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28.\"     from: @(#)swab.3	8.1 (Berkeley) 6/4/93
29.\"	$NetBSD: swab.3,v 1.15 2010/04/30 03:52:13 jruoho Exp $
30.\"
31.Dd April 30, 2010
32.Dt SWAB 3
33.Os
34.Sh NAME
35.Nm swab
36.Nd swap adjacent bytes
37.Sh LIBRARY
38.Lb libc
39.Sh SYNOPSIS
40.In unistd.h
41.Ft void
42.Fn swab "const void * restrict src" "void * restrict dst" "ssize_t len"
43.Sh DESCRIPTION
44The function
45.Fn swab
46copies
47.Fa len
48bytes from the location referenced by
49.Fa src
50to the location referenced by
51.Fa dst ,
52swapping adjacent bytes.
53.Pp
54If
55.Fa len
56is negative or zero,
57.Fn swab
58does nothing.
59If
60.Fa len
61is odd,
62.Fn swab
63copies
64.Fa len - 1
65bytes and the disposition of the last byte is unspecified.
66.Sh SEE ALSO
67.Xr bzero 3 ,
68.Xr memset 3
69.Sh STANDARDS
70The
71.Fn swab
72function conforms to
73.St -p1003.1-2001 .
74.Sh HISTORY
75A
76.Fn swab
77function appeared in
78.At v7 .
79It was originally documented to be
80.Dq useful for carrying binary data between PDP11's and other machines .
81.Pp
82In
83.Nx 6.0
84the type of
85.Fa len
86was changed from
87.Vt size_t
88to
89.Vt ssize_t
90for
91.Tn POSIX
92compliance.
93