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#include <stdio.h>
#include <stdlib.h>
#include "grib2.h"
g2int simunpack(unsigned char *cpack,g2int *idrstmpl,g2int ndpts,g2float *fld)
////$$$ SUBPROGRAM DOCUMENTATION BLOCK
// . . . .
// SUBPROGRAM: simunpack
// PRGMMR: Gilbert ORG: W/NP11 DATE: 2002-10-29
//
// ABSTRACT: This subroutine unpacks a data field that was packed using a
// simple packing algorithm as defined in the GRIB2 documention,
// using info from the GRIB2 Data Representation Template 5.0.
//
// PROGRAM HISTORY LOG:
// 2002-10-29 Gilbert
//
// USAGE: int simunpack(unsigned char *cpack,g2int *idrstmpl,g2int ndpts,
// g2float *fld)
// INPUT ARGUMENT LIST:
// cpack - pointer to the packed data field.
// idrstmpl - pointer to the array of values for Data Representation
// Template 5.0
// ndpts - The number of data values to unpack
//
// OUTPUT ARGUMENT LIST:
// fld - Contains the unpacked data values. fld must be allocated
// with at least ndpts*sizeof(g2float) bytes before
// calling this routine.
//
// REMARKS: None
//
// ATTRIBUTES:
// LANGUAGE: C
// MACHINE:
//
//$$$//
{
g2int *ifld;
g2int j,nbits,itype;
g2float ref,bscale,dscale;
rdieee(idrstmpl+0,&ref,1);
bscale = int_power(2.0,idrstmpl[1]);
dscale = int_power(10.0,-idrstmpl[2]);
nbits = idrstmpl[3];
itype = idrstmpl[4];
ifld=(g2int *)calloc(ndpts,sizeof(g2int));
if ( ifld == 0 ) {
fprintf(stderr,"Could not allocate space in simunpack.\n Data field NOT upacked.\n");
return(1);
}
//
// if nbits equals 0, we have a constant field where the reference value
// is the data value at each gridpoint
//
if (nbits != 0) {
gbits(cpack,ifld,0,nbits,0,ndpts);
for (j=0;j<ndpts;j++) {
fld[j]=(((g2float)ifld[j]*bscale)+ref)*dscale;
}
}
else {
for (j=0;j<ndpts;j++) {
fld[j]=ref;
}
}
free(ifld);
return(0);
}
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