/*	$NetBSD: dlz_list.h,v 1.6 2023/01/25 21:43:29 christos Exp $	*/

/*
 * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
 *
 * SPDX-License-Identifier: ISC
 *
 * Permission to use, copy, modify, and distribute this software for any purpose
 * with or without fee is hereby granted, provided that the above copyright
 * notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
 * OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 * PERFORMANCE OF THIS SOFTWARE.
 */

#ifndef DLZ_LIST_H
#define DLZ_LIST_H 1

#define DLZ_LIST(type)             \
	struct {                   \
		type *head, *tail; \
	}
#define DLZ_LIST_INIT(list)         \
	do {                        \
		(list).head = NULL; \
		(list).tail = NULL; \
	} while (0)

#define DLZ_LINK(type)             \
	struct {                   \
		type *prev, *next; \
	}
#define DLZ_LINK_INIT(elt, link)                 \
	do {                                     \
		(elt)->link.prev = (void *)(-1); \
		(elt)->link.next = (void *)(-1); \
	} while (0)

#define DLZ_LIST_HEAD(list) ((list).head)
#define DLZ_LIST_TAIL(list) ((list).tail)

#define DLZ_LIST_APPEND(list, elt, link)                \
	do {                                            \
		if ((list).tail != NULL)                \
			(list).tail->link.next = (elt); \
		else                                    \
			(list).head = (elt);            \
		(elt)->link.prev = (list).tail;         \
		(elt)->link.next = NULL;                \
		(list).tail = (elt);                    \
	} while (0)

#define DLZ_LIST_PREV(elt, link) ((elt)->link.prev)
#define DLZ_LIST_NEXT(elt, link) ((elt)->link.next)

#define DLZ_LIST_UNLINK(list, elt, link)                                \
	do {                                                            \
		if ((elt)->link.next != NULL)                           \
			(elt)->link.next->link.prev = (elt)->link.prev; \
		else                                                    \
			(list).tail = (elt)->link.prev;                 \
		if ((elt)->link.prev != NULL)                           \
			(elt)->link.prev->link.next = (elt)->link.next; \
		else                                                    \
			(list).head = (elt)->link.next;                 \
		(elt)->link.prev = (void *)(-1);                        \
		(elt)->link.next = (void *)(-1);                        \
	} while (0)

#endif /* DLZ_LIST_H */