[openssh.git] / openbsd-compat / sys-queue.h

/* OPENBSD ORIGINAL: sys/sys/queue.h */

/*	$OpenBSD: queue.h,v 1.25 2004/04/08 16:08:21 henning Exp $	*/
/*	$NetBSD: queue.h,v 1.11 1996/05/16 05:17:14 mycroft Exp $	*/

/*
 * Copyright (c) 1991, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	@(#)queue.h	8.5 (Berkeley) 8/20/94
 */

#ifndef	_SYS_QUEUE_H_
#define	_SYS_QUEUE_H_

/*
 * This file defines five types of data structures: singly-linked lists, 
 * lists, simple queues, tail queues, and circular queues.
 *
 *
 * A singly-linked list is headed by a single forward pointer. The elements
 * are singly linked for minimum space and pointer manipulation overhead at
 * the expense of O(n) removal for arbitrary elements. New elements can be
 * added to the list after an existing element or at the head of the list.
 * Elements being removed from the head of the list should use the explicit
 * macro for this purpose for optimum efficiency. A singly-linked list may
 * only be traversed in the forward direction.  Singly-linked lists are ideal
 * for applications with large datasets and few or no removals or for
 * implementing a LIFO queue.
 *
 * A list is headed by a single forward pointer (or an array of forward
 * pointers for a hash table header). The elements are doubly linked
 * so that an arbitrary element can be removed without a need to
 * traverse the list. New elements can be added to the list before
 * or after an existing element or at the head of the list. A list
 * may only be traversed in the forward direction.
 *
 * A simple queue is headed by a pair of pointers, one the head of the
 * list and the other to the tail of the list. The elements are singly
 * linked to save space, so elements can only be removed from the
 * head of the list. New elements can be added to the list before or after
 * an existing element, at the head of the list, or at the end of the
 * list. A simple queue may only be traversed in the forward direction.
 *
 * A tail queue is headed by a pair of pointers, one to the head of the
 * list and the other to the tail of the list. The elements are doubly
 * linked so that an arbitrary element can be removed without a need to
 * traverse the list. New elements can be added to the list before or
 * after an existing element, at the head of the list, or at the end of
 * the list. A tail queue may be traversed in either direction.
 *
 * A circle queue is headed by a pair of pointers, one to the head of the
 * list and the other to the tail of the list. The elements are doubly
 * linked so that an arbitrary element can be removed without a need to
 * traverse the list. New elements can be added to the list before or after
 * an existing element, at the head of the list, or at the end of the list.
 * A circle queue may be traversed in either direction, but has a more
 * complex end of list detection.
 *
 * For details on the use of these macros, see the queue(3) manual page.
 */

/*
 * Singly-linked List definitions.
 */
#define SLIST_HEAD(name, type)						\
struct name {								\
	struct type *slh_first;	/* first element */			\
}
 
#define	SLIST_HEAD_INITIALIZER(head)					\
	{ NULL }
 
#define SLIST_ENTRY(type)						\
struct {								\
	struct type *sle_next;	/* next element */			\
}
 
/*
 * Singly-linked List access methods.
 */
#define	SLIST_FIRST(head)	((head)->slh_first)
#define	SLIST_END(head)		NULL
#define	SLIST_EMPTY(head)	(SLIST_FIRST(head) == SLIST_END(head))
#define	SLIST_NEXT(elm, field)	((elm)->field.sle_next)

#define	SLIST_FOREACH(var, head, field)					\
	for((var) = SLIST_FIRST(head);					\
	    (var) != SLIST_END(head);					\
	    (var) = SLIST_NEXT(var, field))

#define	SLIST_FOREACH_PREVPTR(var, varp, head, field)			\
	for ((varp) = &SLIST_FIRST((head));				\
	    ((var) = *(varp)) != SLIST_END(head);			\
	    (varp) = &SLIST_NEXT((var), field))

/*
 * Singly-linked List functions.
 */
#define	SLIST_INIT(head) {						\
	SLIST_FIRST(head) = SLIST_END(head);				\
}

#define	SLIST_INSERT_AFTER(slistelm, elm, field) do {			\
	(elm)->field.sle_next = (slistelm)->field.sle_next;		\
	(slistelm)->field.sle_next = (elm);				\
} while (0)

#define	SLIST_INSERT_HEAD(head, elm, field) do {			\
	(elm)->field.sle_next = (head)->slh_first;			\
	(head)->slh_first = (elm);					\
} while (0)

#define	SLIST_REMOVE_NEXT(head, elm, field) do {			\
	(elm)->field.sle_next = (elm)->field.sle_next->field.sle_next;	\
} while (0)

#define	SLIST_REMOVE_HEAD(head, field) do {				\
	(head)->slh_first = (head)->slh_first->field.sle_next;		\
} while (0)

#define SLIST_REMOVE(head, elm, type, field) do {			\
	if ((head)->slh_first == (elm)) {				\
		SLIST_REMOVE_HEAD((head), field);			\
	}								\
	else {								\
		struct type *curelm = (head)->slh_first;		\
		while( curelm->field.sle_next != (elm) )		\
			curelm = curelm->field.sle_next;		\
		curelm->field.sle_next =				\
		    curelm->field.sle_next->field.sle_next;		\
	}								\
} while (0)

/*
 * List definitions.
 */
#define LIST_HEAD(name, type)						\
struct name {								\
	struct type *lh_first;	/* first element */			\
}

#define LIST_HEAD_INITIALIZER(head)					\
	{ NULL }

#define LIST_ENTRY(type)						\
struct {								\
	struct type *le_next;	/* next element */			\
	struct type **le_prev;	/* address of previous next element */	\
}

/*
 * List access methods
 */
#define	LIST_FIRST(head)		((head)->lh_first)
#define	LIST_END(head)			NULL
#define	LIST_EMPTY(head)		(LIST_FIRST(head) == LIST_END(head))
#define	LIST_NEXT(elm, field)		((elm)->field.le_next)

#define LIST_FOREACH(var, head, field)					\
	for((var) = LIST_FIRST(head);					\
	    (var)!= LIST_END(head);					\
	    (var) = LIST_NEXT(var, field))

/*
 * List functions.
 */
#define	LIST_INIT(head) do {						\
	LIST_FIRST(head) = LIST_END(head);				\
} while (0)

#define LIST_INSERT_AFTER(listelm, elm, field) do {			\
	if (((elm)->field.le_next = (listelm)->field.le_next) != NULL)	\
		(listelm)->field.le_next->field.le_prev =		\
		    &(elm)->field.le_next;				\
	(listelm)->field.le_next = (elm);				\
	(elm)->field.le_prev = &(listelm)->field.le_next;		\
} while (0)

#define	LIST_INSERT_BEFORE(listelm, elm, field) do {			\
	(elm)->field.le_prev = (listelm)->field.le_prev;		\
	(elm)->field.le_next = (listelm);				\
	*(listelm)->field.le_prev = (elm);				\
	(listelm)->field.le_prev = &(elm)->field.le_next;		\
} while (0)

#define LIST_INSERT_HEAD(head, elm, field) do {				\
	if (((elm)->field.le_next = (head)->lh_first) != NULL)		\
		(head)->lh_first->field.le_prev = &(elm)->field.le_next;\
	(head)->lh_first = (elm);					\
	(elm)->field.le_prev = &(head)->lh_first;			\
} while (0)

#define LIST_REMOVE(elm, field) do {					\
	if ((elm)->field.le_next != NULL)				\
		(elm)->field.le_next->field.le_prev =			\
		    (elm)->field.le_prev;				\
	*(elm)->field.le_prev = (elm)->field.le_next;			\
} while (0)

#define LIST_REPLACE(elm, elm2, field) do {				\
	if (((elm2)->field.le_next = (elm)->field.le_next) != NULL)	\
		(elm2)->field.le_next->field.le_prev =			\
		    &(elm2)->field.le_next;				\
	(elm2)->field.le_prev = (elm)->field.le_prev;			\
	*(elm2)->field.le_prev = (elm2);				\
} while (0)

/*
 * Simple queue definitions.
 */
#define SIMPLEQ_HEAD(name, type)					\
struct name {								\
	struct type *sqh_first;	/* first element */			\
	struct type **sqh_last;	/* addr of last next element */		\
}

#define SIMPLEQ_HEAD_INITIALIZER(head)					\
	{ NULL, &(head).sqh_first }

#define SIMPLEQ_ENTRY(type)						\
struct {								\
	struct type *sqe_next;	/* next element */			\
}

/*
 * Simple queue access methods.
 */
#define	SIMPLEQ_FIRST(head)	    ((head)->sqh_first)
#define	SIMPLEQ_END(head)	    NULL
#define	SIMPLEQ_EMPTY(head)	    (SIMPLEQ_FIRST(head) == SIMPLEQ_END(head))
#define	SIMPLEQ_NEXT(elm, field)    ((elm)->field.sqe_next)

#define SIMPLEQ_FOREACH(var, head, field)				\
	for((var) = SIMPLEQ_FIRST(head);				\
	    (var) != SIMPLEQ_END(head);					\
	    (var) = SIMPLEQ_NEXT(var, field))

/*
 * Simple queue functions.
 */
#define	SIMPLEQ_INIT(head) do {						\
	(head)->sqh_first = NULL;					\
	(head)->sqh_last = &(head)->sqh_first;				\
} while (0)

#define SIMPLEQ_INSERT_HEAD(head, elm, field) do {			\
	if (((elm)->field.sqe_next = (head)->sqh_first) == NULL)	\
		(head)->sqh_last = &(elm)->field.sqe_next;		\
	(head)->sqh_first = (elm);					\
} while (0)

#define SIMPLEQ_INSERT_TAIL(head, elm, field) do {			\
	(elm)->field.sqe_next = NULL;					\
	*(head)->sqh_last = (elm);					\
	(head)->sqh_last = &(elm)->field.sqe_next;			\
} while (0)

#define SIMPLEQ_INSERT_AFTER(head, listelm, elm, field) do {		\
	if (((elm)->field.sqe_next = (listelm)->field.sqe_next) == NULL)\
		(head)->sqh_last = &(elm)->field.sqe_next;		\
	(listelm)->field.sqe_next = (elm);				\
} while (0)

#define SIMPLEQ_REMOVE_HEAD(head, elm, field) do {			\
	if (((head)->sqh_first = (elm)->field.sqe_next) == NULL)	\
		(head)->sqh_last = &(head)->sqh_first;			\
} while (0)

/*
 * Tail queue definitions.
 */
#define TAILQ_HEAD(name, type)						\
struct name {								\
	struct type *tqh_first;	/* first element */			\
	struct type **tqh_last;	/* addr of last next element */		\
}

#define TAILQ_HEAD_INITIALIZER(head)					\
	{ NULL, &(head).tqh_first }

#define TAILQ_ENTRY(type)						\
struct {								\
	struct type *tqe_next;	/* next element */			\
	struct type **tqe_prev;	/* address of previous next element */	\
}

/* 
 * tail queue access methods 
 */
#define	TAILQ_FIRST(head)		((head)->tqh_first)
#define	TAILQ_END(head)			NULL
#define	TAILQ_NEXT(elm, field)		((elm)->field.tqe_next)
#define TAILQ_LAST(head, headname)					\
	(*(((struct headname *)((head)->tqh_last))->tqh_last))
/* XXX */
#define TAILQ_PREV(elm, headname, field)				\
	(*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
#define	TAILQ_EMPTY(head)						\
	(TAILQ_FIRST(head) == TAILQ_END(head))

#define TAILQ_FOREACH(var, head, field)					\
	for((var) = TAILQ_FIRST(head);					\
	    (var) != TAILQ_END(head);					\
	    (var) = TAILQ_NEXT(var, field))

#define TAILQ_FOREACH_REVERSE(var, head, headname, field)		\
	for((var) = TAILQ_LAST(head, headname);				\
	    (var) != TAILQ_END(head);					\
	    (var) = TAILQ_PREV(var, headname, field))

/*
 * Tail queue functions.
 */
#define	TAILQ_INIT(head) do {						\
	(head)->tqh_first = NULL;					\
	(head)->tqh_last = &(head)->tqh_first;				\
} while (0)

#define TAILQ_INSERT_HEAD(head, elm, field) do {			\
	if (((elm)->field.tqe_next = (head)->tqh_first) != NULL)	\
		(head)->tqh_first->field.tqe_prev =			\
		    &(elm)->field.tqe_next;				\
	else								\
		(head)->tqh_last = &(elm)->field.tqe_next;		\
	(head)->tqh_first = (elm);					\
	(elm)->field.tqe_prev = &(head)->tqh_first;			\
} while (0)

#define TAILQ_INSERT_TAIL(head, elm, field) do {			\
	(elm)->field.tqe_next = NULL;					\
	(elm)->field.tqe_prev = (head)->tqh_last;			\
	*(head)->tqh_last = (elm);					\
	(head)->tqh_last = &(elm)->field.tqe_next;			\
} while (0)

#define TAILQ_INSERT_AFTER(head, listelm, elm, field) do {		\
	if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\
		(elm)->field.tqe_next->field.tqe_prev =			\
		    &(elm)->field.tqe_next;				\
	else								\
		(head)->tqh_last = &(elm)->field.tqe_next;		\
	(listelm)->field.tqe_next = (elm);				\
	(elm)->field.tqe_prev = &(listelm)->field.tqe_next;		\
} while (0)

#define	TAILQ_INSERT_BEFORE(listelm, elm, field) do {			\
	(elm)->field.tqe_prev = (listelm)->field.tqe_prev;		\
	(elm)->field.tqe_next = (listelm);				\
	*(listelm)->field.tqe_prev = (elm);				\
	(listelm)->field.tqe_prev = &(elm)->field.tqe_next;		\
} while (0)

#define TAILQ_REMOVE(head, elm, field) do {				\
	if (((elm)->field.tqe_next) != NULL)				\
		(elm)->field.tqe_next->field.tqe_prev =			\
		    (elm)->field.tqe_prev;				\
	else								\
		(head)->tqh_last = (elm)->field.tqe_prev;		\
	*(elm)->field.tqe_prev = (elm)->field.tqe_next;			\
} while (0)

#define TAILQ_REPLACE(head, elm, elm2, field) do {			\
	if (((elm2)->field.tqe_next = (elm)->field.tqe_next) != NULL)	\
		(elm2)->field.tqe_next->field.tqe_prev =		\
		    &(elm2)->field.tqe_next;				\
	else								\
		(head)->tqh_last = &(elm2)->field.tqe_next;		\
	(elm2)->field.tqe_prev = (elm)->field.tqe_prev;			\
	*(elm2)->field.tqe_prev = (elm2);				\
} while (0)

/*
 * Circular queue definitions.
 */
#define CIRCLEQ_HEAD(name, type)					\
struct name {								\
	struct type *cqh_first;		/* first element */		\
	struct type *cqh_last;		/* last element */		\
}

#define CIRCLEQ_HEAD_INITIALIZER(head)					\
	{ CIRCLEQ_END(&head), CIRCLEQ_END(&head) }

#define CIRCLEQ_ENTRY(type)						\
struct {								\
	struct type *cqe_next;		/* next element */		\
	struct type *cqe_prev;		/* previous element */		\
}

/*
 * Circular queue access methods 
 */
#define	CIRCLEQ_FIRST(head)		((head)->cqh_first)
#define	CIRCLEQ_LAST(head)		((head)->cqh_last)
#define	CIRCLEQ_END(head)		((void *)(head))
#define	CIRCLEQ_NEXT(elm, field)	((elm)->field.cqe_next)
#define	CIRCLEQ_PREV(elm, field)	((elm)->field.cqe_prev)
#define	CIRCLEQ_EMPTY(head)						\
	(CIRCLEQ_FIRST(head) == CIRCLEQ_END(head))

#define CIRCLEQ_FOREACH(var, head, field)				\
	for((var) = CIRCLEQ_FIRST(head);				\
	    (var) != CIRCLEQ_END(head);					\
	    (var) = CIRCLEQ_NEXT(var, field))

#define CIRCLEQ_FOREACH_REVERSE(var, head, field)			\
	for((var) = CIRCLEQ_LAST(head);					\
	    (var) != CIRCLEQ_END(head);					\
	    (var) = CIRCLEQ_PREV(var, field))

/*
 * Circular queue functions.
 */
#define	CIRCLEQ_INIT(head) do {						\
	(head)->cqh_first = CIRCLEQ_END(head);				\
	(head)->cqh_last = CIRCLEQ_END(head);				\
} while (0)

#define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) do {		\
	(elm)->field.cqe_next = (listelm)->field.cqe_next;		\
	(elm)->field.cqe_prev = (listelm);				\
	if ((listelm)->field.cqe_next == CIRCLEQ_END(head))		\
		(head)->cqh_last = (elm);				\
	else								\
		(listelm)->field.cqe_next->field.cqe_prev = (elm);	\
	(listelm)->field.cqe_next = (elm);				\
} while (0)

#define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) do {		\
	(elm)->field.cqe_next = (listelm);				\
	(elm)->field.cqe_prev = (listelm)->field.cqe_prev;		\
	if ((listelm)->field.cqe_prev == CIRCLEQ_END(head))		\
		(head)->cqh_first = (elm);				\
	else								\
		(listelm)->field.cqe_prev->field.cqe_next = (elm);	\
	(listelm)->field.cqe_prev = (elm);				\
} while (0)

#define CIRCLEQ_INSERT_HEAD(head, elm, field) do {			\
	(elm)->field.cqe_next = (head)->cqh_first;			\
	(elm)->field.cqe_prev = CIRCLEQ_END(head);			\
	if ((head)->cqh_last == CIRCLEQ_END(head))			\
		(head)->cqh_last = (elm);				\
	else								\
		(head)->cqh_first->field.cqe_prev = (elm);		\
	(head)->cqh_first = (elm);					\
} while (0)

#define CIRCLEQ_INSERT_TAIL(head, elm, field) do {			\
	(elm)->field.cqe_next = CIRCLEQ_END(head);			\
	(elm)->field.cqe_prev = (head)->cqh_last;			\
	if ((head)->cqh_first == CIRCLEQ_END(head))			\
		(head)->cqh_first = (elm);				\
	else								\
		(head)->cqh_last->field.cqe_next = (elm);		\
	(head)->cqh_last = (elm);					\
} while (0)

#define	CIRCLEQ_REMOVE(head, elm, field) do {				\
	if ((elm)->field.cqe_next == CIRCLEQ_END(head))			\
		(head)->cqh_last = (elm)->field.cqe_prev;		\
	else								\
		(elm)->field.cqe_next->field.cqe_prev =			\
		    (elm)->field.cqe_prev;				\
	if ((elm)->field.cqe_prev == CIRCLEQ_END(head))			\
		(head)->cqh_first = (elm)->field.cqe_next;		\
	else								\
		(elm)->field.cqe_prev->field.cqe_next =			\
		    (elm)->field.cqe_next;				\
} while (0)

#define CIRCLEQ_REPLACE(head, elm, elm2, field) do {			\
	if (((elm2)->field.cqe_next = (elm)->field.cqe_next) ==		\
	    CIRCLEQ_END(head))						\
		(head).cqh_last = (elm2);				\
	else								\
		(elm2)->field.cqe_next->field.cqe_prev = (elm2);	\
	if (((elm2)->field.cqe_prev = (elm)->field.cqe_prev) ==		\
	    CIRCLEQ_END(head))						\
		(head).cqh_first = (elm2);				\
	else								\
		(elm2)->field.cqe_prev->field.cqe_next = (elm2);	\
} while (0)

#endif	/* !_SYS_QUEUE_H_ */
Commit	Line	Data
d74671e4	1	/* OPENBSD ORIGINAL: sys/sys/queue.h */
d74671e4	2
22ca4f57	3	/* $OpenBSD: queue.h,v 1.25 2004/04/08 16:08:21 henning Exp $ */
bf5f69f7	4	/* $NetBSD: queue.h,v 1.11 1996/05/16 05:17:14 mycroft Exp $ */
	5
	6	/*
	7	* Copyright (c) 1991, 1993
	8	* The Regents of the University of California. All rights reserved.
	9	*
	10	* Redistribution and use in source and binary forms, with or without
	11	* modification, are permitted provided that the following conditions
	12	* are met:
	13	* 1. Redistributions of source code must retain the above copyright
	14	* notice, this list of conditions and the following disclaimer.
	15	* 2. Redistributions in binary form must reproduce the above copyright
	16	* notice, this list of conditions and the following disclaimer in the
	17	* documentation and/or other materials provided with the distribution.
3e67f7df	18	* 3. Neither the name of the University nor the names of its contributors
bf5f69f7	19	* may be used to endorse or promote products derived from this software
	20	* without specific prior written permission.
	21	*
	22	* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	23	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	24	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	25	* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	26	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	27	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	28	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	29	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	30	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	31	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	32	* SUCH DAMAGE.
	33	*
	34	* @(#)queue.h 8.5 (Berkeley) 8/20/94
	35	*/
	36
22ca4f57	37	#ifndef _SYS_QUEUE_H_
22ca4f57	38	#define _SYS_QUEUE_H_
bf5f69f7	39
	40	/*
	41	* This file defines five types of data structures: singly-linked lists,
	42	* lists, simple queues, tail queues, and circular queues.
	43	*
	44	*
	45	* A singly-linked list is headed by a single forward pointer. The elements
	46	* are singly linked for minimum space and pointer manipulation overhead at
	47	* the expense of O(n) removal for arbitrary elements. New elements can be
	48	* added to the list after an existing element or at the head of the list.
	49	* Elements being removed from the head of the list should use the explicit
	50	* macro for this purpose for optimum efficiency. A singly-linked list may
	51	* only be traversed in the forward direction. Singly-linked lists are ideal
	52	* for applications with large datasets and few or no removals or for
	53	* implementing a LIFO queue.
	54	*
	55	* A list is headed by a single forward pointer (or an array of forward
	56	* pointers for a hash table header). The elements are doubly linked
	57	* so that an arbitrary element can be removed without a need to
	58	* traverse the list. New elements can be added to the list before
	59	* or after an existing element or at the head of the list. A list
	60	* may only be traversed in the forward direction.
	61	*
	62	* A simple queue is headed by a pair of pointers, one the head of the
	63	* list and the other to the tail of the list. The elements are singly
	64	* linked to save space, so elements can only be removed from the
	65	* head of the list. New elements can be added to the list before or after
	66	* an existing element, at the head of the list, or at the end of the
	67	* list. A simple queue may only be traversed in the forward direction.
	68	*
	69	* A tail queue is headed by a pair of pointers, one to the head of the
	70	* list and the other to the tail of the list. The elements are doubly
	71	* linked so that an arbitrary element can be removed without a need to
	72	* traverse the list. New elements can be added to the list before or
	73	* after an existing element, at the head of the list, or at the end of
	74	* the list. A tail queue may be traversed in either direction.
	75	*
	76	* A circle queue is headed by a pair of pointers, one to the head of the
	77	* list and the other to the tail of the list. The elements are doubly
	78	* linked so that an arbitrary element can be removed without a need to
	79	* traverse the list. New elements can be added to the list before or after
	80	* an existing element, at the head of the list, or at the end of the list.
	81	* A circle queue may be traversed in either direction, but has a more
	82	* complex end of list detection.
	83	*
	84	* For details on the use of these macros, see the queue(3) manual page.
	85	*/
	86
	87	/*
	88	* Singly-linked List definitions.
	89	*/
	90	#define SLIST_HEAD(name, type) \
	91	struct name { \
	92	struct type slh_first; / first element */ \
	93	}
	94
	95	#define SLIST_HEAD_INITIALIZER(head) \
	96	{ NULL }
	97
	98	#define SLIST_ENTRY(type) \
	99	struct { \
	100	struct type sle_next; / next element */ \
	101	}
	102
103	/*
104	* Singly-linked List access methods.
105	*/
106	#define SLIST_FIRST(head) ((head)->slh_first)
107	#define SLIST_END(head) NULL
108	#define SLIST_EMPTY(head) (SLIST_FIRST(head) == SLIST_END(head))
109	#define SLIST_NEXT(elm, field) ((elm)->field.sle_next)
110
111	#define SLIST_FOREACH(var, head, field) \
112	for((var) = SLIST_FIRST(head); \
113	(var) != SLIST_END(head); \
114	(var) = SLIST_NEXT(var, field))
115
22ca4f57	116	#define SLIST_FOREACH_PREVPTR(var, varp, head, field) \
	117	for ((varp) = &SLIST_FIRST((head)); \
	118	((var) = *(varp)) != SLIST_END(head); \
	119	(varp) = &SLIST_NEXT((var), field))
	120
bf5f69f7	121	/*
	122	* Singly-linked List functions.
	123	*/
	124	#define SLIST_INIT(head) { \
	125	SLIST_FIRST(head) = SLIST_END(head); \
	126	}
	127
	128	#define SLIST_INSERT_AFTER(slistelm, elm, field) do { \
	129	(elm)->field.sle_next = (slistelm)->field.sle_next; \
	130	(slistelm)->field.sle_next = (elm); \
	131	} while (0)
	132
	133	#define SLIST_INSERT_HEAD(head, elm, field) do { \
	134	(elm)->field.sle_next = (head)->slh_first; \
	135	(head)->slh_first = (elm); \
	136	} while (0)
	137
22ca4f57	138	#define SLIST_REMOVE_NEXT(head, elm, field) do { \
	139	(elm)->field.sle_next = (elm)->field.sle_next->field.sle_next; \
	140	} while (0)
	141
bf5f69f7	142	#define SLIST_REMOVE_HEAD(head, field) do { \
	143	(head)->slh_first = (head)->slh_first->field.sle_next; \
	144	} while (0)
	145
1656cbed	146	#define SLIST_REMOVE(head, elm, type, field) do { \
	147	if ((head)->slh_first == (elm)) { \
	148	SLIST_REMOVE_HEAD((head), field); \
	149	} \
	150	else { \
	151	struct type *curelm = (head)->slh_first; \
	152	while( curelm->field.sle_next != (elm) ) \
	153	curelm = curelm->field.sle_next; \
	154	curelm->field.sle_next = \
	155	curelm->field.sle_next->field.sle_next; \
	156	} \
	157	} while (0)
	158
bf5f69f7	159	/*
	160	* List definitions.
	161	*/
	162	#define LIST_HEAD(name, type) \
	163	struct name { \
	164	struct type lh_first; / first element */ \
	165	}
	166
	167	#define LIST_HEAD_INITIALIZER(head) \
	168	{ NULL }
	169
	170	#define LIST_ENTRY(type) \
	171	struct { \
	172	struct type le_next; / next element */ \
	173	struct type *le_prev; / address of previous next element */ \
	174	}
	175
	176	/*
	177	* List access methods
	178	*/
	179	#define LIST_FIRST(head) ((head)->lh_first)
	180	#define LIST_END(head) NULL
	181	#define LIST_EMPTY(head) (LIST_FIRST(head) == LIST_END(head))
	182	#define LIST_NEXT(elm, field) ((elm)->field.le_next)
	183
	184	#define LIST_FOREACH(var, head, field) \
	185	for((var) = LIST_FIRST(head); \
	186	(var)!= LIST_END(head); \
	187	(var) = LIST_NEXT(var, field))
	188
	189	/*
	190	* List functions.
	191	*/
	192	#define LIST_INIT(head) do { \
	193	LIST_FIRST(head) = LIST_END(head); \
	194	} while (0)
	195
	196	#define LIST_INSERT_AFTER(listelm, elm, field) do { \
	197	if (((elm)->field.le_next = (listelm)->field.le_next) != NULL) \
	198	(listelm)->field.le_next->field.le_prev = \
	199	&(elm)->field.le_next; \
	200	(listelm)->field.le_next = (elm); \
	201	(elm)->field.le_prev = &(listelm)->field.le_next; \
	202	} while (0)
	203
	204	#define LIST_INSERT_BEFORE(listelm, elm, field) do { \
	205	(elm)->field.le_prev = (listelm)->field.le_prev; \
	206	(elm)->field.le_next = (listelm); \
	207	*(listelm)->field.le_prev = (elm); \
	208	(listelm)->field.le_prev = &(elm)->field.le_next; \
	209	} while (0)
	210
	211	#define LIST_INSERT_HEAD(head, elm, field) do { \
	212	if (((elm)->field.le_next = (head)->lh_first) != NULL) \
	213	(head)->lh_first->field.le_prev = &(elm)->field.le_next;\
	214	(head)->lh_first = (elm); \
	215	(elm)->field.le_prev = &(head)->lh_first; \
	216	} while (0)
	217
	218	#define LIST_REMOVE(elm, field) do { \
	219	if ((elm)->field.le_next != NULL) \
	220	(elm)->field.le_next->field.le_prev = \
	221	(elm)->field.le_prev; \
	222	*(elm)->field.le_prev = (elm)->field.le_next; \
223	} while (0)
224
225	#define LIST_REPLACE(elm, elm2, field) do { \
226	if (((elm2)->field.le_next = (elm)->field.le_next) != NULL) \
227	(elm2)->field.le_next->field.le_prev = \
228	&(elm2)->field.le_next; \
229	(elm2)->field.le_prev = (elm)->field.le_prev; \
230	*(elm2)->field.le_prev = (elm2); \
231	} while (0)
232
233	/*
234	* Simple queue definitions.
235	*/
236	#define SIMPLEQ_HEAD(name, type) \
237	struct name { \
238	struct type sqh_first; / first element */ \
239	struct type *sqh_last; / addr of last next element */ \
240	}
241
242	#define SIMPLEQ_HEAD_INITIALIZER(head) \
243	{ NULL, &(head).sqh_first }
244
245	#define SIMPLEQ_ENTRY(type) \
246	struct { \
247	struct type sqe_next; / next element */ \
248	}
249
250	/*
251	* Simple queue access methods.
252	*/
253	#define SIMPLEQ_FIRST(head) ((head)->sqh_first)
254	#define SIMPLEQ_END(head) NULL
255	#define SIMPLEQ_EMPTY(head) (SIMPLEQ_FIRST(head) == SIMPLEQ_END(head))
256	#define SIMPLEQ_NEXT(elm, field) ((elm)->field.sqe_next)
257
258	#define SIMPLEQ_FOREACH(var, head, field) \
259	for((var) = SIMPLEQ_FIRST(head); \
260	(var) != SIMPLEQ_END(head); \
261	(var) = SIMPLEQ_NEXT(var, field))
262
263	/*
264	* Simple queue functions.
265	*/
266	#define SIMPLEQ_INIT(head) do { \
267	(head)->sqh_first = NULL; \
268	(head)->sqh_last = &(head)->sqh_first; \
269	} while (0)
270
271	#define SIMPLEQ_INSERT_HEAD(head, elm, field) do { \
272	if (((elm)->field.sqe_next = (head)->sqh_first) == NULL) \
273	(head)->sqh_last = &(elm)->field.sqe_next; \
274	(head)->sqh_first = (elm); \
275	} while (0)
276
277	#define SIMPLEQ_INSERT_TAIL(head, elm, field) do { \
278	(elm)->field.sqe_next = NULL; \
279	*(head)->sqh_last = (elm); \
280	(head)->sqh_last = &(elm)->field.sqe_next; \
281	} while (0)
282
283	#define SIMPLEQ_INSERT_AFTER(head, listelm, elm, field) do { \
284	if (((elm)->field.sqe_next = (listelm)->field.sqe_next) == NULL)\
285	(head)->sqh_last = &(elm)->field.sqe_next; \
286	(listelm)->field.sqe_next = (elm); \
287	} while (0)
288
289	#define SIMPLEQ_REMOVE_HEAD(head, elm, field) do { \
290	if (((head)->sqh_first = (elm)->field.sqe_next) == NULL) \
291	(head)->sqh_last = &(head)->sqh_first; \
292	} while (0)
293
294	/*
295	* Tail queue definitions.
296	*/
297	#define TAILQ_HEAD(name, type) \
298	struct name { \
299	struct type tqh_first; / first element */ \
300	struct type *tqh_last; / addr of last next element */ \
301	}
302
303	#define TAILQ_HEAD_INITIALIZER(head) \
304	{ NULL, &(head).tqh_first }
305
306	#define TAILQ_ENTRY(type) \
307	struct { \
308	struct type tqe_next; / next element */ \
309	struct type *tqe_prev; / address of previous next element */ \
310	}
311
312	/*
313	* tail queue access methods
314	*/
315	#define TAILQ_FIRST(head) ((head)->tqh_first)
316	#define TAILQ_END(head) NULL
317	#define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
318	#define TAILQ_LAST(head, headname) \
319	((((struct headname )((head)->tqh_last))->tqh_last))
320	/* XXX */
321	#define TAILQ_PREV(elm, headname, field) \
322	((((struct headname )((elm)->field.tqe_prev))->tqh_last))
323	#define TAILQ_EMPTY(head) \
324	(TAILQ_FIRST(head) == TAILQ_END(head))
325
326	#define TAILQ_FOREACH(var, head, field) \
327	for((var) = TAILQ_FIRST(head); \
328	(var) != TAILQ_END(head); \
329	(var) = TAILQ_NEXT(var, field))
330
22ca4f57	331	#define TAILQ_FOREACH_REVERSE(var, head, headname, field) \
bf5f69f7	332	for((var) = TAILQ_LAST(head, headname); \
	333	(var) != TAILQ_END(head); \
	334	(var) = TAILQ_PREV(var, headname, field))
	335
	336	/*
	337	* Tail queue functions.
	338	*/
	339	#define TAILQ_INIT(head) do { \
	340	(head)->tqh_first = NULL; \
	341	(head)->tqh_last = &(head)->tqh_first; \
	342	} while (0)
	343
	344	#define TAILQ_INSERT_HEAD(head, elm, field) do { \
	345	if (((elm)->field.tqe_next = (head)->tqh_first) != NULL) \
	346	(head)->tqh_first->field.tqe_prev = \
	347	&(elm)->field.tqe_next; \
	348	else \
	349	(head)->tqh_last = &(elm)->field.tqe_next; \
	350	(head)->tqh_first = (elm); \
	351	(elm)->field.tqe_prev = &(head)->tqh_first; \
	352	} while (0)
	353
	354	#define TAILQ_INSERT_TAIL(head, elm, field) do { \
	355	(elm)->field.tqe_next = NULL; \
	356	(elm)->field.tqe_prev = (head)->tqh_last; \
	357	*(head)->tqh_last = (elm); \
	358	(head)->tqh_last = &(elm)->field.tqe_next; \
	359	} while (0)
	360
	361	#define TAILQ_INSERT_AFTER(head, listelm, elm, field) do { \
	362	if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\
	363	(elm)->field.tqe_next->field.tqe_prev = \
	364	&(elm)->field.tqe_next; \
	365	else \
	366	(head)->tqh_last = &(elm)->field.tqe_next; \
	367	(listelm)->field.tqe_next = (elm); \
	368	(elm)->field.tqe_prev = &(listelm)->field.tqe_next; \
	369	} while (0)
	370
	371	#define TAILQ_INSERT_BEFORE(listelm, elm, field) do { \
	372	(elm)->field.tqe_prev = (listelm)->field.tqe_prev; \
	373	(elm)->field.tqe_next = (listelm); \
	374	*(listelm)->field.tqe_prev = (elm); \
	375	(listelm)->field.tqe_prev = &(elm)->field.tqe_next; \
	376	} while (0)
	377
	378	#define TAILQ_REMOVE(head, elm, field) do { \
	379	if (((elm)->field.tqe_next) != NULL) \
	380	(elm)->field.tqe_next->field.tqe_prev = \
	381	(elm)->field.tqe_prev; \
	382	else \
	383	(head)->tqh_last = (elm)->field.tqe_prev; \
	384	*(elm)->field.tqe_prev = (elm)->field.tqe_next; \
	385	} while (0)
	386
	387	#define TAILQ_REPLACE(head, elm, elm2, field) do { \
	388	if (((elm2)->field.tqe_next = (elm)->field.tqe_next) != NULL) \
	389	(elm2)->field.tqe_next->field.tqe_prev = \
	390	&(elm2)->field.tqe_next; \
	391	else \
	392	(head)->tqh_last = &(elm2)->field.tqe_next; \
	393	(elm2)->field.tqe_prev = (elm)->field.tqe_prev; \
	394	*(elm2)->field.tqe_prev = (elm2); \
	395	} while (0)
396
397	/*
398	* Circular queue definitions.
399	*/
400	#define CIRCLEQ_HEAD(name, type) \
401	struct name { \
402	struct type cqh_first; / first element */ \
403	struct type cqh_last; / last element */ \
404	}
405
406	#define CIRCLEQ_HEAD_INITIALIZER(head) \
407	{ CIRCLEQ_END(&head), CIRCLEQ_END(&head) }
408
409	#define CIRCLEQ_ENTRY(type) \
410	struct { \
411	struct type cqe_next; / next element */ \
412	struct type cqe_prev; / previous element */ \
413	}
414
415	/*
416	* Circular queue access methods
417	*/
418	#define CIRCLEQ_FIRST(head) ((head)->cqh_first)
419	#define CIRCLEQ_LAST(head) ((head)->cqh_last)
420	#define CIRCLEQ_END(head) ((void *)(head))
421	#define CIRCLEQ_NEXT(elm, field) ((elm)->field.cqe_next)
422	#define CIRCLEQ_PREV(elm, field) ((elm)->field.cqe_prev)
423	#define CIRCLEQ_EMPTY(head) \
424	(CIRCLEQ_FIRST(head) == CIRCLEQ_END(head))
425
426	#define CIRCLEQ_FOREACH(var, head, field) \
427	for((var) = CIRCLEQ_FIRST(head); \
428	(var) != CIRCLEQ_END(head); \
429	(var) = CIRCLEQ_NEXT(var, field))
430
431	#define CIRCLEQ_FOREACH_REVERSE(var, head, field) \
432	for((var) = CIRCLEQ_LAST(head); \
433	(var) != CIRCLEQ_END(head); \
434	(var) = CIRCLEQ_PREV(var, field))
435
436	/*
437	* Circular queue functions.
438	*/
439	#define CIRCLEQ_INIT(head) do { \
440	(head)->cqh_first = CIRCLEQ_END(head); \
441	(head)->cqh_last = CIRCLEQ_END(head); \
442	} while (0)
443
444	#define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) do { \
445	(elm)->field.cqe_next = (listelm)->field.cqe_next; \
446	(elm)->field.cqe_prev = (listelm); \
447	if ((listelm)->field.cqe_next == CIRCLEQ_END(head)) \
448	(head)->cqh_last = (elm); \
449	else \
450	(listelm)->field.cqe_next->field.cqe_prev = (elm); \
451	(listelm)->field.cqe_next = (elm); \
452	} while (0)
453
454	#define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) do { \
455	(elm)->field.cqe_next = (listelm); \
456	(elm)->field.cqe_prev = (listelm)->field.cqe_prev; \
457	if ((listelm)->field.cqe_prev == CIRCLEQ_END(head)) \
458	(head)->cqh_first = (elm); \
459	else \
460	(listelm)->field.cqe_prev->field.cqe_next = (elm); \
461	(listelm)->field.cqe_prev = (elm); \
462	} while (0)
463
464	#define CIRCLEQ_INSERT_HEAD(head, elm, field) do { \
465	(elm)->field.cqe_next = (head)->cqh_first; \
466	(elm)->field.cqe_prev = CIRCLEQ_END(head); \
467	if ((head)->cqh_last == CIRCLEQ_END(head)) \
468	(head)->cqh_last = (elm); \
469	else \
470	(head)->cqh_first->field.cqe_prev = (elm); \
471	(head)->cqh_first = (elm); \
472	} while (0)
473
474	#define CIRCLEQ_INSERT_TAIL(head, elm, field) do { \
475	(elm)->field.cqe_next = CIRCLEQ_END(head); \
476	(elm)->field.cqe_prev = (head)->cqh_last; \
477	if ((head)->cqh_first == CIRCLEQ_END(head)) \
478	(head)->cqh_first = (elm); \
479	else \
480	(head)->cqh_last->field.cqe_next = (elm); \
481	(head)->cqh_last = (elm); \
482	} while (0)
483
484	#define CIRCLEQ_REMOVE(head, elm, field) do { \
485	if ((elm)->field.cqe_next == CIRCLEQ_END(head)) \
486	(head)->cqh_last = (elm)->field.cqe_prev; \
487	else \
488	(elm)->field.cqe_next->field.cqe_prev = \
489	(elm)->field.cqe_prev; \
490	if ((elm)->field.cqe_prev == CIRCLEQ_END(head)) \
491	(head)->cqh_first = (elm)->field.cqe_next; \
492	else \
493	(elm)->field.cqe_prev->field.cqe_next = \
494	(elm)->field.cqe_next; \
495	} while (0)
496
497	#define CIRCLEQ_REPLACE(head, elm, elm2, field) do { \
498	if (((elm2)->field.cqe_next = (elm)->field.cqe_next) == \
499	CIRCLEQ_END(head)) \
500	(head).cqh_last = (elm2); \
501	else \
502	(elm2)->field.cqe_next->field.cqe_prev = (elm2); \
503	if (((elm2)->field.cqe_prev = (elm)->field.cqe_prev) == \
504	CIRCLEQ_END(head)) \
505	(head).cqh_first = (elm2); \
506	else \
507	(elm2)->field.cqe_prev->field.cqe_next = (elm2); \
508	} while (0)
509
22ca4f57	510	#endif /* !_SYS_QUEUE_H_ */