arch/amd64/include/atomic.h

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/*
 * Copyright (C) 2001-2004 Jakub Jermar
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - 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.
 * - 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.
 */

#ifndef __amd64_ATOMIC_H__
#define __amd64_ATOMIC_H__

static inline void atomic_inc(atomic_t *val) {
        __asm__ volatile ("lock incq %0\n" : "=m" (val->count));
}

static inline void atomic_dec(atomic_t *val) {
        __asm__ volatile ("lock decq %0\n" : "=m" (val->count));
}

static inline long atomic_postinc(atomic_t *val) 
{
        long r;

        __asm__ volatile (
                "movq $1, %0\n"
                "lock xaddq %0, %1\n"
                : "=r" (r), "=m" (val->count)
        );

        return r;
}

static inline long atomic_postdec(atomic_t *val) 
{
        long r;
        
        __asm__ volatile (
                "movq $-1, %0\n"
                "lock xaddq %0, %1\n"
                : "=r" (r), "=m" (val->count)
        );
        
        return r;
}

#define atomic_preinc(val) (atomic_postinc(val)+1)
#define atomic_predec(val) (atomic_postdec(val)-1)

#endif

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