Line data    Source code

       1             : #include <float.h>
       2             : #include <stdio.h>
       3             : #include <stdlib.h>
       4             : #include "grib2.h"
       5             : 
       6             : #ifndef DoubleToFloatClamp_defined
       7             : #define DoubleToFloatClamp_defined
       8          72 : static float DoubleToFloatClamp(double val) {
       9          72 :    if (val >= FLT_MAX) return FLT_MAX;
      10          72 :    if (val <= -FLT_MAX) return -FLT_MAX;
      11          72 :    return (float)val;
      12             : }
      13             : #endif
      14             : 
      15          36 : g2int simunpack(unsigned char *cpack,g2int cpack_length,g2int *idrstmpl,g2int ndpts,g2float *fld)
      16             : ////$$$  SUBPROGRAM DOCUMENTATION BLOCK
      17             : //                .      .    .                                       .
      18             : // SUBPROGRAM:    simunpack
      19             : //   PRGMMR: Gilbert          ORG: W/NP11    DATE: 2002-10-29
      20             : //
      21             : // ABSTRACT: This subroutine unpacks a data field that was packed using a
      22             : //   simple packing algorithm as defined in the GRIB2 documentation,
      23             : //   using info from the GRIB2 Data Representation Template 5.0.
      24             : //
      25             : // PROGRAM HISTORY LOG:
      26             : // 2002-10-29  Gilbert
      27             : //
      28             : // USAGE:    int simunpack(unsigned char *cpack,g2int *idrstmpl,g2int ndpts,
      29             : //                         g2float *fld)
      30             : //   INPUT ARGUMENT LIST:
      31             : //     cpack    - pointer to the packed data field.
      32             : //     idrstmpl - pointer to the array of values for Data Representation
      33             : //                Template 5.0
      34             : //     ndpts    - The number of data values to unpack
      35             : //
      36             : //   OUTPUT ARGUMENT LIST:
      37             : //     fld      - Contains the unpacked data values.  fld must be allocated
      38             : //                with at least ndpts*sizeof(g2float) bytes before
      39             : //                calling this routine.
      40             : //
      41             : // REMARKS: None
      42             : //
      43             : // ATTRIBUTES:
      44             : //   LANGUAGE: C
      45             : //   MACHINE:
      46             : //
      47             : //$$$//
      48             : {
      49             : 
      50             :       g2int  *ifld;
      51             :       g2int  j,nbits /* ,itype */;
      52             :       g2float ref,bscale,dscale;
      53             : 
      54          36 :       rdieee(idrstmpl+0,&ref,1);
      55          36 :       bscale = DoubleToFloatClamp(int_power(2.0,idrstmpl[1]));
      56          36 :       dscale = DoubleToFloatClamp(int_power(10.0,-idrstmpl[2]));
      57          36 :       nbits = idrstmpl[3];
      58             :       /* itype = idrstmpl[4]; */
      59             : 
      60          36 :       ifld=(g2int *)calloc(ndpts,sizeof(g2int));
      61          36 :       if ( ifld == 0 ) {
      62           0 :          fprintf(stderr,"Could not allocate space in simunpack.\n"
      63             :                  "Data field NOT unpacked.\n");
      64           0 :          return(1);
      65             :       }
      66             : 
      67             : //
      68             : //  if nbits equals 0, we have a constant field where the reference value
      69             : //  is the data value at each gridpoint
      70             : //
      71          36 :       if (nbits != 0) {
      72          33 :          gbits(cpack,cpack_length,ifld,0,nbits,0,ndpts);
      73       35359 :          for (j=0;j<ndpts;j++) {
      74       35326 :            fld[j]=(((g2float)ifld[j]*bscale)+ref)*dscale;
      75             :          }
      76             :       }
      77             :       else {
      78           6 :          for (j=0;j<ndpts;j++) {
      79           3 :            fld[j]=ref * dscale;
      80             :          }
      81             :       }
      82             : 
      83          36 :       free(ifld);
      84          36 :       return(0);
      85             : }