.\" $OpenBSD: atomic.9,v 1.3 2007/05/14 13:10:24 jmc Exp $
.\"
.\" Copyright (c) 2007 Artur Grabowski <art@openbsd.org>
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.Dd April 27, 2007
.Dt ATOMIC 9
.Os
.Sh NAME
.Nm atomic ,
.Nm atomic_setbits_int ,
.Nm atomic_clearbits_int
.Nd interface to perform atomic operations on data
.Sh SYNOPSIS
.Fd #include <machine/atomic.h>
.Ft void
.Fn atomic_setbits_int "unsigned int *p" "unsigned int b"
.Ft void
.Fn atomic_clearbits_int "unsigned int *p" "unsigned int b"
.Sh DESCRIPTION
The
.Nm
set of functions provide an interface for changing data atomically with
respect to interrupts and multiple processors in the system.
.Pp
The
.Fn atomic_setbits_int
function sets the bits in
.Fa b
in the integer pointed to by
.Fa p .
It is equivalent to
.Bd -literal -offset indent
*p |= b;
.Ed
.Pp
The
.Fn atomic_clearbits_int
function clears the bits in
.Fa b
in the integer pointed to by
.Fa p .
It is equivalent to
.Bd -literal -offset indent
*p &= ~b;
.Ed
.Sh HISTORY
The
.Nm
functions first appeared in
.Ox 4.1 .