.\" Copyright (c) 1990, 1991 The Regents of the University of California.
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\"	$OpenBSD: swab.3,v 1.10 2022/09/28 20:27:12 jmc Exp $
.\"
.Dd $Mdocdate: September 28 2022 $
.Dt SWAB 3
.Os
.Sh NAME
.Nm swab
.Nd swap adjacent bytes
.Sh SYNOPSIS
.In unistd.h
.Ft void
.Fo swab
.Fa "const void *restrict src"
.Fa "void *restrict dst"
.Fa "ssize_t len"
.Fc
.Sh DESCRIPTION
The
.Fn swab
function copies
.Fa len
bytes from the location referenced by
.Fa src
to the location referenced by
.Fa dst ,
swapping adjacent bytes.
.Pp
If
.Fa len
is zero or less,
.Fn swab
does nothing.
If it is odd, what happens to the last byte is unspecified.
If
.Fa src
and
.Fa dst
overlap, behaviour is undefined.
.Sh SEE ALSO
.Xr bzero 3 ,
.Xr memset 3
.Sh STANDARDS
The
.Fn swab
function is compliant with the X/Open System Interfaces option of the
.St -p1003.1-2008
specification.
.Sh HISTORY
The
.Fn swab
function first appeared in
.At v7 .