/*	$OpenBSD: queue.h,v 1.38 2013/07/03 15:05:21 fgsch 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. */ #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) /* * 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								\

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