new.c

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/*
 **  Written by David Gerdes  US Army Construction Engineering Research Lab
 **     April 1992
 **  Copyright 1992 USA-CERL   All rights reserved.
 **
 */
#include <string.h>
#include <stdlib.h>
#include <grass/linkm.h>


VOID_T *link_new(struct link_head *Head)
{
    VOID_T *tmp;
    char *ctmp, *p;
    register int i;

    if (Head->Unused == NULL) {
        if (Head->max_ptr >= Head->alloced) {
            /*DEBUG fprintf (stderr, "REALLOCING PTR_ARRAY (%d -> %d)\n", Head->alloced, Head->alloced * 2); */
            if (NULL ==
                (tmp =
                 (VOID_T *) realloc(Head->ptr_array,
                                    sizeof(VOID_T *) * Head->alloced * 2))) {
                if (Head->exit_flag)
                    link_out_of_memory();
                return NULL;
            }
            Head->ptr_array = (VOID_T **) tmp;
            Head->alloced *= 2;
        }

        /*DEBUG fprintf (stderr, "Mallocing another chunk: %d\n", Head->max_ptr); */
        if (NULL == (tmp = (VOID_T *)
                     malloc(Head->chunk_size * Head->unit_size))) {
            if (Head->exit_flag)
                link_out_of_memory();
            return NULL;
        }

        Head->ptr_array[Head->max_ptr++] = (VOID_T *) tmp;
        Head->Unused = (VOID_T *) tmp;

        p = ctmp = (char *)tmp;
        for (i = 0; i < Head->chunk_size - 1; i++) {
            link__set_next((VOID_T *) p,
                           (VOID_T *) & (ctmp[(i + 1) * Head->unit_size]));
            /* p->next = p+1 */

            p = &(ctmp[(i + 1) * Head->unit_size]);     /* p = p->next */
        }
        link__set_next((VOID_T *) p, NULL);     /* p->next = NULL */
    }

    tmp = Head->Unused;

    /* Unused = Unused->next */
    Head->Unused = link__get_next(Head->Unused);

    return tmp;
}