atomic_c11_compare_exchange_cas_16.c revision 1.2 
1/*	$NetBSD: atomic_c11_compare_exchange_cas_16.c,v 1.2 2014/11/04 19:56:44 joerg Exp $	*/
2
3/*-
4 * Copyright (c) 2007 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Martin Husemann.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 * POSSIBILITY OF SUCH DAMAGE.
30 */
31
32#include "atomic_op_namespace.h"
33
34#if !defined(_KERNEL) && !defined(_STANDALONE)
35#include <stdbool.h>
36#endif
37#include <sys/atomic.h>
38
39bool __atomic_compare_exchange_2(volatile uint16_t *, uint16_t *, uint16_t,
40    bool, int, int);
41
42bool
43__atomic_compare_exchange_2(volatile uint16_t *mem,
44    uint16_t *expected, uint16_t desired,
45    bool weak, int success, int failure)
46{
47	uint16_t old = *expected;
48
49	/*
50	 * Ignore the details (weak, memory model on success and failure)
51	 * and just do the cas. If we get here the compiler couldn't
52	 * do better and it mostly will not matter at all.
53	 */
54	return atomic_cas_16(mem, old, desired) == old;
55}
56