queue.h

/*	$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	_UFIBER_QUEUE_H_
#define	_UFIBER_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 UFIBER_Q_INVALIDATE(a) (a) = ((void *)-1)
#else
#define UFIBER_Q_INVALIDATE(a)
#endif

/*
 * Singly-linked List definitions.
 */
#define UFIBER_SLIST_HEAD(name, type)                                          \
struct name {                                                                \
	struct type *slh_first;                                              \
}
 
#define	UFIBER_SLIST_HEAD_INITIALIZER(head)                                    \
	{ NULL }
 
#define UFIBER_SLIST_ENTRY(type)                                               \
struct {                                                                     \
	struct type *sle_next;                                               \
}
 
/*
 * Singly-linked List access methods.
 */
#define	UFIBER_SLIST_FIRST(head)      ((head)->slh_first)
#define	UFIBER_SLIST_END(head)        NULL
#define	UFIBER_SLIST_EMPTY(head)      (SLIST_FIRST(head) == SLIST_END(head))
#define	UFIBER_SLIST_NEXT(elm, field) ((elm)->field.sle_next)

#define	UFIBER_SLIST_FOREACH(var, head, field)                                 \
	for((var) = UFIBER_SLIST_FIRST(head);                                  \
	    (var) != UFIBER_SLIST_END(head);                                   \
	    (var) = UFIBER_SLIST_NEXT(var, field))

#define	UFIBER_SLIST_FOREACH_SAFE(var, head, field, tvar)                      \
	for ((var) = UFIBER_SLIST_FIRST(head);                                 \
	    (var) && ((tvar) = UFIBER_SLIST_NEXT(var, field), 1);              \
	    (var) = (tvar))

/*
 * Singly-linked List functions.
 */
#define	UFIBER_SLIST_INIT(head) {                                              \
	UFIBER_SLIST_FIRST(head) = UFIBER_SLIST_END(head);                       \
}

#define	UFIBER_SLIST_INSERT_AFTER(slistelm, elm, field) do {                   \
	(elm)->field.sle_next = (slistelm)->field.sle_next;                  \
	(slistelm)->field.sle_next = (elm);                                  \
} while (0)

#define	UFIBER_SLIST_INSERT_HEAD(head, elm, field) do {                        \
	(elm)->field.sle_next = (head)->slh_first;                           \
	(head)->slh_first = (elm);                                           \
} while (0)

#define	UFIBER_SLIST_REMOVE_AFTER(elm, field) do {                             \
	(elm)->field.sle_next = (elm)->field.sle_next->field.sle_next;       \
} while (0)

#define	UFIBER_SLIST_REMOVE_HEAD(head, field) do {                             \
	(head)->slh_first = (head)->slh_first->field.sle_next;               \
} while (0)

#define UFIBER_SLIST_REMOVE(head, elm, type, field) do {                       \
	if ((head)->slh_first == (elm)) {                                    \
		UFIBER_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;                  \
		UFIBER_Q_INVALIDATE((elm)->field.sle_next);                    \
	}                                                                    \
} while (0)

/*
 * List definitions.
 */
#define UFIBER_LIST_HEAD(name, type)                                           \
struct name {                                                                \
	struct type *lh_first;                                               \
}

#define UFIBER_LIST_HEAD_INITIALIZER(head)                                     \
	{ NULL }

#define UFIBER_LIST_ENTRY(type)                                                \
struct {                                                                     \
	struct type *le_next;                                                \
	struct type **le_prev;                                               \
}

/*
 * List access methods
 */
#define	UFIBER_LIST_FIRST(head)      ((head)->lh_first)
#define	UFIBER_LIST_END(head)        NULL
#define	UFIBER_LIST_NEXT(elm, field) ((elm)->field.le_next)
#define	UFIBER_LIST_EMPTY(head)                                                \
	(UFIBER_LIST_FIRST(head) == UFIBER_LIST_END(head))

#define UFIBER_LIST_FOREACH(var, head, field)                                  \
	for((var) = UFIBER_LIST_FIRST(head);                                   \
	    (var)!= UFIBER_LIST_END(head);                                     \
	    (var) = UFIBER_LIST_NEXT(var, field))

#define	UFIBER_LIST_FOREACH_SAFE(var, head, field, tvar)                       \
	for ((var) = UFIBER_LIST_FIRST(head);                                  \
	    (var) && ((tvar) = UFIBER_LIST_NEXT(var, field), 1);               \
	    (var) = (tvar))

/*
 * List functions.
 */
#define	UFIBER_LIST_INIT(head) do {                                            \
	UFIBER_LIST_FIRST(head) = UFIBER_LIST_END(head);                         \
} while (0)

#define UFIBER_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	UFIBER_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 UFIBER_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 UFIBER_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;                        \
	UFIBER_Q_INVALIDATE((elm)->field.le_prev);                             \
	UFIBER_Q_INVALIDATE((elm)->field.le_next);                             \
} while (0)

#define UFIBER_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);                                     \
	UFIBER_Q_INVALIDATE((elm)->field.le_prev);                             \
	UFIBER_Q_INVALIDATE((elm)->field.le_next);                             \
} while (0)

/*
 * Simple queue definitions.
 */
#define UFIBER_SIMPLEQ_HEAD(name, type)                                        \
struct name {                                                                \
	struct type *sqh_first;                                              \
	struct type **sqh_last;                                              \
}

#define UFIBER_SIMPLEQ_HEAD_INITIALIZER(head)                                  \
	{ NULL, &(head).sqh_first }

#define UFIBER_SIMPLEQ_ENTRY(type)                                             \
struct {                                                                     \
	struct type *sqe_next;                                               \
}

/*
 * Simple queue access methods.
 */
#define	UFIBER_SIMPLEQ_FIRST(head)      ((head)->sqh_first)
#define	UFIBER_SIMPLEQ_END(head)        NULL
#define	UFIBER_SIMPLEQ_NEXT(elm, field) ((elm)->field.sqe_next)
#define	UFIBER_SIMPLEQ_EMPTY(head)	                                     \
	(UFIBER_SIMPLEQ_FIRST(head) == UFIBER_SIMPLEQ_END(head))

#define UFIBER_SIMPLEQ_FOREACH(var, head, field)                               \
	for((var) = UFIBER_SIMPLEQ_FIRST(head);                                \
	    (var) != UFIBER_SIMPLEQ_END(head);                                 \
	    (var) = UFIBER_SIMPLEQ_NEXT(var, field))

#define	UFIBER_SIMPLEQ_FOREACH_SAFE(var, head, field, tvar)                    \
	for ((var) = UFIBER_SIMPLEQ_FIRST(head);                               \
	    (var) && ((tvar) = UFIBER_SIMPLEQ_NEXT(var, field), 1);            \
	    (var) = (tvar))

/*
 * Simple queue functions.
 */
#define	UFIBER_SIMPLEQ_INIT(head) do {                                         \
	(head)->sqh_first = NULL;                                            \
	(head)->sqh_last = &(head)->sqh_first;                               \
} while (0)

#define UFIBER_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 UFIBER_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 UFIBER_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 UFIBER_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 UFIBER_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)

/*
 * Tail queue definitions.
 */
#define UFIBER_TAILQ_HEAD(name, type)                                          \
struct name {                                                                \
	struct type *tqh_first;                                              \
	struct type **tqh_last;                                              \
}

#define UFIBER_TAILQ_HEAD_INITIALIZER(head)                                    \
	{ NULL, &(head).tqh_first }

#define UFIBER_TAILQ_ENTRY(type)                                               \
struct {                                                                     \
	struct type *tqe_next;                                               \
	struct type **tqe_prev;                                              \
}

/* 
 * tail queue access methods 
 */
#define	UFIBER_TAILQ_FIRST(head)      ((head)->tqh_first)
#define	UFIBER_TAILQ_END(head)        NULL
#define	UFIBER_TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
#define UFIBER_TAILQ_LAST(head, headname)                                      \
	(*(((struct headname *)((head)->tqh_last))->tqh_last))
/* XXX */
#define UFIBER_TAILQ_PREV(elm, headname, field)                                \
	(*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
#define	UFIBER_TAILQ_EMPTY(head)                                               \
	(UFIBER_TAILQ_FIRST(head) == UFIBER_TAILQ_END(head))

#define UFIBER_TAILQ_FOREACH(var, head, field)                                 \
	for((var) = UFIBER_TAILQ_FIRST(head);                                  \
	    (var) != UFIBER_TAILQ_END(head);                                   \
	    (var) = UFIBER_TAILQ_NEXT(var, field))

#define	UFIBER_TAILQ_FOREACH_SAFE(var, head, field, tvar)                      \
	for ((var) = UFIBER_TAILQ_FIRST(head);                                 \
	    (var) != UFIBER_TAILQ_END(head) &&                                 \
	    ((tvar) = UFIBER_TAILQ_NEXT(var, field), 1);                       \
	    (var) = (tvar))


#define UFIBER_TAILQ_FOREACH_REVERSE(var, head, headname, field)               \
	for((var) = UFIBER_TAILQ_LAST(head, headname);                         \
	    (var) != UFIBER_TAILQ_END(head);                                   \
	    (var) = UFIBER_TAILQ_PREV(var, headname, field))

#define	UFIBER_TAILQ_FOREACH_REVERSE_SAFE(var, head, headname, field, tvar)    \
	for ((var) = UFIBER_TAILQ_LAST(head, headname);                        \
	    (var) != UFIBER_TAILQ_END(head) &&                                 \
	    ((tvar) = UFIBER_TAILQ_PREV(var, headname, field), 1);             \
	    (var) = (tvar))

/*
 * Tail queue functions.
 */
#define	UFIBER_TAILQ_INIT(head) do {                                           \
	(head)->tqh_first = NULL;                                            \
	(head)->tqh_last = &(head)->tqh_first;                               \
} while (0)

#define UFIBER_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 UFIBER_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 UFIBER_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	UFIBER_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 UFIBER_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;                      \
	UFIBER_Q_INVALIDATE((elm)->field.tqe_prev);                            \
	UFIBER_Q_INVALIDATE((elm)->field.tqe_next);                            \
} while (0)

#define UFIBER_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);                                    \
	UFIBER_Q_INVALIDATE((elm)->field.tqe_prev);                            \
	UFIBER_Q_INVALIDATE((elm)->field.tqe_next);                            \
} while (0)

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

#define UFIBER_CIRCLEQ_HEAD_INITIALIZER(head)                                  \
	{ UFIBER_CIRCLEQ_END(&head), UFIBER_CIRCLEQ_END(&head) }

#define UFIBER_CIRCLEQ_ENTRY(type)                                             \
struct {                                                                     \
	struct type *cqe_next;                                               \
	struct type *cqe_prev;                                               \
}

/*
 * Circular queue access methods 
 */
#define	UFIBER_CIRCLEQ_FIRST(head)      ((head)->cqh_first)
#define	UFIBER_CIRCLEQ_LAST(head)       ((head)->cqh_last)
#define	UFIBER_CIRCLEQ_END(head)        ((void *)(head))
#define	UFIBER_CIRCLEQ_NEXT(elm, field) ((elm)->field.cqe_next)
#define	UFIBER_CIRCLEQ_PREV(elm, field) ((elm)->field.cqe_prev)
#define	UFIBER_CIRCLEQ_EMPTY(head)                                             \
	(UFIBER_CIRCLEQ_FIRST(head) == UFIBER_CIRCLEQ_END(head))

#define UFIBER_CIRCLEQ_FOREACH(var, head, field)                               \
	for((var) = UFIBER_CIRCLEQ_FIRST(head);                                \
	    (var) != UFIBER_CIRCLEQ_END(head);                                 \
	    (var) = UFIBER_CIRCLEQ_NEXT(var, field))

#define	UFIBER_CIRCLEQ_FOREACH_SAFE(var, head, field, tvar)                    \
	for ((var) = UFIBER_CIRCLEQ_FIRST(head);                               \
	    (var) != UFIBER_CIRCLEQ_END(head) &&                               \
	    ((tvar) = UFIBER_CIRCLEQ_NEXT(var, field), 1);                     \
	    (var) = (tvar))

#define UFIBER_CIRCLEQ_FOREACH_REVERSE(var, head, field)                       \
	for((var) = UFIBER_CIRCLEQ_LAST(head);                                 \
	    (var) != UFIBER_CIRCLEQ_END(head);                                 \
	    (var) = UFIBER_CIRCLEQ_PREV(var, field))

#define	UFIBER_CIRCLEQ_FOREACH_REVERSE_SAFE(var, head, headname, field, tvar)  \
	for ((var) = UFIBER_CIRCLEQ_LAST(head, headname);                      \
	    (var) != UFIBER_CIRCLEQ_END(head) &&                               \
	    ((tvar) = UFIBER_CIRCLEQ_PREV(var, headname, field), 1);           \
	    (var) = (tvar))

/*
 * Circular queue functions.
 */
#define	UFIBER_CIRCLEQ_INIT(head) do {                                         \
	(head)->cqh_first = UFIBER_CIRCLEQ_END(head);                          \
	(head)->cqh_last = UFIBER_CIRCLEQ_END(head);                           \
} while (0)

#define UFIBER_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 == UFIBER_CIRCLEQ_END(head))             \
		(head)->cqh_last = (elm);                                    \
	else                                                                 \
		(listelm)->field.cqe_next->field.cqe_prev = (elm);           \
	(listelm)->field.cqe_next = (elm);                                   \
} while (0)

#define UFIBER_CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) do {           \
	(elm)->field.cqe_next = (listelm);                                   \
	(elm)->field.cqe_prev = (listelm)->field.cqe_prev;                   \
	if ((listelm)->field.cqe_prev == UFIBER_CIRCLEQ_END(head))             \
		(head)->cqh_first = (elm);                                   \
	else                                                                 \
		(listelm)->field.cqe_prev->field.cqe_next = (elm);           \
	(listelm)->field.cqe_prev = (elm);                                   \
} while (0)

#define UFIBER_CIRCLEQ_INSERT_HEAD(head, elm, field) do {                      \
	(elm)->field.cqe_next = (head)->cqh_first;                           \
	(elm)->field.cqe_prev = UFIBER_CIRCLEQ_END(head);                      \
	if ((head)->cqh_last == UFIBER_CIRCLEQ_END(head))                      \
		(head)->cqh_last = (elm);                                    \
	else                                                                 \
		(head)->cqh_first->field.cqe_prev = (elm);                   \
	(head)->cqh_first = (elm);                                           \
} while (0)

#define UFIBER_CIRCLEQ_INSERT_TAIL(head, elm, field) do {                      \
	(elm)->field.cqe_next = UFIBER_CIRCLEQ_END(head);                      \
	(elm)->field.cqe_prev = (head)->cqh_last;                            \
	if ((head)->cqh_first == UFIBER_CIRCLEQ_END(head))                     \
		(head)->cqh_first = (elm);                                   \
	else                                                                 \
		(head)->cqh_last->field.cqe_next = (elm);                    \
	(head)->cqh_last = (elm);                                            \
} while (0)

#define	UFIBER_CIRCLEQ_REMOVE(head, elm, field) do {                           \
	if ((elm)->field.cqe_next == UFIBER_CIRCLEQ_END(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 == UFIBER_CIRCLEQ_END(head))                 \
		(head)->cqh_first = (elm)->field.cqe_next;                   \
	else                                                                 \
		(elm)->field.cqe_prev->field.cqe_next =                      \
		    (elm)->field.cqe_next;                                   \
	UFIBER_Q_INVALIDATE((elm)->field.cqe_prev);                            \
	UFIBER_Q_INVALIDATE((elm)->field.cqe_next);                            \
} while (0)

#define UFIBER_CIRCLEQ_REPLACE(head, elm, elm2, field) do {                    \
	if (((elm2)->field.cqe_next = (elm)->field.cqe_next) ==              \
	    UFIBER_CIRCLEQ_END(head))                                          \
		(head)->cqh_last = (elm2);                                   \
	else                                                                 \
		(elm2)->field.cqe_next->field.cqe_prev = (elm2);             \
	if (((elm2)->field.cqe_prev = (elm)->field.cqe_prev) ==              \
	    UFIBER_CIRCLEQ_END(head))                                          \
		(head)->cqh_first = (elm2);                                  \
	else                                                                 \
		(elm2)->field.cqe_prev->field.cqe_next = (elm2);             \
	UFIBER_Q_INVALIDATE((elm)->field.cqe_prev);                            \
	UFIBER_Q_INVALIDATE((elm)->field.cqe_next);                            \
} while (0)

#endif	/* !_UFIBER_QUEUE_H_ */