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/*
* Copyright 2004 by Peter Grehan. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $FreeBSD$
*/
#ifndef _ATOMIC_OPS_H_
#define _ATOMIC_OPS_H_
/*
* Atomic swap:
* Atomic (tmp = *dst, *dst = val), then *res = tmp
*
* void atomic_swap32(intptr_t *dst, intptr_t val, intptr_t *res);
*/
static inline void
atomic_swap32(volatile intptr_t *dst, intptr_t val, intptr_t *res)
{
int tmp;
tmp = 0; /* should be a better way to quieten cc1... */
#ifdef __GNUC__
__asm __volatile(
"1: lwarx %0, 0, %4\n" /* load with reservation */
" stwcx. %3, 0, %4\n" /* attempt to store val */
" bne- 1b\n" /* interrupted? retry */
" stw %0, %1\n" /* else, *dst -> *res */
: "=&r" (tmp), "=m" (*res), "+m" (*dst)
: "r" (val), "r" (dst)
: "cc", "memory");
#endif
}
#define atomic_swap_ptr(d, v, r) \
atomic_swap32((volatile intptr_t *)d, (intptr_t)v, (intptr_t *)r)
#define atomic_swap_int(d, v, r) \
atomic_swap32((volatile intptr_t *)d, (intptr_t)v, (intptr_t *)r)
#endif
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