'\" t
.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
.\"
.\" SPDX-License-Identifier: Linux-man-pages-copyleft
.\"
.\" References consulted:
.\"     Linux libc source code
.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
.\"     386BSD man pages
.\" Modified Sat Jul 24 17:52:15 1993 by Rik Faith (faith@cs.unc.edu)
.\" Modified 2001-12-15, aeb
.TH swab 3 2023-03-30 "Linux man-pages 6.04"
.SH NAME
swab \- swap adjacent bytes
.SH LIBRARY
Standard C library
.RI ( libc ", " \-lc )
.SH SYNOPSIS
.nf
.BR "#define _XOPEN_SOURCE" "       /* See feature_test_macros(7) */"
.B #include <unistd.h>
.PP
.BI "void swab(const void " from "[restrict ." n "], void " to "[restrict ." n ],
.BI "          ssize_t " n );
.fi
.SH DESCRIPTION
The
.BR swab ()
function copies
.I n
bytes from the array pointed
to by
.I from
to the array pointed to by
.IR to ,
exchanging
adjacent even and odd bytes.
This function is used to exchange data
between machines that have different low/high byte ordering.
.PP
This function does nothing when
.I n
is negative.
When
.I n
is positive and odd, it handles
.I n\-1
bytes
as above, and does something unspecified with the last byte.
(In other words,
.I n
should be even.)
.SH RETURN VALUE
The
.BR swab ()
function returns no value.
.SH ATTRIBUTES
For an explanation of the terms used in this section, see
.BR attributes (7).
.ad l
.nh
.TS
allbox;
lbx lb lb
l l l.
Interface	Attribute	Value
T{
.BR swab ()
T}	Thread safety	MT-Safe
.TE
.hy
.ad
.sp 1
.SH STANDARDS
POSIX.1-2008.
.SH HISTORY
POSIX.1-2001, SVr4, 4.3BSD.
.SH SEE ALSO
.BR bstring (3)