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