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.\" $OpenBSD: byteorder.3,v 1.19 2014/07/13 13:17:16 guenther Exp $
.\"
.\" Copyright (c) 1983, 1991, 1993
.\" 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.
.\"
.Dd $Mdocdate: July 13 2014 $
.Dt BYTEORDER 3
.Os
.Sh NAME
.Nm htobe64 ,
.Nm htobe32 ,
.Nm htobe16 ,
.Nm be64toh ,
.Nm be32toh ,
.Nm be16toh ,
.Nm betoh64 ,
.Nm betoh32 ,
.Nm betoh16 ,
.Nm htole64 ,
.Nm htole32 ,
.Nm htole16 ,
.Nm le64toh ,
.Nm le32toh ,
.Nm le16toh ,
.Nm letoh64 ,
.Nm letoh32 ,
.Nm letoh16 ,
.Nm swap64 ,
.Nm swap32 ,
.Nm swap16
.Nd convert values between different byte orderings
.Sh SYNOPSIS
.In endian.h
.Ft uint64_t
.Fn htobe64 "uint64_t host64"
.Ft uint32_t
.Fn htobe32 "uint32_t host32"
.Ft uint16_t
.Fn htobe16 "uint16_t host16"
.Ft uint64_t
.Fn be64toh "uint64_t big64"
.Ft uint32_t
.Fn be32toh "uint32_t big32"
.Ft uint16_t
.Fn be16toh "uint16_t big16"
.Ft uint64_t
.Fn betoh64 "uint64_t big64"
.Ft uint32_t
.Fn betoh32 "uint32_t big32"
.Ft uint16_t
.Fn betoh16 "uint16_t big16"
.Ft uint64_t
.Fn htole64 "uint64_t host64"
.Ft uint32_t
.Fn htole32 "uint32_t host32"
.Ft uint16_t
.Fn htole16 "uint16_t host16"
.Ft uint64_t
.Fn letoh64 "uint64_t little64"
.Ft uint64_t
.Fn le64toh "uint64_t little64"
.Ft uint32_t
.Fn le32toh "uint32_t little32"
.Ft uint16_t
.Fn le16toh "uint16_t little16"
.Ft uint32_t
.Fn letoh32 "uint32_t little32"
.Ft uint16_t
.Fn letoh16 "uint16_t little16"
.Ft uint64_t
.Fn swap64 "uint64_t val64"
.Ft uint32_t
.Fn swap32 "uint32_t val32"
.Ft uint16_t
.Fn swap16 "uint16_t val16"
.Sh DESCRIPTION
These routines convert 16, 32 and 64-bit quantities between different
byte orderings.
The
.Dq swap
functions reverse the byte ordering of
the given quantity; the others convert either from/to the native
byte order used by the host to/from either little- or big-endian (a.k.a
network) order.
.Pp
Apart from the swap functions,
the names containing
.Dq be
convert between host and big-endian (most significant byte first) order
of the given quantity, while the names containing
.Dq le
convert between host and little-endian least significant byte first) order
of the given quantity.
.Pp
All these functions use the numbers
16, 32, or 64 for specifying the bitwidth of the quantities they operate on.
Currently all supported architectures are either big- or little-endian
so either the
.Dq be
or
.Dq le
variants are implemented as null macros.
.Sh SEE ALSO
.Xr htonl 3
.Sh STANDARDS
The
.Fn htobe64 ,
.Fn htobe32 ,
.Fn htobe16 ,
.Fn be64toh ,
.Fn be32toh ,
.Fn be16toh ,
.Fn htole64 ,
.Fn htole32 ,
.Fn htole16 ,
.Fn le64toh ,
.Fn le32toh ,
and
.Fn le16toh
functions are expected to conform to a future version of
.St -p1003.1 .
The other functions are extensions that should not be used
when portability is required.
.Sh HISTORY
The
.Nm swap{size}
and
.Nm {src-order}to{dst-order}{size}
functions appeared in
.Bx 4.2 .
The
.Nm {src-order}{size}to{dst-order}
functions appeared in
.Ox 5.6 .
A subset of them was submitted for standardization after
.St -p1003.1-2008 .
.Sh BUGS
On the vax, alpha, amd64, i386, and some mips and arm architectures,
bytes are handled backwards from most everyone else in the world.
This is not expected to be fixed in the near future.
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