LIST.C

/*
 * Functions for dealing with linked lists of goodies
 * Functions with names starting with an "_" have compainion #defines
 * in rogue.h which take the address of the first argument and pass it on.
 *
 * list.c	1.4 (A.I. Design) 12/5/85
 */

#include "rogue.h"
#include "curses.h"

extern THING *_things;
extern int   *_t_alloc;
/*
 * detach:
 *	Takes an item out of whatever linked list it might be in
 */
_detach(list, item)
register THING **list, *item;
{
    if (*list == item)
	*list = next(item);
    if (prev(item) != NULL) item->l_prev->l_next = next(item);
    if (next(item) != NULL) item->l_next->l_prev = prev(item);
    item->l_next = NULL;
    item->l_prev = NULL;
}

/*
 * _attach:
 *	add an item to the head of a list
 */
_attach(list, item)
register THING **list, *item;
{
    if (*list != NULL)
    {
	item->l_next = *list;
	(*list)->l_prev = item;
	item->l_prev = NULL;
    }
    else
    {
	item->l_next = NULL;
	item->l_prev = NULL;
    }
    *list = item;
}

/*
 * _free_list:
 *	Throw the whole blamed thing away
 */
_free_list(ptr)
register THING **ptr;
{
    register THING *item;

    while (*ptr != NULL)
    {
	item = *ptr;
	*ptr = next(item);
	discard(item);
    }
}


/*
 * new_item
 *	Get a new item with a specified size
 */
THING *
new_item()
{
    register THING *item;
#ifdef DEBUG
    if ((item = (THING *) talloc()) == NULL)
	    if (me())msg("no more things!");
	else
#else
    if ((item = (THING *) talloc()) != NULL)
#endif DEBUG
             item->l_next = item->l_prev = NULL;
    return item;
}

/*
 * talloc: simple allocation of a THING
 */
talloc()
{
    register int i;

    for (i=0;i<MAXITEMS;i++)
    {
    	if (_t_alloc[i] == 0)
    	{
    	    if (++total > maxitems)
    		maxitems = total;
    	    _t_alloc[i]++;
    	    setmem(&_things[i],sizeof(THING),0);
    	    return &_things[i];
    	}
    }
    return NULL;
}

/*
 * discard:
 *	Free up an item
 */
discard(item)
register THING *item;
{
    register int i;

    for (i=0;i<MAXITEMS;i++)
    {
    	if (item == &_things[i])
    	{
    	    --total;
    	    _t_alloc[i] = 0;
    	    return 1;
    	}
    }
    return NULL;
}