1060 lines
28 KiB
Groff
1060 lines
28 KiB
Groff
.\" $NetBSD: queue.3,v 1.17 2001/02/11 03:22:46 enami Exp $
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.\"
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.\" Copyright (c) 2000 The NetBSD Foundation, Inc.
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.\" 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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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the NetBSD
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.\" Foundation, Inc. and its contributors.
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.\" 4. Neither the name of The NetBSD Foundation nor the names of its
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.\" contributors may be used to endorse or promote products derived
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.\" from this software without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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.\" POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\" Copyright (c) 1993 The Regents of the University of California.
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.\" 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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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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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.3 8.1 (Berkeley) 12/13/93
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.\"
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.Dd July 19, 2000
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.Dt QUEUE 3
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.Os
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.Sh NAME
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.Nm LIST_ENTRY ,
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.Nm LIST_HEAD ,
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.Nm LIST_HEAD_INITIALIZER ,
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.Nm LIST_INIT ,
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.Nm LIST_INSERT_AFTER ,
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.Nm LIST_INSERT_BEFORE ,
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.Nm LIST_INSERT_HEAD ,
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.Nm LIST_REMOVE ,
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.Nm LIST_FOREACH ,
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.Nm LIST_EMPTY ,
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.Nm LIST_FIRST ,
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.Nm LIST_NEXT ,
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.Nm SLIST_ENTRY ,
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.Nm SLIST_HEAD ,
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.Nm SLIST_HEAD_INITIALIZER ,
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.Nm SLIST_INIT ,
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.Nm SLIST_INSERT_AFTER ,
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.Nm SLIST_INSERT_HEAD ,
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.Nm SLIST_REMOVE ,
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.Nm SLIST_REMOVE_HEAD ,
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.Nm SLIST_FOREACH ,
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.Nm SLIST_EMPTY ,
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.Nm SLIST_FIRST ,
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.Nm SLIST_NEXT ,
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.Nm SIMPLEQ_ENTRY ,
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.Nm SIMPLEQ_HEAD ,
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.Nm SIMPLEQ_HEAD_INITIALIZER ,
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.Nm SIMPLEQ_INIT ,
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.Nm SIMPLEQ_INSERT_HEAD ,
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.Nm SIMPLEQ_INSERT_TAIL ,
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.Nm SIMPLEQ_INSERT_AFTER ,
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.Nm SIMPLEQ_REMOVE_HEAD ,
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.Nm SIMPLEQ_FOREACH ,
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.Nm SIMPLEQ_EMPTY ,
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.Nm SIMPLEQ_FIRST ,
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.Nm SIMPLEQ_NEXT ,
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.Nm TAILQ_ENTRY ,
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.Nm TAILQ_HEAD ,
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.Nm TAILQ_HEAD_INITIALIZER ,
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.Nm TAILQ_INIT ,
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.Nm TAILQ_INSERT_AFTER ,
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.Nm TAILQ_INSERT_BEFORE ,
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.Nm TAILQ_INSERT_HEAD ,
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.Nm TAILQ_INSERT_TAIL ,
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.Nm TAILQ_REMOVE ,
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.Nm TAILQ_FOREACH ,
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.Nm TAILQ_FOREACH_REVERSE ,
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.Nm TAILQ_EMPTY ,
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.Nm TAILQ_FIRST ,
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.Nm TAILQ_NEXT ,
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.Nm CIRCLEQ_ENTRY ,
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.Nm CIRCLEQ_HEAD ,
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.Nm CIRCLEQ_HEAD_INITIALIZER ,
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.Nm CIRCLEQ_INIT ,
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.Nm CIRCLEQ_INSERT_AFTER ,
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.Nm CIRCLEQ_INSERT_BEFORE ,
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.Nm CIRCLEQ_INSERT_HEAD ,
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.Nm CIRCLEQ_INSERT_TAIL ,
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.Nm CIRCLEQ_REMOVE ,
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.Nm CIRCLEQ_FOREACH ,
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.Nm CIRCLEQ_FOREACH_REVERSE ,
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.Nm CIRCLEQ_EMPTY ,
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.Nm CIRCLEQ_FIRST ,
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.Nm CIRCLEQ_LAST ,
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.Nm CIRCLEQ_NEXT ,
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.Nm CIRCLEQ_PREV
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.Nd "implementations of singly-linked lists, lists, simple queues, tail queues, and circular queues"
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.Sh SYNOPSIS
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.Fd #include <sys/queue.h>
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.sp
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.Fn LIST_ENTRY "TYPE"
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.Fn LIST_FOREACH "TYPE *var" "LIST_HEAD *head" "LIST_ENTRY NAME"
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.Fn LIST_HEAD "HEADNAME" "TYPE"
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.Fn LIST_HEAD_INITIALIZER "head"
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.Fn LIST_INIT "LIST_HEAD *head"
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.Fn LIST_INSERT_AFTER "TYPE *listelm" "TYPE *elm" "LIST_ENTRY NAME"
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.Fn LIST_INSERT_BEFORE "TYPE *listelm" "TYPE *elm" "LIST_ENTRY NAME"
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.Fn LIST_INSERT_HEAD "LIST_HEAD *head" "TYPE *elm" "LIST_ENTRY NAME"
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.Fn LIST_REMOVE "TYPE *elm" "LIST_ENTRY NAME"
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.Ft int
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.Fn LIST_EMPTY "LIST_HEAD *head"
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.Ft TYPE *
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.Fn LIST_FIRST "LIST_HEAD *head"
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.Ft TYPE *
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.Fn LIST_NEXT "TYPE *elm" "LIST_ENTRY NAME"
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.sp
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.Fn SLIST_ENTRY "TYPE"
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.Fn SLIST_FOREACH "TYPE *var" "SLIST_HEAD *head" "SLIST_ENTRY NAME"
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.Fn SLIST_HEAD "HEADNAME" "TYPE"
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.Fn SLIST_HEAD_INITIALIZER "head"
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.Fn SLIST_INIT "SLIST_HEAD *head"
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.Fn SLIST_INSERT_AFTER "TYPE *listelm" "TYPE *elm" "SLIST_ENTRY NAME"
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.Fn SLIST_INSERT_HEAD "SLIST_HEAD *head" "TYPE *elm" "SLIST_ENTRY NAME"
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.Fn SLIST_REMOVE "SLIST_HEAD *head" "TYPE *elm" "TYPE" "SLIST_ENTRY NAME"
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.Fn SLIST_REMOVE_HEAD "TYPE *elm" "SLIST_ENTRY NAME"
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.Ft int
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.Fn SLIST_EMPTY "SLIST_HEAD *head"
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.Ft TYPE *
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.Fn SLIST_FIRST "SLIST_HEAD *head"
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.Ft TYPE *
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.Fn SLIST_NEXT "TYPE *elm" "SLIST_ENTRY NAME"
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.sp
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.Fn SIMPLEQ_ENTRY "TYPE"
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.Fn SIMPLEQ_FOREACH "TYPE *var" "SIMPLEQ_HEAD *head" "SIMPLEQ_ENTRY NAME"
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.Fn SIMPLEQ_HEAD "HEADNAME" "TYPE"
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.Fn SIMPLEQ_HEAD_INITIALIZER "head"
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.Fn SIMPLEQ_INIT "SIMPLEQ_HEAD *head"
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.Fn SIMPLEQ_INSERT_AFTER "SIMPLEQ_HEAD *head" "TYPE *listelm" "TYPE *elm" "SIMPLEQ_ENTRY NAME"
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.Fn SIMPLEQ_INSERT_HEAD "SIMPLEQ_HEAD *head" "TYPE *elm" "SIMPLEQ_ENTRY NAME"
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.Fn SIMPLEQ_INSERT_TAIL "SIMPLEQ_HEAD *head" "TYPE *elm" "SIMPLEQ_ENTRY NAME"
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.Fn SIMPLEQ_REMOVE_HEAD "SIMPLEQ_HEAD *head" "TYPE *elm" "SIMPLEQ_ENTRY NAME"
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.Ft int
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.Fn SIMPLEQ_EMPTY "SIMPLEQ_HEAD *head"
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.Ft TYPE *
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.Fn SIMPLEQ_FIRST "SIMPLEQ_HEAD *head"
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.Ft TYPE *
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.Fn SIMPLEQ_NEXT "TYPE *elm" "SIMPLEQ_ENTRY NAME"
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.sp
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.Fn TAILQ_ENTRY "TYPE"
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.Fn TAILQ_FOREACH "TYPE *var" "TAILQ_HEAD *head" "TAILQ_ENTRY NAME"
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.Fn TAILQ_FOREACH_REVERSE "TYPE *var" "TAILQ_HEAD *head" "HEADNAME" "TAILQ_ENTRY NAME"
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.Fn TAILQ_HEAD "HEADNAME" "TYPE"
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.Fn TAILQ_HEAD_INITIALIZER "head"
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.Fn TAILQ_INIT "TAILQ_HEAD *head"
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.Fn TAILQ_INSERT_AFTER "TAILQ_HEAD *head" "TYPE *listelm" "TYPE *elm" "TAILQ_ENTRY NAME"
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.Fn TAILQ_INSERT_BEFORE "TYPE *listelm" "TYPE *elm" "TAILQ_ENTRY NAME"
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.Fn TAILQ_INSERT_HEAD "TAILQ_HEAD *head" "TYPE *elm" "TAILQ_ENTRY NAME"
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.Fn TAILQ_INSERT_TAIL "TAILQ_HEAD *head" "TYPE *elm" "TAILQ_ENTRY NAME"
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.Fn TAILQ_REMOVE "TAILQ_HEAD *head" "TYPE *elm" "TAILQ_ENTRY NAME"
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.Ft int
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.Fn TAILQ_EMPTY "TAILQ_HEAD *head"
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.Ft TYPE *
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.Fn TAILQ_FIRST "TAILQ_HEAD *head"
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.Ft TYPE *
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.Fn TAILQ_NEXT "TYPE *elm" "TAILQ_ENTRY NAME"
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.sp
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.Fn CIRCLEQ_ENTRY "TYPE"
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.Fn CIRCLEQ_FOREACH "TYPE *var" "CIRCLEQ_HEAD *head" "CIRCLEQ_ENTRY NAME"
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.Fn CIRCLEQ_FOREACH_REVERSE "TYPE *var" "CIRCLEQ_HEAD *head" "CIRCLEQ_ENTRY NAME"
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.Fn CIRCLEQ_HEAD "HEADNAME" "TYPE"
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.Fn CIRCLEQ_HEAD_INITIALIZER "head"
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.Fn CIRCLEQ_INIT "CIRCLEQ_HEAD *head"
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.Fn CIRCLEQ_INSERT_AFTER "CIRCLEQ_HEAD *head" "TYPE *listelm" "TYPE *elm" "CIRCLEQ_ENTRY NAME"
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.Fn CIRCLEQ_INSERT_BEFORE "CIRCLEQ_HEAD *head" "TYPE *listelm" "TYPE *elm" "CIRCLEQ_ENTRY NAME"
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.Fn CIRCLEQ_INSERT_HEAD "CIRCLEQ_HEAD *head" "TYPE *elm" "CIRCLEQ_ENTRY NAME"
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.Fn CIRCLEQ_INSERT_TAIL "CIRCLEQ_HEAD *head" "TYPE *elm" "CIRCLEQ_ENTRY NAME"
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.Fn CIRCLEQ_REMOVE "CIRCLEQ_HEAD *head" "TYPE *elm" "CIRCLEQ_ENTRY NAME"
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.Ft int
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.Fn CIRCLEQ_EMPTY "CIRCLEQ_HEAD *head"
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.Ft TYPE *
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.Fn CIRCLEQ_FIRST "CIRCLEQ_HEAD *head"
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.Ft TYPE *
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.Fn CIRCLEQ_LAST "CIRCLEQ_HEAD *head"
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.Ft TYPE *
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.Fn CIRCLEQ_NEXT "TYPE *elm" "CIRCLEQ_ENTRY NAME"
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.Ft TYPE *
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.Fn CIRCLEQ_PREV "TYPE *elm" "CIRCLEQ_ENTRY NAME"
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.Sh DESCRIPTION
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These macros define and operate on five types of data structures:
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singly-linked lists, lists, simple queues, tail queues, and circular
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queues. All four structures support the following functionality:
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.Bl -enum -compact -offset indent
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.It
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Insertion of a new entry at the head of the list.
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.It
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Insertion of a new entry before or after any element in the list.
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.It
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Removal of any entry in the list.
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.It
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Forward traversal through the list.
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.El
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.Pp
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Singly-linked lists are the simplest of the five data structures and
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support only the above functionality.
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Singly-linked lists are ideal for applications with large datasets and
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few or no removals,
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or for implementing a LIFO queue.
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.Pp
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Simple queues add the following functionality:
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.Bl -enum -compact -offset indent
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.It
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Entries can be added at the end of a list.
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.El
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However:
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.Bl -enum -compact -offset indent
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.It
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Entries may not be added before any element in the list.
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.It
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Only the first entry in the list may be removed.
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.It
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All list insertions and removals must specify the head of the list.
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.It
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Each head entry requires two pointers rather than one.
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.El
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.Pp
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Simple queues are ideal for applications with large datasets and few or
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no removals, or for implementing a FIFO queue.
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.Pp
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All doubly linked types of data structures (lists, tail queues, and circle
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queues) additionally allow:
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.Bl -enum -compact -offset indent
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.It
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Insertion of a new entry before any element in the list.
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.It
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O(1) removal of any entry in the list.
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.El
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However:
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.Bl -enum -compact -offset indent
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.It
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Each elements requires two pointers rather than one.
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.It
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Code size and execution time of operations (except for removal) is about
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twice that of the singly-linked data-structures.
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.El
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.Pp
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Linked lists are the simplest of the doubly linked data structures and
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support only the above functionality over singly-linked lists.
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.Pp
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Tail queues add the following functionality:
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.Bl -enum -compact -offset indent
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.It
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Entries can be added at the end of a list.
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.El
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However:
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.Bl -enum -compact -offset indent
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.It
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All list insertions and removals, except insertion before another element, must
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specify the head of the list.
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.It
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Each head entry requires two pointers rather than one.
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.It
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Code size is about 15% greater and operations run about 20% slower
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than lists.
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.El
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.Pp
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Circular queues add the following functionality:
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.Bl -enum -compact -offset indent
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.It
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Entries can be added at the end of a list.
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.It
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They may be traversed backwards, from tail to head.
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.El
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However:
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.Bl -enum -compact -offset indent
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.It
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All list insertions and removals must specify the head of the list.
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.It
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Each head entry requires two pointers rather than one.
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.It
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The termination condition for traversal is more complex.
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.It
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Code size is about 40% greater and operations run about 45% slower
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than lists.
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.El
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.Pp
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In the macro definitions,
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.Fa TYPE
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is the name of a user defined structure,
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that must contain a field of type
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.Li LIST_ENTRY ,
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.Li SIMPLEQ_ENTRY ,
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.Li SLIST_ENTRY ,
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.Li TAILQ_ENTRY ,
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or
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.Li CIRCLEQ_ENTRY ,
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named
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.Fa NAME .
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The argument
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.Fa HEADNAME
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is the name of a user defined structure that must be declared
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using the macros
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.Li LIST_HEAD ,
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.Li SIMPLEQ_HEAD ,
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.Li SLIST_HEAD ,
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.Li TAILQ_HEAD ,
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or
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.Li CIRCLEQ_HEAD .
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See the examples below for further explanation of how these
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macros are used.
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.Sh SINGLY-LINKED LISTS
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A singly-linked list is headed by a structure defined by the
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.Nm SLIST_HEAD
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macro.
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This structure contains a single pointer to the first element
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on the list.
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The elements are singly linked for minimum space and pointer manipulation
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overhead at the expense of O(n) removal for arbitrary elements.
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New elements can be added to the list after an existing element or
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at the head of the list.
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An
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.Fa SLIST_HEAD
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structure is declared as follows:
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.Bd -literal -offset indent
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SLIST_HEAD(HEADNAME, TYPE) head;
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.Ed
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.Pp
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where
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.Fa HEADNAME
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is the name of the structure to be defined, and
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.Fa TYPE
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is the type of the elements to be linked into the list.
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A pointer to the head of the list can later be declared as:
|
|
.Bd -literal -offset indent
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struct HEADNAME *headp;
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.Ed
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.Pp
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(The names
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.Li head
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and
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.Li headp
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are user selectable.)
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.Pp
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The macro
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.Nm SLIST_HEAD_INITIALIZER
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evaluates to an initializer for the list
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.Fa head .
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.Pp
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The macro
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.Nm SLIST_EMPTY
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evaluates to true if there are no elements in the list.
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.Pp
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The macro
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.Nm SLIST_ENTRY
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declares a structure that connects the elements in
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the list.
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.Pp
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The macro
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.Nm SLIST_FIRST
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returns the first element in the list or NULL if the list is empty.
|
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.Pp
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The macro
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|
.Nm SLIST_FOREACH
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|
traverses the list referenced by
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|
.Fa head
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|
in the forward direction, assigning each element in
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|
turn to
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|
.Fa var .
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|
.Pp
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|
The macro
|
|
.Nm SLIST_INIT
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|
initializes the list referenced by
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.Fa head .
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|
.Pp
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|
The macro
|
|
.Nm SLIST_INSERT_HEAD
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|
inserts the new element
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.Fa elm
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at the head of the list.
|
|
.Pp
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The macro
|
|
.Nm SLIST_INSERT_AFTER
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inserts the new element
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.Fa elm
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after the element
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.Fa listelm .
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.Pp
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The macro
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.Nm SLIST_NEXT
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returns the next element in the list.
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.Pp
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The macro
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|
.Nm SLIST_REMOVE_HEAD
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removes the element
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.Fa elm
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from the head of the list.
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|
For optimum efficiency,
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|
elements being removed from the head of the list should explicitly use
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|
this macro instead of the generic
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|
.Fa SLIST_REMOVE
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macro.
|
|
.Pp
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The macro
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.Nm SLIST_REMOVE
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removes the element
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.Fa elm
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from the list.
|
|
.Sh SINGLY-LINKED LIST EXAMPLE
|
|
.Bd -literal
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|
SLIST_HEAD(slisthead, entry) head =
|
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SLIST_HEAD_INITIALIZER(head);
|
|
struct slisthead *headp; /* Singly-linked List head. */
|
|
struct entry {
|
|
...
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|
SLIST_ENTRY(entry) entries; /* Singly-linked List. */
|
|
...
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|
} *n1, *n2, *n3, *np;
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|
|
|
SLIST_INIT(&head); /* Initialize the list. */
|
|
|
|
n1 = malloc(sizeof(struct entry)); /* Insert at the head. */
|
|
SLIST_INSERT_HEAD(&head, n1, entries);
|
|
|
|
n2 = malloc(sizeof(struct entry)); /* Insert after. */
|
|
SLIST_INSERT_AFTER(n1, n2, entries);
|
|
|
|
SLIST_REMOVE(&head, n2, entry, entries);/* Deletion. */
|
|
free(n2);
|
|
|
|
n3 = SLIST_FIRST(&head);
|
|
SLIST_REMOVE_HEAD(&head, entries); /* Deletion from the head. */
|
|
free(n3);
|
|
/* Forward traversal. */
|
|
SLIST_FOREACH(np, &head, entries)
|
|
np-> ...
|
|
|
|
while (!SLIST_EMPTY(&head)) { /* List Deletion. */
|
|
n1 = SLIST_FIRST(&head);
|
|
SLIST_REMOVE_HEAD(&head, entries);
|
|
free(n1);
|
|
}
|
|
.Ed
|
|
.Sh LISTS
|
|
A list is headed by a structure defined by the
|
|
.Nm LIST_HEAD
|
|
macro.
|
|
This structure contains a single pointer to the first element
|
|
on the list.
|
|
The elements are doubly linked so that an arbitrary element can be
|
|
removed without traversing the list.
|
|
New elements can be added to the list after an existing element,
|
|
before an existing element, or at the head of the list.
|
|
A
|
|
.Fa LIST_HEAD
|
|
structure is declared as follows:
|
|
.Bd -literal -offset indent
|
|
LIST_HEAD(HEADNAME, TYPE) head;
|
|
.Ed
|
|
.sp
|
|
where
|
|
.Fa HEADNAME
|
|
is the name of the structure to be defined, and
|
|
.Fa TYPE
|
|
is the type of the elements to be linked into the list.
|
|
A pointer to the head of the list can later be declared as:
|
|
.Bd -literal -offset indent
|
|
struct HEADNAME *headp;
|
|
.Ed
|
|
.sp
|
|
(The names
|
|
.Li head
|
|
and
|
|
.Li headp
|
|
are user selectable.)
|
|
.Pp
|
|
The macro
|
|
.Nm LIST_ENTRY
|
|
declares a structure that connects the elements in
|
|
the list.
|
|
.Pp
|
|
The macro
|
|
.Nm LIST_HEAD_INITIALIZER
|
|
provides a value which can be used to initialize a list head at
|
|
compile time, and is used at the point that the list head
|
|
variable is declared, like:
|
|
.Bd -literal -offset indent
|
|
struct HEADNAME head = LIST_HEAD_INITIALIZER(head);
|
|
.Ed
|
|
.Pp
|
|
The macro
|
|
.Nm LIST_INIT
|
|
initializes the list referenced by
|
|
.Fa head .
|
|
.Pp
|
|
The macro
|
|
.Nm LIST_INSERT_HEAD
|
|
inserts the new element
|
|
.Fa elm
|
|
at the head of the list.
|
|
.Pp
|
|
The macro
|
|
.Nm LIST_INSERT_AFTER
|
|
inserts the new element
|
|
.Fa elm
|
|
after the element
|
|
.Fa listelm .
|
|
.Pp
|
|
The macro
|
|
.Nm LIST_INSERT_BEFORE
|
|
inserts the new element
|
|
.Fa elm
|
|
before the element
|
|
.Fa listelm .
|
|
.Pp
|
|
The macro
|
|
.Nm LIST_REMOVE
|
|
removes the element
|
|
.Fa elm
|
|
from the list.
|
|
.Pp
|
|
The macro
|
|
.Nm LIST_EMPTY
|
|
return true if the list
|
|
.Fa head
|
|
has no elements.
|
|
.Pp
|
|
The macro
|
|
.Nm LIST_FIRST
|
|
returns the first elemement of the list
|
|
.Fa head .
|
|
.Pp
|
|
The macro
|
|
.Nm LIST_FOREACH
|
|
traverses the list referenced by
|
|
.Fa head
|
|
in the forward direction, assigning each element in turn to
|
|
.Fa var .
|
|
.Pp
|
|
The macro
|
|
.Nm LIST_NEXT
|
|
returns the element after the element
|
|
.Fa elm .
|
|
.Sh LIST EXAMPLE
|
|
.Bd -literal
|
|
LIST_HEAD(listhead, entry) head;
|
|
struct listhead *headp; /* List head. */
|
|
struct entry {
|
|
...
|
|
LIST_ENTRY(entry) entries; /* List. */
|
|
...
|
|
} *n1, *n2, *np;
|
|
|
|
LIST_INIT(&head); /* Initialize the list. */
|
|
|
|
n1 = malloc(sizeof(struct entry)); /* Insert at the head. */
|
|
LIST_INSERT_HEAD(&head, n1, entries);
|
|
|
|
n2 = malloc(sizeof(struct entry)); /* Insert after. */
|
|
LIST_INSERT_AFTER(n1, n2, entries);
|
|
|
|
n2 = malloc(sizeof(struct entry)); /* Insert before. */
|
|
LIST_INSERT_BEFORE(n1, n2, entries);
|
|
/* Forward traversal. */
|
|
LIST_FOREACH(np, &head, entries)
|
|
np-> ...
|
|
/* Delete. */
|
|
while (LIST_FIRST(&head) != NULL)
|
|
LIST_REMOVE(LIST_FIRST(&head), entries);
|
|
if (LIST_EMPTY(&head)) /* Test for emptiness. */
|
|
printf("nothing to do\\n");
|
|
.Ed
|
|
.Sh SIMPLE QUEUES
|
|
A simple queue is headed by a structure defined by the
|
|
.Nm SIMPLEQ_HEAD
|
|
macro.
|
|
This structure contains a pair of pointers,
|
|
one to the first element in the simple queue and the other to
|
|
the last element in the simple queue.
|
|
The elements are doubly linked so that an arbitrary element can be
|
|
removed without traversing the simple queue.
|
|
New elements can be added to the queue after an existing element,
|
|
before an existing element, at the head of the queue, or at the end
|
|
the queue.
|
|
A
|
|
.Fa SIMPLEQ_HEAD
|
|
structure is declared as follows:
|
|
.Bd -literal -offset indent
|
|
SIMPLEQ_HEAD(HEADNAME, TYPE) head;
|
|
.Ed
|
|
.sp
|
|
where
|
|
.Li HEADNAME
|
|
is the name of the structure to be defined, and
|
|
.Li TYPE
|
|
is the type of the elements to be linked into the simple queue.
|
|
A pointer to the head of the simple queue can later be declared as:
|
|
.Bd -literal -offset indent
|
|
struct HEADNAME *headp;
|
|
.Ed
|
|
.sp
|
|
(The names
|
|
.Li head
|
|
and
|
|
.Li headp
|
|
are user selectable.)
|
|
.Pp
|
|
The macro
|
|
.Nm SIMPLEQ_ENTRY
|
|
declares a structure that connects the elements in
|
|
the simple queue.
|
|
.Pp
|
|
The macro
|
|
.Nm SIMPLEQ_HEAD_INITIALIZER
|
|
provides a value which can be used to initialize a simple queue head at
|
|
compile time, and is used at the point that the simple queue head
|
|
variable is declared, like:
|
|
.Bd -literal -offset indent
|
|
struct HEADNAME head = SIMPLEQ_HEAD_INITIALIZER(head);
|
|
.Ed
|
|
.Pp
|
|
The macro
|
|
.Nm SIMPLEQ_INIT
|
|
initializes the simple queue referenced by
|
|
.Fa head .
|
|
.Pp
|
|
The macro
|
|
.Nm SIMPLEQ_INSERT_HEAD
|
|
inserts the new element
|
|
.Fa elm
|
|
at the head of the simple queue.
|
|
.Pp
|
|
The macro
|
|
.Nm SIMPLEQ_INSERT_TAIL
|
|
inserts the new element
|
|
.Fa elm
|
|
at the end of the simple queue.
|
|
.Pp
|
|
The macro
|
|
.Nm SIMPLEQ_INSERT_AFTER
|
|
inserts the new element
|
|
.Fa elm
|
|
after the element
|
|
.Fa listelm .
|
|
.Pp
|
|
The macro
|
|
.Nm SIMPLEQ_REMOVE_HEAD
|
|
removes the first element from the simple queue.
|
|
.Pp
|
|
The macro
|
|
.Nm SIMPLEQ_EMPTY
|
|
return true if the simple queue
|
|
.Fa head
|
|
has no elements.
|
|
.Pp
|
|
The macro
|
|
.Nm SIMPLEQ_FIRST
|
|
returns the first elemement of the simple queue
|
|
.Fa head .
|
|
.Pp
|
|
The macro
|
|
.Nm SIMPLEQ_FOREACH
|
|
traverses the tail queue referenced by
|
|
.Fa head
|
|
in the forward direction, assigning each element
|
|
in turn to
|
|
.Fa var .
|
|
.Pp
|
|
The macro
|
|
.Nm SIMPLEQ_NEXT
|
|
returns the element after the element
|
|
.Fa elm .
|
|
.Sh SIMPLE QUEUE EXAMPLE
|
|
.Bd -literal
|
|
SIMPLEQ_HEAD(simplehead, entry) head;
|
|
struct simplehead *headp; /* Simple queue head. */
|
|
struct entry {
|
|
...
|
|
SIMPLEQ_ENTRY(entry) entries; /* Simple queue. */
|
|
...
|
|
} *n1, *n2, *np;
|
|
|
|
SIMPLEQ_INIT(&head); /* Initialize the queue. */
|
|
|
|
n1 = malloc(sizeof(struct entry)); /* Insert at the head. */
|
|
SIMPLEQ_INSERT_HEAD(&head, n1, entries);
|
|
|
|
n1 = malloc(sizeof(struct entry)); /* Insert at the tail. */
|
|
SIMPLEQ_INSERT_TAIL(&head, n1, entries);
|
|
|
|
n2 = malloc(sizeof(struct entry)); /* Insert after. */
|
|
SIMPLEQ_INSERT_AFTER(&head, n1, n2, entries);
|
|
/* Forward traversal. */
|
|
SIMPLEQ_FOREACH(np, &head, entries)
|
|
np-> ...
|
|
/* Delete. */
|
|
while (SIMPLEQ_FIRST(&head) != NULL)
|
|
SIMPLEQ_REMOVE_HEAD(&head, SIMPLEQ_FIRST(&head), entries);
|
|
if (SIMPLEQ_EMPTY(&head)) /* Test for emptiness. */
|
|
printf("nothing to do\\n");
|
|
.Ed
|
|
.Sh TAIL QUEUES
|
|
A tail queue is headed by a structure defined by the
|
|
.Nm TAILQ_HEAD
|
|
macro.
|
|
This structure contains a pair of pointers,
|
|
one to the first element in the tail queue and the other to
|
|
the last element in the tail queue.
|
|
The elements are doubly linked so that an arbitrary element can be
|
|
removed without traversing the tail queue.
|
|
New elements can be added to the queue after an existing element,
|
|
before an existing element, at the head of the queue, or at the end
|
|
the queue.
|
|
A
|
|
.Fa TAILQ_HEAD
|
|
structure is declared as follows:
|
|
.Bd -literal -offset indent
|
|
TAILQ_HEAD(HEADNAME, TYPE) head;
|
|
.Ed
|
|
.sp
|
|
where
|
|
.Li HEADNAME
|
|
is the name of the structure to be defined, and
|
|
.Li TYPE
|
|
is the type of the elements to be linked into the tail queue.
|
|
A pointer to the head of the tail queue can later be declared as:
|
|
.Bd -literal -offset indent
|
|
struct HEADNAME *headp;
|
|
.Ed
|
|
.sp
|
|
(The names
|
|
.Li head
|
|
and
|
|
.Li headp
|
|
are user selectable.)
|
|
.Pp
|
|
The macro
|
|
.Nm TAILQ_ENTRY
|
|
declares a structure that connects the elements in
|
|
the tail queue.
|
|
.Pp
|
|
The macro
|
|
.Nm TAILQ_HEAD_INITIALIZER
|
|
provides a value which can be used to initialize a tail queue head at
|
|
compile time, and is used at the point that the tail queue head
|
|
variable is declared, like:
|
|
.Bd -literal -offset indent
|
|
struct HEADNAME head = TAILQ_HEAD_INITIALIZER(head);
|
|
.Ed
|
|
.Pp
|
|
The macro
|
|
.Nm TAILQ_INIT
|
|
initializes the tail queue referenced by
|
|
.Fa head .
|
|
.Pp
|
|
The macro
|
|
.Nm TAILQ_INSERT_HEAD
|
|
inserts the new element
|
|
.Fa elm
|
|
at the head of the tail queue.
|
|
.Pp
|
|
The macro
|
|
.Nm TAILQ_INSERT_TAIL
|
|
inserts the new element
|
|
.Fa elm
|
|
at the end of the tail queue.
|
|
.Pp
|
|
The macro
|
|
.Nm TAILQ_INSERT_AFTER
|
|
inserts the new element
|
|
.Fa elm
|
|
after the element
|
|
.Fa listelm .
|
|
.Pp
|
|
The macro
|
|
.Nm TAILQ_INSERT_BEFORE
|
|
inserts the new element
|
|
.Fa elm
|
|
before the element
|
|
.Fa listelm .
|
|
.Pp
|
|
The macro
|
|
.Nm TAILQ_REMOVE
|
|
removes the element
|
|
.Fa elm
|
|
from the tail queue.
|
|
.Pp
|
|
The macro
|
|
.Nm TAILQ_EMPTY
|
|
return true if the tail queue
|
|
.Fa head
|
|
has no elements.
|
|
.Pp
|
|
The macro
|
|
.Nm TAILQ_FIRST
|
|
returns the first elemement of the tail queue
|
|
.Fa head .
|
|
.Pp
|
|
The macro
|
|
.Nm TAILQ_FOREACH
|
|
traverses the tail queue referenced by
|
|
.Fa head
|
|
in the forward direction, assigning each element in turn to
|
|
.Fa var .
|
|
.Pp
|
|
The macro
|
|
.Nm TAILQ_FOREACH_REVERSE
|
|
traverses the tail queue referenced by
|
|
.Fa head
|
|
in the reverse direction, assigning each element in turn to
|
|
.Fa var .
|
|
.Pp
|
|
The macro
|
|
.Nm TAILQ_NEXT
|
|
returns the element after the element
|
|
.Fa elm .
|
|
.Sh TAIL QUEUE EXAMPLE
|
|
.Bd -literal
|
|
TAILQ_HEAD(tailhead, entry) head;
|
|
struct tailhead *headp; /* Tail queue head. */
|
|
struct entry {
|
|
...
|
|
TAILQ_ENTRY(entry) entries; /* Tail queue. */
|
|
...
|
|
} *n1, *n2, *np;
|
|
|
|
TAILQ_INIT(&head); /* Initialize the queue. */
|
|
|
|
n1 = malloc(sizeof(struct entry)); /* Insert at the head. */
|
|
TAILQ_INSERT_HEAD(&head, n1, entries);
|
|
|
|
n1 = malloc(sizeof(struct entry)); /* Insert at the tail. */
|
|
TAILQ_INSERT_TAIL(&head, n1, entries);
|
|
|
|
n2 = malloc(sizeof(struct entry)); /* Insert after. */
|
|
TAILQ_INSERT_AFTER(&head, n1, n2, entries);
|
|
|
|
n2 = malloc(sizeof(struct entry)); /* Insert before. */
|
|
TAILQ_INSERT_BEFORE(n1, n2, entries);
|
|
/* Forward traversal. */
|
|
TAILQ_FOREACH(np, &head, entries)
|
|
np-> ...
|
|
/* Reverse traversal. */
|
|
TAILQ_FOREACH_REVERSE(np, &head, tailhead, entries)
|
|
np-> ...
|
|
/* Delete. */
|
|
while (TAILQ_FIRST(&head) != NULL)
|
|
TAILQ_REMOVE(&head, TAILQ_FIRST(&head), entries);
|
|
if (TAILQ_EMPTY(&head)) /* Test for emptiness. */
|
|
printf("nothing to do\\n");
|
|
.Ed
|
|
.Sh CIRCULAR QUEUES
|
|
A circular queue is headed by a structure defined by the
|
|
.Nm CIRCLEQ_HEAD
|
|
macro.
|
|
This structure contains a pair of pointers,
|
|
one to the first element in the circular queue and the other to the
|
|
last element in the circular queue.
|
|
The elements are doubly linked so that an arbitrary element can be
|
|
removed without traversing the queue.
|
|
New elements can be added to the queue after an existing element,
|
|
before an existing element, at the head of the queue, or at the end
|
|
of the queue.
|
|
A
|
|
.Fa CIRCLEQ_HEAD
|
|
structure is declared as follows:
|
|
.Bd -literal -offset indent
|
|
CIRCLEQ_HEAD(HEADNAME, TYPE) head;
|
|
.Ed
|
|
.sp
|
|
where
|
|
.Li HEADNAME
|
|
is the name of the structure to be defined, and
|
|
.Li TYPE
|
|
is the type of the elements to be linked into the circular queue.
|
|
A pointer to the head of the circular queue can later be declared as:
|
|
.Bd -literal -offset indent
|
|
struct HEADNAME *headp;
|
|
.Ed
|
|
.sp
|
|
(The names
|
|
.Li head
|
|
and
|
|
.Li headp
|
|
are user selectable.)
|
|
.Pp
|
|
The macro
|
|
.Nm CIRCLEQ_ENTRY
|
|
declares a structure that connects the elements in
|
|
the circular queue.
|
|
.Pp
|
|
The macro
|
|
.Nm CIRCLEQ_HEAD_INITIALIZER
|
|
provides a value which can be used to initialize a circular queue head at
|
|
compile time, and is used at the point that the circular queue head
|
|
variable is declared, like:
|
|
.Bd -literal -offset indent
|
|
struct HEADNAME head = CIRCLEQ_HEAD_INITIALIZER(head);
|
|
.Ed
|
|
.Pp
|
|
The macro
|
|
.Nm CIRCLEQ_INIT
|
|
initializes the circular queue referenced by
|
|
.Fa head .
|
|
.Pp
|
|
The macro
|
|
.Nm CIRCLEQ_INSERT_HEAD
|
|
inserts the new element
|
|
.Fa elm
|
|
at the head of the circular queue.
|
|
.Pp
|
|
The macro
|
|
.Nm CIRCLEQ_INSERT_TAIL
|
|
inserts the new element
|
|
.Fa elm
|
|
at the end of the circular queue.
|
|
.Pp
|
|
The macro
|
|
.Nm CIRCLEQ_INSERT_AFTER
|
|
inserts the new element
|
|
.Fa elm
|
|
after the element
|
|
.Fa listelm .
|
|
.Pp
|
|
The macro
|
|
.Nm CIRCLEQ_INSERT_BEFORE
|
|
inserts the new element
|
|
.Fa elm
|
|
before the element
|
|
.Fa listelm .
|
|
.Pp
|
|
The macro
|
|
.Nm CIRCLEQ_REMOVE
|
|
removes the element
|
|
.Fa elm
|
|
from the circular queue.
|
|
.Pp
|
|
The macro
|
|
.Nm CIRCLEQ_EMPTY
|
|
return true if the circular queue
|
|
.Fa head
|
|
has no elements.
|
|
.Pp
|
|
The macro
|
|
.Nm CIRCLEQ_FIRST
|
|
returns the first elemement of the circular queue
|
|
.Fa head .
|
|
.Pp
|
|
The macro
|
|
.Nm CICRLEQ_FOREACH
|
|
traverses the circle queue referenced by
|
|
.Fa head
|
|
in the forward direction, assigning each element in turn to
|
|
.Fa var .
|
|
.Pp
|
|
The macro
|
|
.Nm CICRLEQ_FOREACH_REVERSE
|
|
traverses the circle queue referenced by
|
|
.Fa head
|
|
in the reverse direction, assigning each element in turn to
|
|
.Fa var .
|
|
.Pp
|
|
The macro
|
|
.Nm CIRCLEQ_LAST
|
|
returns the last element of the circular queue
|
|
.Fa head .
|
|
.Pp
|
|
The macro
|
|
.Nm CIRCLEQ_NEXT
|
|
returns the element after the element
|
|
.Fa elm .
|
|
.Pp
|
|
The macro
|
|
.Nm CIRCLEQ_PREV
|
|
returns the element before the element
|
|
.Fa elm .
|
|
.Sh CIRCULAR QUEUE EXAMPLE
|
|
.Bd -literal
|
|
CIRCLEQ_HEAD(circleq, entry) head;
|
|
struct circleq *headp; /* Circular queue head. */
|
|
struct entry {
|
|
...
|
|
CIRCLEQ_ENTRY entries; /* Circular queue. */
|
|
...
|
|
} *n1, *n2, *np;
|
|
|
|
CIRCLEQ_INIT(&head); /* Initialize the circular queue. */
|
|
|
|
n1 = malloc(sizeof(struct entry)); /* Insert at the head. */
|
|
CIRCLEQ_INSERT_HEAD(&head, n1, entries);
|
|
|
|
n1 = malloc(sizeof(struct entry)); /* Insert at the tail. */
|
|
CIRCLEQ_INSERT_TAIL(&head, n1, entries);
|
|
|
|
n2 = malloc(sizeof(struct entry)); /* Insert after. */
|
|
CIRCLEQ_INSERT_AFTER(&head, n1, n2, entries);
|
|
|
|
n2 = malloc(sizeof(struct entry)); /* Insert before. */
|
|
CIRCLEQ_INSERT_BEFORE(&head, n1, n2, entries);
|
|
/* Forward traversal. */
|
|
CIRCLEQ_FOREACH(np, &head, entries)
|
|
np-> ...
|
|
/* Reverse traversal. */
|
|
CIRCLEQ_FOREACH_REVERSE(np, &head, entries)
|
|
np-> ...
|
|
/* Delete. */
|
|
while (CIRCLEQ_FIRST(&head) != (void *)&head)
|
|
CIRCLEQ_REMOVE(&head, CIRCLEQ_FIRST(&head), entries);
|
|
if (CIRCLEQ_EMPTY(&head)) /* Test for emptiness. */
|
|
printf("nothing to do\\n");
|
|
.Ed
|
|
.Sh HISTORY
|
|
The
|
|
.Nm queue
|
|
functions first appeared in
|
|
.Bx 4.4 .
|
|
The
|
|
.Nm SIMPLEQ
|
|
functions first appeared in
|
|
.Nx 1.2 .
|