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				|  |  | +/*
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				|  |  | + * Copyright (c) 1991, 1993
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				|  |  | + *	The Regents of the University of California.  All rights reserved.
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				|  |  | + *
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				|  |  | + * Redistribution and use in source and binary forms, with or without
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				|  |  | + * modification, are permitted provided that the following conditions
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				|  |  | + * are met:
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				|  |  | + * 1. Redistributions of source code must retain the above copyright
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				|  |  | + *    notice, this list of conditions and the following disclaimer.
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				|  |  | + * 2. Redistributions in binary form must reproduce the above copyright
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				|  |  | + *    notice, this list of conditions and the following disclaimer in the
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				|  |  | + *    documentation and/or other materials provided with the distribution.
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				|  |  | + * 4. Neither the name of the University nor the names of its contributors
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				|  |  | + *    may be used to endorse or promote products derived from this software
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				|  |  | + *    without specific prior written permission.
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				|  |  | + *
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				|  |  | + * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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				|  |  | + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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				|  |  | + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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				|  |  | + * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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				|  |  | + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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				|  |  | + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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				|  |  | + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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				|  |  | + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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				|  |  | + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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				|  |  | + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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				|  |  | + * SUCH DAMAGE.
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				|  |  | + *
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				|  |  | + *	@(#)queue.h	8.3 (Berkeley) 12/13/93
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				|  |  | + */
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				|  |  | +
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				|  |  | +#ifndef	_SYS_QUEUE_H
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				|  |  | +#define	_SYS_QUEUE_H 1
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				|  |  | +
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				|  |  | +/*
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				|  |  | + * This file defines three types of data structures: lists, tail queues,
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				|  |  | + * and circular queues.
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				|  |  | + *
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				|  |  | + * A list is headed by a single forward pointer (or an array of forward
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				|  |  | + * pointers for a hash table header). The elements are doubly linked
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				|  |  | + * so that an arbitrary element can be removed without a need to
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				|  |  | + * traverse the list. New elements can be added to the list after
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				|  |  | + * an existing element or at the head of the list. A list may only be
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				|  |  | + * traversed in the forward direction.
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				|  |  | + *
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				|  |  | + * A tail queue is headed by a pair of pointers, one to the head of the
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				|  |  | + * list and the other to the tail of the list. The elements are doubly
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				|  |  | + * linked so that an arbitrary element can be removed without a need to
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				|  |  | + * traverse the list. New elements can be added to the list after
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				|  |  | + * an existing element, at the head of the list, or at the end of the
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				|  |  | + * list. A tail queue may only be traversed in the forward direction.
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				|  |  | + *
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				|  |  | + * A circle queue is headed by a pair of pointers, one to the head of the
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				|  |  | + * list and the other to the tail of the list. The elements are doubly
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				|  |  | + * linked so that an arbitrary element can be removed without a need to
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				|  |  | + * traverse the list. New elements can be added to the list before or after
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				|  |  | + * an existing element, at the head of the list, or at the end of the list.
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				|  |  | + * A circle queue may be traversed in either direction, but has a more
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				|  |  | + * complex end of list detection.
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				|  |  | + *
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				|  |  | + * For details on the use of these macros, see the queue(3) manual page.
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				|  |  | + */
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				|  |  | +
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				|  |  | +/*
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				|  |  | + * List definitions.
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				|  |  | + */
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				|  |  | +#define LIST_HEAD(name, type)						\
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				|  |  | +struct name {								\
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				|  |  | +	struct type *lh_first;	/* first element */			\
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				|  |  | +}
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				|  |  | +
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				|  |  | +#define LIST_ENTRY(type)						\
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				|  |  | +struct {								\
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				|  |  | +	struct type *le_next;	/* next element */			\
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				|  |  | +	struct type **le_prev;	/* address of previous next element */	\
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				|  |  | +}
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				|  |  | +
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				|  |  | +/*
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				|  |  | + * List functions.
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				|  |  | + */
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				|  |  | +#define	LIST_INIT(head) {						\
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				|  |  | +	(head)->lh_first = NULL;					\
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				|  |  | +}
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				|  |  | +
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				|  |  | +#define LIST_INSERT_AFTER(listelm, elm, field) {			\
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				|  |  | +	if (((elm)->field.le_next = (listelm)->field.le_next) != NULL)	\
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				|  |  | +		(listelm)->field.le_next->field.le_prev =		\
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				|  |  | +		    &(elm)->field.le_next;				\
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				|  |  | +	(listelm)->field.le_next = (elm);				\
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				|  |  | +	(elm)->field.le_prev = &(listelm)->field.le_next;		\
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				|  |  | +}
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				|  |  | +
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				|  |  | +#define LIST_INSERT_HEAD(head, elm, field) {				\
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				|  |  | +	if (((elm)->field.le_next = (head)->lh_first) != NULL)		\
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				|  |  | +		(head)->lh_first->field.le_prev = &(elm)->field.le_next;\
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				|  |  | +	(head)->lh_first = (elm);					\
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				|  |  | +	(elm)->field.le_prev = &(head)->lh_first;			\
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				|  |  | +}
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				|  |  | +
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				|  |  | +#define LIST_REMOVE(elm, field) {					\
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				|  |  | +	if ((elm)->field.le_next != NULL)				\
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				|  |  | +		(elm)->field.le_next->field.le_prev = 			\
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				|  |  | +		    (elm)->field.le_prev;				\
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				|  |  | +	*(elm)->field.le_prev = (elm)->field.le_next;			\
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				|  |  | +}
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				|  |  | +
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				|  |  | +/*
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				|  |  | + * Tail queue definitions.
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				|  |  | + */
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				|  |  | +#define TAILQ_HEAD(name, type)						\
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				|  |  | +struct name {								\
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				|  |  | +	struct type *tqh_first;	/* first element */			\
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				|  |  | +	struct type **tqh_last;	/* addr of last next element */		\
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				|  |  | +}
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				|  |  | +
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				|  |  | +#define TAILQ_ENTRY(type)						\
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				|  |  | +struct {								\
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				|  |  | +	struct type *tqe_next;	/* next element */			\
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				|  |  | +	struct type **tqe_prev;	/* address of previous next element */	\
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				|  |  | +}
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				|  |  | +
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				|  |  | +/*
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				|  |  | + * Tail queue functions.
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				|  |  | + */
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				|  |  | +#define	TAILQ_INIT(head) {						\
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				|  |  | +	(head)->tqh_first = NULL;					\
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				|  |  | +	(head)->tqh_last = &(head)->tqh_first;				\
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				|  |  | +}
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				|  |  | +
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				|  |  | +#define TAILQ_INSERT_HEAD(head, elm, field) {				\
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				|  |  | +	if (((elm)->field.tqe_next = (head)->tqh_first) != NULL)	\
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				|  |  | +		(elm)->field.tqe_next->field.tqe_prev =			\
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				|  |  | +		    &(elm)->field.tqe_next;				\
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				|  |  | +	else								\
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				|  |  | +		(head)->tqh_last = &(elm)->field.tqe_next;		\
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				|  |  | +	(head)->tqh_first = (elm);					\
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				|  |  | +	(elm)->field.tqe_prev = &(head)->tqh_first;			\
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				|  |  | +}
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				|  |  | +
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				|  |  | +#define TAILQ_INSERT_TAIL(head, elm, field) {				\
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				|  |  | +	(elm)->field.tqe_next = NULL;					\
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				|  |  | +	(elm)->field.tqe_prev = (head)->tqh_last;			\
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				|  |  | +	*(head)->tqh_last = (elm);					\
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				|  |  | +	(head)->tqh_last = &(elm)->field.tqe_next;			\
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				|  |  | +}
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				|  |  | +
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				|  |  | +#define TAILQ_INSERT_AFTER(head, listelm, elm, field) {			\
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				|  |  | +	if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\
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				|  |  | +		(elm)->field.tqe_next->field.tqe_prev = 		\
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				|  |  | +		    &(elm)->field.tqe_next;				\
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				|  |  | +	else								\
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				|  |  | +		(head)->tqh_last = &(elm)->field.tqe_next;		\
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				|  |  | +	(listelm)->field.tqe_next = (elm);				\
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				|  |  | +	(elm)->field.tqe_prev = &(listelm)->field.tqe_next;		\
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				|  |  | +}
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				|  |  | +
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				|  |  | +#define TAILQ_REMOVE(head, elm, field) {				\
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				|  |  | +	if (((elm)->field.tqe_next) != NULL)				\
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				|  |  | +		(elm)->field.tqe_next->field.tqe_prev = 		\
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				|  |  | +		    (elm)->field.tqe_prev;				\
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				|  |  | +	else								\
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				|  |  | +		(head)->tqh_last = (elm)->field.tqe_prev;		\
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				|  |  | +	*(elm)->field.tqe_prev = (elm)->field.tqe_next;			\
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				|  |  | +}
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				|  |  | +
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				|  |  | +/*
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				|  |  | + * Circular queue definitions.
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				|  |  | + */
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				|  |  | +#define CIRCLEQ_HEAD(name, type)					\
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				|  |  | +struct name {								\
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				|  |  | +	struct type *cqh_first;		/* first element */		\
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				|  |  | +	struct type *cqh_last;		/* last element */		\
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				|  |  | +}
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				|  |  | +
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				|  |  | +#define CIRCLEQ_ENTRY(type)						\
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				|  |  | +struct {								\
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				|  |  | +	struct type *cqe_next;		/* next element */		\
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				|  |  | +	struct type *cqe_prev;		/* previous element */		\
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				|  |  | +}
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				|  |  | +
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				|  |  | +/*
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				|  |  | + * Circular queue functions.
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				|  |  | + */
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				|  |  | +#define	CIRCLEQ_INIT(head) {						\
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				|  |  | +	(head)->cqh_first = (void *)(head);				\
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				|  |  | +	(head)->cqh_last = (void *)(head);				\
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				|  |  | +}
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				|  |  | +
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				|  |  | +#define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) {		\
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				|  |  | +	(elm)->field.cqe_next = (listelm)->field.cqe_next;		\
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				|  |  | +	(elm)->field.cqe_prev = (listelm);				\
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				|  |  | +	if ((listelm)->field.cqe_next == (void *)(head))		\
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				|  |  | +		(head)->cqh_last = (elm);				\
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				|  |  | +	else								\
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				|  |  | +		(listelm)->field.cqe_next->field.cqe_prev = (elm);	\
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				|  |  | +	(listelm)->field.cqe_next = (elm);				\
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				|  |  | +}
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				|  |  | +
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				|  |  | +#define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) {		\
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				|  |  | +	(elm)->field.cqe_next = (listelm);				\
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				|  |  | +	(elm)->field.cqe_prev = (listelm)->field.cqe_prev;		\
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				|  |  | +	if ((listelm)->field.cqe_prev == (void *)(head))		\
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				|  |  | +		(head)->cqh_first = (elm);				\
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				|  |  | +	else								\
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				|  |  | +		(listelm)->field.cqe_prev->field.cqe_next = (elm);	\
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				|  |  | +	(listelm)->field.cqe_prev = (elm);				\
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				|  |  | +}
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				|  |  | +
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				|  |  | +#define CIRCLEQ_INSERT_HEAD(head, elm, field) {				\
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				|  |  | +	(elm)->field.cqe_next = (head)->cqh_first;			\
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				|  |  | +	(elm)->field.cqe_prev = (void *)(head);				\
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				|  |  | +	if ((head)->cqh_last == (void *)(head))				\
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				|  |  | +		(head)->cqh_last = (elm);				\
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				|  |  | +	else								\
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				|  |  | +		(head)->cqh_first->field.cqe_prev = (elm);		\
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				|  |  | +	(head)->cqh_first = (elm);					\
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				|  |  | +}
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				|  |  | +
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				|  |  | +#define CIRCLEQ_INSERT_TAIL(head, elm, field) {				\
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				|  |  | +	(elm)->field.cqe_next = (void *)(head);				\
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				|  |  | +	(elm)->field.cqe_prev = (head)->cqh_last;			\
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				|  |  | +	if ((head)->cqh_first == (void *)(head))			\
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				|  |  | +		(head)->cqh_first = (elm);				\
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				|  |  | +	else								\
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				|  |  | +		(head)->cqh_last->field.cqe_next = (elm);		\
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				|  |  | +	(head)->cqh_last = (elm);					\
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				|  |  | +}
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				|  |  | +
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				|  |  | +#define	CIRCLEQ_REMOVE(head, elm, field) {				\
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				|  |  | +	if ((elm)->field.cqe_next == (void *)(head))			\
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				|  |  | +		(head)->cqh_last = (elm)->field.cqe_prev;		\
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				|  |  | +	else								\
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				|  |  | +		(elm)->field.cqe_next->field.cqe_prev =			\
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				|  |  | +		    (elm)->field.cqe_prev;				\
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				|  |  | +	if ((elm)->field.cqe_prev == (void *)(head))			\
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				|  |  | +		(head)->cqh_first = (elm)->field.cqe_next;		\
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				|  |  | +	else								\
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				|  |  | +		(elm)->field.cqe_prev->field.cqe_next =			\
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				|  |  | +		    (elm)->field.cqe_next;				\
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				|  |  | +}
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				|  |  | +#endif	/* sys/queue.h */
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