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- FreeBSD macros that implement linked lists

Jan Janak authored on 29/03/2007 10:00:26
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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	8.5 (Berkeley) 8/20/94
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+ * $FreeBSD: /repoman/r/ncvs/src/sys/sys/queue.h,v 1.68 2006/10/24 11:20:29 ru Exp $
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+ */
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+
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+#ifndef _LIST_H
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+#define	_LIST_H
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+
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+#include <sys/cdefs.h>
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+
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+/*
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+ * This file defines four types of data structures: singly-linked lists,
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+ * singly-linked tail queues, lists and tail queues.
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+ *
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+ * A singly-linked list is headed by a single forward pointer. The elements
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+ * are singly linked for minimum space and pointer manipulation overhead at
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+ * the expense of O(n) removal for arbitrary elements. New elements can be
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+ * added to the list after an existing element or at the head of the list.
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+ * Elements being removed from the head of the list should use the explicit
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+ * macro for this purpose for optimum efficiency. A singly-linked list may
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+ * only be traversed in the forward direction.  Singly-linked lists are ideal
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+ * for applications with large datasets and few or no removals or for
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+ * implementing a LIFO queue.
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+ *
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+ * A singly-linked tail queue is headed by a pair of pointers, one to the
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+ * head of the list and the other to the tail of the list. The elements are
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+ * singly linked for minimum space and pointer manipulation overhead at the
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+ * expense of O(n) removal for arbitrary elements. New elements can be added
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+ * to the list after an existing element, at the head of the list, or at the
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+ * end of the list. Elements being removed from the head of the tail queue
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+ * should use the explicit macro for this purpose for optimum efficiency.
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+ * A singly-linked tail queue may only be traversed in the forward direction.
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+ * Singly-linked tail queues are ideal for applications with large datasets
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+ * and few or no removals or for implementing a FIFO queue.
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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 before
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+ * or after an existing element or at the head of the list. A list
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+ * may only be 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 before or
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+ * after an existing element, at the head of the list, or at the end of
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+ * the list. A tail queue may be traversed in either direction.
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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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+ *				SLIST	LIST	STAILQ	TAILQ
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+ * _HEAD			+	+	+	+
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+ * _HEAD_INITIALIZER		+	+	+	+
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+ * _ENTRY			+	+	+	+
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+ * _INIT			+	+	+	+
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+ * _EMPTY			+	+	+	+
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+ * _FIRST			+	+	+	+
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+ * _NEXT			+	+	+	+
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+ * _PREV			-	-	-	+
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+ * _LAST			-	-	+	+
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+ * _FOREACH			+	+	+	+
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+ * _FOREACH_SAFE		+	+	+	+
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+ * _FOREACH_REVERSE		-	-	-	+
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+ * _FOREACH_REVERSE_SAFE	-	-	-	+
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+ * _INSERT_HEAD			+	+	+	+
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+ * _INSERT_BEFORE		-	+	-	+
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+ * _INSERT_AFTER		+	+	+	+
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+ * _INSERT_TAIL			-	-	+	+
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+ * _CONCAT			-	-	+	+
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+ * _REMOVE_HEAD			+	-	+	-
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+ * _REMOVE			+	+	+	+
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+ *
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+ */
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+#ifdef QUEUE_MACRO_DEBUG
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+/* Store the last 2 places the queue element or head was altered */
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+struct qm_trace {
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+	char * lastfile;
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+	int lastline;
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+	char * prevfile;
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+	int prevline;
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+};
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+
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+#define	TRACEBUF	struct qm_trace trace;
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+#define	TRASHIT(x)	do {(x) = (void *)-1;} while (0)
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+
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+#define	QMD_TRACE_HEAD(head) do {					\
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+	(head)->trace.prevline = (head)->trace.lastline;		\
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+	(head)->trace.prevfile = (head)->trace.lastfile;		\
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+	(head)->trace.lastline = __LINE__;				\
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+	(head)->trace.lastfile = __FILE__;				\
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+} while (0)
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+
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+#define	QMD_TRACE_ELEM(elem) do {					\
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+	(elem)->trace.prevline = (elem)->trace.lastline;		\
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+	(elem)->trace.prevfile = (elem)->trace.lastfile;		\
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+	(elem)->trace.lastline = __LINE__;				\
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+	(elem)->trace.lastfile = __FILE__;				\
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+} while (0)
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+
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+#else
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+#define	QMD_TRACE_ELEM(elem)
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+#define	QMD_TRACE_HEAD(head)
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+#define	TRACEBUF
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+#define	TRASHIT(x)
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+#endif	/* QUEUE_MACRO_DEBUG */
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+
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+/*
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+ * Singly-linked List declarations.
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+ */
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+#define	SLIST_HEAD(name, type)						\
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+struct name {								\
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+	struct type *slh_first;	/* first element */			\
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+}
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+
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+#define	SLIST_HEAD_INITIALIZER(head)					\
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+	{ NULL }
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+
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+#define	SLIST_ENTRY(type)						\
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+struct {								\
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+	struct type *sle_next;	/* next element */			\
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+}
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+
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+/*
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+ * Singly-linked List functions.
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+ */
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+#define	SLIST_EMPTY(head)	((head)->slh_first == NULL)
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+
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+#define	SLIST_FIRST(head)	((head)->slh_first)
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+
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+#define	SLIST_FOREACH(var, head, field)					\
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+	for ((var) = SLIST_FIRST((head));				\
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+	    (var);							\
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+	    (var) = SLIST_NEXT((var), field))
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+
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+#define	SLIST_FOREACH_SAFE(var, head, field, tvar)			\
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+	for ((var) = SLIST_FIRST((head));				\
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+	    (var) && ((tvar) = SLIST_NEXT((var), field), 1);		\
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+	    (var) = (tvar))
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+
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+#define	SLIST_FOREACH_PREVPTR(var, varp, head, field)			\
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+	for ((varp) = &SLIST_FIRST((head));				\
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+	    ((var) = *(varp)) != NULL;					\
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+	    (varp) = &SLIST_NEXT((var), field))
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+
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+#define	SLIST_INIT(head) do {						\
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+	SLIST_FIRST((head)) = NULL;					\
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+} while (0)
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+
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+#define	SLIST_INSERT_AFTER(slistelm, elm, field) do {			\
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+	SLIST_NEXT((elm), field) = SLIST_NEXT((slistelm), field);	\
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+	SLIST_NEXT((slistelm), field) = (elm);				\
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+} while (0)
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+
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+#define	SLIST_INSERT_HEAD(head, elm, field) do {			\
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+	SLIST_NEXT((elm), field) = SLIST_FIRST((head));			\
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+	SLIST_FIRST((head)) = (elm);					\
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+} while (0)
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+
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+#define	SLIST_NEXT(elm, field)	((elm)->field.sle_next)
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+
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+#define	SLIST_REMOVE(head, elm, type, field) do {			\
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+	if (SLIST_FIRST((head)) == (elm)) {				\
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+		SLIST_REMOVE_HEAD((head), field);			\
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+	}								\
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+	else {								\
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+		struct type *curelm = SLIST_FIRST((head));		\
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+		while (SLIST_NEXT(curelm, field) != (elm))		\
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+			curelm = SLIST_NEXT(curelm, field);		\
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+		SLIST_NEXT(curelm, field) =				\
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+		    SLIST_NEXT(SLIST_NEXT(curelm, field), field);	\
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+	}								\
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+	TRASHIT((elm)->field.sle_next);					\
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+} while (0)
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+
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+#define	SLIST_REMOVE_HEAD(head, field) do {				\
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+	SLIST_FIRST((head)) = SLIST_NEXT(SLIST_FIRST((head)), field);	\
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+} while (0)
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+
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+/*
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+ * Singly-linked Tail queue declarations.
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+ */
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+#define	STAILQ_HEAD(name, type)						\
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+struct name {								\
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+	struct type *stqh_first;/* first element */			\
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+	struct type **stqh_last;/* addr of last next element */		\
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+}
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+
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+#define	STAILQ_HEAD_INITIALIZER(head)					\
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+	{ NULL, &(head).stqh_first }
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+
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+#define	STAILQ_ENTRY(type)						\
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+struct {								\
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+	struct type *stqe_next;	/* next element */			\
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+}
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+
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+/*
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+ * Singly-linked Tail queue functions.
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+ */
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+#define	STAILQ_CONCAT(head1, head2) do {				\
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+	if (!STAILQ_EMPTY((head2))) {					\
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+		*(head1)->stqh_last = (head2)->stqh_first;		\
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+		(head1)->stqh_last = (head2)->stqh_last;		\
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+		STAILQ_INIT((head2));					\
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+	}								\
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+} while (0)
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+
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+#define	STAILQ_EMPTY(head)	((head)->stqh_first == NULL)
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+
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+#define	STAILQ_FIRST(head)	((head)->stqh_first)
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+
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+#define	STAILQ_FOREACH(var, head, field)				\
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+	for((var) = STAILQ_FIRST((head));				\
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+	   (var);							\
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+	   (var) = STAILQ_NEXT((var), field))
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+
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+
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+#define	STAILQ_FOREACH_SAFE(var, head, field, tvar)			\
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+	for ((var) = STAILQ_FIRST((head));				\
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+	    (var) && ((tvar) = STAILQ_NEXT((var), field), 1);		\
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+	    (var) = (tvar))
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+
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+#define	STAILQ_INIT(head) do {						\
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+	STAILQ_FIRST((head)) = NULL;					\
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+	(head)->stqh_last = &STAILQ_FIRST((head));			\
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+} while (0)
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+
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+#define	STAILQ_INSERT_AFTER(head, tqelm, elm, field) do {		\
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+	if ((STAILQ_NEXT((elm), field) = STAILQ_NEXT((tqelm), field)) == NULL)\
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+		(head)->stqh_last = &STAILQ_NEXT((elm), field);		\
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+	STAILQ_NEXT((tqelm), field) = (elm);				\
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+} while (0)
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+
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+#define	STAILQ_INSERT_HEAD(head, elm, field) do {			\
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+	if ((STAILQ_NEXT((elm), field) = STAILQ_FIRST((head))) == NULL)	\
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+		(head)->stqh_last = &STAILQ_NEXT((elm), field);		\
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+	STAILQ_FIRST((head)) = (elm);					\
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+} while (0)
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+
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+#define	STAILQ_INSERT_TAIL(head, elm, field) do {			\
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+	STAILQ_NEXT((elm), field) = NULL;				\
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+	*(head)->stqh_last = (elm);					\
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+	(head)->stqh_last = &STAILQ_NEXT((elm), field);			\
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+} while (0)
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+
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+#define	STAILQ_LAST(head, type, field)					\
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+	(STAILQ_EMPTY((head)) ?						\
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+		NULL :							\
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+	        ((struct type *)(void *)				\
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+		((char *)((head)->stqh_last) - __offsetof(struct type, field))))
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+
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+#define	STAILQ_NEXT(elm, field)	((elm)->field.stqe_next)
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+
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+#define	STAILQ_REMOVE(head, elm, type, field) do {			\
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+	if (STAILQ_FIRST((head)) == (elm)) {				\
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+		STAILQ_REMOVE_HEAD((head), field);			\
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+	}								\
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+	else {								\
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+		struct type *curelm = STAILQ_FIRST((head));		\
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+		while (STAILQ_NEXT(curelm, field) != (elm))		\
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+			curelm = STAILQ_NEXT(curelm, field);		\
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+		if ((STAILQ_NEXT(curelm, field) =			\
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+		     STAILQ_NEXT(STAILQ_NEXT(curelm, field), field)) == NULL)\
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+			(head)->stqh_last = &STAILQ_NEXT((curelm), field);\
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+	}								\
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+	TRASHIT((elm)->field.stqe_next);				\
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+} while (0)
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+
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+#define	STAILQ_REMOVE_HEAD(head, field) do {				\
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+	if ((STAILQ_FIRST((head)) =					\
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+	     STAILQ_NEXT(STAILQ_FIRST((head)), field)) == NULL)		\
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+		(head)->stqh_last = &STAILQ_FIRST((head));		\
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+} while (0)
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+
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+/*
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+ * List declarations.
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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_HEAD_INITIALIZER(head)					\
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+	{ NULL }
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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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+
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+#define	LIST_EMPTY(head)	((head)->lh_first == NULL)
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+
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+#define	LIST_FIRST(head)	((head)->lh_first)
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+
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+#define	LIST_FOREACH(var, head, field)					\
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+	for ((var) = LIST_FIRST((head));				\
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+	    (var);							\
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+	    (var) = LIST_NEXT((var), field))
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+
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+#define	LIST_FOREACH_SAFE(var, head, field, tvar)			\
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+	for ((var) = LIST_FIRST((head));				\
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+	    (var) && ((tvar) = LIST_NEXT((var), field), 1);		\
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+	    (var) = (tvar))
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+
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+#define	LIST_INIT(head) do {						\
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+	LIST_FIRST((head)) = NULL;					\
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+} while (0)
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+
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+#define	LIST_INSERT_AFTER(listelm, elm, field) do {			\
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+	QMD_LIST_CHECK_NEXT(listelm, field);				\
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+	if ((LIST_NEXT((elm), field) = LIST_NEXT((listelm), field)) != NULL)\
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+		LIST_NEXT((listelm), field)->field.le_prev =		\
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+		    &LIST_NEXT((elm), field);				\
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+	LIST_NEXT((listelm), field) = (elm);				\
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+	(elm)->field.le_prev = &LIST_NEXT((listelm), field);		\
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+} while (0)
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+
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+#define	LIST_INSERT_BEFORE(listelm, elm, field) do {			\
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+	QMD_LIST_CHECK_PREV(listelm, field);				\
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+	(elm)->field.le_prev = (listelm)->field.le_prev;		\
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+	LIST_NEXT((elm), field) = (listelm);				\
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+	*(listelm)->field.le_prev = (elm);				\
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+	(listelm)->field.le_prev = &LIST_NEXT((elm), field);		\
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+} while (0)
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+
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+#define	LIST_INSERT_HEAD(head, elm, field) do {				\
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+	QMD_LIST_CHECK_HEAD((head), field);				\
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+	if ((LIST_NEXT((elm), field) = LIST_FIRST((head))) != NULL)	\
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+		LIST_FIRST((head))->field.le_prev = &LIST_NEXT((elm), field);\
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+	LIST_FIRST((head)) = (elm);					\
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+	(elm)->field.le_prev = &LIST_FIRST((head));			\
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+} while (0)
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+
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+#define	LIST_NEXT(elm, field)	((elm)->field.le_next)
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+
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+#define	LIST_REMOVE(elm, field) do {					\
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+	QMD_LIST_CHECK_NEXT(elm, field);				\
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+	QMD_LIST_CHECK_PREV(elm, field);				\
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+	if (LIST_NEXT((elm), field) != NULL)				\
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+		LIST_NEXT((elm), field)->field.le_prev = 		\
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+		    (elm)->field.le_prev;				\
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+	*(elm)->field.le_prev = LIST_NEXT((elm), field);		\
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+	TRASHIT((elm)->field.le_next);					\
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+	TRASHIT((elm)->field.le_prev);					\
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+} while (0)
379
+
380
+/*
381
+ * Tail queue declarations.
382
+ */
383
+#define	TAILQ_HEAD(name, type)						\
384
+struct name {								\
385
+	struct type *tqh_first;	/* first element */			\
386
+	struct type **tqh_last;	/* addr of last next element */		\
387
+	TRACEBUF							\
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+}
389
+
390
+#define	TAILQ_HEAD_INITIALIZER(head)					\
391
+	{ NULL, &(head).tqh_first }
392
+
393
+#define	TAILQ_ENTRY(type)						\
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+struct {								\
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+	struct type *tqe_next;	/* next element */			\
396
+	struct type **tqe_prev;	/* address of previous next element */	\
397
+	TRACEBUF							\
398
+}
399
+
400
+/*
401
+ * Tail queue functions.
402
+ */
403
+
404
+#define	TAILQ_CONCAT(head1, head2, field) do {				\
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+	if (!TAILQ_EMPTY(head2)) {					\
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+		*(head1)->tqh_last = (head2)->tqh_first;		\
407
+		(head2)->tqh_first->field.tqe_prev = (head1)->tqh_last;	\
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+		(head1)->tqh_last = (head2)->tqh_last;			\
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+		TAILQ_INIT((head2));					\
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+		QMD_TRACE_HEAD(head1);					\
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+		QMD_TRACE_HEAD(head2);					\
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+	}								\
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+} while (0)
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+
415
+#define	TAILQ_EMPTY(head)	((head)->tqh_first == NULL)
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+
417
+#define	TAILQ_FIRST(head)	((head)->tqh_first)
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+
419
+#define	TAILQ_FOREACH(var, head, field)					\
420
+	for ((var) = TAILQ_FIRST((head));				\
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+	    (var);							\
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+	    (var) = TAILQ_NEXT((var), field))
423
+
424
+#define	TAILQ_FOREACH_SAFE(var, head, field, tvar)			\
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+	for ((var) = TAILQ_FIRST((head));				\
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+	    (var) && ((tvar) = TAILQ_NEXT((var), field), 1);		\
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+	    (var) = (tvar))
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+
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+#define	TAILQ_FOREACH_REVERSE(var, head, headname, field)		\
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+	for ((var) = TAILQ_LAST((head), headname);			\
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+	    (var);							\
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+	    (var) = TAILQ_PREV((var), headname, field))
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+
434
+#define	TAILQ_FOREACH_REVERSE_SAFE(var, head, headname, field, tvar)	\
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+	for ((var) = TAILQ_LAST((head), headname);			\
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+	    (var) && ((tvar) = TAILQ_PREV((var), headname, field), 1);	\
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+	    (var) = (tvar))
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+
439
+#define	TAILQ_INIT(head) do {						\
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+	TAILQ_FIRST((head)) = NULL;					\
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+	(head)->tqh_last = &TAILQ_FIRST((head));			\
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+	QMD_TRACE_HEAD(head);						\
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+} while (0)
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+
445
+#define	TAILQ_INSERT_AFTER(head, listelm, elm, field) do {		\
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+	QMD_TAILQ_CHECK_NEXT(listelm, field);				\
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+	if ((TAILQ_NEXT((elm), field) = TAILQ_NEXT((listelm), field)) != NULL)\
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+		TAILQ_NEXT((elm), field)->field.tqe_prev = 		\
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+		    &TAILQ_NEXT((elm), field);				\
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+	else {								\
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+		(head)->tqh_last = &TAILQ_NEXT((elm), field);		\
452
+		QMD_TRACE_HEAD(head);					\
453
+	}								\
454
+	TAILQ_NEXT((listelm), field) = (elm);				\
455
+	(elm)->field.tqe_prev = &TAILQ_NEXT((listelm), field);		\
456
+	QMD_TRACE_ELEM(&(elm)->field);					\
457
+	QMD_TRACE_ELEM(&listelm->field);				\
458
+} while (0)
459
+
460
+#define	TAILQ_INSERT_BEFORE(listelm, elm, field) do {			\
461
+	QMD_TAILQ_CHECK_PREV(listelm, field);				\
462
+	(elm)->field.tqe_prev = (listelm)->field.tqe_prev;		\
463
+	TAILQ_NEXT((elm), field) = (listelm);				\
464
+	*(listelm)->field.tqe_prev = (elm);				\
465
+	(listelm)->field.tqe_prev = &TAILQ_NEXT((elm), field);		\
466
+	QMD_TRACE_ELEM(&(elm)->field);					\
467
+	QMD_TRACE_ELEM(&listelm->field);				\
468
+} while (0)
469
+
470
+#define	TAILQ_INSERT_HEAD(head, elm, field) do {			\
471
+	QMD_TAILQ_CHECK_HEAD(head, field);				\
472
+	if ((TAILQ_NEXT((elm), field) = TAILQ_FIRST((head))) != NULL)	\
473
+		TAILQ_FIRST((head))->field.tqe_prev =			\
474
+		    &TAILQ_NEXT((elm), field);				\
475
+	else								\
476
+		(head)->tqh_last = &TAILQ_NEXT((elm), field);		\
477
+	TAILQ_FIRST((head)) = (elm);					\
478
+	(elm)->field.tqe_prev = &TAILQ_FIRST((head));			\
479
+	QMD_TRACE_HEAD(head);						\
480
+	QMD_TRACE_ELEM(&(elm)->field);					\
481
+} while (0)
482
+
483
+#define	TAILQ_INSERT_TAIL(head, elm, field) do {			\
484
+	QMD_TAILQ_CHECK_TAIL(head, field);				\
485
+	TAILQ_NEXT((elm), field) = NULL;				\
486
+	(elm)->field.tqe_prev = (head)->tqh_last;			\
487
+	*(head)->tqh_last = (elm);					\
488
+	(head)->tqh_last = &TAILQ_NEXT((elm), field);			\
489
+	QMD_TRACE_HEAD(head);						\
490
+	QMD_TRACE_ELEM(&(elm)->field);					\
491
+} while (0)
492
+
493
+#define	TAILQ_LAST(head, headname)					\
494
+	(*(((struct headname *)((head)->tqh_last))->tqh_last))
495
+
496
+#define	TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
497
+
498
+#define	TAILQ_PREV(elm, headname, field)				\
499
+	(*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
500
+
501
+#define	TAILQ_REMOVE(head, elm, field) do {				\
502
+	QMD_TAILQ_CHECK_NEXT(elm, field);				\
503
+	QMD_TAILQ_CHECK_PREV(elm, field);				\
504
+	if ((TAILQ_NEXT((elm), field)) != NULL)				\
505
+		TAILQ_NEXT((elm), field)->field.tqe_prev = 		\
506
+		    (elm)->field.tqe_prev;				\
507
+	else {								\
508
+		(head)->tqh_last = (elm)->field.tqe_prev;		\
509
+		QMD_TRACE_HEAD(head);					\
510
+	}								\
511
+	*(elm)->field.tqe_prev = TAILQ_NEXT((elm), field);		\
512
+	TRASHIT((elm)->field.tqe_next);					\
513
+	TRASHIT((elm)->field.tqe_prev);					\
514
+	QMD_TRACE_ELEM(&(elm)->field);					\
515
+} while (0)
516
+
517
+#endif /* !_LIST_H */