/*
**  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>


struct link_head *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 (struct link_head *) 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 (struct link_head *)tmp;
}