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.\"     from: @(#)swab.3	8.1 (Berkeley) 6/4/93
.\"	$NetBSD: swab.3,v 1.15 2010/04/30 03:52:13 jruoho Exp $
.\"
.Dd April 30, 2010
.Dt SWAB 3
.Os
.Sh NAME
.Nm swab
.Nd swap adjacent bytes
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In unistd.h
.Ft void
.Fn swab "const void * restrict src" "void * restrict dst" "ssize_t len"
.Sh DESCRIPTION
The function
.Fn swab
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 negative or zero,
.Fn swab
does nothing.
If
.Fa len
is odd,
.Fn swab
copies
.Fa len - 1
bytes and the disposition of the last byte is unspecified.
.Sh SEE ALSO
.Xr bzero 3 ,
.Xr memset 3
.Sh STANDARDS
The
.Fn swab
function conforms to
.St -p1003.1-2001 .
.Sh HISTORY
A
.Fn swab
function appeared in
.At v7 .
It was originally documented to be
.Dq useful for carrying binary data between PDP11's and other machines .
.Pp
In
.Nx 6.0
the type of
.Fa len
was changed from
.Vt size_t
to
.Vt ssize_t
for
.Tn POSIX
compliance.