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.\" $FreeBSD: src/share/man/man9/byteorder.9,v 1.6 2003/05/21 17:32:55 ru Exp $
.\"
.Dd October 16, 2017
.Dt BYTEORDER 9
.Os
.Sh NAME
.Nm bswap16 ,
.Nm bswap32 ,
.Nm bswap64 ,
.Nm be16toh ,
.Nm be32toh ,
.Nm be64toh ,
.Nm htobe16 ,
.Nm htobe32 ,
.Nm htobe64 ,
.Nm htole16 ,
.Nm htole32 ,
.Nm htole64 ,
.Nm le16toh ,
.Nm le32toh ,
.Nm le64toh ,
.Nm be16enc ,
.Nm be16dec ,
.Nm be32enc ,
.Nm be32dec ,
.Nm be64enc ,
.Nm be64dec ,
.Nm le16enc ,
.Nm le16dec ,
.Nm le32enc ,
.Nm le32dec ,
.Nm le64enc ,
.Nm le64dec
.Nd byte order operations
.Sh SYNOPSIS
.In sys/endian.h
.Ft uint16_t
.Fn bswap16 "uint16_t int16"
.Ft uint32_t
.Fn bswap32 "uint32_t int32"
.Ft uint64_t
.Fn bswap64 "uint64_t int64"
.Ft uint16_t
.Fn be16toh "uint16_t big16"
.Ft uint32_t
.Fn be32toh "uint32_t big32"
.Ft uint64_t
.Fn be64toh "uint64_t big64"
.Ft uint16_t
.Fn htobe16 "uint16_t host16"
.Ft uint32_t
.Fn htobe32 "uint32_t host32"
.Ft uint64_t
.Fn htobe64 "uint64_t host64"
.Ft uint16_t
.Fn htole16 "uint16_t host16"
.Ft uint32_t
.Fn htole32 "uint32_t host32"
.Ft uint64_t
.Fn htole64 "uint64_t host64"
.Ft uint16_t
.Fn le16toh "uint16_t little16"
.Ft uint32_t
.Fn le32toh "uint32_t little32"
.Ft uint64_t
.Fn le64toh "uint64_t little64"
.Ft uint16_t
.Fn be16dec "const void *stream"
.Ft uint32_t
.Fn be32dec "const void *stream"
.Ft uint64_t
.Fn be64dec "const void *stream"
.Ft uint16_t
.Fn le16dec "const void *stream"
.Ft uint32_t
.Fn le32dec "const void *stream"
.Ft uint64_t
.Fn le64dec "const void *stream"
.Ft void
.Fn be16enc "void *stream" "uint16_t host16"
.Ft void
.Fn be32enc "void *stream" "uint32_t host32"
.Ft void
.Fn be64enc "void *stream" "uint64_t host64"
.Ft void
.Fn le16enc "void *stream" "uint16_t host16"
.Ft void
.Fn le32enc "void *stream" "uint32_t host32"
.Ft void
.Fn le64enc "void *stream" "uint64_t host64"
.Sh DESCRIPTION
The
.Fn bswap16 ,
.Fn bswap32 ,
and
.Fn bswap64
functions return a byte order swapped integer.
On big endian systems, the number is converted to little endian byte order.
On little endian systems, the number is converted to big endian byte order.
.Pp
The
.Fn be16toh ,
.Fn be32toh ,
and
.Fn be64toh
functions return a big endian byte ordered integer
converted to the system's native byte order.
The return value will be the same as the argument on big endian systems.
.Pp
The
.Fn le16toh ,
.Fn le32toh ,
and
.Fn le64toh
functions return a little endian byte ordered integer
converted to the system's native byte order.
The return value will be the same as the argument on little endian systems.
.Pp
The
.Fn htobe16 ,
.Fn htobe32 ,
and
.Fn htobe64
functions return an integer in the system's native
byte order converted to big endian byte order.
The return value will be the same as the argument on big endian systems.
.Pp
The
.Fn htole16 ,
.Fn htole32 ,
and
.Fn htole64
functions return an integer in the system's native
byte order converted to little endian byte order.
The return value will be the same as the argument on little endian systems.
.Pp
The
.Fn be16enc ,
.Fn be16dec ,
.Fn be32enc ,
.Fn be32dec ,
.Fn be64enc ,
.Fn be64dec ,
.Fn le16enc ,
.Fn le16dec ,
.Fn le32enc ,
.Fn le32dec ,
.Fn le64enc ,
and
.Fn le64dec
functions encode and decode integers to/from octet stream
on any alignment in big/little endian format.
.Sh SEE ALSO
.Xr bswap 3 ,
.Xr byteorder 3
.Sh HISTORY
The
.Fn hto*
and
.Fn *toh
functions first appeared in
.Nx 1.5 .
These were later ported to
.Fx 5.0 .
These functions were originally introduced to handle PCI bus master
devices that (via DMA) transfer little endian data even on big
endian systems.
.Pp
The encode/decode functions first appeared in
.Fx 5.1 .
These were later ported to
.Nx 3.0
as a part of the
.Xr uuidgen 2
support.