Line data Source code
1 : /*
2 : * Copyright (c) 1988-1997 Sam Leffler
3 : * Copyright (c) 1991-1997 Silicon Graphics, Inc.
4 : *
5 : * Permission to use, copy, modify, distribute, and sell this software and
6 : * its documentation for any purpose is hereby granted without fee, provided
7 : * that (i) the above copyright notices and this permission notice appear in
8 : * all copies of the software and related documentation, and (ii) the names of
9 : * Sam Leffler and Silicon Graphics may not be used in any advertising or
10 : * publicity relating to the software without the specific, prior written
11 : * permission of Sam Leffler and Silicon Graphics.
12 : *
13 : * THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND,
14 : * EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY
15 : * WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
16 : *
17 : * IN NO EVENT SHALL SAM LEFFLER OR SILICON GRAPHICS BE LIABLE FOR
18 : * ANY SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND,
19 : * OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
20 : * WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF
21 : * LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
22 : * OF THIS SOFTWARE.
23 : */
24 :
25 : #include "tiffiop.h"
26 : #include <assert.h>
27 : #ifdef THUNDER_SUPPORT
28 : /*
29 : * TIFF Library.
30 : *
31 : * ThunderScan 4-bit Compression Algorithm Support
32 : */
33 :
34 : /*
35 : * ThunderScan uses an encoding scheme designed for
36 : * 4-bit pixel values. Data is encoded in bytes, with
37 : * each byte split into a 2-bit code word and a 6-bit
38 : * data value. The encoding gives raw data, runs of
39 : * pixels, or pixel values encoded as a delta from the
40 : * previous pixel value. For the latter, either 2-bit
41 : * or 3-bit delta values are used, with the deltas packed
42 : * into a single byte.
43 : */
44 : #define THUNDER_DATA 0x3f /* mask for 6-bit data */
45 : #define THUNDER_CODE 0xc0 /* mask for 2-bit code word */
46 : /* code values */
47 : #define THUNDER_RUN 0x00 /* run of pixels w/ encoded count */
48 : #define THUNDER_2BITDELTAS 0x40 /* 3 pixels w/ encoded 2-bit deltas */
49 : #define DELTA2_SKIP 2 /* skip code for 2-bit deltas */
50 : #define THUNDER_3BITDELTAS 0x80 /* 2 pixels w/ encoded 3-bit deltas */
51 : #define DELTA3_SKIP 4 /* skip code for 3-bit deltas */
52 : #define THUNDER_RAW 0xc0 /* raw data encoded */
53 :
54 : static const int twobitdeltas[4] = {0, 1, 0, -1};
55 : static const int threebitdeltas[8] = {0, 1, 2, 3, 0, -3, -2, -1};
56 :
57 : #define SETPIXEL(op, v) \
58 : { \
59 : lastpixel = (v)&0xf; \
60 : if (npixels < maxpixels) \
61 : { \
62 : if (npixels++ & 1) \
63 : *op++ |= lastpixel; \
64 : else \
65 : op[0] = (uint8_t)(lastpixel << 4); \
66 : } \
67 : }
68 :
69 1 : static int ThunderSetupDecode(TIFF *tif)
70 : {
71 : static const char module[] = "ThunderSetupDecode";
72 :
73 1 : if (tif->tif_dir.td_bitspersample != 4)
74 : {
75 0 : TIFFErrorExtR(tif, module,
76 : "Wrong bitspersample value (%d), Thunder decoder only "
77 : "supports 4bits per sample.",
78 0 : (int)tif->tif_dir.td_bitspersample);
79 0 : return 0;
80 : }
81 :
82 1 : return (1);
83 : }
84 :
85 1 : static int ThunderDecode(TIFF *tif, uint8_t *op, tmsize_t maxpixels)
86 : {
87 : static const char module[] = "ThunderDecode";
88 : register unsigned char *bp;
89 : register tmsize_t cc;
90 : unsigned int lastpixel;
91 : tmsize_t npixels;
92 :
93 1 : bp = (unsigned char *)tif->tif_rawcp;
94 1 : cc = tif->tif_rawcc;
95 1 : lastpixel = 0;
96 1 : npixels = 0;
97 3 : while (cc > 0 && npixels < maxpixels)
98 : {
99 : int n, delta;
100 :
101 2 : n = *bp++;
102 2 : cc--;
103 2 : switch (n & THUNDER_CODE)
104 : {
105 1 : case THUNDER_RUN: /* pixel run */
106 : /*
107 : * Replicate the last pixel n times,
108 : * where n is the lower-order 6 bits.
109 : */
110 1 : if (npixels & 1)
111 : {
112 0 : op[0] |= lastpixel;
113 0 : lastpixel = *op++;
114 0 : npixels++;
115 0 : n--;
116 : }
117 : else
118 1 : lastpixel |= lastpixel << 4;
119 1 : npixels += n;
120 1 : if (npixels < maxpixels)
121 : {
122 1 : for (; n > 0; n -= 2)
123 0 : *op++ = (uint8_t)lastpixel;
124 : }
125 1 : if (n == -1)
126 0 : *--op &= 0xf0;
127 1 : lastpixel &= 0xf;
128 1 : break;
129 1 : case THUNDER_2BITDELTAS: /* 2-bit deltas */
130 1 : if ((delta = ((n >> 4) & 3)) != DELTA2_SKIP)
131 1 : SETPIXEL(op,
132 : (unsigned)((int)lastpixel + twobitdeltas[delta]));
133 1 : if ((delta = ((n >> 2) & 3)) != DELTA2_SKIP)
134 1 : SETPIXEL(op,
135 : (unsigned)((int)lastpixel + twobitdeltas[delta]));
136 1 : if ((delta = (n & 3)) != DELTA2_SKIP)
137 1 : SETPIXEL(op,
138 : (unsigned)((int)lastpixel + twobitdeltas[delta]));
139 1 : break;
140 0 : case THUNDER_3BITDELTAS: /* 3-bit deltas */
141 0 : if ((delta = ((n >> 3) & 7)) != DELTA3_SKIP)
142 0 : SETPIXEL(
143 : op, (unsigned)((int)lastpixel + threebitdeltas[delta]));
144 0 : if ((delta = (n & 7)) != DELTA3_SKIP)
145 0 : SETPIXEL(
146 : op, (unsigned)((int)lastpixel + threebitdeltas[delta]));
147 0 : break;
148 0 : case THUNDER_RAW: /* raw data */
149 0 : SETPIXEL(op, n);
150 0 : break;
151 : }
152 3 : }
153 1 : tif->tif_rawcp = (uint8_t *)bp;
154 1 : tif->tif_rawcc = cc;
155 1 : if (npixels != maxpixels)
156 : {
157 0 : TIFFErrorExtR(tif, module,
158 : "%s data at scanline %lu (%" PRIu64 " != %" PRIu64 ")",
159 : npixels < maxpixels ? "Not enough" : "Too much",
160 0 : (unsigned long)tif->tif_row, (uint64_t)npixels,
161 : (uint64_t)maxpixels);
162 0 : return (0);
163 : }
164 :
165 1 : return (1);
166 : }
167 :
168 1 : static int ThunderDecodeRow(TIFF *tif, uint8_t *buf, tmsize_t occ, uint16_t s)
169 : {
170 : static const char module[] = "ThunderDecodeRow";
171 1 : uint8_t *row = buf;
172 :
173 : (void)s;
174 1 : if (occ % tif->tif_scanlinesize)
175 : {
176 0 : TIFFErrorExtR(tif, module, "Fractional scanlines cannot be read");
177 0 : return (0);
178 : }
179 2 : while (occ > 0)
180 : {
181 1 : if (!ThunderDecode(tif, row, tif->tif_dir.td_imagewidth))
182 0 : return (0);
183 1 : occ -= tif->tif_scanlinesize;
184 1 : row += tif->tif_scanlinesize;
185 : }
186 1 : return (1);
187 : }
188 :
189 2 : int TIFFInitThunderScan(TIFF *tif, int scheme)
190 : {
191 : (void)scheme;
192 :
193 2 : tif->tif_setupdecode = ThunderSetupDecode;
194 2 : tif->tif_decoderow = ThunderDecodeRow;
195 2 : tif->tif_decodestrip = ThunderDecodeRow;
196 2 : return (1);
197 : }
198 : #endif /* THUNDER_SUPPORT */
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