drstemplates.c

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#include <stdlib.h>
#include "grib2_int.h"
 
#define MAXDRSTEMP 9 
#define MAXDRSMAPLEN 200 
struct drstemplate
{
    g2int template_num; 
    g2int mapdrslen; 
    g2int needext; 
    g2int mapdrs[MAXDRSMAPLEN]; 
};
 
static const struct drstemplate templatesdrs[MAXDRSTEMP] =
{
    { 0, 5, 0, {4,-2,-2,1,1} },
 
    { 2, 16, 0, {4,-2,-2,1,1,1,1,4,4,4,1,1,4,1,4,1} },
 
    { 3, 18, 0, {4,-2,-2,1,1,1,1,4,4,4,1,1,4,1,4,1,1,1} },
 
    { 50, 5, 0, {4,-2,-2,1,4} },
 
    { 51, 10, 0, {4,-2,-2,1,-4,2,2,2,4,1} },
 
    /* 5.1: Matrix values at gridpoint - Simple packing.
     * Comment from Stephen Gilbert in 2021:
     *
     * This encoder/decoder was written in the early days of GRIB2
     * adoption as a standard. It was used to help WMO validate the
     * templates in the specification by sharing GRIB2 encoded message
     * with other organizations to verify that the data could be
     * transmitted and processed successfully.
     *
     * We did not have a use case for DRS template 5.1 at that time
     * and did not produce any GRIB2 messages using that template. It
     * appears that other organizations did not work on it as
     * well. The latest GRIB2 specification still includes the DRS
     * Template 5.1 definition, but there is a disclaimer to use it
     * with caution, since it has not yet been validated. I assume we
     * commented it out because it was not validated, which means it's
     * definition could possibly change during any validation attempts
     * in the future.
     */
 
    /* { 1, 15, 1, {4,-2,-2,1,1,1,4,2,2,1,1,1,1,1,1} }, */
 
    { 40, 7, 0, {4,-2,-2,1,1,1,1} },
 
    { 41, 5, 0, {4,-2,-2,1,1} },
 
    { 40000, 7, 0, {4,-2,-2,1,1,1,1} },
 
    { 40010, 5, 0, {4,-2,-2,1,1} }
} ;
 
static g2int
getdrsindex(g2int number)
{
    g2int j, getdrsindex = -1;
 
    for (j = 0; j < MAXDRSTEMP; j++)
    {
        if (number == templatesdrs[j].template_num)
        {
            getdrsindex = j;
            return(getdrsindex);
        }
    }
 
    return(getdrsindex);
}
 
gtemplate *
getdrstemplate(g2int number)
{
    g2int index;
    gtemplate *new;
 
    index = getdrsindex(number);
 
    if (index != -1)
    {
        new = malloc(sizeof(gtemplate));
        new->type = 5;
        new->num = templatesdrs[index].template_num;
        new->maplen = templatesdrs[index].mapdrslen;
        new->needext = templatesdrs[index].needext;
        new->map = (g2int *)templatesdrs[index].mapdrs;
        new->extlen = 0;
        new->ext = NULL;
        return(new);
    }
    else
    {
        printf("getdrstemplate: DRS Template 5.%d not defined.\n", (int)number);
        return(NULL);
    }
 
    return(NULL);
}
 
gtemplate *
extdrstemplate(g2int number, g2int *list)
{
    gtemplate *new;
 
    if (getdrsindex(number) == -1)
        return NULL;
 
    new = getdrstemplate(number);
 
    if (!new->needext)
        return(new);
 
    /* This template is commented out (see comment in struct
     * drstemplate for explanation). */
    /* if (number == 1) */
    /* { */
    /*     new->extlen = list[10] + list[12]; */
    /*     new->ext = malloc(sizeof(g2int) * new->extlen); */
    /*     for (i = 0; i < new->extlen; i++) */
    /*     { */
    /*         new->ext[i] = 4; */
    /*     } */
    /* } */
    
    return new;
}