/* * 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. All advertising materials mentioning features or use of this software *    must display the following acknowledgement: *	This product includes software developed by the University of *	California, Berkeley and its contributors. * 4. 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 * $FreeBSD: src/sys/sys/queue.h,v 1.54 2002/08/05 05:18:43 alfred Exp $ */#ifndef _SYS_QUEUE_H_#define	_SYS_QUEUE_H_#include <sys/cdefs.h>/* * This file defines four types of data structures: singly-linked lists, * singly-linked tail queues, lists and tail 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 singly-linked 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 * 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, at the head of the list, or at the * end of the list. Elements being removed from the head of the tail queue * should use the explicit macro for this purpose for optimum efficiency. * A singly-linked tail queue may only be traversed in the forward direction. * Singly-linked tail queues are ideal for applications with large datasets * and few or no removals or for implementing a FIFO 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 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. * * For details on the use of these macros, see the queue(3) manual page. * * *			SLIST	LIST	STAILQ	TAILQ * _HEAD		+	+	+	+ * _HEAD_INITIALIZER	+	+	+	+ * _ENTRY		+	+	+	+ * _INIT		+	+	+	+ * _EMPTY		+	+	+	+ * _FIRST		+	+	+	+ * _NEXT		+	+	+	+ * _PREV		-	-	-	+ * _LAST		-	-	+	+ * _FOREACH		+	+	+	+ * _FOREACH_REVERSE	-	-	-	+ * _INSERT_HEAD		+	+	+	+ * _INSERT_BEFORE	-	+	-	+ * _INSERT_AFTER	+	+	+	+ * _INSERT_TAIL		-	-	+	+ * _CONCAT		-	-	+	+ * _REMOVE_HEAD		+	-	+	- * _REMOVE		+	+	+	+ * */#define QUEUE_MACRO_DEBUG 0#if QUEUE_MACRO_DEBUG/* Store the last 2 places the queue element or head was altered */struct qm_trace {	char * lastfile;	int lastline;	char * prevfile;	int prevline;};#define TRACEBUF	struct qm_trace trace;#define TRASHIT(x)	do {(x) = (void *)-1;} while (0)#define QMD_TRACE_HEAD(head) do {					\	(head)->trace.prevline = (head)->trace.lastline;		\	(head)->trace.prevfile = (head)->trace.lastfile;		\	(head)->trace.lastline = __LINE__;				\	(head)->trace.lastfile = __FILE__;				\} while (0)#define QMD_TRACE_ELEM(elem) do {					\	(elem)->trace.prevline = (elem)->trace.lastline;		\	(elem)->trace.prevfile = (elem)->trace.lastfile;		\	(elem)->trace.lastline = __LINE__;				\	(elem)->trace.lastfile = __FILE__;				\} while (0)#else#define QMD_TRACE_ELEM(elem)#define QMD_TRACE_HEAD(head)#define TRACEBUF#define TRASHIT(x)#endif	/* QUEUE_MACRO_DEBUG *//* * Singly-linked List declarations. */#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_EMPTY(head)	((head)->slh_first == NULL)#define	SLIST_FIRST(head)	((head)->slh_first)#define	SLIST_FOREACH(var, head, field)					\	for ((var) = SLIST_FIRST((head));				\	    (var);							\	    (var) = SLIST_NEXT((var), field))#define SLIST_FOREACH_PREVPTR(var, varp, head, field)			\	for ((varp) = &SLIST_FIRST((head));				\	    ((var) = *(varp)) != NULL;					\	    (varp) = &SLIST_NEXT((var), field))#define	SLIST_INIT(head) do {						\	SLIST_FIRST((head)) = NULL;					\} while (0)#define	SLIST_INSERT_AFTER(slistelm, elm, field) do {			\	SLIST_NEXT((elm), field) = SLIST_NEXT((slistelm), field);	\	SLIST_NEXT((slistelm), field) = (elm);				\} while (0)#define	SLIST_INSERT_HEAD(head, elm, field) do {			\	SLIST_NEXT((elm), field) = SLIST_FIRST((head));			\	SLIST_FIRST((head)) = (elm);					\} while (0)#define	SLIST_NEXT(elm, field)	((elm)->field.sle_next)#define	SLIST_REMOVE(head, elm, type, field) do {			\	if (SLIST_FIRST((head)) == (elm)) {				\		SLIST_REMOVE_HEAD((head), field);			\	}								\	else {								\		struct type *curelm = SLIST_FIRST((head));		\		while (SLIST_NEXT(curelm, field) != (elm))		\			curelm = SLIST_NEXT(curelm, field);		\		SLIST_NEXT(curelm, field) =				\		    SLIST_NEXT(SLIST_NEXT(curelm, field), field);	\	}								\} while (0)#define	SLIST_REMOVE_HEAD(head, field) do {				\	SLIST_FIRST((head)) = SLIST_NEXT(SLIST_FIRST((head)), field);	\} while (0)/* * 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_CONCAT(head1, head2) do {				\	if (!STAILQ_EMPTY((head2))) {					\		*(head1)->stqh_last = (head2)->stqh_first;		\		(head1)->stqh_last = (head2)->stqh_last;		\		STAILQ_INIT((head2));					\	}								\} while (0)#define	STAILQ_EMPTY(head)	((head)->stqh_first == NULL)#define	STAILQ_FIRST(head)	((head)->stqh_first)#define	STAILQ_FOREACH(var, head, field)				\	for((var) = STAILQ_FIRST((head));				\	   (var);							\	   (var) = STAILQ_NEXT((var), field))#define	STAILQ_INIT(head) do {						\	STAILQ_FIRST((head)) = NULL;					\	(head)->stqh_last = &STAILQ_FIRST((head));			\} while (0)#define	STAILQ_INSERT_AFTER(head, tqelm, elm, field) do {		\	if ((STAILQ_NEXT((elm), field) = STAILQ_NEXT((tqelm), field)) == NULL)\		(head)->stqh_last = &STAILQ_NEXT((elm), field);		\	STAILQ_NEXT((tqelm), field) = (elm);				\} while (0)#define	STAILQ_INSERT_HEAD(head, elm, field) do {			\	if ((STAILQ_NEXT((elm), field) = STAILQ_FIRST((head))) == NULL)	\		(head)->stqh_last = &STAILQ_NEXT((elm), field);		\	STAILQ_FIRST((head)) = (elm);					\} while (0)#define	STAILQ_INSERT_TAIL(head, elm, field) do {			\	STAILQ_NEXT((elm), field) = NULL;				\	*(head)->stqh_last = (elm);					\	(head)->stqh_last = &STAILQ_NEXT((elm), field);			\} while (0)#define	STAILQ_LAST(head, type, field)					\