/* * 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 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. */ /* * 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 functions. */#define	LIST_INIT(head) do {						\	(head)->lh_first = NULL;					\} while (/*CONSTCOND*/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 (/*CONSTCOND*/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 (/*CONSTCOND*/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 (/*CONSTCOND*/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 (/*CONSTCOND*/0) #define	LIST_FOREACH(var, head, field)					\	for ((var) = ((head)->lh_first);				\		(var);							\		(var) = ((var)->field.le_next)) /* * List access methods. */#define	LIST_EMPTY(head)		((head)->lh_first == NULL)#define	LIST_FIRST(head)		((head)->lh_first)#define	LIST_NEXT(elm, field)		((elm)->field.le_next)  /* * 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 functions. */#define	SLIST_INIT(head) do {						\	(head)->slh_first = NULL;					\} while (/*CONSTCOND*/0) #define	SLIST_INSERT_AFTER(slistelm, elm, field) do {			\	(elm)->field.sle_next = (slistelm)->field.sle_next;		\	(slistelm)->field.sle_next = (elm);				\} while (/*CONSTCOND*/0) #define	SLIST_INSERT_HEAD(head, elm, field) do {			\	(elm)->field.sle_next = (head)->slh_first;			\	(head)->slh_first = (elm);					\} while (/*CONSTCOND*/0) #define	SLIST_REMOVE_HEAD(head, field) do {				\	(head)->slh_first = (head)->slh_first->field.sle_next;		\} while (/*CONSTCOND*/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 (/*CONSTCOND*/0) #define	SLIST_FOREACH(var, head, field)					\	for((var) = (head)->slh_first; (var); (var) = (var)->field.sle_next) /* * Singly-linked List access methods. */#define	SLIST_EMPTY(head)	((head)->slh_first == NULL)#define	SLIST_FIRST(head)	((head)->slh_first)#define	SLIST_NEXT(elm, field)	((elm)->field.sle_next)  /* * Singly-linked Tail queue declarations. */#define	STAILQ_HEAD(name, type)					\struct name {								\	struct type *stqh_first;	/* first element */			\	struct type **stqh_last;	/* addr of last next element */		\} #define	STAILQ_HEAD_INITIALIZER(head)					\	{ NULL, &(head).stqh_first } #define	STAILQ_ENTRY(type)						\struct {								\	struct type *stqe_next;	/* next element */			\} /* * Singly-linked Tail queue functions. */#define	STAILQ_INIT(head) do {						\	(head)->stqh_first = NULL;					\	(head)->stqh_last = &(head)->stqh_first;				\} while (/*CONSTCOND*/0) #define	STAILQ_INSERT_HEAD(head, elm, field) do {			\	if (((elm)->field.stqe_next = (head)->stqh_first) == NULL)	\		(head)->stqh_last = &(elm)->field.stqe_next;		\	(head)->stqh_first = (elm);					\} while (/*CONSTCOND*/0) #define	STAILQ_INSERT_TAIL(head, elm, field) do {			\	(elm)->field.stqe_next = NULL;					\	*(head)->stqh_last = (elm);					\	(head)->stqh_last = &(elm)->field.stqe_next;			\} while (/*CONSTCOND*/0) #define	STAILQ_INSERT_AFTER(head, listelm, elm, field) do {		\	if (((elm)->field.stqe_next = (listelm)->field.stqe_next) == NULL)\		(head)->stqh_last = &(elm)->field.stqe_next;		\	(listelm)->field.stqe_next = (elm);				\} while (/*CONSTCOND*/0) #define	STAILQ_REMOVE_HEAD(head, field) do {				\	if (((head)->stqh_first = (head)->stqh_first->field.stqe_next) == NULL) \		(head)->stqh_last = &(head)->stqh_first;			\} while (/*CONSTCOND*/0) #define	STAILQ_REMOVE(head, elm, type, field) do {			\	if ((head)->stqh_first == (elm)) {				\		STAILQ_REMOVE_HEAD((head), field);			\	} else {							\		struct type *curelm = (head)->stqh_first;		\		while (curelm->field.stqe_next != (elm))			\			curelm = curelm->field.stqe_next;		\		if ((curelm->field.stqe_next =				\			curelm->field.stqe_next->field.stqe_next) == NULL) \			    (head)->stqh_last = &(curelm)->field.stqe_next; \	}								\} while (/*CONSTCOND*/0) #define	STAILQ_FOREACH(var, head, field)				\	for ((var) = ((head)->stqh_first);				\		(var);							\		(var) = ((var)->field.stqe_next)) #define	STAILQ_CONCAT(head1, head2) do {				\	if (!STAILQ_EMPTY((head2))) {					\		*(head1)->stqh_last = (head2)->stqh_first;		\		(head1)->stqh_last = (head2)->stqh_last;		\		STAILQ_INIT((head2));					\	}								\} while (/*CONSTCOND*/0) /* * Singly-linked Tail queue access methods. */#define	STAILQ_EMPTY(head)	((head)->stqh_first == NULL)#define	STAILQ_FIRST(head)	((head)->stqh_first)#define	STAILQ_NEXT(elm, field)	((elm)->field.stqe_next)  /* * 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 functions. */#define	SIMPLEQ_INIT(head) do {						\	(head)->sqh_first = NULL;					\	(head)->sqh_last = &(head)->sqh_first;				\} while (/*CONSTCOND*/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 (/*CONSTCOND*/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 (/*CONSTCOND*/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 (/*CONSTCOND*/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 (/*CONSTCOND*/0) #define	SIMPLEQ_REMOVE(head, elm, type, field) do {			\	if ((head)->sqh_first == (elm)) {				\		SIMPLEQ_REMOVE_HEAD((head), field);			\	} else {							\		struct type *curelm = (head)->sqh_first;		\		while (curelm->field.sqe_next != (elm))			\			curelm = curelm->field.sqe_next;		\		if ((curelm->field.sqe_next =				\			curelm->field.sqe_next->field.sqe_next) == NULL) \			    (head)->sqh_last = &(curelm)->field.sqe_next; \	}								\} while (/*CONSTCOND*/0) #define	SIMPLEQ_FOREACH(var, head, field)				\	for ((var) = ((head)->sqh_first);				\		(var);							\		(var) = ((var)->field.sqe_next)) /* * Simple queue access methods. */#define	SIMPLEQ_EMPTY(head)		((head)->sqh_first == NULL)#define	SIMPLEQ_FIRST(head)		((head)->sqh_first)#define	SIMPLEQ_NEXT(elm, field)	((elm)->field.sqe_next)  /* * Tail queue definitions. */#define	_TAILQ_HEAD(name, type, qual)					\struct name {								\	qual type *tqh_first;		/* first element */		\	qual type *qual *tqh_last;	/* addr of last next element */	\}#define TAILQ_HEAD(name, type)	_TAILQ_HEAD(name, struct type,) #define	TAILQ_HEAD_INITIALIZER(head)					\	{ NULL, &(head).tqh_first } #define	_TAILQ_ENTRY(type, qual)					\struct {								\	qual type *tqe_next;		/* next element */		\	qual type *qual *tqe_prev;	/* address of previous next element */\}#define TAILQ_ENTRY(type)	_TAILQ_ENTRY(struct type,) /* * Tail queue functions. */#define	TAILQ_INIT(head) do {						\	(head)->tqh_first = NULL;					\	(head)->tqh_last = &(head)->tqh_first;				\} while (/*CONSTCOND*/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 (/*CONSTCOND*/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 (/*CONSTCOND*/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 (/*CONSTCOND*/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 (/*CONSTCOND*/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 (/*CONSTCOND*/0) #define	TAILQ_FOREACH(var, head, field)					\	for ((var) = ((head)->tqh_first);				\		(var);							\		(var) = ((var)->field.tqe_next)) #define	TAILQ_FOREACH_REVERSE(var, head, headname, field)		\	for ((var) = (*(((struct headname *)((head)->tqh_last))->tqh_last));	\		(var);							\		(var) = (*(((struct headname *)((var)->field.tqe_prev))->tqh_last))) #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 (/*CONSTCOND*/0) /* * Tail queue access methods. */#define	TAILQ_EMPTY(head)		((head)->tqh_first == NULL)#define	TAILQ_FIRST(head)		((head)->tqh_first)#define	TAILQ_NEXT(elm, field)		((elm)->field.tqe_next) #define	TAILQ_LAST(head, headname) \	(*(((struct headname *)((head)->tqh_last))->tqh_last))#define	TAILQ_PREV(elm, headname, field) \	(*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))  /* * 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)					\	{ (void *)&head, (void *)&head } #define	CIRCLEQ_ENTRY(type)						\struct {								\	struct type *cqe_next;		/* next element */		\	struct type *cqe_prev;		/* previous element */		\} /* * Circular queue functions. */#define	CIRCLEQ_INIT(head) do {						\	(head)->cqh_first = (void *)(head);				\	(head)->cqh_last = (void *)(head);				\} while (/*CONSTCOND*/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 == (void *)(head))		\		(head)->cqh_last = (elm);				\	else								\		(listelm)->field.cqe_next->field.cqe_prev = (elm);	\	(listelm)->field.cqe_next = (elm);				\

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