1*b6a8cdecSdlg.\" $OpenBSD: atomic_swap_uint.9,v 1.6 2014/07/18 10:40:14 dlg Exp $ 21c7e942eSdlg.\" 31c7e942eSdlg.\" Copyright (c) 2014 David Gwynne <dlg@openbsd.org> 41c7e942eSdlg.\" All rights reserved. 51c7e942eSdlg.\" 61c7e942eSdlg.\" Permission to use, copy, modify, and distribute this software for any 71c7e942eSdlg.\" purpose with or without fee is hereby granted, provided that the above 81c7e942eSdlg.\" copyright notice and this permission notice appear in all copies. 91c7e942eSdlg.\" 101c7e942eSdlg.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 111c7e942eSdlg.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 121c7e942eSdlg.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 131c7e942eSdlg.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 141c7e942eSdlg.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 151c7e942eSdlg.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 161c7e942eSdlg.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 171c7e942eSdlg.\" 18*b6a8cdecSdlg.Dd $Mdocdate: July 18 2014 $ 193be71636Sdlg.Dt ATOMIC_SWAP_UINT 9 201c7e942eSdlg.Os 211c7e942eSdlg.Sh NAME 221c7e942eSdlg.Nm atomic_swap_uint , 231c7e942eSdlg.Nm atomic_swap_ulong , 241c7e942eSdlg.Nm atomic_swap_ptr 251c7e942eSdlg.Nd atomic swap operations 261c7e942eSdlg.Sh SYNOPSIS 271c7e942eSdlg.In sys/atomic.h 281c7e942eSdlg.Ft unsigned int 291c7e942eSdlg.Fn atomic_swap_uint "volatile unsigned int *p" "unsigned int new" 301c7e942eSdlg.Ft unsigned long 311c7e942eSdlg.Fn atomic_swap_ulong "volatile unsigned long *p" "unsigned long new" 321c7e942eSdlg.Ft void * 33*b6a8cdecSdlg.Fn atomic_swap_ptr "volatile void *p" "void *new" 341c7e942eSdlg.Sh DESCRIPTION 351c7e942eSdlgThe atomic_swap set of functions provide an interface for atomically 361c7e942eSdlgperforming swap operations with respect to interrupts and multiple 371c7e942eSdlgprocessors in the system. 381c7e942eSdlg.Pp 391c7e942eSdlgThe value referenced by the pointer 401c7e942eSdlg.Fa p 411c7e942eSdlgis replaced by the value 421c7e942eSdlg.Fa new . 43c468d2a2Sdlg.Sh CONTEXT 44c468d2a2Sdlg.Fn atomic_swap_uint , 45c468d2a2Sdlg.Fn atomic_swap_ulong , 46c468d2a2Sdlgand 47c468d2a2Sdlg.Fn atomic_swap_ptr 48c468d2a2Sdlgcan all be called during autoconf, from process context, or from interrupt context. 491c7e942eSdlg.Sh RETURN VALUES 501c7e942eSdlgThese functions return the value at 511c7e942eSdlg.Fa p 521c7e942eSdlgas it was before the swap operation. 531c7e942eSdlg.Sh SEE ALSO 541c7e942eSdlg.Xr atomic_cas_uint 9 551c7e942eSdlg.Sh HISTORY 561c7e942eSdlgThe atomic_swap functions first appeared in 576cd55c5fSdlg.Nx 5.0 586cd55c5fSdlgand 591c7e942eSdlg.Ox 5.5 . 60