failure, CPLE_UserInterrupt, "User terminated");
    5205           0 :             eErr = CE_Failure;
    5206             :         }
    5207             : 
    5208         813 :         if (nFullResYChunk + nChunkYOff > nHeight)
    5209         805 :             nFullResYChunk = nHeight - nChunkYOff;
    5210             : 
    5211         813 :         int nChunkYOffQueried = nChunkYOff - nKernelRadius * nMaxOvrFactor;
    5212         813 :         int nChunkYSizeQueried =
    5213         813 :             nFullResYChunk + 2 * nKernelRadius * nMaxOvrFactor;
    5214         813 :         if (nChunkYOffQueried < 0)
    5215             :         {
    5216          83 :             nChunkYSizeQueried += nChunkYOffQueried;
    5217          83 :             nChunkYOffQueried = 0;
    5218             :         }
    5219         813 :         if (nChunkYOffQueried + nChunkYSizeQueried > nHeight)
    5220          83 :             nChunkYSizeQueried = nHeight - nChunkYOffQueried;
    5221             : 
    5222             :         // Avoid accumulating too many tasks and exhaust RAM
    5223             :         // Try to complete already finished jobs
    5224         813 :         while (eErr == CE_None && !jobList.empty())
    5225             :         {
    5226           0 :             auto poOldestJob = jobList.front().get();
    5227           0 :             if (!poOldestJob->IsFinished())
    5228           0 :                 break;
    5229           0 :             eErr = poOldestJob->eErr;
    5230           0 :             if (eErr == CE_None)
    5231             :             {
    5232           0 :                 eErr = WriteJobData(poOldestJob);
    5233             :             }
    5234             : 
    5235           0 :             jobList.pop_front();
    5236             :         }
    5237             : 
    5238             :         // And in case we have saturated the number of threads,
    5239             :         // wait for completion of tasks to go below the threshold.
    5240        1626 :         while (eErr == CE_None &&
    5241         813 :                jobList.size() >= static_cast<size_t>(nThreads))
    5242             :         {
    5243           0 :             eErr = WaitAndFinalizeOldestJob(jobList);
    5244             :         }
    5245             : 
    5246             :         // (Re)allocate buffers if needed
    5247         813 :         if (pChunk == nullptr)
    5248             :         {
    5249         808 :             pChunk = VSI_MALLOC3_VERBOSE(GDALGetDataTypeSizeBytes(eWrkDataType),
    5250             :                                          nMaxChunkYSizeQueried, nWidth);
    5251             :         }
    5252         813 :         if (bUseNoDataMask && pabyChunkNodataMask == nullptr)
    5253             :         {
    5254         287 :             pabyChunkNodataMask = static_cast<GByte *>(
    5255         287 :                 VSI_MALLOC2_VERBOSE(nMaxChunkYSizeQueried, nWidth));
    5256             :         }
    5257             : 
    5258         813 :         if (pChunk == nullptr ||
    5259         287 :             (bUseNoDataMask && pabyChunkNodataMask == nullptr))
    5260             :         {
    5261           0 :             CPLFree(pChunk);
    5262           0 :             CPLFree(pabyChunkNodataMask);
    5263           0 :             return CE_Failure;
    5264             :         }
    5265             : 
    5266             :         // Read chunk.
    5267         813 :         if (eErr == CE_None)
    5268         813 :             eErr = poSrcBand->RasterIO(GF_Read, 0, nChunkYOffQueried, nWidth,
    5269             :                                        nChunkYSizeQueried, pChunk, nWidth,
    5270             :                                        nChunkYSizeQueried, eWrkDataType, 0, 0,
    5271             :                                        nullptr);
    5272         813 :         if (eErr == CE_None && bUseNoDataMask)
    5273         287 :             eErr = poMaskBand->RasterIO(GF_Read, 0, nChunkYOffQueried, nWidth,
    5274             :                                         nChunkYSizeQueried, pabyChunkNodataMask,
    5275             :                                         nWidth, nChunkYSizeQueried, GDT_UInt8,
    5276             :                                         0, 0, nullptr);
    5277             : 
    5278             :         // Special case to promote 1bit data to 8bit 0/255 values.
    5279         813 :         if (EQUAL(pszResampling, "AVERAGE_BIT2GRAYSCALE"))
    5280             :         {
    5281           9 :             if (eWrkDataType == GDT_Float32)
    5282             :             {
    5283           0 :                 float *pafChunk = static_cast<float *>(pChunk);
    5284           0 :                 for (size_t i = 0;
    5285           0 :                      i < static_cast<size_t>(nChunkYSizeQueried) * nWidth; i++)
    5286             :                 {
    5287           0 :                     if (pafChunk[i] == 1.0f)
    5288           0 :                         pafChunk[i] = 255.0f;
    5289             :                 }
    5290             :             }
    5291           9 :             else if (eWrkDataType == GDT_UInt8)
    5292             :             {
    5293           9 :                 GByte *pabyChunk = static_cast<GByte *>(pChunk);
    5294      168417 :                 for (size_t i = 0;
    5295      168417 :                      i < static_cast<size_t>(nChunkYSizeQueried) * nWidth; i++)
    5296             :                 {
    5297      168408 :                     if (pabyChunk[i] == 1)
    5298      127437 :                         pabyChunk[i] = 255;
    5299             :                 }
    5300             :             }
    5301           0 :             else if (eWrkDataType == GDT_UInt16)
    5302             :             {
    5303           0 :                 GUInt16 *pasChunk = static_cast<GUInt16 *>(pChunk);
    5304           0 :                 for (size_t i = 0;
    5305           0 :                      i < static_cast<size_t>(nChunkYSizeQueried) * nWidth; i++)
    5306             :                 {
    5307           0 :                     if (pasChunk[i] == 1)
    5308           0 :                         pasChunk[i] = 255;
    5309             :                 }
    5310             :             }
    5311           0 :             else if (eWrkDataType == GDT_Float64)
    5312             :             {
    5313           0 :                 double *padfChunk = static_cast<double *>(pChunk);
    5314           0 :                 for (size_t i = 0;
    5315           0 :                      i < static_cast<size_t>(nChunkYSizeQueried) * nWidth; i++)
    5316             :                 {
    5317           0 :                     if (padfChunk[i] == 1.0)
    5318           0 :                         padfChunk[i] = 255.0;
    5319             :                 }
    5320             :             }
    5321             :             else
    5322             :             {
    5323           0 :                 CPLAssert(false);
    5324             :             }
    5325             :         }
    5326         804 :         else if (EQUAL(pszResampling, "AVERAGE_BIT2GRAYSCALE_MINISWHITE"))
    5327             :         {
    5328           0 :             if (eWrkDataType == GDT_Float32)
    5329             :             {
    5330           0 :                 float *pafChunk = static_cast<float *>(pChunk);
    5331           0 :                 for (size_t i = 0;
    5332           0 :                      i < static_cast<size_t>(nChunkYSizeQueried) * nWidth; i++)
    5333             :                 {
    5334           0 :                     if (pafChunk[i] == 1.0f)
    5335           0 :                         pafChunk[i] = 0.0f;
    5336           0 :                     else if (pafChunk[i] == 0.0f)
    5337           0 :                         pafChunk[i] = 255.0f;
    5338             :                 }
    5339             :             }
    5340           0 :             else if (eWrkDataType == GDT_UInt8)
    5341             :             {
    5342           0 :                 GByte *pabyChunk = static_cast<GByte *>(pChunk);
    5343           0 :                 for (size_t i = 0;
    5344           0 :                      i < static_cast<size_t>(nChunkYSizeQueried) * nWidth; i++)
    5345             :                 {
    5346           0 :                     if (pabyChunk[i] == 1)
    5347           0 :                         pabyChunk[i] = 0;
    5348           0 :                     else if (pabyChunk[i] == 0)
    5349           0 :                         pabyChunk[i] = 255;
    5350             :                 }
    5351             :             }
    5352           0 :             else if (eWrkDataType == GDT_UInt16)
    5353             :             {
    5354           0 :                 GUInt16 *pasChunk = static_cast<GUInt16 *>(pChunk);
    5355           0 :                 for (size_t i = 0;
    5356           0 :                      i < static_cast<size_t>(nChunkYSizeQueried) * nWidth; i++)
    5357             :                 {
    5358           0 :                     if (pasChunk[i] == 1)
    5359           0 :                         pasChunk[i] = 0;
    5360           0 :                     else if (pasChunk[i] == 0)
    5361           0 :                         pasChunk[i] = 255;
    5362             :                 }
    5363             :             }
    5364           0 :             else if (eWrkDataType == GDT_Float64)
    5365             :             {
    5366           0 :                 double *padfChunk = static_cast<double *>(pChunk);
    5367           0 :                 for (size_t i = 0;
    5368           0 :                      i < static_cast<size_t>(nChunkYSizeQueried) * nWidth; i++)
    5369             :                 {
    5370           0 :                     if (padfChunk[i] == 1.0)
    5371           0 :                         padfChunk[i] = 0.0;
    5372           0 :                     else if (padfChunk[i] == 0.0)
    5373           0 :                         padfChunk[i] = 255.0;
    5374             :                 }
    5375             :             }
    5376             :             else
    5377             :             {
    5378           0 :                 CPLAssert(false);
    5379             :             }
    5380             :         }
    5381             : 
    5382         813 :         auto pChunkRaw = pChunk;
    5383         813 :         auto pabyChunkNodataMaskRaw = pabyChunkNodataMask;
    5384         813 :         std::shared_ptr<PointerHolder> oSrcBufferHolder;
    5385         813 :         std::shared_ptr<PointerHolder> oSrcMaskBufferHolder;
    5386         813 :         if (poJobQueue)
    5387             :         {
    5388           0 :             oSrcBufferHolder = std::make_shared<PointerHolder>(pChunk);
    5389             :             oSrcMaskBufferHolder =
    5390           0 :                 std::make_shared<PointerHolder>(pabyChunkNodataMask);
    5391             :         }
    5392             : 
    5393        1723 :         for (int iOverview = 0; iOverview < nOverviewCount && eErr == CE_None;
    5394             :              ++iOverview)
    5395             :         {
    5396         910 :             GDALRasterBand *poDstBand = papoOvrBands[iOverview];
    5397         910 :             const int nDstWidth = poDstBand->GetXSize();
    5398         910 :             const int nDstHeight = poDstBand->GetYSize();
    5399             : 
    5400         910 :             const double dfXRatioDstToSrc =
    5401         910 :                 static_cast<double>(nWidth) / nDstWidth;
    5402         910 :             const double dfYRatioDstToSrc =
    5403         910 :                 static_cast<double>(nHeight) / nDstHeight;
    5404             : 
    5405             :             /* --------------------------------------------------------------------
    5406             :              */
    5407             :             /*      Figure out the line to start writing to, and the first line
    5408             :              */
    5409             :             /*      to not write to.  In theory this approach should ensure that
    5410             :              */
    5411             :             /*      every output line will be written if all input chunks are */
    5412             :             /*      processed. */
    5413             :             /* --------------------------------------------------------------------
    5414             :              */
    5415         910 :             int nDstYOff =
    5416         910 :                 static_cast<int>(0.5 + nChunkYOff / dfYRatioDstToSrc);
    5417         910 :             if (nDstYOff == nDstHeight)
    5418           0 :                 continue;
    5419         910 :             int nDstYOff2 = static_cast<int>(
    5420         910 :                 0.5 + (nChunkYOff + nFullResYChunk) / dfYRatioDstToSrc);
    5421             : 
    5422         910 :             if (nChunkYOff + nFullResYChunk == nHeight)
    5423         903 :                 nDstYOff2 = nDstHeight;
    5424             : #if DEBUG_VERBOSE
    5425             :             CPLDebug("GDAL",
    5426             :                      "Reading (%dx%d -> %dx%d) for output (%dx%d -> %dx%d)", 0,
    5427             :                      nChunkYOffQueried, nWidth, nChunkYSizeQueried, 0, nDstYOff,
    5428             :                      nDstWidth, nDstYOff2 - nDstYOff);
    5429             : #endif
    5430             : 
    5431        1820 :             auto poJob = std::make_unique<OvrJob>();
    5432         910 :             poJob->pfnResampleFn = pfnResampleFn;
    5433         910 :             poJob->bUseGenericResampleFn = bUseGenericResampleFn;
    5434         910 :             poJob->args.eOvrDataType = poDstBand->GetRasterDataType();
    5435         910 :             poJob->args.nOvrXSize = poDstBand->GetXSize();
    5436         910 :             poJob->args.nOvrYSize = poDstBand->GetYSize();
    5437             :             const char *pszNBITS =
    5438         910 :                 poDstBand->GetMetadataItem("NBITS", "IMAGE_STRUCTURE");
    5439         910 :             poJob->args.nOvrNBITS = pszNBITS ? atoi(pszNBITS) : 0;
    5440         910 :             poJob->args.dfXRatioDstToSrc = dfXRatioDstToSrc;
    5441         910 :             poJob->args.dfYRatioDstToSrc = dfYRatioDstToSrc;
    5442         910 :             poJob->args.eWrkDataType = eWrkDataType;
    5443         910 :             poJob->pChunk = pChunkRaw;
    5444         910 :             poJob->args.pabyChunkNodataMask = pabyChunkNodataMaskRaw;
    5445         910 :             poJob->nSrcWidth = nWidth;
    5446         910 :             poJob->nSrcHeight = nHeight;
    5447         910 :             poJob->args.nChunkXOff = 0;
    5448         910 :             poJob->args.nChunkXSize = nWidth;
    5449         910 :             poJob->args.nChunkYOff = nChunkYOffQueried;
    5450         910 :             poJob->args.nChunkYSize = nChunkYSizeQueried;
    5451         910 :             poJob->nDstWidth = nDstWidth;
    5452         910 :             poJob->args.nDstXOff = 0;
    5453         910 :             poJob->args.nDstXOff2 = nDstWidth;
    5454         910 :             poJob->args.nDstYOff = nDstYOff;
    5455         910 :             poJob->args.nDstYOff2 = nDstYOff2;
    5456         910 :             poJob->poDstBand = poDstBand;
    5457         910 :             poJob->args.pszResampling = pszResampling;
    5458         910 :             poJob->args.bHasNoData = bHasNoData;
    5459         910 :             poJob->args.dfNoDataValue = dfNoDataValue;
    5460         910 :             poJob->args.poColorTable = poColorTable;
    5461         910 :             poJob->args.eSrcDataType = eSrcDataType;
    5462         910 :             poJob->args.bPropagateNoData = bPropagateNoData;
    5463             : 
    5464         910 :             if (poJobQueue)
    5465             :             {
    5466           0 :                 poJob->SetSrcMaskBufferHolder(oSrcMaskBufferHolder);
    5467           0 :                 poJob->SetSrcBufferHolder(oSrcBufferHolder);
    5468           0 :                 poJobQueue->SubmitJob(JobResampleFunc, poJob.get());
    5469           0 :                 jobList.emplace_back(std::move(poJob));
    5470             :             }
    5471             :             else
    5472             :             {
    5473         910 :                 JobResampleFunc(poJob.get());
    5474         910 :                 eErr = poJob->eErr;
    5475         910 :                 if (eErr == CE_None)
    5476             :                 {
    5477         910 :                     eErr = WriteJobData(poJob.get());
    5478             :                 }
    5479             :             }
    5480             :         }
    5481             :     }
    5482             : 
    5483         808 :     VSIFree(pChunk);
    5484         808 :     VSIFree(pabyChunkNodataMask);
    5485             : 
    5486             :     // Wait for all pending jobs to complete
    5487         808 :     while (!jobList.empty())
    5488             :     {
    5489           0 :         const auto l_eErr = WaitAndFinalizeOldestJob(jobList);
    5490           0 :         if (l_eErr != CE_None && eErr == CE_None)
    5491           0 :             eErr = l_eErr;
    5492             :     }
    5493             : 
    5494             :     /* -------------------------------------------------------------------- */
    5495             :     /*      Renormalized overview mean / stddev if needed.                  */
    5496             :     /* -------------------------------------------------------------------- */
    5497         808 :     if (eErr == CE_None && EQUAL(pszResampling, "AVERAGE_MP"))
    5498             :     {
    5499           0 :         GDALOverviewMagnitudeCorrection(
    5500             :             poSrcBand, nOverviewCount,
    5501             :             reinterpret_cast<GDALRasterBandH *>(papoOvrBands),
    5502             :             GDALDummyProgress, nullptr);
    5503             :     }
    5504             : 
    5505             :     /* -------------------------------------------------------------------- */
    5506             :     /*      It can be important to flush out data to overviews.             */
    5507             :     /* -------------------------------------------------------------------- */
    5508        1711 :     for (int iOverview = 0; eErr == CE_None && iOverview < nOverviewCount;
    5509             :          ++iOverview)
    5510             :     {
    5511         903 :         eErr = papoOvrBands[iOverview]->FlushCache(false);
    5512             :     }
    5513             : 
    5514         808 :     if (eErr == CE_None)
    5515         808 :         pfnProgress(1.0, nullptr, pProgressData);
    5516             : 
    5517         808 :     return eErr;
    5518             : }
    5519             : 
    5520             : /************************************************************************/
    5521             : /*                  GDALRegenerateOverviewsMultiBand()                  */
    5522             : /************************************************************************/
    5523             : 
    5524             : /**
    5525             :  * \brief Variant of GDALRegenerateOverviews, specially dedicated for generating
    5526             :  * compressed pixel-interleaved overviews (JPEG-IN-TIFF for example)
    5527             :  *
    5528             :  * This function will generate one or more overview images from a base
    5529             :  * image using the requested downsampling algorithm.  Its primary use
    5530             :  * is for generating overviews via GDALDataset::BuildOverviews(), but it
    5531             :  * can also be used to generate downsampled images in one file from another
    5532             :  * outside the overview architecture.
    5533             :  *
    5534             :  * The output bands need to exist in advance and share the same characteristics
    5535             :  * (type, dimensions)
    5536             :  *
    5537             :  * The resampling algorithms supported for the moment are "NEAREST", "AVERAGE",
    5538             :  * "RMS", "GAUSS", "CUBIC", "CUBICSPLINE", "LANCZOS" and "BILINEAR"
    5539             :  *
    5540             :  * It does not support color tables or complex data types.
    5541             :  *
    5542             :  * The pseudo-algorithm used by the function is :
    5543             :  *    for each overview
    5544             :  *       iterate on lines of the source by a step of deltay
    5545             :  *           iterate on columns of the source  by a step of deltax
    5546             :  *               read the source data of size deltax * deltay for all the bands
    5547             :  *               generate the corresponding overview block for all the bands
    5548             :  *
    5549             :  * This function will honour properly NODATA_VALUES tuples (special dataset
    5550             :  * metadata) so that only a given RGB triplet (in case of a RGB image) will be
    5551             :  * considered as the nodata value and not each value of the triplet
    5552             :  * independently per band.
    5553             :  *
    5554             :  * Starting with GDAL 3.2, the GDAL_NUM_THREADS configuration option can be set
    5555             :  * to "ALL_CPUS" or a integer value to specify the number of threads to use for
    5556             :  * overview computation.
    5557             :  *
    5558             :  * @param nBands the number of bands, size of papoSrcBands and size of
    5559             :  *               first dimension of papapoOverviewBands
    5560             :  * @param papoSrcBands the list of source bands to downsample
    5561             :  * @param nOverviews the number of downsampled overview levels being generated.
    5562             :  * @param papapoOverviewBands bidimension array of bands. First dimension is
    5563             :  *                            indexed by nBands. Second dimension is indexed by
    5564             :  *                            nOverviews.
    5565             :  * @param pszResampling Resampling algorithm ("NEAREST", "AVERAGE", "RMS",
    5566             :  * "GAUSS", "CUBIC", "CUBICSPLINE", "LANCZOS" or "BILINEAR").
    5567             :  * @param pfnProgress progress report function.
    5568             :  * @param pProgressData progress function callback data.
    5569             :  * @param papszOptions (GDAL >= 3.6) NULL terminated list of options as
    5570             :  *                     key=value pairs, or NULL
    5571             :  *                     Starting with GDAL 3.8, the XOFF, YOFF, XSIZE and YSIZE
    5572             :  *                     options can be specified to express that overviews should
    5573             :  *                     be regenerated only in the specified subset of the source
    5574             :  *                     dataset.
    5575             :  * @return CE_None on success or CE_Failure on failure.
    5576             :  */
    5577             : 
    5578         383 : CPLErr GDALRegenerateOverviewsMultiBand(
    5579             :     int nBands, GDALRasterBand *const *papoSrcBands, int nOverviews,
    5580             :     GDALRasterBand *const *const *papapoOverviewBands,
    5581             :     const char *pszResampling, GDALProgressFunc pfnProgress,
    5582             :     void *pProgressData, CSLConstList papszOptions)
    5583             : {
    5584         383 :     CPL_IGNORE_RET_VAL(papszOptions);
    5585             : 
    5586         383 :     if (pfnProgress == nullptr)
    5587          11 :         pfnProgress = GDALDummyProgress;
    5588             : 
    5589         383 :     if (EQUAL(pszResampling, "NONE") || nBands == 0 || nOverviews == 0)
    5590           3 :         return CE_None;
    5591             : 
    5592             :     // Sanity checks.
    5593         380 :     if (!STARTS_WITH_CI(pszResampling, "NEAR") &&
    5594         187 :         !EQUAL(pszResampling, "RMS") && !EQUAL(pszResampling, "AVERAGE") &&
    5595          78 :         !EQUAL(pszResampling, "GAUSS") && !EQUAL(pszResampling, "CUBIC") &&
    5596          22 :         !EQUAL(pszResampling, "CUBICSPLINE") &&
    5597          21 :         !EQUAL(pszResampling, "LANCZOS") && !EQUAL(pszResampling, "BILINEAR") &&
    5598           5 :         !EQUAL(pszResampling, "MODE"))
    5599             :     {
    5600           0 :         CPLError(CE_Failure, CPLE_NotSupported,
    5601             :                  "GDALRegenerateOverviewsMultiBand: pszResampling='%s' "
    5602             :                  "not supported",
    5603             :                  pszResampling);
    5604           0 :         return CE_Failure;
    5605             :     }
    5606             : 
    5607         380 :     int nKernelRadius = 0;
    5608             :     GDALResampleFunction pfnResampleFn =
    5609         380 :         GDALGetResampleFunction(pszResampling, &nKernelRadius);
    5610         380 :     if (pfnResampleFn == nullptr)
    5611           0 :         return CE_Failure;
    5612             : 
    5613         380 :     const int nToplevelSrcWidth = papoSrcBands[0]->GetXSize();
    5614         380 :     const int nToplevelSrcHeight = papoSrcBands[0]->GetYSize();
    5615         380 :     if (nToplevelSrcWidth <= 0 || nToplevelSrcHeight <= 0)
    5616           0 :         return CE_None;
    5617         380 :     GDALDataType eDataType = papoSrcBands[0]->GetRasterDataType();
    5618       66221 :     for (int iBand = 1; iBand < nBands; ++iBand)
    5619             :     {
    5620      131682 :         if (papoSrcBands[iBand]->GetXSize() != nToplevelSrcWidth ||
    5621       65841 :             papoSrcBands[iBand]->GetYSize() != nToplevelSrcHeight)
    5622             :         {
    5623           0 :             CPLError(
    5624             :                 CE_Failure, CPLE_NotSupported,
    5625             :                 "GDALRegenerateOverviewsMultiBand: all the source bands must "
    5626             :                 "have the same dimensions");
    5627           0 :             return CE_Failure;
    5628             :         }
    5629       65841 :         if (papoSrcBands[iBand]->GetRasterDataType() != eDataType)
    5630             :         {
    5631           0 :             CPLError(
    5632             :                 CE_Failure, CPLE_NotSupported,
    5633             :                 "GDALRegenerateOverviewsMultiBand: all the source bands must "
    5634             :                 "have the same data type");
    5635           0 :             return CE_Failure;
    5636             :         }
    5637             :     }
    5638             : 
    5639        1013 :     for (int iOverview = 0; iOverview < nOverviews; ++iOverview)
    5640             :     {
    5641         633 :         const auto poOvrFirstBand = papapoOverviewBands[0][iOverview];
    5642         633 :         const int nDstWidth = poOvrFirstBand->GetXSize();
    5643         633 :         const int nDstHeight = poOvrFirstBand->GetYSize();
    5644       66732 :         for (int iBand = 1; iBand < nBands; ++iBand)
    5645             :         {
    5646       66099 :             const auto poOvrBand = papapoOverviewBands[iBand][iOverview];
    5647      132198 :             if (poOvrBand->GetXSize() != nDstWidth ||
    5648       66099 :                 poOvrBand->GetYSize() != nDstHeight)
    5649             :             {
    5650           0 :                 CPLError(
    5651             :                     CE_Failure, CPLE_NotSupported,
    5652             :                     "GDALRegenerateOverviewsMultiBand: all the overviews bands "
    5653             :                     "of the same level must have the same dimensions");
    5654           0 :                 return CE_Failure;
    5655             :             }
    5656       66099 :             if (poOvrBand->GetRasterDataType() != eDataType)
    5657             :             {
    5658           0 :                 CPLError(
    5659             :                     CE_Failure, CPLE_NotSupported,
    5660             :                     "GDALRegenerateOverviewsMultiBand: all the overviews bands "
    5661             :                     "must have the same data type as the source bands");
    5662           0 :                 return CE_Failure;
    5663             :             }
    5664             :         }
    5665             :     }
    5666             : 
    5667             :     // First pass to compute the total number of pixels to write.
    5668         380 :     double dfTotalPixelCount = 0;
    5669         380 :     const int nSrcXOff = atoi(CSLFetchNameValueDef(papszOptions, "XOFF", "0"));
    5670         380 :     const int nSrcYOff = atoi(CSLFetchNameValueDef(papszOptions, "YOFF", "0"));
    5671         380 :     const int nSrcXSize = atoi(CSLFetchNameValueDef(
    5672             :         papszOptions, "XSIZE", CPLSPrintf("%d", nToplevelSrcWidth)));
    5673         380 :     const int nSrcYSize = atoi(CSLFetchNameValueDef(
    5674             :         papszOptions, "YSIZE", CPLSPrintf("%d", nToplevelSrcHeight)));
    5675        1013 :     for (int iOverview = 0; iOverview < nOverviews; ++iOverview)
    5676             :     {
    5677         633 :         dfTotalPixelCount +=
    5678        1266 :             static_cast<double>(nSrcXSize) / nToplevelSrcWidth *
    5679         633 :             papapoOverviewBands[0][iOverview]->GetXSize() *
    5680        1266 :             static_cast<double>(nSrcYSize) / nToplevelSrcHeight *
    5681         633 :             papapoOverviewBands[0][iOverview]->GetYSize();
    5682             :     }
    5683             : 
    5684             :     const GDALDataType eWrkDataType =
    5685         380 :         GDALGetOvrWorkDataType(pszResampling, eDataType);
    5686             :     const int nWrkDataTypeSize =
    5687         380 :         std::max(1, GDALGetDataTypeSizeBytes(eWrkDataType));
    5688             : 
    5689         380 :     const bool bIsMask = papoSrcBands[0]->IsMaskBand();
    5690             : 
    5691             :     // If we have a nodata mask and we are doing something more complicated
    5692             :     // than nearest neighbouring, we have to fetch to nodata mask.
    5693             :     const bool bUseNoDataMask =
    5694         561 :         !STARTS_WITH_CI(pszResampling, "NEAR") &&
    5695         181 :         (bIsMask || (papoSrcBands[0]->GetMaskFlags() & GMF_ALL_VALID) == 0);
    5696             : 
    5697         760 :     std::vector<bool> abHasNoData(nBands);
    5698         760 :     std::vector<double> adfNoDataValue(nBands);
    5699             : 
    5700       66601 :     for (int iBand = 0; iBand < nBands; ++iBand)
    5701             :     {
    5702       66221 :         int nHasNoData = 0;
    5703      132442 :         adfNoDataValue[iBand] =
    5704       66221 :             papoSrcBands[iBand]->GetNoDataValue(&nHasNoData);
    5705       66221 :         abHasNoData[iBand] = CPL_TO_BOOL(nHasNoData);
    5706             :     }
    5707             : 
    5708         760 :     std::string osDetailMessage;
    5709         432 :     if (bUseNoDataMask &&
    5710          52 :         papoSrcBands[0]->HasConflictingMaskSources(&osDetailMessage, false))
    5711             :     {
    5712           9 :         CPLError(CE_Warning, CPLE_AppDefined, "%s%s", osDetailMessage.c_str(),
    5713          18 :                  abHasNoData[0]
    5714             :                      ? "Only the nodata value will be taken into account."
    5715           9 :                      : "Only the first listed one will be taken into account.");
    5716             :     }
    5717             : 
    5718             :     const bool bPropagateNoData =
    5719         380 :         CPLTestBool(CPLGetConfigOption("GDAL_OVR_PROPAGATE_NODATA", "NO"));
    5720             : 
    5721         380 :     const int nThreads = GDALGetNumThreads(GDAL_DEFAULT_MAX_THREAD_COUNT,
    5722             :                                            /* bDefaultToAllCPUs=*/false);
    5723             :     auto poThreadPool =
    5724         380 :         nThreads > 1 ? GDALGetGlobalThreadPool(nThreads) : nullptr;
    5725             :     auto poJobQueue = poThreadPool ? poThreadPool->CreateJobQueue()
    5726         760 :                                    : std::unique_ptr<CPLJobQueue>(nullptr);
    5727             : 
    5728             :     // Only configurable for debug / testing
    5729         380 :     const GIntBig nChunkMaxSize = []() -> GIntBig
    5730             :     {
    5731             :         const char *pszVal =
    5732         380 :             CPLGetConfigOption("GDAL_OVR_CHUNK_MAX_SIZE", nullptr);
    5733         380 :         if (pszVal)
    5734             :         {
    5735          15 :             GIntBig nRet = 0;
    5736          15 :             CPLParseMemorySize(pszVal, &nRet, nullptr);
    5737          15 :             return std::max<GIntBig>(100, nRet);
    5738             :         }
    5739         365 :         return 10 * 1024 * 1024;
    5740         380 :     }();
    5741             : 
    5742             :     // Only configurable for debug / testing
    5743         380 :     const GIntBig nChunkMaxSizeForTempFile = []() -> GIntBig
    5744             :     {
    5745         380 :         const char *pszVal = CPLGetConfigOption(
    5746             :             "GDAL_OVR_CHUNK_MAX_SIZE_FOR_TEMP_FILE", nullptr);
    5747         380 :         if (pszVal)
    5748             :         {
    5749          14 :             GIntBig nRet = 0;
    5750          14 :             CPLParseMemorySize(pszVal, &nRet, nullptr);
    5751          14 :             return std::max<GIntBig>(100, nRet);
    5752             :         }
    5753         366 :         const auto nUsableRAM = CPLGetUsablePhysicalRAM();
    5754         366 :         if (nUsableRAM > 0)
    5755         366 :             return nUsableRAM / 10;
    5756             :         // Select a value to be able to at least downsample by 2 for a RGB
    5757             :         // 1024x1024 tiled output: (2 * 1024 + 2) * (2 * 1024 + 2) * 3 = 12 MB
    5758           0 :         return 100 * 1024 * 1024;
    5759         380 :     }();
    5760             : 
    5761             :     // Second pass to do the real job.
    5762         380 :     double dfCurPixelCount = 0;
    5763         380 :     CPLErr eErr = CE_None;
    5764        1007 :     for (int iOverview = 0; iOverview < nOverviews && eErr == CE_None;
    5765             :          ++iOverview)
    5766             :     {
    5767         632 :         int iSrcOverview = -1;  // -1 means the source bands.
    5768             : 
    5769             :         const int nDstTotalWidth =
    5770         632 :             papapoOverviewBands[0][iOverview]->GetXSize();
    5771             :         const int nDstTotalHeight =
    5772         632 :             papapoOverviewBands[0][iOverview]->GetYSize();
    5773             : 
    5774             :         // Compute the coordinates of the target region to refresh
    5775         632 :         constexpr double EPS = 1e-8;
    5776         632 :         const int nDstXOffStart = static_cast<int>(
    5777         632 :             static_cast<double>(nSrcXOff) / nToplevelSrcWidth * nDstTotalWidth +
    5778             :             EPS);
    5779             :         const int nDstXOffEnd =
    5780        1264 :             std::min(static_cast<int>(
    5781         632 :                          std::ceil(static_cast<double>(nSrcXOff + nSrcXSize) /
    5782         632 :                                        nToplevelSrcWidth * nDstTotalWidth -
    5783             :                                    EPS)),
    5784         632 :                      nDstTotalWidth);
    5785         632 :         const int nDstWidth = nDstXOffEnd - nDstXOffStart;
    5786         632 :         const int nDstYOffStart =
    5787         632 :             static_cast<int>(static_cast<double>(nSrcYOff) /
    5788         632 :                                  nToplevelSrcHeight * nDstTotalHeight +
    5789             :                              EPS);
    5790             :         const int nDstYOffEnd =
    5791        1264 :             std::min(static_cast<int>(
    5792         632 :                          std::ceil(static_cast<double>(nSrcYOff + nSrcYSize) /
    5793         632 :                                        nToplevelSrcHeight * nDstTotalHeight -
    5794             :                                    EPS)),
    5795         632 :                      nDstTotalHeight);
    5796         632 :         const int nDstHeight = nDstYOffEnd - nDstYOffStart;
    5797             : 
    5798             :         // Try to use previous level of overview as the source to compute
    5799             :         // the next level.
    5800         632 :         int nSrcWidth = nToplevelSrcWidth;
    5801         632 :         int nSrcHeight = nToplevelSrcHeight;
    5802         884 :         if (iOverview > 0 &&
    5803         252 :             papapoOverviewBands[0][iOverview - 1]->GetXSize() > nDstTotalWidth)
    5804             :         {
    5805         244 :             nSrcWidth = papapoOverviewBands[0][iOverview - 1]->GetXSize();
    5806         244 :             nSrcHeight = papapoOverviewBands[0][iOverview - 1]->GetYSize();
    5807         244 :             iSrcOverview = iOverview - 1;
    5808             :         }
    5809             : 
    5810         632 :         const double dfXRatioDstToSrc =
    5811         632 :             static_cast<double>(nSrcWidth) / nDstTotalWidth;
    5812         632 :         const double dfYRatioDstToSrc =
    5813         632 :             static_cast<double>(nSrcHeight) / nDstTotalHeight;
    5814             : 
    5815             :         const int nOvrFactor =
    5816        1896 :             std::max(1, std::max(static_cast<int>(0.5 + dfXRatioDstToSrc),
    5817         632 :                                  static_cast<int>(0.5 + dfYRatioDstToSrc)));
    5818             : 
    5819         632 :         int nDstChunkXSize = 0;
    5820         632 :         int nDstChunkYSize = 0;
    5821         632 :         papapoOverviewBands[0][iOverview]->GetBlockSize(&nDstChunkXSize,
    5822             :                                                         &nDstChunkYSize);
    5823             : 
    5824         632 :         constexpr int PIXEL_MARGIN = 2;
    5825             :         // Try to extend the chunk size so that the memory needed to acquire
    5826             :         // source pixels goes up to 10 MB.
    5827             :         // This can help for drivers that support multi-threaded reading
    5828         632 :         const int nFullResYChunk = static_cast<int>(std::min<double>(
    5829         632 :             nSrcHeight, PIXEL_MARGIN + nDstChunkYSize * dfYRatioDstToSrc));
    5830         632 :         const int nFullResYChunkQueried = static_cast<int>(std::min<int64_t>(
    5831        1264 :             nSrcHeight,
    5832        1264 :             nFullResYChunk + static_cast<int64_t>(RADIUS_TO_DIAMETER) *
    5833         632 :                                  nKernelRadius * nOvrFactor));
    5834         861 :         while (nDstChunkXSize < nDstWidth)
    5835             :         {
    5836         248 :             constexpr int INCREASE_FACTOR = 2;
    5837             : 
    5838         248 :             const int nFullResXChunk = static_cast<int>(std::min<double>(
    5839         496 :                 nSrcWidth, PIXEL_MARGIN + INCREASE_FACTOR * nDstChunkXSize *
    5840         248 :                                               dfXRatioDstToSrc));
    5841             : 
    5842             :             const int nFullResXChunkQueried =
    5843         248 :                 static_cast<int>(std::min<int64_t>(
    5844         496 :                     nSrcWidth,
    5845         496 :                     nFullResXChunk + static_cast<int64_t>(RADIUS_TO_DIAMETER) *
    5846         248 :                                          nKernelRadius * nOvrFactor));
    5847             : 
    5848         248 :             if (nBands > nChunkMaxSize / nFullResXChunkQueried /
    5849         248 :                              nFullResYChunkQueried / nWrkDataTypeSize)
    5850             :             {
    5851          19 :                 break;
    5852             :             }
    5853             : 
    5854         229 :             nDstChunkXSize *= INCREASE_FACTOR;
    5855             :         }
    5856         632 :         nDstChunkXSize = std::min(nDstChunkXSize, nDstWidth);
    5857             : 
    5858         632 :         const int nFullResXChunk = static_cast<int>(std::min<double>(
    5859         632 :             nSrcWidth, PIXEL_MARGIN + nDstChunkXSize * dfXRatioDstToSrc));
    5860         632 :         const int nFullResXChunkQueried = static_cast<int>(std::min<int64_t>(
    5861        1264 :             nSrcWidth,
    5862        1264 :             nFullResXChunk + static_cast<int64_t>(RADIUS_TO_DIAMETER) *
    5863         632 :                                  nKernelRadius * nOvrFactor));
    5864             : 
    5865             :         // Make sure that the RAM requirements to acquire the source data does
    5866             :         // not exceed nChunkMaxSizeForTempFile
    5867             :         // If so, reduce the destination chunk size, generate overviews in a
    5868             :         // temporary dataset, and copy that temporary dataset over the target
    5869             :         // overview bands (to avoid issues with lossy compression)
    5870             :         const bool bOverflowFullResXChunkYChunkQueried =
    5871         632 :             nBands > std::numeric_limits<int64_t>::max() /
    5872         632 :                          nFullResXChunkQueried / nFullResYChunkQueried /
    5873         632 :                          nWrkDataTypeSize;
    5874             : 
    5875         632 :         const auto nMemRequirement =
    5876             :             bOverflowFullResXChunkYChunkQueried
    5877         632 :                 ? 0
    5878         628 :                 : static_cast<GIntBig>(nFullResXChunkQueried) *
    5879         628 :                       nFullResYChunkQueried * nBands * nWrkDataTypeSize;
    5880             :         // Use a temporary dataset with a smaller destination chunk size
    5881         632 :         const auto nOverShootFactor =
    5882             :             nMemRequirement / nChunkMaxSizeForTempFile;
    5883             : 
    5884         632 :         constexpr int MIN_OVERSHOOT_FACTOR = 4;
    5885             :         const auto nSqrtOverShootFactor = std::max<GIntBig>(
    5886        1264 :             MIN_OVERSHOOT_FACTOR, static_cast<GIntBig>(std::ceil(std::sqrt(
    5887         632 :                                       static_cast<double>(nOverShootFactor)))));
    5888         632 :         constexpr int DEFAULT_CHUNK_SIZE = 256;
    5889         632 :         constexpr int GTIFF_BLOCK_SIZE_MULTIPLE = 16;
    5890             :         const int nReducedDstChunkXSize =
    5891             :             bOverflowFullResXChunkYChunkQueried
    5892        1260 :                 ? DEFAULT_CHUNK_SIZE
    5893        1260 :                 : std::max(1, static_cast<int>(nDstChunkXSize /
    5894        1260 :                                                nSqrtOverShootFactor) &
    5895         628 :                                   ~(GTIFF_BLOCK_SIZE_MULTIPLE - 1));
    5896             :         const int nReducedDstChunkYSize =
    5897             :             bOverflowFullResXChunkYChunkQueried
    5898        1260 :                 ? DEFAULT_CHUNK_SIZE
    5899        1260 :                 : std::max(1, static_cast<int>(nDstChunkYSize /
    5900        1260 :                                                nSqrtOverShootFactor) &
    5901         628 :                                   ~(GTIFF_BLOCK_SIZE_MULTIPLE - 1));
    5902             : 
    5903         632 :         if (bOverflowFullResXChunkYChunkQueried ||
    5904             :             nMemRequirement > nChunkMaxSizeForTempFile)
    5905             :         {
    5906             :             const auto nDTSize =
    5907          43 :                 std::max(1, GDALGetDataTypeSizeBytes(eDataType));
    5908             :             const bool bTmpDSMemRequirementOverflow =
    5909          43 :                 nBands > std::numeric_limits<int64_t>::max() / nDstWidth /
    5910          43 :                              nDstHeight / nDTSize;
    5911          43 :             const auto nTmpDSMemRequirement =
    5912             :                 bTmpDSMemRequirementOverflow
    5913          43 :                     ? 0
    5914          41 :                     : static_cast<GIntBig>(nDstWidth) * nDstHeight * nBands *
    5915          41 :                           nDTSize;
    5916             : 
    5917             :             // make sure that one band buffer doesn't overflow size_t
    5918             :             const bool bChunkSizeOverflow =
    5919          43 :                 static_cast<size_t>(nDTSize) >
    5920          43 :                 std::numeric_limits<size_t>::max() / nDstWidth / nDstHeight;
    5921          43 :             const size_t nChunkSize =
    5922             :                 bChunkSizeOverflow
    5923          43 :                     ? 0
    5924          41 :                     : static_cast<size_t>(nDstWidth) * nDstHeight * nDTSize;
    5925             : 
    5926             :             const auto CreateVRT =
    5927          41 :                 [nBands, nSrcWidth, nSrcHeight, nDstTotalWidth, nDstTotalHeight,
    5928             :                  pszResampling, eWrkDataType, papoSrcBands, papapoOverviewBands,
    5929             :                  iSrcOverview, &abHasNoData,
    5930      393585 :                  &adfNoDataValue](int nVRTBlockXSize, int nVRTBlockYSize)
    5931             :             {
    5932             :                 auto poVRTDS = std::make_unique<VRTDataset>(
    5933          41 :                     nDstTotalWidth, nDstTotalHeight, nVRTBlockXSize,
    5934          41 :                     nVRTBlockYSize);
    5935             : 
    5936       65620 :                 for (int iBand = 0; iBand < nBands; ++iBand)
    5937             :                 {
    5938      131158 :                     auto poVRTSrc = std::make_unique<VRTSimpleSource>();
    5939       65579 :                     poVRTSrc->SetResampling(pszResampling);
    5940       65579 :                     poVRTDS->AddBand(eWrkDataType);
    5941             :                     auto poVRTBand = static_cast<VRTSourcedRasterBand *>(
    5942       65579 :                         poVRTDS->GetRasterBand(iBand + 1));
    5943             : 
    5944       65579 :                     auto poSrcBand = papoSrcBands[iBand];
    5945       65579 :                     if (iSrcOverview != -1)
    5946          24 :                         poSrcBand = papapoOverviewBands[iBand][iSrcOverview];
    5947       65579 :                     poVRTBand->ConfigureSource(
    5948             :                         poVRTSrc.get(), poSrcBand, false, 0, 0, nSrcWidth,
    5949             :                         nSrcHeight, 0, 0, nDstTotalWidth, nDstTotalHeight);
    5950             :                     // Add the source to the band
    5951       65579 :                     poVRTBand->AddSource(poVRTSrc.release());
    5952       65579 :                     if (abHasNoData[iBand])
    5953           3 :                         poVRTBand->SetNoDataValue(adfNoDataValue[iBand]);
    5954             :                 }
    5955             : 
    5956          42 :                 if (papoSrcBands[0]->GetMaskFlags() == GMF_PER_DATASET &&
    5957           1 :                     poVRTDS->CreateMaskBand(GMF_PER_DATASET) == CE_None)
    5958             :                 {
    5959             :                     VRTSourcedRasterBand *poMaskVRTBand =
    5960           1 :                         cpl::down_cast<VRTSourcedRasterBand *>(
    5961           1 :                             poVRTDS->GetRasterBand(1)->GetMaskBand());
    5962           1 :                     auto poSrcBand = papoSrcBands[0];
    5963           1 :                     if (iSrcOverview != -1)
    5964           0 :                         poSrcBand = papapoOverviewBands[0][iSrcOverview];
    5965           1 :                     poMaskVRTBand->AddMaskBandSource(
    5966           1 :                         poSrcBand->GetMaskBand(), 0, 0, nSrcWidth, nSrcHeight,
    5967             :                         0, 0, nDstTotalWidth, nDstTotalHeight);
    5968             :                 }
    5969             : 
    5970          41 :                 return poVRTDS;
    5971          43 :             };
    5972             : 
    5973             :             // If the overview accommodates chunking, do so and recurse
    5974             :             // to avoid generating full size temporary files
    5975          43 :             if (!bOverflowFullResXChunkYChunkQueried &&
    5976          39 :                 !bTmpDSMemRequirementOverflow && !bChunkSizeOverflow &&
    5977          39 :                 (nDstChunkXSize < nDstWidth || nDstChunkYSize < nDstHeight))
    5978             :             {
    5979             :                 // Create a VRT with the smaller chunk to do the scaling
    5980             :                 auto poVRTDS =
    5981          13 :                     CreateVRT(nReducedDstChunkXSize, nReducedDstChunkYSize);
    5982             : 
    5983          13 :                 std::vector<GDALRasterBand *> apoVRTBand(nBands);
    5984          13 :                 std::vector<GDALRasterBand *> apoDstBand(nBands);
    5985       65560 :                 for (int iBand = 0; iBand < nBands; ++iBand)
    5986             :                 {
    5987       65547 :                     apoDstBand[iBand] = papapoOverviewBands[iBand][iOverview];
    5988       65547 :                     apoVRTBand[iBand] = poVRTDS->GetRasterBand(iBand + 1);
    5989             :                 }
    5990             : 
    5991             :                 // Use a flag to avoid reading from the overview being built
    5992             :                 GDALRasterIOExtraArg sExtraArg;
    5993          13 :                 INIT_RASTERIO_EXTRA_ARG(sExtraArg);
    5994          13 :                 if (iSrcOverview == -1)
    5995          13 :                     sExtraArg.bUseOnlyThisScale = true;
    5996             : 
    5997             :                 // A single band buffer for data transfer to the overview
    5998          13 :                 std::vector<GByte> abyChunk;
    5999             :                 try
    6000             :                 {
    6001          13 :                     abyChunk.resize(nChunkSize);
    6002             :                 }
    6003           0 :                 catch (const std::exception &)
    6004             :                 {
    6005           0 :                     CPLError(CE_Failure, CPLE_OutOfMemory,
    6006             :                              "Out of memory allocating temporary buffer");
    6007           0 :                     return CE_Failure;
    6008             :                 }
    6009             : 
    6010             :                 // Loop over output height, in chunks
    6011          13 :                 for (int nDstYOff = nDstYOffStart;
    6012          38 :                      nDstYOff < nDstYOffEnd && eErr == CE_None;
    6013             :                      /* */)
    6014             :                 {
    6015             :                     const int nDstYCount =
    6016          25 :                         std::min(nDstChunkYSize, nDstYOffEnd - nDstYOff);
    6017             :                     // Loop over output width, in output chunks
    6018          25 :                     for (int nDstXOff = nDstXOffStart;
    6019          74 :                          nDstXOff < nDstXOffEnd && eErr == CE_None;
    6020             :                          /* */)
    6021             :                     {
    6022             :                         const int nDstXCount =
    6023          49 :                             std::min(nDstChunkXSize, nDstXOffEnd - nDstXOff);
    6024             :                         // Read and transfer the chunk to the overview
    6025          98 :                         for (int iBand = 0; iBand < nBands && eErr == CE_None;
    6026             :                              ++iBand)
    6027             :                         {
    6028          98 :                             eErr = apoVRTBand[iBand]->RasterIO(
    6029             :                                 GF_Read, nDstXOff, nDstYOff, nDstXCount,
    6030          49 :                                 nDstYCount, abyChunk.data(), nDstXCount,
    6031             :                                 nDstYCount, eDataType, 0, 0, &sExtraArg);
    6032          49 :                             if (eErr == CE_None)
    6033             :                             {
    6034          96 :                                 eErr = apoDstBand[iBand]->RasterIO(
    6035             :                                     GF_Write, nDstXOff, nDstYOff, nDstXCount,
    6036          48 :                                     nDstYCount, abyChunk.data(), nDstXCount,
    6037             :                                     nDstYCount, eDataType, 0, 0, nullptr);
    6038             :                             }
    6039             :                         }
    6040             : 
    6041          49 :                         dfCurPixelCount +=
    6042          49 :                             static_cast<double>(nDstXCount) * nDstYCount;
    6043             : 
    6044          49 :                         nDstXOff += nDstXCount;
    6045             :                     }  // width
    6046             : 
    6047          25 :                     if (!pfnProgress(dfCurPixelCount / dfTotalPixelCount,
    6048             :                                      nullptr, pProgressData))
    6049             :                     {
    6050           0 :                         CPLError(CE_Failure, CPLE_UserInterrupt,
    6051             :                                  "User terminated");
    6052           0 :                         eErr = CE_Failure;
    6053             :                     }
    6054             : 
    6055          25 :                     nDstYOff += nDstYCount;
    6056             :                 }  // height
    6057             : 
    6058          13 :                 if (CE_None != eErr)
    6059             :                 {
    6060           1 :                     CPLError(CE_Failure, CPLE_AppDefined,
    6061             :                              "Error while writing overview");
    6062           1 :                     return CE_Failure;
    6063             :                 }
    6064             : 
    6065          12 :                 pfnProgress(1.0, nullptr, pProgressData);
    6066             :                 // Flush the overviews we just generated
    6067          24 :                 for (int iBand = 0; iBand < nBands; ++iBand)
    6068          12 :                     apoDstBand[iBand]->FlushCache(false);
    6069             : 
    6070          12 :                 continue;  // Next overview
    6071             :             }  // chunking via temporary dataset
    6072             : 
    6073           0 :             std::unique_ptr<GDALDataset> poTmpDS;
    6074             :             // Config option mostly/only for autotest purposes
    6075             :             const char *pszGDAL_OVR_TEMP_DRIVER =
    6076          30 :                 CPLGetConfigOption("GDAL_OVR_TEMP_DRIVER", "");
    6077          30 :             if ((!bTmpDSMemRequirementOverflow &&
    6078           4 :                  nTmpDSMemRequirement <= nChunkMaxSizeForTempFile &&
    6079           4 :                  !EQUAL(pszGDAL_OVR_TEMP_DRIVER, "GTIFF")) ||
    6080          26 :                 EQUAL(pszGDAL_OVR_TEMP_DRIVER, "MEM"))
    6081             :             {
    6082          10 :                 auto poTmpDrv = GetGDALDriverManager()->GetDriverByName("MEM");
    6083          10 :                 if (!poTmpDrv)
    6084             :                 {
    6085           0 :                     eErr = CE_Failure;
    6086           0 :                     break;
    6087             :                 }
    6088          10 :                 poTmpDS.reset(poTmpDrv->Create("", nDstTotalWidth,
    6089             :                                                nDstTotalHeight, nBands,
    6090          10 :                                                eDataType, nullptr));
    6091             :             }
    6092             :             else
    6093             :             {
    6094             :                 // Create a temporary file for the overview
    6095             :                 auto poTmpDrv =
    6096          20 :                     GetGDALDriverManager()->GetDriverByName("GTiff");
    6097          20 :                 if (!poTmpDrv)
    6098             :                 {
    6099           0 :                     eErr = CE_Failure;
    6100           0 :                     break;
    6101             :                 }
    6102          40 :                 std::string osTmpFilename;
    6103          20 :                 auto poDstDS = papapoOverviewBands[0][0]->GetDataset();
    6104          20 :                 if (poDstDS)
    6105             :                 {
    6106          20 :                     osTmpFilename = poDstDS->GetDescription();
    6107             :                     VSIStatBufL sStatBuf;
    6108          20 :                     if (!osTmpFilename.empty() &&
    6109           0 :                         VSIStatL(osTmpFilename.c_str(), &sStatBuf) == 0)
    6110           0 :                         osTmpFilename += "_tmp_ovr.tif";
    6111             :                 }
    6112          20 :                 if (osTmpFilename.empty())
    6113             :                 {
    6114          20 :                     osTmpFilename = CPLGenerateTempFilenameSafe(nullptr);
    6115          20 :                     osTmpFilename += ".tif";
    6116             :                 }
    6117          20 :                 CPLDebug("GDAL", "Creating temporary file %s of %d x %d x %d",
    6118             :                          osTmpFilename.c_str(), nDstWidth, nDstHeight, nBands);
    6119          40 :                 CPLStringList aosCO;
    6120          20 :                 if (0 == ((nReducedDstChunkXSize % GTIFF_BLOCK_SIZE_MULTIPLE) |
    6121          20 :                           (nReducedDstChunkYSize % GTIFF_BLOCK_SIZE_MULTIPLE)))
    6122             :                 {
    6123          14 :                     aosCO.SetNameValue("TILED", "YES");
    6124             :                     aosCO.SetNameValue("BLOCKXSIZE",
    6125          14 :                                        CPLSPrintf("%d", nReducedDstChunkXSize));
    6126             :                     aosCO.SetNameValue("BLOCKYSIZE",
    6127          14 :                                        CPLSPrintf("%d", nReducedDstChunkYSize));
    6128             :                 }
    6129          20 :                 if (const char *pszCOList =
    6130          20 :                         poTmpDrv->GetMetadataItem(GDAL_DMD_CREATIONOPTIONLIST))
    6131             :                 {
    6132             :                     aosCO.SetNameValue(
    6133          20 :                         "COMPRESS", strstr(pszCOList, "ZSTD") ? "ZSTD" : "LZW");
    6134             :                 }
    6135          20 :                 poTmpDS.reset(poTmpDrv->Create(osTmpFilename.c_str(), nDstWidth,
    6136             :                                                nDstHeight, nBands, eDataType,
    6137          20 :                                                aosCO.List()));
    6138          20 :                 if (poTmpDS)
    6139             :                 {
    6140          18 :                     poTmpDS->MarkSuppressOnClose();
    6141          18 :                     VSIUnlink(osTmpFilename.c_str());
    6142             :                 }
    6143             :             }
    6144          30 :             if (!poTmpDS)
    6145             :             {
    6146           2 :                 eErr = CE_Failure;
    6147           2 :                 break;
    6148             :             }
    6149             : 
    6150             :             // Create a full size VRT to do the resampling without edge effects
    6151             :             auto poVRTDS =
    6152          28 :                 CreateVRT(nReducedDstChunkXSize, nReducedDstChunkYSize);
    6153             : 
    6154             :             // Allocate a band buffer with the overview chunk size
    6155             :             std::unique_ptr<void, VSIFreeReleaser> pDstBuffer(
    6156             :                 VSI_MALLOC3_VERBOSE(size_t(nWrkDataTypeSize), nDstChunkXSize,
    6157          28 :                                     nDstChunkYSize));
    6158          28 :             if (pDstBuffer == nullptr)
    6159             :             {
    6160           0 :                 eErr = CE_Failure;
    6161           0 :                 break;
    6162             :             }
    6163             : 
    6164             :             // Use a flag to avoid reading the overview being built
    6165             :             GDALRasterIOExtraArg sExtraArg;
    6166          28 :             INIT_RASTERIO_EXTRA_ARG(sExtraArg);
    6167          28 :             if (iSrcOverview == -1)
    6168           4 :                 sExtraArg.bUseOnlyThisScale = true;
    6169             : 
    6170             :             // Scale and copy data from the VRT to the temp file
    6171          28 :             for (int nDstYOff = nDstYOffStart;
    6172         914 :                  nDstYOff < nDstYOffEnd && eErr == CE_None;
    6173             :                  /* */)
    6174             :             {
    6175             :                 const int nDstYCount =
    6176         886 :                     std::min(nReducedDstChunkYSize, nDstYOffEnd - nDstYOff);
    6177         886 :                 for (int nDstXOff = nDstXOffStart;
    6178      201218 :                      nDstXOff < nDstXOffEnd && eErr == CE_None;
    6179             :                      /* */)
    6180             :                 {
    6181             :                     const int nDstXCount =
    6182      200332 :                         std::min(nReducedDstChunkXSize, nDstXOffEnd - nDstXOff);
    6183      400668 :                     for (int iBand = 0; iBand < nBands && eErr == CE_None;
    6184             :                          ++iBand)
    6185             :                     {
    6186      200336 :                         auto poSrcBand = poVRTDS->GetRasterBand(iBand + 1);
    6187      200336 :                         eErr = poSrcBand->RasterIO(
    6188             :                             GF_Read, nDstXOff, nDstYOff, nDstXCount, nDstYCount,
    6189             :                             pDstBuffer.get(), nDstXCount, nDstYCount,
    6190             :                             eWrkDataType, 0, 0, &sExtraArg);
    6191      200336 :                         if (eErr == CE_None)
    6192             :                         {
    6193             :                             // Write to the temporary dataset, shifted
    6194      200334 :                             auto poOvrBand = poTmpDS->GetRasterBand(iBand + 1);
    6195      200334 :                             eErr = poOvrBand->RasterIO(
    6196             :                                 GF_Write, nDstXOff - nDstXOffStart,
    6197             :                                 nDstYOff - nDstYOffStart, nDstXCount,
    6198             :                                 nDstYCount, pDstBuffer.get(), nDstXCount,
    6199             :                                 nDstYCount, eWrkDataType, 0, 0, nullptr);
    6200             :                         }
    6201             :                     }
    6202      200332 :                     nDstXOff += nDstXCount;
    6203             :                 }
    6204         886 :                 nDstYOff += nDstYCount;
    6205             :             }
    6206             : 
    6207             :             // Copy from the temporary to the overview
    6208          28 :             for (int nDstYOff = nDstYOffStart;
    6209          54 :                  nDstYOff < nDstYOffEnd && eErr == CE_None;
    6210             :                  /* */)
    6211             :             {
    6212             :                 const int nDstYCount =
    6213          26 :                     std::min(nDstChunkYSize, nDstYOffEnd - nDstYOff);
    6214          26 :                 for (int nDstXOff = nDstXOffStart;
    6215          52 :                      nDstXOff < nDstXOffEnd && eErr == CE_None;
    6216             :                      /* */)
    6217             :                 {
    6218             :                     const int nDstXCount =
    6219          26 :                         std::min(nDstChunkXSize, nDstXOffEnd - nDstXOff);
    6220          56 :                     for (int iBand = 0; iBand < nBands && eErr == CE_None;
    6221             :                          ++iBand)
    6222             :                     {
    6223          30 :                         auto poSrcBand = poTmpDS->GetRasterBand(iBand + 1);
    6224          30 :                         eErr = poSrcBand->RasterIO(
    6225             :                             GF_Read, nDstXOff - nDstXOffStart,
    6226             :                             nDstYOff - nDstYOffStart, nDstXCount, nDstYCount,
    6227             :                             pDstBuffer.get(), nDstXCount, nDstYCount,
    6228             :                             eWrkDataType, 0, 0, nullptr);
    6229          30 :                         if (eErr == CE_None)
    6230             :                         {
    6231             :                             // Write to the destination overview bands
    6232          30 :                             auto poOvrBand =
    6233          30 :                                 papapoOverviewBands[iBand][iOverview];
    6234          30 :                             eErr = poOvrBand->RasterIO(
    6235             :                                 GF_Write, nDstXOff, nDstYOff, nDstXCount,
    6236             :                                 nDstYCount, pDstBuffer.get(), nDstXCount,
    6237             :                                 nDstYCount, eWrkDataType, 0, 0, nullptr);
    6238             :                         }
    6239             :                     }
    6240          26 :                     nDstXOff += nDstXCount;
    6241             :                 }
    6242          26 :                 nDstYOff += nDstYCount;
    6243             :             }
    6244             : 
    6245          28 :             if (eErr != CE_None)
    6246             :             {
    6247           2 :                 CPLError(CE_Failure, CPLE_AppDefined,
    6248             :                          "Failed to write overview %d", iOverview);
    6249           2 :                 return eErr;
    6250             :             }
    6251             : 
    6252             :             // Flush the data to overviews.
    6253          56 :             for (int iBand = 0; iBand < nBands; ++iBand)
    6254          30 :                 papapoOverviewBands[iBand][iOverview]->FlushCache(false);
    6255             : 
    6256          26 :             continue;
    6257             :         }
    6258             : 
    6259             :         // Structure describing a resampling job
    6260             :         struct OvrJob
    6261             :         {
    6262             :             // Buffers to free when job is finished
    6263             :             std::unique_ptr<PointerHolder> oSrcMaskBufferHolder{};
    6264             :             std::unique_ptr<PointerHolder> oSrcBufferHolder{};
    6265             :             std::unique_ptr<PointerHolder> oDstBufferHolder{};
    6266             : 
    6267             :             GDALRasterBand *poDstBand = nullptr;
    6268             : 
    6269             :             // Input parameters of pfnResampleFn
    6270             :             GDALResampleFunction pfnResampleFn = nullptr;
    6271             :             GDALOverviewResampleArgs args{};
    6272             :             const void *pChunk = nullptr;
    6273             : 
    6274             :             // Output values of resampling function
    6275             :             CPLErr eErr = CE_Failure;
    6276             :             void *pDstBuffer = nullptr;
    6277             :             GDALDataType eDstBufferDataType = GDT_Unknown;
    6278             : 
    6279        3268 :             void NotifyFinished()
    6280             :             {
    6281        6536 :                 std::lock_guard guard(mutex);
    6282        3268 :                 bFinished = true;
    6283        3268 :                 cv.notify_one();
    6284        3268 :             }
    6285             : 
    6286           2 :             bool IsFinished()
    6287             :             {
    6288           2 :                 std::lock_guard guard(mutex);
    6289           4 :                 return bFinished;
    6290             :             }
    6291             : 
    6292          16 :             void WaitFinished()
    6293             :             {
    6294          32 :                 std::unique_lock oGuard(mutex);
    6295          21 :                 while (!bFinished)
    6296             :                 {
    6297           5 :                     cv.wait(oGuard);
    6298             :                 }
    6299          16 :             }
    6300             : 
    6301             :           private:
    6302             :             // Synchronization
    6303             :             bool bFinished = false;
    6304             :             std::mutex mutex{};
    6305             :             std::condition_variable cv{};
    6306             :         };
    6307             : 
    6308             :         // Thread function to resample
    6309        3268 :         const auto JobResampleFunc = [](void *pData)
    6310             :         {
    6311        3268 :             OvrJob *poJob = static_cast<OvrJob *>(pData);
    6312             : 
    6313        3268 :             poJob->eErr = poJob->pfnResampleFn(poJob->args, poJob->pChunk,
    6314             :                                                &(poJob->pDstBuffer),
    6315             :                                                &(poJob->eDstBufferDataType));
    6316             : 
    6317        3268 :             auto pDstBuffer = poJob->pDstBuffer;
    6318             :             poJob->oDstBufferHolder =
    6319        3268 :                 std::make_unique<PointerHolder>(pDstBuffer);
    6320             : 
    6321        3268 :             poJob->NotifyFinished();
    6322        3268 :         };
    6323             : 
    6324             :         // Function to write resample data to target band
    6325        3268 :         const auto WriteJobData = [](const OvrJob *poJob)
    6326             :         {
    6327        6536 :             return poJob->poDstBand->RasterIO(
    6328        3268 :                 GF_Write, poJob->args.nDstXOff, poJob->args.nDstYOff,
    6329        3268 :                 poJob->args.nDstXOff2 - poJob->args.nDstXOff,
    6330        3268 :                 poJob->args.nDstYOff2 - poJob->args.nDstYOff, poJob->pDstBuffer,
    6331        3268 :                 poJob->args.nDstXOff2 - poJob->args.nDstXOff,
    6332        3268 :                 poJob->args.nDstYOff2 - poJob->args.nDstYOff,
    6333        3268 :                 poJob->eDstBufferDataType, 0, 0, nullptr);
    6334             :         };
    6335             : 
    6336             :         // Wait for completion of oldest job and serialize it
    6337             :         const auto WaitAndFinalizeOldestJob =
    6338          16 :             [WriteJobData](std::list<std::unique_ptr<OvrJob>> &jobList)
    6339             :         {
    6340          16 :             auto poOldestJob = jobList.front().get();
    6341          16 :             poOldestJob->WaitFinished();
    6342          16 :             CPLErr l_eErr = poOldestJob->eErr;
    6343          16 :             if (l_eErr == CE_None)
    6344             :             {
    6345          16 :                 l_eErr = WriteJobData(poOldestJob);
    6346             :             }
    6347             : 
    6348          16 :             jobList.pop_front();
    6349          16 :             return l_eErr;
    6350             :         };
    6351             : 
    6352             :         // Queue of jobs
    6353        1178 :         std::list<std::unique_ptr<OvrJob>> jobList;
    6354             : 
    6355        1178 :         std::vector<std::unique_ptr<void, VSIFreeReleaser>> apaChunk(nBands);
    6356             :         std::vector<std::unique_ptr<GByte, VSIFreeReleaser>>
    6357        1178 :             apabyChunkNoDataMask(nBands);
    6358             : 
    6359             :         // Iterate on destination overview, block by block.
    6360         589 :         for (int nDstYOff = nDstYOffStart;
    6361        2078 :              nDstYOff < nDstYOffEnd && eErr == CE_None;
    6362        1489 :              nDstYOff += nDstChunkYSize)
    6363             :         {
    6364             :             int nDstYCount;
    6365        1489 :             if (nDstYOff + nDstChunkYSize <= nDstYOffEnd)
    6366        1077 :                 nDstYCount = nDstChunkYSize;
    6367             :             else
    6368         412 :                 nDstYCount = nDstYOffEnd - nDstYOff;
    6369             : 
    6370        1489 :             int nChunkYOff = static_cast<int>(nDstYOff * dfYRatioDstToSrc);
    6371        1489 :             int nChunkYOff2 = static_cast<int>(
    6372        1489 :                 ceil((nDstYOff + nDstYCount) * dfYRatioDstToSrc));
    6373        1489 :             if (nChunkYOff2 > nSrcHeight ||
    6374        1489 :                 nDstYOff + nDstYCount == nDstTotalHeight)
    6375         582 :                 nChunkYOff2 = nSrcHeight;
    6376        1489 :             int nYCount = nChunkYOff2 - nChunkYOff;
    6377        1489 :             CPLAssert(nYCount <= nFullResYChunk);
    6378             : 
    6379        1489 :             int nChunkYOffQueried = nChunkYOff - nKernelRadius * nOvrFactor;
    6380        1489 :             int nChunkYSizeQueried =
    6381        1489 :                 nYCount + RADIUS_TO_DIAMETER * nKernelRadius * nOvrFactor;
    6382        1489 :             if (nChunkYOffQueried < 0)
    6383             :             {
    6384         136 :                 nChunkYSizeQueried += nChunkYOffQueried;
    6385         136 :                 nChunkYOffQueried = 0;
    6386             :             }
    6387        1489 :             if (nChunkYSizeQueried + nChunkYOffQueried > nSrcHeight)
    6388         135 :                 nChunkYSizeQueried = nSrcHeight - nChunkYOffQueried;
    6389        1489 :             CPLAssert(nChunkYSizeQueried <= nFullResYChunkQueried);
    6390             : 
    6391        1489 :             if (!pfnProgress(std::min(1.0, dfCurPixelCount / dfTotalPixelCount),
    6392             :                              nullptr, pProgressData))
    6393             :             {
    6394           1 :                 CPLError(CE_Failure, CPLE_UserInterrupt, "User terminated");
    6395           1 :                 eErr = CE_Failure;
    6396             :             }
    6397             : 
    6398             :             // Iterate on destination overview, block by block.
    6399        1489 :             for (int nDstXOff = nDstXOffStart;
    6400        3017 :                  nDstXOff < nDstXOffEnd && eErr == CE_None;
    6401        1528 :                  nDstXOff += nDstChunkXSize)
    6402             :             {
    6403        1528 :                 int nDstXCount = 0;
    6404        1528 :                 if (nDstXOff + nDstChunkXSize <= nDstXOffEnd)
    6405        1511 :                     nDstXCount = nDstChunkXSize;
    6406             :                 else
    6407          17 :                     nDstXCount = nDstXOffEnd - nDstXOff;
    6408             : 
    6409        1528 :                 dfCurPixelCount += static_cast<double>(nDstXCount) * nDstYCount;
    6410             : 
    6411        1528 :                 int nChunkXOff = static_cast<int>(nDstXOff * dfXRatioDstToSrc);
    6412        1528 :                 int nChunkXOff2 = static_cast<int>(
    6413        1528 :                     ceil((nDstXOff + nDstXCount) * dfXRatioDstToSrc));
    6414        1528 :                 if (nChunkXOff2 > nSrcWidth ||
    6415        1528 :                     nDstXOff + nDstXCount == nDstTotalWidth)
    6416        1453 :                     nChunkXOff2 = nSrcWidth;
    6417        1528 :                 const int nXCount = nChunkXOff2 - nChunkXOff;
    6418        1528 :                 CPLAssert(nXCount <= nFullResXChunk);
    6419             : 
    6420        1528 :                 int nChunkXOffQueried = nChunkXOff - nKernelRadius * nOvrFactor;
    6421        1528 :                 int nChunkXSizeQueried =
    6422        1528 :                     nXCount + RADIUS_TO_DIAMETER * nKernelRadius * nOvrFactor;
    6423        1528 :                 if (nChunkXOffQueried < 0)
    6424             :                 {
    6425         191 :                     nChunkXSizeQueried += nChunkXOffQueried;
    6426         191 :                     nChunkXOffQueried = 0;
    6427             :                 }
    6428        1528 :                 if (nChunkXSizeQueried + nChunkXOffQueried > nSrcWidth)
    6429         200 :                     nChunkXSizeQueried = nSrcWidth - nChunkXOffQueried;
    6430        1528 :                 CPLAssert(nChunkXSizeQueried <= nFullResXChunkQueried);
    6431             : #if DEBUG_VERBOSE
    6432             :                 CPLDebug("GDAL",
    6433             :                          "Reading (%dx%d -> %dx%d) for output (%dx%d -> %dx%d)",
    6434             :                          nChunkXOffQueried, nChunkYOffQueried,
    6435             :                          nChunkXSizeQueried, nChunkYSizeQueried, nDstXOff,
    6436             :                          nDstYOff, nDstXCount, nDstYCount);
    6437             : #endif
    6438             : 
    6439             :                 // Avoid accumulating too many tasks and exhaust RAM
    6440             : 
    6441             :                 // Try to complete already finished jobs
    6442        1528 :                 while (eErr == CE_None && !jobList.empty())
    6443             :                 {
    6444           2 :                     auto poOldestJob = jobList.front().get();
    6445           2 :                     if (!poOldestJob->IsFinished())
    6446           2 :                         break;
    6447           0 :                     eErr = poOldestJob->eErr;
    6448           0 :                     if (eErr == CE_None)
    6449             :                     {
    6450           0 :                         eErr = WriteJobData(poOldestJob);
    6451             :                     }
    6452             : 
    6453           0 :                     jobList.pop_front();
    6454             :                 }
    6455             : 
    6456             :                 // And in case we have saturated the number of threads,
    6457             :                 // wait for completion of tasks to go below the threshold.
    6458        3056 :                 while (eErr == CE_None &&
    6459        1528 :                        jobList.size() >= static_cast<size_t>(nThreads))
    6460             :                 {
    6461           0 :                     eErr = WaitAndFinalizeOldestJob(jobList);
    6462             :                 }
    6463             : 
    6464             :                 // Read the source buffers for all the bands.
    6465        4797 :                 for (int iBand = 0; iBand < nBands && eErr == CE_None; ++iBand)
    6466             :                 {
    6467             :                     // (Re)allocate buffers if needed
    6468        3269 :                     if (apaChunk[iBand] == nullptr)
    6469             :                     {
    6470        1152 :                         apaChunk[iBand].reset(VSI_MALLOC3_VERBOSE(
    6471             :                             nFullResXChunkQueried, nFullResYChunkQueried,
    6472             :                             nWrkDataTypeSize));
    6473        1152 :                         if (apaChunk[iBand] == nullptr)
    6474             :                         {
    6475           0 :                             eErr = CE_Failure;
    6476             :                         }
    6477             :                     }
    6478        3586 :                     if (bUseNoDataMask &&
    6479         317 :                         apabyChunkNoDataMask[iBand] == nullptr)
    6480             :                     {
    6481         266 :                         apabyChunkNoDataMask[iBand].reset(
    6482         266 :                             static_cast<GByte *>(VSI_MALLOC2_VERBOSE(
    6483             :                                 nFullResXChunkQueried, nFullResYChunkQueried)));
    6484         266 :                         if (apabyChunkNoDataMask[iBand] == nullptr)
    6485             :                         {
    6486           0 :                             eErr = CE_Failure;
    6487             :                         }
    6488             :                     }
    6489             : 
    6490        3269 :                     if (eErr == CE_None)
    6491             :                     {
    6492        3269 :                         GDALRasterBand *poSrcBand = nullptr;
    6493        3269 :                         if (iSrcOverview == -1)
    6494        2383 :                             poSrcBand = papoSrcBands[iBand];
    6495             :                         else
    6496         886 :                             poSrcBand =
    6497         886 :                                 papapoOverviewBands[iBand][iSrcOverview];
    6498        3269 :                         eErr = poSrcBand->RasterIO(
    6499             :                             GF_Read, nChunkXOffQueried, nChunkYOffQueried,
    6500             :                             nChunkXSizeQueried, nChunkYSizeQueried,
    6501        3269 :                             apaChunk[iBand].get(), nChunkXSizeQueried,
    6502             :                             nChunkYSizeQueried, eWrkDataType, 0, 0, nullptr);
    6503             : 
    6504        3269 :                         if (bUseNoDataMask && eErr == CE_None)
    6505             :                         {
    6506         317 :                             auto poMaskBand = poSrcBand->IsMaskBand()
    6507         317 :                                                   ? poSrcBand
    6508         244 :                                                   : poSrcBand->GetMaskBand();
    6509         317 :                             eErr = poMaskBand->RasterIO(
    6510             :                                 GF_Read, nChunkXOffQueried, nChunkYOffQueried,
    6511             :                                 nChunkXSizeQueried, nChunkYSizeQueried,
    6512         317 :                                 apabyChunkNoDataMask[iBand].get(),
    6513             :                                 nChunkXSizeQueried, nChunkYSizeQueried,
    6514             :                                 GDT_UInt8, 0, 0, nullptr);
    6515             :                         }
    6516             :                     }
    6517             :                 }
    6518             : 
    6519             :                 // Compute the resulting overview block.
    6520        4796 :                 for (int iBand = 0; iBand < nBands && eErr == CE_None; ++iBand)
    6521             :                 {
    6522        6536 :                     auto poJob = std::make_unique<OvrJob>();
    6523        3268 :                     poJob->pfnResampleFn = pfnResampleFn;
    6524        3268 :                     poJob->poDstBand = papapoOverviewBands[iBand][iOverview];
    6525        6536 :                     poJob->args.eOvrDataType =
    6526        3268 :                         poJob->poDstBand->GetRasterDataType();
    6527        3268 :                     poJob->args.nOvrXSize = poJob->poDstBand->GetXSize();
    6528        3268 :                     poJob->args.nOvrYSize = poJob->poDstBand->GetYSize();
    6529        3268 :                     const char *pszNBITS = poJob->poDstBand->GetMetadataItem(
    6530        3268 :                         "NBITS", "IMAGE_STRUCTURE");
    6531        3268 :                     poJob->args.nOvrNBITS = pszNBITS ? atoi(pszNBITS) : 0;
    6532        3268 :                     poJob->args.dfXRatioDstToSrc = dfXRatioDstToSrc;
    6533        3268 :                     poJob->args.dfYRatioDstToSrc = dfYRatioDstToSrc;
    6534        3268 :                     poJob->args.eWrkDataType = eWrkDataType;
    6535        3268 :                     poJob->pChunk = apaChunk[iBand].get();
    6536        3268 :                     poJob->args.pabyChunkNodataMask =
    6537        3268 :                         apabyChunkNoDataMask[iBand].get();
    6538        3268 :                     poJob->args.nChunkXOff = nChunkXOffQueried;
    6539        3268 :                     poJob->args.nChunkXSize = nChunkXSizeQueried;
    6540        3268 :                     poJob->args.nChunkYOff = nChunkYOffQueried;
    6541        3268 :                     poJob->args.nChunkYSize = nChunkYSizeQueried;
    6542        3268 :                     poJob->args.nDstXOff = nDstXOff;
    6543        3268 :                     poJob->args.nDstXOff2 = nDstXOff + nDstXCount;
    6544        3268 :                     poJob->args.nDstYOff = nDstYOff;
    6545        3268 :                     poJob->args.nDstYOff2 = nDstYOff + nDstYCount;
    6546        3268 :                     poJob->args.pszResampling = pszResampling;
    6547        3268 :                     poJob->args.bHasNoData = abHasNoData[iBand];
    6548        3268 :                     poJob->args.dfNoDataValue = adfNoDataValue[iBand];
    6549        3268 :                     poJob->args.eSrcDataType = eDataType;
    6550        3268 :                     poJob->args.bPropagateNoData = bPropagateNoData;
    6551             : 
    6552        3268 :                     if (poJobQueue)
    6553             :                     {
    6554          16 :                         poJob->oSrcMaskBufferHolder =
    6555          32 :                             std::make_unique<PointerHolder>(
    6556          32 :                                 std::move(apabyChunkNoDataMask[iBand]));
    6557             : 
    6558          16 :                         poJob->oSrcBufferHolder =
    6559          32 :                             std::make_unique<PointerHolder>(
    6560          32 :                                 std::move(apaChunk[iBand]));
    6561             : 
    6562          16 :                         poJobQueue->SubmitJob(JobResampleFunc, poJob.get());
    6563          16 :                         jobList.emplace_back(std::move(poJob));
    6564             :                     }
    6565             :                     else
    6566             :                     {
    6567        3252 :                         JobResampleFunc(poJob.get());
    6568        3252 :                         eErr = poJob->eErr;
    6569        3252 :                         if (eErr == CE_None)
    6570             :                         {
    6571        3252 :                             eErr = WriteJobData(poJob.get());
    6572             :                         }
    6573             :                     }
    6574             :                 }
    6575             :             }
    6576             :         }
    6577             : 
    6578             :         // Wait for all pending jobs to complete
    6579         605 :         while (!jobList.empty())
    6580             :         {
    6581          16 :             const auto l_eErr = WaitAndFinalizeOldestJob(jobList);
    6582          16 :             if (l_eErr != CE_None && eErr == CE_None)
    6583           0 :                 eErr = l_eErr;
    6584             :         }
    6585             : 
    6586             :         // Flush the data to overviews.
    6587        1739 :         for (int iBand = 0; iBand < nBands; ++iBand)
    6588             :         {
    6589        1150 :             if (papapoOverviewBands[iBand][iOverview]->FlushCache(false) !=
    6590             :                 CE_None)
    6591           0 :                 eErr = CE_Failure;
    6592             :         }
    6593             :     }
    6594             : 
    6595         377 :     if (eErr == CE_None)
    6596         373 :         pfnProgress(1.0, nullptr, pProgressData);
    6597             : 
    6598         377 :     return eErr;
    6599             : }
    6600             : 
    6601             : /************************************************************************/
    6602             : /*                  GDALRegenerateOverviewsMultiBand()                  */
    6603             : /************************************************************************/
    6604             : 
    6605             : /**
    6606             :  * \brief Variant of GDALRegenerateOverviews, specially dedicated for generating
    6607             :  * compressed pixel-interleaved overviews (JPEG-IN-TIFF for example)
    6608             :  *
    6609             :  * This function will generate one or more overview images from a base
    6610             :  * image using the requested downsampling algorithm.  Its primary use
    6611             :  * is for generating overviews via GDALDataset::BuildOverviews(), but it
    6612             :  * can also be used to generate downsampled images in one file from another
    6613             :  * outside the overview architecture.
    6614             :  *
    6615             :  * The output bands need to exist in advance and share the same characteristics
    6616             :  * (type, dimensions)
    6617             :  *
    6618             :  * The resampling algorithms supported for the moment are "NEAREST", "AVERAGE",
    6619             :  * "RMS", "GAUSS", "CUBIC", "CUBICSPLINE", "LANCZOS" and "BILINEAR"
    6620             :  *
    6621             :  * It does not support color tables or complex data types.
    6622             :  *
    6623             :  * The pseudo-algorithm used by the function is :
    6624             :  *    for each overview
    6625             :  *       iterate on lines of the source by a step of deltay
    6626             :  *           iterate on columns of the source  by a step of deltax
    6627             :  *               read the source data of size deltax * deltay for all the bands
    6628             :  *               generate the corresponding overview block for all the bands
    6629             :  *
    6630             :  * This function will honour properly NODATA_VALUES tuples (special dataset
    6631             :  * metadata) so that only a given RGB triplet (in case of a RGB image) will be
    6632             :  * considered as the nodata value and not each value of the triplet
    6633             :  * independently per band.
    6634             :  *
    6635             :  * The GDAL_NUM_THREADS configuration option can be set
    6636             :  * to "ALL_CPUS" or a integer value to specify the number of threads to use for
    6637             :  * overview computation.
    6638             :  *
    6639             :  * @param apoSrcBands the list of source bands to downsample
    6640             :  * @param aapoOverviewBands bidimension array of bands. First dimension is
    6641             :  *                          indexed by bands. Second dimension is indexed by
    6642             :  *                          overview levels. All aapoOverviewBands[i] arrays
    6643             :  *                          must have the same size (i.e. same number of
    6644             :  *                          overviews)
    6645             :  * @param pszResampling Resampling algorithm ("NEAREST", "AVERAGE", "RMS",
    6646             :  * "GAUSS", "CUBIC", "CUBICSPLINE", "LANCZOS" or "BILINEAR").
    6647             :  * @param pfnProgress progress report function.
    6648             :  * @param pProgressData progress function callback data.
    6649             :  * @param papszOptions NULL terminated list of options as
    6650             :  *                     key=value pairs, or NULL
    6651             :  *                     The XOFF, YOFF, XSIZE and YSIZE
    6652             :  *                     options can be specified to express that overviews should
    6653             :  *                     be regenerated only in the specified subset of the source
    6654             :  *                     dataset.
    6655             :  * @return CE_None on success or CE_Failure on failure.
    6656             :  * @since 3.10
    6657             :  */
    6658             : 
    6659          19 : CPLErr GDALRegenerateOverviewsMultiBand(
    6660             :     const std::vector<GDALRasterBand *> &apoSrcBands,
    6661             :     const std::vector<std::vector<GDALRasterBand *>> &aapoOverviewBands,
    6662             :     const char *pszResampling, GDALProgressFunc pfnProgress,
    6663             :     void *pProgressData, CSLConstList papszOptions)
    6664             : {
    6665          19 :     CPLAssert(apoSrcBands.size() == aapoOverviewBands.size());
    6666          29 :     for (size_t i = 1; i < aapoOverviewBands.size(); ++i)
    6667             :     {
    6668          10 :         CPLAssert(aapoOverviewBands[i].size() == aapoOverviewBands[0].size());
    6669             :     }
    6670             : 
    6671          19 :     if (aapoOverviewBands.empty())
    6672           0 :         return CE_None;
    6673             : 
    6674          19 :     std::vector<GDALRasterBand **> apapoOverviewBands;
    6675          48 :     for (auto &apoOverviewBands : aapoOverviewBands)
    6676             :     {
    6677             :         auto papoOverviewBands = static_cast<GDALRasterBand **>(
    6678          29 :             CPLMalloc(apoOverviewBands.size() * sizeof(GDALRasterBand *)));
    6679          61 :         for (size_t i = 0; i < apoOverviewBands.size(); ++i)
    6680             :         {
    6681          32 :             papoOverviewBands[i] = apoOverviewBands[i];
    6682             :         }
    6683          29 :         apapoOverviewBands.push_back(papoOverviewBands);
    6684             :     }
    6685          38 :     const CPLErr eErr = GDALRegenerateOverviewsMultiBand(
    6686          19 :         static_cast<int>(apoSrcBands.size()), apoSrcBands.data(),
    6687          19 :         static_cast<int>(aapoOverviewBands[0].size()),
    6688          19 :         apapoOverviewBands.data(), pszResampling, pfnProgress, pProgressData,
    6689             :         papszOptions);
    6690          48 :     for (GDALRasterBand **papoOverviewBands : apapoOverviewBands)
    6691          29 :         CPLFree(papoOverviewBands);
    6692          19 :     return eErr;
    6693             : }
    6694             : 
    6695             : /************************************************************************/
    6696             : /*                        GDALComputeBandStats()                        */
    6697             : /************************************************************************/
    6698             : 
    6699             : /** Undocumented
    6700             :  * @param hSrcBand undocumented.
    6701             :  * @param nSampleStep Step between scanlines used to compute statistics.
    6702             :  *                    When nSampleStep is equal to 1, all scanlines will
    6703             :  *                    be processed.
    6704             :  * @param pdfMean undocumented.
    6705             :  * @param pdfStdDev undocumented.
    6706             :  * @param pfnProgress undocumented.
    6707             :  * @param pProgressData undocumented.
    6708             :  * @return undocumented
    6709             :  */
    6710          18 : CPLErr CPL_STDCALL GDALComputeBandStats(GDALRasterBandH hSrcBand,
    6711             :                                         int nSampleStep, double *pdfMean,
    6712             :                                         double *pdfStdDev,
    6713             :                                         GDALProgressFunc pfnProgress,
    6714             :                                         void *pProgressData)
    6715             : 
    6716             : {
    6717          18 :     VALIDATE_POINTER1(hSrcBand, "GDALComputeBandStats", CE_Failure);
    6718             : 
    6719          18 :     GDALRasterBand *poSrcBand = GDALRasterBand::FromHandle(hSrcBand);
    6720             : 
    6721          18 :     if (pfnProgress == nullptr)
    6722          18 :         pfnProgress = GDALDummyProgress;
    6723             : 
    6724          18 :     const int nWidth = poSrcBand->GetXSize();
    6725          18 :     const int nHeight = poSrcBand->GetYSize();
    6726             : 
    6727          18 :     if (nSampleStep >= nHeight || nSampleStep < 1)
    6728           5 :         nSampleStep = 1;
    6729             : 
    6730          18 :     GDALDataType eWrkType = GDT_Unknown;
    6731          18 :     float *pafData = nullptr;
    6732          18 :     GDALDataType eType = poSrcBand->GetRasterDataType();
    6733          18 :     const bool bComplex = CPL_TO_BOOL(GDALDataTypeIsComplex(eType));
    6734          18 :     if (bComplex)
    6735             :     {
    6736             :         pafData = static_cast<float *>(
    6737           0 :             VSI_MALLOC2_VERBOSE(nWidth, 2 * sizeof(float)));
    6738           0 :         eWrkType = GDT_CFloat32;
    6739             :     }
    6740             :     else
    6741             :     {
    6742             :         pafData =
    6743          18 :             static_cast<float *>(VSI_MALLOC2_VERBOSE(nWidth, sizeof(float)));
    6744          18 :         eWrkType = GDT_Float32;
    6745             :     }
    6746             : 
    6747          18 :     if (nWidth == 0 || pafData == nullptr)
    6748             :     {
    6749           0 :         VSIFree(pafData);
    6750           0 :         return CE_Failure;
    6751             :     }
    6752             : 
    6753             :     /* -------------------------------------------------------------------- */
    6754             :     /*      Loop over all sample lines.                                     */
    6755             :     /* -------------------------------------------------------------------- */
    6756          18 :     double dfSum = 0.0;
    6757          18 :     double dfSum2 = 0.0;
    6758          18 :     int iLine = 0;
    6759          18 :     GIntBig nSamples = 0;
    6760             : 
    6761        2143 :     do
    6762             :     {
    6763        2161 :         if (!pfnProgress(iLine / static_cast<double>(nHeight), nullptr,
    6764             :                          pProgressData))
    6765             :         {
    6766           0 :             CPLError(CE_Failure, CPLE_UserInterrupt, "User terminated");
    6767           0 :             CPLFree(pafData);
    6768           0 :             return CE_Failure;
    6769             :         }
    6770             : 
    6771             :         const CPLErr eErr =
    6772        2161 :             poSrcBand->RasterIO(GF_Read, 0, iLine, nWidth, 1, pafData, nWidth,
    6773             :                                 1, eWrkType, 0, 0, nullptr);
    6774        2161 :         if (eErr != CE_None)
    6775             :         {
    6776           1 :             CPLFree(pafData);
    6777           1 :             return eErr;
    6778             :         }
    6779             : 
    6780      725208 :         for (int iPixel = 0; iPixel < nWidth; ++iPixel)
    6781             :         {
    6782      723048 :             float fValue = 0.0f;
    6783             : 
    6784      723048 :             if (bComplex)
    6785             :             {
    6786             :                 // Compute the magnitude of the complex value.
    6787             :                 fValue =
    6788           0 :                     std::hypot(pafData[static_cast<size_t>(iPixel) * 2],
    6789           0 :                                pafData[static_cast<size_t>(iPixel) * 2 + 1]);
    6790             :             }
    6791             :             else
    6792             :             {
    6793      723048 :                 fValue = pafData[iPixel];
    6794             :             }
    6795             : 
    6796      723048 :             dfSum += static_cast<double>(fValue);
    6797      723048 :             dfSum2 += static_cast<double>(fValue) * static_cast<double>(fValue);
    6798             :         }
    6799             : 
    6800        2160 :         nSamples += nWidth;
    6801        2160 :         iLine += nSampleStep;
    6802        2160 :     } while (iLine < nHeight);
    6803             : 
    6804          17 :     if (!pfnProgress(1.0, nullptr, pProgressData))
    6805             :     {
    6806           0 :         CPLError(CE_Failure, CPLE_UserInterrupt, "User terminated");
    6807           0 :         CPLFree(pafData);
    6808           0 :         return CE_Failure;
    6809             :     }
    6810             : 
    6811             :     /* -------------------------------------------------------------------- */
    6812             :     /*      Produce the result values.                                      */
    6813             :     /* -------------------------------------------------------------------- */
    6814          17 :     if (pdfMean != nullptr)
    6815          17 :         *pdfMean = dfSum / nSamples;
    6816             : 
    6817          17 :     if (pdfStdDev != nullptr)
    6818             :     {
    6819          17 :         const double dfMean = dfSum / nSamples;
    6820             : 
    6821          17 :         *pdfStdDev = sqrt((dfSum2 / nSamples) - (dfMean * dfMean));
    6822             :     }
    6823             : 
    6824          17 :     CPLFree(pafData);
    6825             : 
    6826          17 :     return CE_None;
    6827             : }
    6828             : 
    6829             : /************************************************************************/
    6830             : /*                  GDALOverviewMagnitudeCorrection()                   */
    6831             : /*                                                                      */
    6832             : /*      Correct the mean and standard deviation of the overviews of     */
    6833             : /*      the given band to match the base layer approximately.           */
    6834             : /************************************************************************/
    6835             : 
    6836             : /** Undocumented
    6837             :  * @param hBaseBand undocumented.
    6838             :  * @param nOverviewCount undocumented.
    6839             :  * @param pahOverviews undocumented.
    6840             :  * @param pfnProgress undocumented.
    6841             :  * @param pProgressData undocumented.
    6842             :  * @return undocumented
    6843             :  */
    6844           0 : CPLErr GDALOverviewMagnitudeCorrection(GDALRasterBandH hBaseBand,
    6845             :                                        int nOverviewCount,
    6846             :                                        GDALRasterBandH *pahOverviews,
    6847             :                                        GDALProgressFunc pfnProgress,
    6848             :                                        void *pProgressData)
    6849             : 
    6850             : {
    6851           0 :     VALIDATE_POINTER1(hBaseBand, "GDALOverviewMagnitudeCorrection", CE_Failure);
    6852             : 
    6853             :     /* -------------------------------------------------------------------- */
    6854             :     /*      Compute mean/stddev for source raster.                          */
    6855             :     /* -------------------------------------------------------------------- */
    6856           0 :     double dfOrigMean = 0.0;
    6857           0 :     double dfOrigStdDev = 0.0;
    6858             :     {
    6859             :         const CPLErr eErr =
    6860           0 :             GDALComputeBandStats(hBaseBand, 2, &dfOrigMean, &dfOrigStdDev,
    6861             :                                  pfnProgress, pProgressData);
    6862             : 
    6863           0 :         if (eErr != CE_None)
    6864           0 :             return eErr;
    6865             :     }
    6866             : 
    6867             :     /* -------------------------------------------------------------------- */
    6868             :     /*      Loop on overview bands.                                         */
    6869             :     /* -------------------------------------------------------------------- */
    6870           0 :     for (int iOverview = 0; iOverview < nOverviewCount; ++iOverview)
    6871             :     {
    6872             :         GDALRasterBand *poOverview =
    6873           0 :             GDALRasterBand::FromHandle(pahOverviews[iOverview]);
    6874             :         double dfOverviewMean, dfOverviewStdDev;
    6875             : 
    6876             :         const CPLErr eErr =
    6877           0 :             GDALComputeBandStats(pahOverviews[iOverview], 1, &dfOverviewMean,
    6878             :                                  &dfOverviewStdDev, pfnProgress, pProgressData);
    6879             : 
    6880           0 :         if (eErr != CE_None)
    6881           0 :             return eErr;
    6882             : 
    6883           0 :         double dfGain = 1.0;
    6884           0 :         if (dfOrigStdDev >= 0.0001)
    6885           0 :             dfGain = dfOrigStdDev / dfOverviewStdDev;
    6886             : 
    6887             :         /* --------------------------------------------------------------------
    6888             :          */
    6889             :         /*      Apply gain and offset. */
    6890             :         /* --------------------------------------------------------------------
    6891             :          */
    6892           0 :         const int nWidth = poOverview->GetXSize();
    6893           0 :         const int nHeight = poOverview->GetYSize();
    6894             : 
    6895           0 :         GDALDataType eWrkType = GDT_Unknown;
    6896           0 :         float *pafData = nullptr;
    6897           0 :         const GDALDataType eType = poOverview->GetRasterDataType();
    6898           0 :         const bool bComplex = CPL_TO_BOOL(GDALDataTypeIsComplex(eType));
    6899           0 :         if (bComplex)
    6900             :         {
    6901             :             pafData = static_cast<float *>(
    6902           0 :                 VSI_MALLOC2_VERBOSE(nWidth, 2 * sizeof(float)));
    6903           0 :             eWrkType = GDT_CFloat32;
    6904             :         }
    6905             :         else
    6906             :         {
    6907             :             pafData = static_cast<float *>(
    6908           0 :                 VSI_MALLOC2_VERBOSE(nWidth, sizeof(float)));
    6909           0 :             eWrkType = GDT_Float32;
    6910             :         }
    6911             : 
    6912           0 :         if (pafData == nullptr)
    6913             :         {
    6914           0 :             return CE_Failure;
    6915             :         }
    6916             : 
    6917           0 :         for (int iLine = 0; iLine < nHeight; ++iLine)
    6918             :         {
    6919           0 :             if (!pfnProgress(iLine / static_cast<double>(nHeight), nullptr,
    6920             :                              pProgressData))
    6921             :             {
    6922           0 :                 CPLError(CE_Failure, CPLE_UserInterrupt, "User terminated");
    6923           0 :                 CPLFree(pafData);
    6924           0 :                 return CE_Failure;
    6925             :             }
    6926             : 
    6927           0 :             if (poOverview->RasterIO(GF_Read, 0, iLine, nWidth, 1, pafData,
    6928             :                                      nWidth, 1, eWrkType, 0, 0,
    6929           0 :                                      nullptr) != CE_None)
    6930             :             {
    6931           0 :                 CPLFree(pafData);
    6932           0 :                 return CE_Failure;
    6933             :             }
    6934             : 
    6935           0 :             for (int iPixel = 0; iPixel < nWidth; ++iPixel)
    6936             :             {
    6937           0 :                 if (bComplex)
    6938             :                 {
    6939           0 :                     pafData[static_cast<size_t>(iPixel) * 2] *=
    6940           0 :                         static_cast<float>(dfGain);
    6941           0 :                     pafData[static_cast<size_t>(iPixel) * 2 + 1] *=
    6942           0 :                         static_cast<float>(dfGain);
    6943             :                 }
    6944             :                 else
    6945             :                 {
    6946           0 :                     pafData[iPixel] = static_cast<float>(
    6947           0 :                         (double(pafData[iPixel]) - dfOverviewMean) * dfGain +
    6948             :                         dfOrigMean);
    6949             :                 }
    6950             :             }
    6951             : 
    6952           0 :             if (poOverview->RasterIO(GF_Write, 0, iLine, nWidth, 1, pafData,
    6953             :                                      nWidth, 1, eWrkType, 0, 0,
    6954           0 :                                      nullptr) != CE_None)
    6955             :             {
    6956           0 :                 CPLFree(pafData);
    6957           0 :                 return CE_Failure;
    6958             :             }
    6959             :         }
    6960             : 
    6961           0 :         if (!pfnProgress(1.0, nullptr, pProgressData))
    6962             :         {
    6963           0 :             CPLError(CE_Failure, CPLE_UserInterrupt, "User terminated");
    6964           0 :             CPLFree(pafData);
    6965           0 :             return CE_Failure;
    6966             :         }
    6967             : 
    6968           0 :         CPLFree(pafData);
    6969             :     }
    6970             : 
    6971           0 :     return CE_None;
    6972             : }

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