atomic_ops.h revision 172491 
1/*-
2 * Copyright (c) 2001 Daniel Eischen <deischen@FreeBSD.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Neither the name of the author nor the names of its contributors
11 *    may be used to endorse or promote products derived from this software
12 *    without specific prior written permission.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 *
26 * $FreeBSD: head/lib/libkse/arch/i386/include/atomic_ops.h 119723 2003-09-03 17:56:26Z deischen $
27 */
28
29#ifndef	_ATOMIC_OPS_H_
30#define	_ATOMIC_OPS_H_
31
32/*
33 * Atomic swap:
34 *   Atomic (tmp = *dst, *dst = val), then *res = tmp
35 *
36 * void atomic_swap32(intptr_t *dst, intptr_t val, intptr_t *res);
37 */
38static inline void
39atomic_swap32(intptr_t *dst, intptr_t val, intptr_t *res)
40{
41	__asm __volatile(
42	"xchgl %2, %1; movl %2, %0"
43	 : "=m" (*res) : "m" (*dst), "r" (val) : "memory");
44}
45
46#define	atomic_swap_ptr(d, v, r) \
47	atomic_swap32((intptr_t *)d, (intptr_t)v, (intptr_t *)r)
48
49#define	atomic_swap_int(d, v, r) \
50	atomic_swap32((intptr_t *)d, (intptr_t)v, (intptr_t *)r)
51#endif
52