cread.c

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#include "bufrlib.h"
#include "cread.h"
 
void
openrb(int nfile, char *ufile) {
    pb[nfile] = fopen(ufile, "rb ");
}
 
void
openwb(int nfile, char *ufile) {
    pb[nfile] = fopen(ufile, "wb ");
}
 
void
openab(int nfile, char *ufile) {
    pb[nfile] = fopen(ufile, "a+b");
}
 
void
backbufr(int nfile) {
    fsetpos(pb[nfile],&lstpos[nfile]);
}
 
void
cewind(int nfile) {
    rewind(pb[nfile]);
}
 
void
closfb(int nfile) {
    fclose(pb[nfile]);
}
 
int
crdbufr(int nfile, int *bufr, int mxwrd) {
 
    int nbytrem, nintrem, nbytx, nintx, wkint[2], ii;
    size_t nb = sizeof(int), nbdi8 = 8/sizeof(int);
    char wkchr[17] = "                ";
    fpos_t nxtpos;
 
    /* Find the start of the next BUFR message within the file. */
    fgetpos(pb[nfile], &lstpos[nfile]);
    while (strncmp(wkchr, "BUFR", 4) != 0) {
        memmove(wkchr, &wkchr[1], 3);
        if (fread(wkchr + 3, 1, 1, pb[nfile]) != 1)
            return -1;
    }
 
    /* Save the current location in case we need to restore it later. */
    fgetpos(pb[nfile], &nxtpos);
 
    /* Read the next 4 bytes of the message. */
    if (fread(wkchr+4, 1, 4, pb[nfile]) != 4)
        return -1;
 
    /* Determine the remaining number of bytes in the message. This doesn't
     * include the first 8 bytes, because we've already read those in. */
    memcpy(wkint, wkchr, 8);
    nbytrem = iupbs01_f(wkint, "LENM") - 8;
 
    nintrem = nbytrem / nb;
    nintx = nbdi8;
    /* Since nbytrem doesn't include the first 8 bytes of the BUFR message, then
     * nintrem is at least nintx integers short of the number needed to hold the
     * entire message.  But there may still be one more integer needed beyond
     * that, depending on whether nbytrem is an exact multiple of nb. */
    if ( ( nbytx = nbytrem % nb ) > 0 ) {
        nintx += 1;
    }
    /* Make sure the output array is large enough to hold the entire message. */
    if (nintrem + nintx > mxwrd) {
        fsetpos(pb[nfile], &nxtpos);
        return -3;
    }
 
    /* Copy the first 8 bytes of the BUFR message into the output array. */
    for ( ii = 0; ii < nbdi8; ii++ ) {
        bufr[ii] = wkint[ii];
    }
    /* Continue reading up to the next-to-last integer of the BUFR message,
     * and copy these into the output array. */
    if (fread(&bufr[ii], nb, nintrem-1, pb[nfile]) != nintrem-1) {
        fsetpos(pb[nfile],&nxtpos);
        return -2;
    }
 
    /* Read the last few bytes of the BUFR message and check for the "7777"
     * indicator. We want to read the end of the message byte-by-byte
     * (rather than integer-by-integer) so that we can easily check for the
     * ending "7777" string. */
    nbytrem = nb + nbytx;
    if (fread(wkchr, 1, nbytrem, pb[nfile]) != nbytrem) {
        fsetpos(pb[nfile], &nxtpos);
        return -2;
    }
    if (strncmp(&wkchr[nbytrem-4], "7777", 4) != 0) {
        fsetpos(pb[nfile], &nxtpos);
        return -2;
    }
    /* Copy the last few bytes of the BUFR message into the output array. */
    memcpy(wkint, wkchr, nbytrem);
    bufr[nintrem + 1] = wkint[0];
    if ( nbytx > 0 ) bufr[nintrem + 2] = wkint[1];
 
    return 0;
}
 
void
cwrbufr(int nfile, int *bufr, int nwrd) {
    size_t nb = sizeof(int);
 
    fwrite(bufr, nb, nwrd, pb[nfile]);
}