[mirror_frr.git] / lib / openbsd-queue.h

/*	$OpenBSD: queue.h,v 1.43 2015/12/28 19:38:40 millert 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 XOR simple 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 to 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.
 *
 * An XOR simple queue is used in the same way as a regular simple queue.
 * The difference is that the head structure also includes a "cookie" that
 * is XOR'd with the queue pointer (first, last or next) to generate the
 * real pointer value.
 *
 * For details on the use of these macros, see the queue(3) manual page.
 */

#if defined(QUEUE_MACRO_DEBUG) || (defined(_KERNEL) && defined(DIAGNOSTIC))
#define _Q_INVALIDATE(a) (a) = ((void *)-1)
#else
#define _Q_INVALIDATE(a)
#endif

/*
 * 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_SAFE(var, head, field, tvar)                             \
	for ((var) = SLIST_FIRST(head);                                        \
	     (var) && ((tvar) = SLIST_NEXT(var, field), 1); (var) = (tvar))

/*
 * 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_AFTER(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;        \
		}                                                              \
		_Q_INVALIDATE((elm)->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))

#define LIST_FOREACH_SAFE(var, head, field, tvar)                              \
	for ((var) = LIST_FIRST(head);                                         \
	     (var) && ((tvar) = LIST_NEXT(var, field), 1); (var) = (tvar))

/*
 * 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;                  \
		_Q_INVALIDATE((elm)->field.le_prev);                           \
		_Q_INVALIDATE((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);                               \
		_Q_INVALIDATE((elm)->field.le_prev);                           \
		_Q_INVALIDATE((elm)->field.le_next);                           \
	} 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))

#define SIMPLEQ_FOREACH_SAFE(var, head, field, tvar)                           \
	for ((var) = SIMPLEQ_FIRST(head);                                      \
	     (var) && ((tvar) = SIMPLEQ_NEXT(var, field), 1); (var) = (tvar))

/*
 * 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, field)                                       \
	do {                                                                   \
		if (((head)->sqh_first = (head)->sqh_first->field.sqe_next)    \
		    == NULL)                                                   \
			(head)->sqh_last = &(head)->sqh_first;                 \
	} while (0)

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

#define SIMPLEQ_CONCAT(head1, head2)                                           \
	do {                                                                   \
		if (!SIMPLEQ_EMPTY((head2))) {                                 \
			*(head1)->sqh_last = (head2)->sqh_first;               \
			(head1)->sqh_last = (head2)->sqh_last;                 \
			SIMPLEQ_INIT((head2));                                 \
		}                                                              \
	} while (0)

/*
 * XOR Simple queue definitions.
 */
#define XSIMPLEQ_HEAD(name, type)                                              \
	struct name {                                                          \
		struct type *sqx_first; /* first element */                    \
		struct type **sqx_last; /* addr of last next element */        \
		unsigned long sqx_cookie;                                      \
	}

#define XSIMPLEQ_ENTRY(type)                                                   \
	struct {                                                               \
		struct type *sqx_next; /* next element */                      \
	}

/*
 * XOR Simple queue access methods.
 */
#define XSIMPLEQ_XOR(head, ptr)                                                \
	((__typeof(ptr))((head)->sqx_cookie ^ (unsigned long)(ptr)))
#define	XSIMPLEQ_FIRST(head)	    XSIMPLEQ_XOR(head, ((head)->sqx_first))
#define	XSIMPLEQ_END(head)	    NULL
#define	XSIMPLEQ_EMPTY(head)	    (XSIMPLEQ_FIRST(head) == XSIMPLEQ_END(head))
#define	XSIMPLEQ_NEXT(head, elm, field)    XSIMPLEQ_XOR(head, ((elm)->field.sqx_next))

#define XSIMPLEQ_FOREACH(var, head, field)                                     \
	for ((var) = XSIMPLEQ_FIRST(head); (var) != XSIMPLEQ_END(head);        \
	     (var) = XSIMPLEQ_NEXT(head, var, field))

#define XSIMPLEQ_FOREACH_SAFE(var, head, field, tvar)                          \
	for ((var) = XSIMPLEQ_FIRST(head);                                     \
	     (var) && ((tvar) = XSIMPLEQ_NEXT(head, var, field), 1);           \
	     (var) = (tvar))

/*
 * XOR Simple queue functions.
 */
#define XSIMPLEQ_INIT(head)                                                    \
	do {                                                                   \
		arc4random_buf(&(head)->sqx_cookie,                            \
			       sizeof((head)->sqx_cookie));                    \
		(head)->sqx_first = XSIMPLEQ_XOR(head, NULL);                  \
		(head)->sqx_last = XSIMPLEQ_XOR(head, &(head)->sqx_first);     \
	} while (0)

#define XSIMPLEQ_INSERT_HEAD(head, elm, field)                                 \
	do {                                                                   \
		if (((elm)->field.sqx_next = (head)->sqx_first)                \
		    == XSIMPLEQ_XOR(head, NULL))                               \
			(head)->sqx_last =                                     \
				XSIMPLEQ_XOR(head, &(elm)->field.sqx_next);    \
		(head)->sqx_first = XSIMPLEQ_XOR(head, (elm));                 \
	} while (0)

#define XSIMPLEQ_INSERT_TAIL(head, elm, field)                                 \
	do {                                                                   \
		(elm)->field.sqx_next = XSIMPLEQ_XOR(head, NULL);              \
		*(XSIMPLEQ_XOR(head, (head)->sqx_last)) =                      \
			XSIMPLEQ_XOR(head, (elm));                             \
		(head)->sqx_last = XSIMPLEQ_XOR(head, &(elm)->field.sqx_next); \
	} while (0)

#define XSIMPLEQ_INSERT_AFTER(head, listelm, elm, field)                       \
	do {                                                                   \
		if (((elm)->field.sqx_next = (listelm)->field.sqx_next)        \
		    == XSIMPLEQ_XOR(head, NULL))                               \
			(head)->sqx_last =                                     \
				XSIMPLEQ_XOR(head, &(elm)->field.sqx_next);    \
		(listelm)->field.sqx_next = XSIMPLEQ_XOR(head, (elm));         \
	} while (0)

#define XSIMPLEQ_REMOVE_HEAD(head, field)                                      \
	do {                                                                   \
		if (((head)->sqx_first = XSIMPLEQ_XOR(head, (head)->sqx_first) \
						 ->field.sqx_next)             \
		    == XSIMPLEQ_XOR(head, NULL))                               \
			(head)->sqx_last =                                     \
				XSIMPLEQ_XOR(head, &(head)->sqx_first);        \
	} while (0)

#define XSIMPLEQ_REMOVE_AFTER(head, elm, field)                                \
	do {                                                                   \
		if (((elm)->field.sqx_next =                                   \
			     XSIMPLEQ_XOR(head, (elm)->field.sqx_next)         \
				     ->field.sqx_next)                         \
		    == XSIMPLEQ_XOR(head, NULL))                               \
			(head)->sqx_last =                                     \
				XSIMPLEQ_XOR(head, &(elm)->field.sqx_next);    \
	} 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_SAFE(var, head, field, tvar)                             \
	for ((var) = TAILQ_FIRST(head);                                        \
	     (var) != TAILQ_END(head) && ((tvar) = TAILQ_NEXT(var, field), 1); \
	     (var) = (tvar))


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

#define TAILQ_FOREACH_REVERSE_SAFE(var, head, headname, field, tvar)           \
	for ((var) = TAILQ_LAST(head, headname);                               \
	     (var) != TAILQ_END(head)                                          \
	     && ((tvar) = TAILQ_PREV(var, headname, field), 1);                \
	     (var) = (tvar))

/*
 * 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;                \
		_Q_INVALIDATE((elm)->field.tqe_prev);                          \
		_Q_INVALIDATE((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);                              \
		_Q_INVALIDATE((elm)->field.tqe_prev);                          \
		_Q_INVALIDATE((elm)->field.tqe_next);                          \
	} while (0)

#define TAILQ_CONCAT(head1, head2, field)                                      \
	do {                                                                   \
		if (!TAILQ_EMPTY(head2)) {                                     \
			*(head1)->tqh_last = (head2)->tqh_first;               \
			(head2)->tqh_first->field.tqe_prev =                   \
				(head1)->tqh_last;                             \
			(head1)->tqh_last = (head2)->tqh_last;                 \
			TAILQ_INIT((head2));                                   \
		}                                                              \
	} while (0)

#endif /* !_SYS_QUEUE_H_ */
Commit	Line	Data
8429abe0 RW	1	/* $OpenBSD: queue.h,v 1.43 2015/12/28 19:38:40 millert Exp $ */
	2	/* $NetBSD: queue.h,v 1.11 1996/05/16 05:17:14 mycroft Exp $ */
	3
	4	/*
	5	* Copyright (c) 1991, 1993
	6	* The Regents of the University of California. All rights reserved.
	7	*
	8	* Redistribution and use in source and binary forms, with or without
	9	* modification, are permitted provided that the following conditions
	10	* are met:
	11	* 1. Redistributions of source code must retain the above copyright
	12	* notice, this list of conditions and the following disclaimer.
	13	* 2. Redistributions in binary form must reproduce the above copyright
	14	* notice, this list of conditions and the following disclaimer in the
	15	* documentation and/or other materials provided with the distribution.
	16	* 3. Neither the name of the University nor the names of its contributors
	17	* may be used to endorse or promote products derived from this software
	18	* without specific prior written permission.
	19	*
	20	* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	21	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	22	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	23	* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	24	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	25	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	26	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	27	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	28	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	29	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	30	* SUCH DAMAGE.
	31	*
	32	* @(#)queue.h 8.5 (Berkeley) 8/20/94
	33	*/
	34
d62a17ae	35	#ifndef _SYS_QUEUE_H_
8429abe0 RW	36	#define _SYS_QUEUE_H_
	37
	38	/*
	39	* This file defines five types of data structures: singly-linked lists,
	40	* lists, simple queues, tail queues and XOR simple queues.
	41	*
	42	*
	43	* A singly-linked list is headed by a single forward pointer. The elements
	44	* are singly linked for minimum space and pointer manipulation overhead at
	45	* the expense of O(n) removal for arbitrary elements. New elements can be
	46	* added to the list after an existing element or at the head of the list.
	47	* Elements being removed from the head of the list should use the explicit
	48	* macro for this purpose for optimum efficiency. A singly-linked list may
	49	* only be traversed in the forward direction. Singly-linked lists are ideal
	50	* for applications with large datasets and few or no removals or for
	51	* implementing a LIFO queue.
	52	*
	53	* A list is headed by a single forward pointer (or an array of forward
	54	* pointers for a hash table header). The elements are doubly linked
	55	* so that an arbitrary element can be removed without a need to
	56	* traverse the list. New elements can be added to the list before
	57	* or after an existing element or at the head of the list. A list
	58	* may only be traversed in the forward direction.
	59	*
	60	* A simple queue is headed by a pair of pointers, one to the head of the
	61	* list and the other to the tail of the list. The elements are singly
	62	* linked to save space, so elements can only be removed from the
	63	* head of the list. New elements can be added to the list before or after
	64	* an existing element, at the head of the list, or at the end of the
	65	* list. A simple queue may only be traversed in the forward direction.
	66	*
	67	* A tail queue is headed by a pair of pointers, one to the head of the
	68	* list and the other to the tail of the list. The elements are doubly
	69	* linked so that an arbitrary element can be removed without a need to
	70	* traverse the list. New elements can be added to the list before or
	71	* after an existing element, at the head of the list, or at the end of
	72	* the list. A tail queue may be traversed in either direction.
	73	*
	74	* An XOR simple queue is used in the same way as a regular simple queue.
	75	* The difference is that the head structure also includes a "cookie" that
	76	* is XOR'd with the queue pointer (first, last or next) to generate the
	77	* real pointer value.
	78	*
	79	* For details on the use of these macros, see the queue(3) manual page.
	80	*/
	81
	82	#if defined(QUEUE_MACRO_DEBUG) \|\| (defined(_KERNEL) && defined(DIAGNOSTIC))
	83	#define _Q_INVALIDATE(a) (a) = ((void *)-1)
	84	#else
	85	#define _Q_INVALIDATE(a)
	86	#endif
	87
	88	/*
	89	* Singly-linked List definitions.
	90	*/
d62a17ae	91	#define SLIST_HEAD(name, type) \
	92	struct name { \
	93	struct type slh_first; / first element */ \
	94	}
8429abe0	95
d62a17ae	96	#define SLIST_HEAD_INITIALIZER(head) \
	97	{ \
	98	NULL \
	99	}
8429abe0	100
d62a17ae	101	#define SLIST_ENTRY(type) \
	102	struct { \
	103	struct type sle_next; / next element */ \
	104	}
8429abe0 RW	105
	106	/*
	107	* Singly-linked List access methods.
	108	*/
	109	#define SLIST_FIRST(head) ((head)->slh_first)
	110	#define SLIST_END(head) NULL
	111	#define SLIST_EMPTY(head) (SLIST_FIRST(head) == SLIST_END(head))
	112	#define SLIST_NEXT(elm, field) ((elm)->field.sle_next)
	113
d62a17ae	114	#define SLIST_FOREACH(var, head, field) \
	115	for ((var) = SLIST_FIRST(head); (var) != SLIST_END(head); \
	116	(var) = SLIST_NEXT(var, field))
8429abe0	117
d62a17ae	118	#define SLIST_FOREACH_SAFE(var, head, field, tvar) \
	119	for ((var) = SLIST_FIRST(head); \
	120	(var) && ((tvar) = SLIST_NEXT(var, field), 1); (var) = (tvar))
8429abe0 RW	121
	122	/*
	123	* Singly-linked List functions.
	124	*/
d62a17ae	125	#define SLIST_INIT(head) \
	126	{ \
	127	SLIST_FIRST(head) = SLIST_END(head); \
	128	}
	129
	130	#define SLIST_INSERT_AFTER(slistelm, elm, field) \
	131	do { \
	132	(elm)->field.sle_next = (slistelm)->field.sle_next; \
	133	(slistelm)->field.sle_next = (elm); \
	134	} while (0)
	135
	136	#define SLIST_INSERT_HEAD(head, elm, field) \
	137	do { \
	138	(elm)->field.sle_next = (head)->slh_first; \
	139	(head)->slh_first = (elm); \
	140	} while (0)
	141
	142	#define SLIST_REMOVE_AFTER(elm, field) \
	143	do { \
	144	(elm)->field.sle_next = (elm)->field.sle_next->field.sle_next; \
	145	} while (0)
	146
	147	#define SLIST_REMOVE_HEAD(head, field) \
	148	do { \
	149	(head)->slh_first = (head)->slh_first->field.sle_next; \
	150	} while (0)
	151
	152	#define SLIST_REMOVE(head, elm, type, field) \
	153	do { \
	154	if ((head)->slh_first == (elm)) { \
	155	SLIST_REMOVE_HEAD((head), field); \
	156	} else { \
	157	struct type *curelm = (head)->slh_first; \
	158	\
	159	while (curelm->field.sle_next != (elm)) \
	160	curelm = curelm->field.sle_next; \
	161	curelm->field.sle_next = \
	162	curelm->field.sle_next->field.sle_next; \
	163	} \
	164	_Q_INVALIDATE((elm)->field.sle_next); \
	165	} while (0)
8429abe0 RW	166
	167	/*
	168	* List definitions.
	169	*/
d62a17ae	170	#define LIST_HEAD(name, type) \
	171	struct name { \
	172	struct type lh_first; / first element */ \
	173	}
	174
	175	#define LIST_HEAD_INITIALIZER(head) \
	176	{ \
	177	NULL \
	178	}
	179
	180	#define LIST_ENTRY(type) \
	181	struct { \
	182	struct type le_next; / next element */ \
	183	struct type *le_prev; / address of previous next element */ \
	184	}
8429abe0 RW	185
	186	/*
	187	* List access methods.
	188	*/
	189	#define LIST_FIRST(head) ((head)->lh_first)
	190	#define LIST_END(head) NULL
	191	#define LIST_EMPTY(head) (LIST_FIRST(head) == LIST_END(head))
	192	#define LIST_NEXT(elm, field) ((elm)->field.le_next)
	193
d62a17ae	194	#define LIST_FOREACH(var, head, field) \
	195	for ((var) = LIST_FIRST(head); (var) != LIST_END(head); \
	196	(var) = LIST_NEXT(var, field))
8429abe0	197
d62a17ae	198	#define LIST_FOREACH_SAFE(var, head, field, tvar) \
	199	for ((var) = LIST_FIRST(head); \
	200	(var) && ((tvar) = LIST_NEXT(var, field), 1); (var) = (tvar))
8429abe0 RW	201
	202	/*
	203	* List functions.
	204	*/
d62a17ae	205	#define LIST_INIT(head) \
	206	do { \
	207	LIST_FIRST(head) = LIST_END(head); \
	208	} while (0)
	209
	210	#define LIST_INSERT_AFTER(listelm, elm, field) \
	211	do { \
	212	if (((elm)->field.le_next = (listelm)->field.le_next) != NULL) \
	213	(listelm)->field.le_next->field.le_prev = \
	214	&(elm)->field.le_next; \
	215	(listelm)->field.le_next = (elm); \
	216	(elm)->field.le_prev = &(listelm)->field.le_next; \
	217	} while (0)
	218
	219	#define LIST_INSERT_BEFORE(listelm, elm, field) \
	220	do { \
	221	(elm)->field.le_prev = (listelm)->field.le_prev; \
	222	(elm)->field.le_next = (listelm); \
	223	*(listelm)->field.le_prev = (elm); \
	224	(listelm)->field.le_prev = &(elm)->field.le_next; \
	225	} while (0)
	226
	227	#define LIST_INSERT_HEAD(head, elm, field) \
	228	do { \
	229	if (((elm)->field.le_next = (head)->lh_first) != NULL) \
	230	(head)->lh_first->field.le_prev = \
	231	&(elm)->field.le_next; \
	232	(head)->lh_first = (elm); \
	233	(elm)->field.le_prev = &(head)->lh_first; \
	234	} while (0)
	235
	236	#define LIST_REMOVE(elm, field) \
	237	do { \
	238	if ((elm)->field.le_next != NULL) \
	239	(elm)->field.le_next->field.le_prev = \
	240	(elm)->field.le_prev; \
	241	*(elm)->field.le_prev = (elm)->field.le_next; \
	242	_Q_INVALIDATE((elm)->field.le_prev); \
	243	_Q_INVALIDATE((elm)->field.le_next); \
	244	} while (0)
	245
	246	#define LIST_REPLACE(elm, elm2, field) \
	247	do { \
	248	if (((elm2)->field.le_next = (elm)->field.le_next) != NULL) \
	249	(elm2)->field.le_next->field.le_prev = \
	250	&(elm2)->field.le_next; \
	251	(elm2)->field.le_prev = (elm)->field.le_prev; \
	252	*(elm2)->field.le_prev = (elm2); \
	253	_Q_INVALIDATE((elm)->field.le_prev); \
	254	_Q_INVALIDATE((elm)->field.le_next); \
	255	} while (0)
8429abe0 RW	256
	257	/*
	258	* Simple queue definitions.
	259	*/
d62a17ae	260	#define SIMPLEQ_HEAD(name, type) \
	261	struct name { \
	262	struct type sqh_first; / first element */ \
	263	struct type *sqh_last; / addr of last next element */ \
	264	}
	265
	266	#define SIMPLEQ_HEAD_INITIALIZER(head) \
	267	{ \
	268	NULL, &(head).sqh_first \
	269	}
	270
	271	#define SIMPLEQ_ENTRY(type) \
	272	struct { \
	273	struct type sqe_next; / next element */ \
	274	}
8429abe0 RW	275
	276	/*
	277	* Simple queue access methods.
	278	*/
	279	#define SIMPLEQ_FIRST(head) ((head)->sqh_first)
	280	#define SIMPLEQ_END(head) NULL
	281	#define SIMPLEQ_EMPTY(head) (SIMPLEQ_FIRST(head) == SIMPLEQ_END(head))
	282	#define SIMPLEQ_NEXT(elm, field) ((elm)->field.sqe_next)
	283
d62a17ae	284	#define SIMPLEQ_FOREACH(var, head, field) \
	285	for ((var) = SIMPLEQ_FIRST(head); (var) != SIMPLEQ_END(head); \
	286	(var) = SIMPLEQ_NEXT(var, field))
8429abe0	287
d62a17ae	288	#define SIMPLEQ_FOREACH_SAFE(var, head, field, tvar) \
	289	for ((var) = SIMPLEQ_FIRST(head); \
	290	(var) && ((tvar) = SIMPLEQ_NEXT(var, field), 1); (var) = (tvar))
8429abe0 RW	291
	292	/*
	293	* Simple queue functions.
	294	*/
d62a17ae	295	#define SIMPLEQ_INIT(head) \
	296	do { \
	297	(head)->sqh_first = NULL; \
	298	(head)->sqh_last = &(head)->sqh_first; \
	299	} while (0)
	300
	301	#define SIMPLEQ_INSERT_HEAD(head, elm, field) \
	302	do { \
	303	if (((elm)->field.sqe_next = (head)->sqh_first) == NULL) \
	304	(head)->sqh_last = &(elm)->field.sqe_next; \
	305	(head)->sqh_first = (elm); \
	306	} while (0)
	307
	308	#define SIMPLEQ_INSERT_TAIL(head, elm, field) \
	309	do { \
	310	(elm)->field.sqe_next = NULL; \
	311	*(head)->sqh_last = (elm); \
	312	(head)->sqh_last = &(elm)->field.sqe_next; \
	313	} while (0)
	314
	315	#define SIMPLEQ_INSERT_AFTER(head, listelm, elm, field) \
	316	do { \
	317	if (((elm)->field.sqe_next = (listelm)->field.sqe_next) \
	318	== NULL) \
	319	(head)->sqh_last = &(elm)->field.sqe_next; \
	320	(listelm)->field.sqe_next = (elm); \
	321	} while (0)
	322
	323	#define SIMPLEQ_REMOVE_HEAD(head, field) \
	324	do { \
	325	if (((head)->sqh_first = (head)->sqh_first->field.sqe_next) \
	326	== NULL) \
	327	(head)->sqh_last = &(head)->sqh_first; \
	328	} while (0)
	329
	330	#define SIMPLEQ_REMOVE_AFTER(head, elm, field) \
	331	do { \
	332	if (((elm)->field.sqe_next = \
	333	(elm)->field.sqe_next->field.sqe_next) \
	334	== NULL) \
	335	(head)->sqh_last = &(elm)->field.sqe_next; \
	336	} while (0)
	337
	338	#define SIMPLEQ_CONCAT(head1, head2) \
	339	do { \
	340	if (!SIMPLEQ_EMPTY((head2))) { \
	341	*(head1)->sqh_last = (head2)->sqh_first; \
	342	(head1)->sqh_last = (head2)->sqh_last; \
	343	SIMPLEQ_INIT((head2)); \
	344	} \
	345	} while (0)
8429abe0 RW	346
	347	/*
	348	* XOR Simple queue definitions.
	349	*/
d62a17ae	350	#define XSIMPLEQ_HEAD(name, type) \
	351	struct name { \
	352	struct type sqx_first; / first element */ \
	353	struct type *sqx_last; / addr of last next element */ \
	354	unsigned long sqx_cookie; \
	355	}
	356
	357	#define XSIMPLEQ_ENTRY(type) \
	358	struct { \
	359	struct type sqx_next; / next element */ \
	360	}
8429abe0 RW	361
	362	/*
	363	* XOR Simple queue access methods.
	364	*/
d62a17ae	365	#define XSIMPLEQ_XOR(head, ptr) \
d62a17ae	366	((__typeof(ptr))((head)->sqx_cookie ^ (unsigned long)(ptr)))
8429abe0 RW	367	#define XSIMPLEQ_FIRST(head) XSIMPLEQ_XOR(head, ((head)->sqx_first))
	368	#define XSIMPLEQ_END(head) NULL
	369	#define XSIMPLEQ_EMPTY(head) (XSIMPLEQ_FIRST(head) == XSIMPLEQ_END(head))
	370	#define XSIMPLEQ_NEXT(head, elm, field) XSIMPLEQ_XOR(head, ((elm)->field.sqx_next))
	371
d62a17ae	372	#define XSIMPLEQ_FOREACH(var, head, field) \
	373	for ((var) = XSIMPLEQ_FIRST(head); (var) != XSIMPLEQ_END(head); \
	374	(var) = XSIMPLEQ_NEXT(head, var, field))
8429abe0	375
d62a17ae	376	#define XSIMPLEQ_FOREACH_SAFE(var, head, field, tvar) \
	377	for ((var) = XSIMPLEQ_FIRST(head); \
	378	(var) && ((tvar) = XSIMPLEQ_NEXT(head, var, field), 1); \
	379	(var) = (tvar))
8429abe0 RW	380
	381	/*
	382	* XOR Simple queue functions.
	383	*/
d62a17ae	384	#define XSIMPLEQ_INIT(head) \
	385	do { \
	386	arc4random_buf(&(head)->sqx_cookie, \
	387	sizeof((head)->sqx_cookie)); \
	388	(head)->sqx_first = XSIMPLEQ_XOR(head, NULL); \
	389	(head)->sqx_last = XSIMPLEQ_XOR(head, &(head)->sqx_first); \
	390	} while (0)
	391
	392	#define XSIMPLEQ_INSERT_HEAD(head, elm, field) \
	393	do { \
	394	if (((elm)->field.sqx_next = (head)->sqx_first) \
	395	== XSIMPLEQ_XOR(head, NULL)) \
	396	(head)->sqx_last = \
	397	XSIMPLEQ_XOR(head, &(elm)->field.sqx_next); \
	398	(head)->sqx_first = XSIMPLEQ_XOR(head, (elm)); \
	399	} while (0)
	400
	401	#define XSIMPLEQ_INSERT_TAIL(head, elm, field) \
	402	do { \
	403	(elm)->field.sqx_next = XSIMPLEQ_XOR(head, NULL); \
	404	*(XSIMPLEQ_XOR(head, (head)->sqx_last)) = \
	405	XSIMPLEQ_XOR(head, (elm)); \
8429abe0	406	(head)->sqx_last = XSIMPLEQ_XOR(head, &(elm)->field.sqx_next); \
d62a17ae	407	} while (0)
	408
	409	#define XSIMPLEQ_INSERT_AFTER(head, listelm, elm, field) \
	410	do { \
	411	if (((elm)->field.sqx_next = (listelm)->field.sqx_next) \
	412	== XSIMPLEQ_XOR(head, NULL)) \
	413	(head)->sqx_last = \
	414	XSIMPLEQ_XOR(head, &(elm)->field.sqx_next); \
	415	(listelm)->field.sqx_next = XSIMPLEQ_XOR(head, (elm)); \
	416	} while (0)
	417
	418	#define XSIMPLEQ_REMOVE_HEAD(head, field) \
	419	do { \
	420	if (((head)->sqx_first = XSIMPLEQ_XOR(head, (head)->sqx_first) \
	421	->field.sqx_next) \
	422	== XSIMPLEQ_XOR(head, NULL)) \
	423	(head)->sqx_last = \
	424	XSIMPLEQ_XOR(head, &(head)->sqx_first); \
	425	} while (0)
	426
	427	#define XSIMPLEQ_REMOVE_AFTER(head, elm, field) \
	428	do { \
	429	if (((elm)->field.sqx_next = \
	430	XSIMPLEQ_XOR(head, (elm)->field.sqx_next) \
	431	->field.sqx_next) \
	432	== XSIMPLEQ_XOR(head, NULL)) \
	433	(head)->sqx_last = \
	434	XSIMPLEQ_XOR(head, &(elm)->field.sqx_next); \
	435	} while (0)
8429abe0 RW	436
	437
	438	/*
	439	* Tail queue definitions.
	440	*/
d62a17ae	441	#define TAILQ_HEAD(name, type) \
	442	struct name { \
	443	struct type tqh_first; / first element */ \
	444	struct type *tqh_last; / addr of last next element */ \
	445	}
	446
	447	#define TAILQ_HEAD_INITIALIZER(head) \
	448	{ \
	449	NULL, &(head).tqh_first \
	450	}
	451
	452	#define TAILQ_ENTRY(type) \
	453	struct { \
	454	struct type tqe_next; / next element */ \
	455	struct type *tqe_prev; / address of previous next element */ \
	456	}
8429abe0 RW	457
	458	/*
	459	* Tail queue access methods.
	460	*/
	461	#define TAILQ_FIRST(head) ((head)->tqh_first)
	462	#define TAILQ_END(head) NULL
	463	#define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
d62a17ae	464	#define TAILQ_LAST(head, headname) \
8429abe0 RW	465	((((struct headname )((head)->tqh_last))->tqh_last))
8429abe0 RW	466	/* XXX */
d62a17ae	467	#define TAILQ_PREV(elm, headname, field) \
8429abe0	468	((((struct headname )((elm)->field.tqe_prev))->tqh_last))
d62a17ae	469	#define TAILQ_EMPTY(head) (TAILQ_FIRST(head) == TAILQ_END(head))
8429abe0	470
d62a17ae	471	#define TAILQ_FOREACH(var, head, field) \
	472	for ((var) = TAILQ_FIRST(head); (var) != TAILQ_END(head); \
	473	(var) = TAILQ_NEXT(var, field))
8429abe0	474
d62a17ae	475	#define TAILQ_FOREACH_SAFE(var, head, field, tvar) \
	476	for ((var) = TAILQ_FIRST(head); \
	477	(var) != TAILQ_END(head) && ((tvar) = TAILQ_NEXT(var, field), 1); \
	478	(var) = (tvar))
8429abe0 RW	479
8429abe0 RW	480
d62a17ae	481	#define TAILQ_FOREACH_REVERSE(var, head, headname, field) \
	482	for ((var) = TAILQ_LAST(head, headname); (var) != TAILQ_END(head); \
	483	(var) = TAILQ_PREV(var, headname, field))
8429abe0	484
d62a17ae	485	#define TAILQ_FOREACH_REVERSE_SAFE(var, head, headname, field, tvar) \
	486	for ((var) = TAILQ_LAST(head, headname); \
	487	(var) != TAILQ_END(head) \
	488	&& ((tvar) = TAILQ_PREV(var, headname, field), 1); \
	489	(var) = (tvar))
8429abe0 RW	490
	491	/*
	492	* Tail queue functions.
	493	*/
d62a17ae	494	#define TAILQ_INIT(head) \
	495	do { \
	496	(head)->tqh_first = NULL; \
	497	(head)->tqh_last = &(head)->tqh_first; \
	498	} while (0)
	499
	500	#define TAILQ_INSERT_HEAD(head, elm, field) \
	501	do { \
	502	if (((elm)->field.tqe_next = (head)->tqh_first) != NULL) \
	503	(head)->tqh_first->field.tqe_prev = \
	504	&(elm)->field.tqe_next; \
	505	else \
	506	(head)->tqh_last = &(elm)->field.tqe_next; \
	507	(head)->tqh_first = (elm); \
	508	(elm)->field.tqe_prev = &(head)->tqh_first; \
	509	} while (0)
	510
	511	#define TAILQ_INSERT_TAIL(head, elm, field) \
	512	do { \
	513	(elm)->field.tqe_next = NULL; \
	514	(elm)->field.tqe_prev = (head)->tqh_last; \
	515	*(head)->tqh_last = (elm); \
	516	(head)->tqh_last = &(elm)->field.tqe_next; \
	517	} while (0)
	518
	519	#define TAILQ_INSERT_AFTER(head, listelm, elm, field) \
	520	do { \
	521	if (((elm)->field.tqe_next = (listelm)->field.tqe_next) \
	522	!= NULL) \
	523	(elm)->field.tqe_next->field.tqe_prev = \
	524	&(elm)->field.tqe_next; \
	525	else \
	526	(head)->tqh_last = &(elm)->field.tqe_next; \
	527	(listelm)->field.tqe_next = (elm); \
	528	(elm)->field.tqe_prev = &(listelm)->field.tqe_next; \
	529	} while (0)
	530
	531	#define TAILQ_INSERT_BEFORE(listelm, elm, field) \
	532	do { \
	533	(elm)->field.tqe_prev = (listelm)->field.tqe_prev; \
	534	(elm)->field.tqe_next = (listelm); \
	535	*(listelm)->field.tqe_prev = (elm); \
	536	(listelm)->field.tqe_prev = &(elm)->field.tqe_next; \
	537	} while (0)
	538
	539	#define TAILQ_REMOVE(head, elm, field) \
	540	do { \
	541	if (((elm)->field.tqe_next) != NULL) \
	542	(elm)->field.tqe_next->field.tqe_prev = \
	543	(elm)->field.tqe_prev; \
	544	else \
	545	(head)->tqh_last = (elm)->field.tqe_prev; \
	546	*(elm)->field.tqe_prev = (elm)->field.tqe_next; \
	547	_Q_INVALIDATE((elm)->field.tqe_prev); \
	548	_Q_INVALIDATE((elm)->field.tqe_next); \
	549	} while (0)
	550
	551	#define TAILQ_REPLACE(head, elm, elm2, field) \
	552	do { \
	553	if (((elm2)->field.tqe_next = (elm)->field.tqe_next) != NULL) \
	554	(elm2)->field.tqe_next->field.tqe_prev = \
	555	&(elm2)->field.tqe_next; \
	556	else \
	557	(head)->tqh_last = &(elm2)->field.tqe_next; \
558	(elm2)->field.tqe_prev = (elm)->field.tqe_prev; \
559	*(elm2)->field.tqe_prev = (elm2); \
560	_Q_INVALIDATE((elm)->field.tqe_prev); \
561	_Q_INVALIDATE((elm)->field.tqe_next); \
562	} while (0)
563
564	#define TAILQ_CONCAT(head1, head2, field) \
565	do { \
566	if (!TAILQ_EMPTY(head2)) { \
567	*(head1)->tqh_last = (head2)->tqh_first; \
568	(head2)->tqh_first->field.tqe_prev = \
569	(head1)->tqh_last; \
570	(head1)->tqh_last = (head2)->tqh_last; \
571	TAILQ_INIT((head2)); \
572	} \
573	} while (0)
574
575	#endif /* !_SYS_QUEUE_H_ */