segment/setup.c

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#include <stdlib.h>
#include <stdio.h>
#include <grass/gis.h>
#include <grass/segment.h>


int segment_setup(SEGMENT * SEG)
{
    int i;

    SEG->open = 0;

    if (SEG->nrows <= 0 || SEG->ncols <= 0
        || SEG->srows <= 0 || SEG->scols <= 0
        || SEG->len <= 0 || SEG->nseg <= 0) {
        G_warning("segment_setup: illegal segment file parameters\n");
        return -1;
    }

    /* This is close to the beginning of the file, so doesn't need to be an off_t */
    SEG->offset = (int)lseek(SEG->fd, 0L, SEEK_CUR);

    SEG->spr = SEG->ncols / SEG->scols;
    SEG->spill = SEG->ncols % SEG->scols;
    if (SEG->spill)
        SEG->spr++;

    if ((SEG->scb =
         (struct SEGMENT_SCB *)G_malloc(SEG->nseg *
                                        sizeof(struct SEGMENT_SCB))) == NULL)
        return -2;

    SEG->size = SEG->srows * SEG->scols * SEG->len;

    for (i = 0; i < SEG->nseg; i++) {
        if ((SEG->scb[i].buf = G_malloc(SEG->size)) == NULL)
            return -2;

        SEG->scb[i].n = -1;     /* mark free */
        SEG->scb[i].dirty = 0;
        SEG->scb[i].age = 0;
    }
    SEG->cur = 0;
    SEG->open = 1;

    return 1;
}