atomic_ops.h revision 172491 
1/*
2 * Copyright 2004 by Peter Grehan. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 *    notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 *    notice, this list of conditions and the following disclaimer in the
11 *    documentation and/or other materials provided with the distribution.
12 * 3. The name of the author may not be used to endorse or promote products
13 *    derived from this software without specific prior written permission.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
20 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
21 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
22 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
23 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 *
27 * $FreeBSD: head/lib/libkse/arch/powerpc/include/atomic_ops.h 132400 2004-07-19 12:19:04Z grehan $
28 */
29
30#ifndef	_ATOMIC_OPS_H_
31#define	_ATOMIC_OPS_H_
32
33/*
34 * Atomic swap:
35 *   Atomic (tmp = *dst, *dst = val), then *res = tmp
36 *
37 * void atomic_swap32(intptr_t *dst, intptr_t val, intptr_t *res);
38 */
39static inline void
40atomic_swap32(intptr_t *dst, intptr_t val, intptr_t *res)
41{
42	int tmp;
43
44	tmp = 0;	/* should be a better way to quieten cc1... */
45#ifdef __GNUC__
46	__asm __volatile(
47		"1:	lwarx	%0, 0, %4\n"	/* load with reservation */
48		"	stwcx.	%3, 0, %4\n"	/* attempt to store val */
49		"	bne- 1b\n"		/* interrupted? retry */
50		"	stw	%0, %1\n"	/* else, *dst -> *res */
51		: "=&r" (tmp), "=m" (*res), "+m" (*dst)
52		: "r" (val), "r" (dst)
53		: "cc", "memory");
54#endif
55}
56
57#define	atomic_swap_ptr(d, v, r) \
58	atomic_swap32((intptr_t *)d, (intptr_t)v, (intptr_t *)r)
59
60#define	atomic_swap_int(d, v, r) \
61	atomic_swap32((intptr_t *)d, (intptr_t)v, (intptr_t *)r)
62#endif
63