1.\" $NetBSD: atomic_swap.3,v 1.1 2008/06/23 10:22:40 ad Exp $ 2.\" 3.\" Copyright (c) 2007 The NetBSD Foundation, Inc. 4.\" All rights reserved. 5.\" 6.\" This code is derived from software contributed to The NetBSD Foundation 7.\" by Jason R. Thorpe. 8.\" 9.\" Redistribution and use in source and binary forms, with or without 10.\" modification, are permitted provided that the following conditions 11.\" are met: 12.\" 1. Redistributions of source code must retain the above copyright 13.\" notice, this list of conditions and the following disclaimer. 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in the 16.\" documentation and/or other materials provided with the distribution. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 19.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 20.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 21.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 22.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 23.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 24.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 25.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 26.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 27.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 28.\" POSSIBILITY OF SUCH DAMAGE. 29.\" 30.Dd April 11, 2007 31.Dt ATOMIC_SWAP 3 32.Os 33.Sh NAME 34.Nm atomic_swap , 35.Nm atomic_swap_32 , 36.Nm atomic_swap_uint , 37.Nm atomic_swap_ulong , 38.Nm atomic_swap_ptr , 39.Nm atomic_swap_64 40.Nd atomic swap operations 41.\" .Sh LIBRARY 42.\" .Lb libc 43.Sh SYNOPSIS 44.In sys/atomic.h 45.Ft uint32_t 46.Fn atomic_swap_32 "volatile uint32_t *ptr" "uint32_t new" 47.Ft unsigned int 48.Fn atomic_swap_uint "volatile unsigned int *ptr" "unsigned int new" 49.Ft unsigned long 50.Fn atomic_swap_ulong "volatile unsigned long *ptr" "unsigned long new" 51.Ft void * 52.Fn atomic_swap_ptr "volatile void *ptr" "void *new" 53.Ft uint64_t 54.Fn atomic_swap_64 "volatile uint64_t *ptr" "uint64_t new" 55.Sh DESCRIPTION 56The 57.Nm atomic_swap 58family of functions perform a swap operation in an atomic fashion. 59The value of the variable referenced by 60.Fa ptr 61is replaced by 62.Fa new 63and the old value returned. 64.Pp 65The 64-bit variants of these functions are available only on platforms 66that can support atomic 64-bit memory access. 67Applications can check for the availability of 64-bit atomic memory 68operations by testing if the pre-processor macro 69.Dv __HAVE_ATOMIC64_OPS 70is defined. 71.Sh SEE ALSO 72.Xr atomic_ops 3 73.Sh HISTORY 74The 75.Nm atomic_swap 76functions first appeared in 77.Nx 5.0 . 78