/*
 * Used only for the Windows build. Unix uses <sys/queue.h> or <sysqueue.h>
 */
/*
 * 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.
 * 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	8.3 (Berkeley) 12/13/93
 */

#if !defined(_SYS_QUEUE_H) && !defined(_SYS_QUEUE_H_)
#define _SYS_QUEUE_H 1
#define _SYS_QUEUE_H_ 1

/*
 * This file defines three types of data structures: lists, tail queues,
 * and circular queues.
 *
 * 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 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 after
 * an existing element, at the head of the list, or at the end of the
 * list. A tail queue may only be traversed in the forward 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_ENTRY(type)                                                \
	struct {                                                                \
		struct type *le_next;   /* next element */                      \
		struct type **le_prev;  /* address of previous next element */  \
	}

/*
 * List functions.
 */
#define LIST_INIT(head) {                                               \
		(head)->lh_first = NULL;                                        \
}

#define LIST_INSERT_AFTER(listelm, elm, field) {                        \
		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;               \
}

#define LIST_INSERT_HEAD(head, elm, field) {                            \
		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;                       \
}

#define LIST_REMOVE(elm, field) {                                       \
		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;                   \
}

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

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

#define TAILQ_INSERT_HEAD(head, elm, field) {                           \
		if (((elm)->field.tqe_next = (head)->tqh_first) != NULL)        \
			(elm)->field.tqe_next->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;                     \
}

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

#define TAILQ_INSERT_AFTER(head, listelm, elm, field) {                 \
		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;             \
}

#define TAILQ_REMOVE(head, elm, field) {                                \
		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;                 \
}

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

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

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

#define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) {               \
		(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);                              \
}

#define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) {              \
		(elm)->field.cqe_next = (listelm);                              \
		(elm)->field.cqe_prev = (listelm)->field.cqe_prev;              \
		if ((listelm)->field.cqe_prev == (void *)(head))                \
			(head)->cqh_first = (elm);                              \
		else                                                            \
			(listelm)->field.cqe_prev->field.cqe_next = (elm);      \
		(listelm)->field.cqe_prev = (elm);                              \
}

#define CIRCLEQ_INSERT_HEAD(head, elm, field) {                         \
		(elm)->field.cqe_next = (head)->cqh_first;                      \
		(elm)->field.cqe_prev = (void *)(head);                         \
		if ((head)->cqh_last == (void *)(head))                         \
			(head)->cqh_last = (elm);                               \
		else                                                            \
			(head)->cqh_first->field.cqe_prev = (elm);              \
		(head)->cqh_first = (elm);                                      \
}

#define CIRCLEQ_INSERT_TAIL(head, elm, field) {                         \
		(elm)->field.cqe_next = (void *)(head);                         \
		(elm)->field.cqe_prev = (head)->cqh_last;                       \
		if ((head)->cqh_first == (void *)(head))                        \
			(head)->cqh_first = (elm);                              \
		else                                                            \
			(head)->cqh_last->field.cqe_next = (elm);               \
		(head)->cqh_last = (elm);                                       \
}

#define CIRCLEQ_REMOVE(head, elm, field) {                              \
		if ((elm)->field.cqe_next == (void *)(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 == (void *)(head))                    \
			(head)->cqh_first = (elm)->field.cqe_next;              \
		else                                                            \
			(elm)->field.cqe_prev->field.cqe_next =                 \
				(elm)->field.cqe_next;                              \
}
#endif  /* sys/queue.h */
