78 lines
2.7 KiB
Groff
78 lines
2.7 KiB
Groff
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.\" $NetBSD: atomic_swap.3,v 1.1 2008/06/23 10:22:40 ad Exp $
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.\"
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.\" Copyright (c) 2007 The NetBSD Foundation, Inc.
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.\" All rights reserved.
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.\"
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.\" This code is derived from software contributed to The NetBSD Foundation
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.\" by Jason R. Thorpe.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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.\" POSSIBILITY OF SUCH DAMAGE.
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.\"
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.Dd April 11, 2007
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.Dt ATOMIC_SWAP 3
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.Os
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.Sh NAME
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.Nm atomic_swap ,
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.Nm atomic_swap_32 ,
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.Nm atomic_swap_uint ,
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.Nm atomic_swap_ulong ,
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.Nm atomic_swap_ptr ,
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.Nm atomic_swap_64
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.Nd atomic swap operations
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.\" .Sh LIBRARY
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.\" .Lb libc
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.Sh SYNOPSIS
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.In sys/atomic.h
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.Ft uint32_t
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.Fn atomic_swap_32 "volatile uint32_t *ptr" "uint32_t new"
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.Ft unsigned int
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.Fn atomic_swap_uint "volatile unsigned int *ptr" "unsigned int new"
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.Ft unsigned long
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.Fn atomic_swap_ulong "volatile unsigned long *ptr" "unsigned long new"
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.Ft void *
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.Fn atomic_swap_ptr "volatile void *ptr" "void *new"
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.Ft uint64_t
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.Fn atomic_swap_64 "volatile uint64_t *ptr" "uint64_t new"
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.Sh DESCRIPTION
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The
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.Nm atomic_swap
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family of functions perform a swap operation in an atomic fashion.
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The value of the variable referenced by
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.Fa ptr
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is replaced by
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.Fa new
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and the old value returned.
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.Pp
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The 64-bit variants of these functions are available only on platforms
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that can support atomic 64-bit memory access.
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Applications can check for the availability of 64-bit atomic memory
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operations by testing if the pre-processor macro
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.Dv __HAVE_ATOMIC64_OPS
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is defined.
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.Sh SEE ALSO
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.Xr atomic_ops 3
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.Sh HISTORY
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The
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.Nm atomic_swap
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functions first appeared in
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.Nx 5.0 .
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