.\" $OpenBSD: bemtoh32.9,v 1.8 2022/03/31 17:27:23 naddy Exp $
.\"
.\" Copyright (c) 2014 David Gwynne <dlg@openbsd.org>
.\" All rights reserved.
.\"
.\" Permission to use, copy, modify, and distribute this software for any
.\" purpose with or without fee is hereby granted, provided that the above
.\" copyright notice and this permission notice appear in all copies.
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.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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.Dd $Mdocdate: March 31 2022 $
.Dt BEMTOH32 9
.Os
.Sh NAME
.Nm bemtoh16 ,
.Nm bemtoh32 ,
.Nm bemtoh64 ,
.Nm lemtoh16 ,
.Nm lemtoh32 ,
.Nm lemtoh64 ,
.Nm htobem16 ,
.Nm htobem32 ,
.Nm htobem64 ,
.Nm htolem16 ,
.Nm htolem32 ,
.Nm htolem64
.Nd byte swapping memory load and store operations
.Sh SYNOPSIS
.In sys/types.h
.Ft uint16_t
.Fn bemtoh16 "volatile const uint16_t *m"
.Ft uint32_t
.Fn bemtoh32 "volatile const uint32_t *m"
.Ft uint64_t
.Fn bemtoh64 "volatile const uint64_t *m"
.Ft uint16_t
.Fn lemtoh16 "volatile const uint16_t *m"
.Ft uint32_t
.Fn lemtoh32 "volatile const uint32_t *m"
.Ft uint64_t
.Fn lemtoh64 "volatile const uint64_t *m"
.Ft void
.Fn htobem16 "volatile uint16_t *m" "uint16_t v"
.Ft void
.Fn htobem32 "volatile uint32_t *m" "uint32_t v"
.Ft void
.Fn htobem64 "volatile uint64_t *m" "uint64_t v"
.Ft void
.Fn htolem16 "volatile uint16_t *m" "uint16_t v"
.Ft void
.Fn htolem32 "volatile uint32_t *m" "uint32_t v"
.Ft void
.Fn htolem64 "volatile uint64_t *m" "uint64_t v"
.Sh DESCRIPTION
This API provides a way to take advantage of an architecture's ability
to load and store words in memory of different endians.
If an architecture has no specialised support for these operations,
they will be implemented as a wrapper around the
.Xr htobe64 3
API.
.Pp
These operations are subject to the same alignment restrictions as
the host's normal memory loads and stores.
.Pp
.Fn bemtoh16 ,
.Fn bemtoh32 ,
and
.Fn bemtoh64
read a big endian value from the memory located at
.Fa m
into the host's native byte order.
.Fn lemtoh16 ,
.Fn lemtoh32 ,
and
.Fn lemtoh64
read a little endian value from the memory located at
.Fa m
into the host's native byte order.
.Pp
.Fn htobem16 ,
.Fn htobem32 ,
and
.Fn htobem64
store the host's native byte ordered value of
.Fa v
as a big endian value in the memory located at
.Fa m .
.Fn htolem16 ,
.Fn htolem32 ,
and
.Fn htolem64
store the host's native byte ordered value of
.Fa v
as a little endian value in the memory located at
.Fa m .
.Sh CONTEXT
.Fn bemtoh16 ,
.Fn bemtoh32 ,
.Fn bemtoh64 ,
.Fn lemtoh16 ,
.Fn lemtoh32 ,
.Fn lemtoh64 ,
.Fn htobem16 ,
.Fn htobem32 ,
.Fn htobem64 ,
.Fn htolem16 ,
.Fn htolem32 ,
and
.Fn htolem64
can be called during autoconf, from process context, or from interrupt
context.
.Sh RETURN VALUES
.Fn bemtoh16 ,
.Fn bemtoh32 ,
.Fn bemtoh64 ,
.Fn lemtoh16 ,
.Fn lemtoh32 ,
and
.Fn lemtoh64
return the host's native byte ordered value of the memory at
.Fa m
after the appropriate byteswapping has occurred.
.Pp
.Fn htobem16 ,
.Fn htobem32 ,
.Fn htobem64 ,
.Fn htolem16 ,
.Fn htolem32 ,
and
.Fn htolem64
do not return a value.
.Sh SEE ALSO
.Xr htobe64 3
.Sh HISTORY
These functions first appeared in
.Ox 5.6 .