/*-
 * 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	8.5 (Berkeley) 8/20/94
 * $FreeBSD$
 */

#ifndef SPDK_QUEUE_EXTRAS_H
#define SPDK_QUEUE_EXTRAS_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 be traversed in either 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_FROM		+	+	+	+
 * _FOREACH_SAFE		+	+	+	+
 * _FOREACH_FROM_SAFE		+	+	+	+
 * _FOREACH_REVERSE		-	-	-	+
 * _FOREACH_REVERSE_FROM	-	-	-	+
 * _FOREACH_REVERSE_SAFE	-	-	-	+
 * _FOREACH_REVERSE_FROM_SAFE	-	-	-	+
 * _INSERT_HEAD			+	+	+	+
 * _INSERT_BEFORE		-	+	-	+
 * _INSERT_AFTER		+	+	+	+
 * _INSERT_TAIL			-	-	+	+
 * _CONCAT			-	-	+	+
 * _REMOVE_AFTER		+	-	+	-
 * _REMOVE_HEAD			+	-	+	-
 * _REMOVE			+	+	+	+
 * _SWAP			+	+	+	+
 *
 */

/*
 * 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 }

/*
 * Singly-linked Tail queue functions.
 */
#define	STAILQ_EMPTY(head)	((head)->stqh_first == NULL)

#define	STAILQ_FIRST(head)	((head)->stqh_first)

#define	STAILQ_FOREACH_FROM(var, head, field)				\
	for ((var) = ((var) ? (var) : STAILQ_FIRST((head)));		\
	   (var);							\
	   (var) = STAILQ_NEXT((var), field))

#define	STAILQ_FOREACH_SAFE(var, head, field, tvar)			\
	for ((var) = STAILQ_FIRST((head));				\
	    (var) && ((tvar) = STAILQ_NEXT((var), field), 1);		\
	    (var) = (tvar))

#define	STAILQ_FOREACH_FROM_SAFE(var, head, field, tvar)		\
	for ((var) = ((var) ? (var) : STAILQ_FIRST((head)));		\
	    (var) && ((tvar) = STAILQ_NEXT((var), field), 1);		\
	    (var) = (tvar))

#define	STAILQ_LAST(head, type, field)					\
	(STAILQ_EMPTY((head)) ? NULL :					\
	    __containerof((head)->stqh_last, struct type, field.stqe_next))

#define	STAILQ_NEXT(elm, field)	((elm)->field.stqe_next)

#define STAILQ_REMOVE_AFTER(head, elm, field) do {			\
	if ((STAILQ_NEXT(elm, field) =					\
	     STAILQ_NEXT(STAILQ_NEXT(elm, field), field)) == NULL)	\
		(head)->stqh_last = &STAILQ_NEXT((elm), field);		\
} while (0)

#define STAILQ_SWAP(head1, head2, type) do {				\
	struct type *swap_first = STAILQ_FIRST(head1);			\
	struct type **swap_last = (head1)->stqh_last;			\
	STAILQ_FIRST(head1) = STAILQ_FIRST(head2);			\
	(head1)->stqh_last = (head2)->stqh_last;			\
	STAILQ_FIRST(head2) = swap_first;				\
	(head2)->stqh_last = swap_last;					\
	if (STAILQ_EMPTY(head1))					\
		(head1)->stqh_last = &STAILQ_FIRST(head1);		\
	if (STAILQ_EMPTY(head2))					\
		(head2)->stqh_last = &STAILQ_FIRST(head2);		\
} while (0)

/*
 * List declarations.
 */
#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.
 */

#if (defined(_KERNEL) && defined(INVARIANTS))
#define	QMD_LIST_CHECK_HEAD(head, field) do {				\
	if (LIST_FIRST((head)) != NULL &&				\
	    LIST_FIRST((head))->field.le_prev !=			\
	     &LIST_FIRST((head)))					\
		panic("Bad list head %p first->prev != head", (head));	\
} while (0)

#define	QMD_LIST_CHECK_NEXT(elm, field) do {				\
	if (LIST_NEXT((elm), field) != NULL &&				\
	    LIST_NEXT((elm), field)->field.le_prev !=			\
	     &((elm)->field.le_next))					\
		panic("Bad link elm %p next->prev != elm", (elm));	\
} while (0)

#define	QMD_LIST_CHECK_PREV(elm, field) do {				\
	if (*(elm)->field.le_prev != (elm))				\
		panic("Bad link elm %p prev->next != elm", (elm));	\
} while (0)
#else
#define	QMD_LIST_CHECK_HEAD(head, field)
#define	QMD_LIST_CHECK_NEXT(elm, field)
#define	QMD_LIST_CHECK_PREV(elm, field)
#endif /* (_KERNEL && INVARIANTS) */

#define	LIST_EMPTY(head)	((head)->lh_first == NULL)

#define	LIST_FIRST(head)	((head)->lh_first)

#define	LIST_FOREACH_FROM(var, head, field)				\
	for ((var) = ((var) ? (var) : LIST_FIRST((head)));		\
	    (var);							\
	    (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))

#define	LIST_FOREACH_FROM_SAFE(var, head, field, tvar)			\
	for ((var) = ((var) ? (var) : LIST_FIRST((head)));		\
	    (var) && ((tvar) = LIST_NEXT((var), field), 1);		\
	    (var) = (tvar))

#define	LIST_NEXT(elm, field)	((elm)->field.le_next)

#define	LIST_PREV(elm, head, type, field)				\
	((elm)->field.le_prev == &LIST_FIRST((head)) ? NULL :		\
	    __containerof((elm)->field.le_prev, struct type, field.le_next))

#define LIST_SWAP(head1, head2, type, field) do {			\
	struct type *swap_tmp = LIST_FIRST((head1));			\
	LIST_FIRST((head1)) = LIST_FIRST((head2));			\
	LIST_FIRST((head2)) = swap_tmp;					\
	if ((swap_tmp = LIST_FIRST((head1))) != NULL)			\
		swap_tmp->field.le_prev = &LIST_FIRST((head1));		\
	if ((swap_tmp = LIST_FIRST((head2))) != NULL)			\
		swap_tmp->field.le_prev = &LIST_FIRST((head2));		\
} while (0)

/*
 * Tail queue functions.
 */
#if (defined(_KERNEL) && defined(INVARIANTS))
#define	QMD_TAILQ_CHECK_HEAD(head, field) do {				\
	if (!TAILQ_EMPTY(head) &&					\
	    TAILQ_FIRST((head))->field.tqe_prev !=			\
	     &TAILQ_FIRST((head)))					\
		panic("Bad tailq head %p first->prev != head", (head));	\
} while (0)

#define	QMD_TAILQ_CHECK_TAIL(head, field) do {				\
	if (*(head)->tqh_last != NULL)					\
		panic("Bad tailq NEXT(%p->tqh_last) != NULL", (head));	\
} while (0)

#define	QMD_TAILQ_CHECK_NEXT(elm, field) do {				\
	if (TAILQ_NEXT((elm), field) != NULL &&				\
	    TAILQ_NEXT((elm), field)->field.tqe_prev !=			\
	     &((elm)->field.tqe_next))					\
		panic("Bad link elm %p next->prev != elm", (elm));	\
} while (0)

#define	QMD_TAILQ_CHECK_PREV(elm, field) do {				\
	if (*(elm)->field.tqe_prev != (elm))				\
		panic("Bad link elm %p prev->next != elm", (elm));	\
} while (0)
#else
#define	QMD_TAILQ_CHECK_HEAD(head, field)
#define	QMD_TAILQ_CHECK_TAIL(head, headname)
#define	QMD_TAILQ_CHECK_NEXT(elm, field)
#define	QMD_TAILQ_CHECK_PREV(elm, field)
#endif /* (_KERNEL && INVARIANTS) */

#define	TAILQ_EMPTY(head)	((head)->tqh_first == NULL)

#define	TAILQ_FIRST(head)	((head)->tqh_first)

#define	TAILQ_FOREACH_FROM(var, head, field)				\
	for ((var) = ((var) ? (var) : TAILQ_FIRST((head)));		\
	    (var);							\
	    (var) = TAILQ_NEXT((var), field))

#define	TAILQ_FOREACH_SAFE(var, head, field, tvar)			\
	for ((var) = TAILQ_FIRST((head));				\
	    (var) && ((tvar) = TAILQ_NEXT((var), field), 1);		\
	    (var) = (tvar))

#define	TAILQ_FOREACH_FROM_SAFE(var, head, field, tvar)			\
	for ((var) = ((var) ? (var) : TAILQ_FIRST((head)));		\
	    (var) && ((tvar) = TAILQ_NEXT((var), field), 1);		\
	    (var) = (tvar))

#define	TAILQ_FOREACH_REVERSE_FROM(var, head, headname, field)		\
	for ((var) = ((var) ? (var) : TAILQ_LAST((head), headname));	\
	    (var);							\
	    (var) = TAILQ_PREV((var), headname, field))

#define	TAILQ_FOREACH_REVERSE_SAFE(var, head, headname, field, tvar)	\
	for ((var) = TAILQ_LAST((head), headname);			\
	    (var) && ((tvar) = TAILQ_PREV((var), headname, field), 1);	\
	    (var) = (tvar))

#define	TAILQ_FOREACH_REVERSE_FROM_SAFE(var, head, headname, field, tvar) \
	for ((var) = ((var) ? (var) : TAILQ_LAST((head), headname));	\
	    (var) && ((tvar) = TAILQ_PREV((var), headname, field), 1);	\
	    (var) = (tvar))

#define	TAILQ_LAST(head, headname)					\
	(*(((struct headname *)((head)->tqh_last))->tqh_last))

#define	TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)

#define	TAILQ_PREV(elm, headname, field)				\
	(*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))

#define TAILQ_SWAP(head1, head2, type, field) do {			\
	struct type *swap_first = (head1)->tqh_first;			\
	struct type **swap_last = (head1)->tqh_last;			\
	(head1)->tqh_first = (head2)->tqh_first;			\
	(head1)->tqh_last = (head2)->tqh_last;				\
	(head2)->tqh_first = swap_first;				\
	(head2)->tqh_last = swap_last;					\
	if ((swap_first = (head1)->tqh_first) != NULL)			\
		swap_first->field.tqe_prev = &(head1)->tqh_first;	\
	else								\
		(head1)->tqh_last = &(head1)->tqh_first;		\
	if ((swap_first = (head2)->tqh_first) != NULL)			\
		swap_first->field.tqe_prev = &(head2)->tqh_first;	\
	else								\
		(head2)->tqh_last = &(head2)->tqh_first;		\
} while (0)

#endif