/* See the end of this file for copyright and license terms. */

#include <gay/clist.h>
#include <gay/config.h>
#include <gay/kprintf.h>

void clist_init(struct clist *head)
{
#	if CFG_DEBUG_CLIST
		if (head->next == head && head->prev == head)
			kprintf("clist_init(%p) called multiple times\n", head);
#	endif

	head->next = head;
	head->prev = head;
}

void clist_add(struct clist *head, struct clist *new)
{
#	if CFG_DEBUG_CLIST
		if (sus_nil(head->next) || sus_nil(head->prev)) {
			kprintf("clist_add(%p, %p): head seems uninitialized\n", head, new);
			return;
		}
		if (sus_nil(new)) {
			kprintf("clist_add(%p, %p): new node is NULL!\n", head, new);
			return;
		}
#	endif

	head->prev->next = new;
	new->next = head;

	new->prev = head->prev;
	head->prev = new;
}

void clist_add_first(struct clist *head, struct clist *new)
{
	head->next->prev = new;
	new->next = head->next;

	new->prev = head;
	head->next = new;
}

void clist_del(struct clist *node)
{
	node->next->prev = node->prev;
	node->prev->next = node->next;

#	if CFG_DEBUG_CLIST
		node->next = nil;
		node->prev = nil;
#	endif
}

struct clist *clist_del_first(struct clist *head)
{
#	if CFG_DEBUG_CLIST
		if (clist_is_empty(head)) {
			kprintf("clist_del_first(%p): empty list!\n", head);
			return nil;
		}
#	endif

	struct clist *first = head->next;
	clist_del(first);
	return first;
}

struct clist *clist_del_last(struct clist *head)
{
#	ifdef CFG_DEBUG_CLIST
		if (clist_is_empty(head)) {
			kprintf("clist_del_last(%p): empty list!\n", head);
			return nil;
		}
#	endif

	struct clist *last = head->prev;
	clist_del(last);
	return last;
}

/*
 * This file is part of GayBSD.
 * Copyright (c) 2021 fef <owo@fef.moe>.
 *
 * GayBSD is nonviolent software: you may only use, redistribute, and/or
 * modify it under the terms of the Cooperative Nonviolent Public License
 * (CNPL) as found in the LICENSE file in the source code root directory
 * or at <https://git.pixie.town/thufie/npl-builder>; either version 7
 * of the license, or (at your option) any later version.
 *
 * GayBSD comes with ABSOLUTELY NO WARRANTY, to the extent
 * permitted by applicable law.  See the CNPL for details.
 */