g2_unpack5.c

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#include <stdio.h>
#include <stdlib.h>
#include "grib2.h"
 
g2int
g2_unpack5(unsigned char *cgrib, g2int *iofst, g2int *ndpts, g2int *idrsnum,
           g2int **idrstmpl, g2int *mapdrslen)
{
    g2int ierr, needext, i, j, nbits, isecnum;
    g2int lensec, isign, newlen;
    g2int *lidrstmpl = 0;
    gtemplate *mapdrs;
 
    ierr = 0;
    *idrstmpl = 0;       /* NULL*/
 
    gbit(cgrib, &lensec, *iofst, 32);        /* Get Length of Section */
    *iofst = *iofst + 32;
    gbit(cgrib, &isecnum, *iofst, 8);         /* Get Section Number */
    *iofst = *iofst + 8;
 
    if (isecnum != 5)
    {
        ierr = 2;
        *ndpts = 0;
        *mapdrslen = 0;
        /* fprintf(stderr, "g2_unpack5: Not Section 5 data.\n"); */
        return(ierr);
    }
 
    gbit(cgrib, ndpts, *iofst, 32);    /* Get num of data points */
    *iofst = *iofst + 32;
    gbit(cgrib, idrsnum, *iofst, 16);     /* Get Data Rep Template Num. */
    *iofst = *iofst + 16;
 
    /*   Gen Data Representation Template */
    mapdrs = getdrstemplate(*idrsnum);
    if (mapdrs == 0)
    {
        ierr = 7;
        *mapdrslen = 0;
        return(ierr);
    }
    *mapdrslen = mapdrs->maplen;
    needext = mapdrs->needext;
 
    /* Unpack each value into array ipdstmpl from the appropriate
     * number of octets, which are specified in corresponding
     * entries in array mapdrs. */
    if (*mapdrslen > 0)
        lidrstmpl = calloc(*mapdrslen, sizeof(g2int));
    if (lidrstmpl == 0)
    {
        ierr = 6;
        *mapdrslen = 0;
        *idrstmpl = NULL;
        if (mapdrs)
            free(mapdrs);
        return(ierr);
    }
    else
    {
        *idrstmpl = lidrstmpl;
    }
    for (i = 0; i < mapdrs->maplen; i++)
    {
        nbits = abs(mapdrs->map[i]) * 8;
        if (mapdrs->map[i] >= 0)
        {
            gbit(cgrib, lidrstmpl + i, *iofst, nbits);
        }
        else
        {
            gbit(cgrib, &isign, *iofst, 1);
            gbit(cgrib, lidrstmpl + i, *iofst + 1, nbits - 1);
            if (isign == 1)
                lidrstmpl[i] = -1 * lidrstmpl[i];
        }
        *iofst = *iofst + nbits;
    }
 
    /* Check to see if the Data Representation Template needs to be
     * extended. The number of values in a specific gtemplate may
     * vary depending on data specified in the "static" part of the
     * gtemplate. */
    if (needext == 1)
    {
        free(mapdrs);
        mapdrs = extdrstemplate(*idrsnum, lidrstmpl);
        newlen = mapdrs->maplen + mapdrs->extlen;
        lidrstmpl = realloc(lidrstmpl, newlen * sizeof(g2int));
        *idrstmpl = lidrstmpl;
        /*   Unpack the rest of the Data Representation Template */
        j = 0;
        for (i = *mapdrslen; i < newlen; i++)
        {
            nbits = abs(mapdrs->ext[j])*8;
            if (mapdrs->ext[j] >= 0)
            {
                gbit(cgrib, lidrstmpl + i, *iofst, nbits);
            }
            else
            {
                gbit(cgrib, &isign, *iofst, 1);
                gbit(cgrib, lidrstmpl + i, *iofst + 1, nbits-1);
                if (isign == 1)
                    lidrstmpl[i] = -1*lidrstmpl[i];
            }
            *iofst = *iofst + nbits;
            j++;
        }
        *mapdrslen = newlen;
    }
    if (mapdrs->ext)
        free(mapdrs->ext);
    if (mapdrs)
        free(mapdrs);
 
    return(ierr);    /* End of Section 5 processing */
 
}