g2_gribend.c

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#include <stdio.h>
#include "grib2.h"
 
g2int g2_gribend(unsigned char *cgrib)
{
 
    g2int iofst, lencurr, len, ilen, isecnum;
    g2int ierr = 0, lengrib;
    static unsigned char G = 0x47;       /* 'G' */
    static unsigned char R = 0x52;       /* 'R' */
    static unsigned char I = 0x49;       /* 'I' */
    static unsigned char B = 0x42;       /* 'B' */
    static unsigned char seven = 0x37;   /* '7' */
 
    /* Check to see if beginning of GRIB message exists. */
    if (cgrib[0] != G || cgrib[1] != R || cgrib[2] != I || cgrib[3] != B) {
        printf("g2_gribend: GRIB not found in given message.\n");
        ierr = -1;
        return (ierr);
    }
 
    /* Get current length of GRIB message. */
    gbit(cgrib, &lencurr, 96, 32);
 
    /*  Loop through all current sections of the GRIB message to find
     *  the last section number. */
    len = 16;    /* Length of Section 0. */
    for (;;) {
        /*    Get number and length of next section. */
        iofst = len * 8;
        gbit(cgrib, &ilen, iofst, 32);
        iofst = iofst + 32;
        gbit(cgrib, &isecnum, iofst, 8);
        len = len + ilen;
        /*    Exit loop if last section reached. */
        if (len == lencurr)
            break;
        /*    If byte count for each section doesn't match current
         *    total length, then there is a problem. */
        if (len > lencurr) {
            printf("g2_gribend: Section byte counts don''t add to total.\n");
            printf("g2_gribend: Sum of section byte counts  =  %d\n", (int)len);
            printf("g2_gribend: Total byte count in Section 0 = %d\n", (int)lencurr);
            ierr = -3;
            return (ierr);
        }
    }
 
    /* Can only add End Section (Section 8) after Section 7. */
    if (isecnum != 7 ) {
        printf("g2_gribend: Section 8 can only be added after Section 7.\n");
        printf("g2_gribend: Section %ld was the last found in given GRIB message.\n", isecnum);
        ierr = -4;
        return (ierr);
    }
 
    /* Add Section 8  - End Section */
    cgrib[lencurr] = seven;
    cgrib[lencurr + 1] = seven;
    cgrib[lencurr + 2] = seven;
    cgrib[lencurr + 3] = seven;
 
    /* Update current byte total of message in Section 0. */
    lengrib = lencurr + 4;
    sbit(cgrib, &lengrib, 96, 32);
 
    return (lengrib);
 
}