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.\" $OpenBSD: insque.3,v 1.7 2007/05/31 19:19:31 jmc Exp $
.\" Copyright (c) 1993 John Brezak
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\" 3. The name of the author may be used to endorse or promote products
.\" derived from this software without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR `AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\"
.Dd $Mdocdate: May 31 2007 $
.Dt INSQUE 3
.Os
.Sh NAME
.Nm insque ,
.Nm remque
.Nd insert/remove element from a queue
.Sh SYNOPSIS
.Fd #include <search.h>
.Ft void
.Fn insque "void *elem" "void *pred"
.Ft void
.Fn remque "void *elem"
.Sh DESCRIPTION
.Bf -symbolic
These interfaces have been superceded by the
.Xr queue 3
macros and are provided for compatibility with legacy code.
.Ef
.Pp
.Fn insque
and
.Fn remque
manipulate queues built from doubly linked lists.
The queue can be either circular or linear.
Each element in the queue must be of the following form:
.Bd -literal -offset indent
struct qelem {
struct qelem *q_forw;
struct qelem *q_back;
char q_data[];
};
.Ed
.Pp
The first two elements in the struct must be pointers of the
same type that point to the previous and next elements in
the queue respectively.
Any subsequent data in the struct is application-dependent.
.Pp
The
.Fn insque
function inserts
.Fa elem
into a queue immediately after
.Fa pred .
.Pp
The
.Fn remque
function removes
.Fa elem
from the queue.
.Pp
These functions are not atomic unless that machine architecture allows it.
.Sh SEE ALSO
.Xr queue 3
.Sh STANDARDS
The
.Fn insque
and
.Fn remque
functions conform to the
.St -p1003.1-2001
and
.St -xpg4.3
specifications.
.Sh HISTORY
The
.Fn insque
and
.Fn remque
functions are derived from the
.Li insque
and
.Li remque
instructions on the
.Tn VAX .
They first appeared in
.Bx 4.2 .
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