g2_addlocal.c

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#include <stdio.h>
#include "grib2.h"
 
g2int
g2_addlocal(unsigned char *cgrib, unsigned char *csec2, g2int lcsec2)
{
    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' */
 
    static g2int two = 2;
    g2int j, k, lensec2, iofst, ibeg, lencurr, ilen, len, istart;
    g2int isecnum;
    g2int ierr = 0;
 
    /* Check to see if beginning of GRIB message exists. */
    if (cgrib[0] != G || cgrib[1] != R || cgrib[2] != I || cgrib[3] != B)
    {
        printf("g2_addlocal: GRIB not found in given message.\n");
        printf("g2_addlocal: Call to routine g2_create required to initialize GRIB messge.\n");
        ierr = -1;
        return(ierr);
    }
 
    /* Get current length of GRIB message. */
    gbit(cgrib, &lencurr, 96, 32);
 
    /* Check to see if GRIB message is already complete. */
    if (cgrib[lencurr - 4] == seven && cgrib[lencurr - 3] == seven &&
         cgrib[lencurr - 2] == seven && cgrib[lencurr - 1] == seven)
    {
        printf("g2_addlocal: GRIB message already complete.  Cannot add new section.\n");
        ierr = -2;
        return(ierr);
    }
 
    /*  Loop through all current sections of the GRIB message to find
     *  the last section number. */
    len = 16;    /* length of Section 0 */
    for (;;)
    {
        /* Get section 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_addlocal: Section byte counts don't add to total.\n");
            printf("g2_addlocal: Sum of section byte counts = %ld\n", len);
            printf("g2_addlocal: Total byte count in Section 0 = %ld\n", lencurr);
            ierr = -3;
            return(ierr);
        }
    }
 
    /* Section 2 can only be added after sections 1 and 7. */
    if (isecnum != 1 && isecnum != 7)
    {
        printf("g2_addlocal: Section 2 can only be added after Section 1 or Section 7.\n");
        printf("g2_addlocal: Section %ld was the last found in given GRIB message.\n", isecnum);
        ierr = -4;
        return(ierr);
    }
 
    /* Add Section 2  - Local Use Section. */
    ibeg = lencurr * 8;        /*   Calculate offset for beginning of section 2 */
    iofst = ibeg + 32;         /*   leave space for length of section */
    sbit(cgrib, &two, iofst, 8);     /* Store section number (2) */
    istart = lencurr + 5;
    //cgrib(istart+1:istart+lcsec2) = csec2(1:lcsec2)
    k = 0;
    for (j = istart; j < istart + lcsec2; j++)
        cgrib[j] = csec2[k++];
 
    /* Calculate length of section 2 and store it in octets 1-4 of section 2. */
    lensec2 = lcsec2 + 5;      /* bytes */
    sbit(cgrib, &lensec2, ibeg, 32);
 
    /*  Update current byte total of message in Section 0. */
    lencurr += lensec2;
    sbit(cgrib, &lencurr, 96, 32);
 
    return(lencurr);
}