atomic.h

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/*
 * Copyright (C) 2005 Martin Decky
 * 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 __ppc32_ATOMIC_H__
#define __ppc32_ATOMIC_H__

static inline void atomic_inc(atomic_t *val)
{
        long tmp;

        asm volatile (
                "1:\n"
                "lwarx %0, 0, %2\n"
                "addic %0, %0, 1\n"
                "stwcx. %0, 0, %2\n"
                "bne- 1b"
                : "=&r" (tmp), "=m" (val->count)
                : "r" (&val->count), "m" (val->count)
                : "cc"
        );
}

static inline void atomic_dec(atomic_t *val)
{
        long tmp;

        asm volatile (
                "1:\n"
                "lwarx %0, 0, %2\n"
                "addic %0, %0, -1\n"
                "stwcx. %0, 0, %2\n"
                "bne- 1b"
                : "=&r" (tmp), "=m" (val->count)
                : "r" (&val->count), "m" (val->count)
                : "cc"
        );
}

static inline long atomic_postinc(atomic_t *val)
{
        atomic_inc(val);
        return val->count - 1;
}

static inline long atomic_postdec(atomic_t *val)
{
        atomic_dec(val);
        return val->count + 1;
}

static inline long atomic_preinc(atomic_t *val)
{
        atomic_inc(val);
        return val->count;
}

static inline long atomic_predec(atomic_t *val)
{
        atomic_dec(val);
        return val->count;
}

#endif

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