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418 jermar 1 
/*
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 * Copyright (C) 2005 Jakub Jermar
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 * 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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 *
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 * - 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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 * - 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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 * - 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, BUT
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 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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 */
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#ifndef __sparc64_ATOMIC_H__
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#define __sparc64_ATOMIC_H__
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#include <arch/types.h>
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#include <typedefs.h>
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/** Atomic add operation.
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 *
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 * Use atomic compare and swap operation to atomically add signed value.
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 *
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 * @param val Atomic variable.
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 * @param i Signed value to be added.
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 *
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 * @return Value of the atomic variable as it existed before addition.
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 */
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static inline long atomic_add(atomic_t *val, int i)
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{
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    __u64 a, b;
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    volatile __u64 x = (__u64) &val->count;
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    __asm__ volatile (
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        "0:\n"
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        "ldx %0, %1\n"
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        "add %1, %3, %2\n"
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        "casx %0, %1, %2\n"
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        "cmp %1, %2\n"
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        "bne 0b\n"      /* The operation failed and must be attempted again if a != b. */
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        "nop\n"
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        : "=m" (*((__u64 *)x)), "=r" (a), "=r" (b)
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        : "r" (i)
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    );
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    return a;
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}
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static inline long atomic_preinc(atomic_t *val)
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{
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    return atomic_add(val, 1) + 1;
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}
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static inline long atomic_postinc(atomic_t *val)
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{
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    return atomic_add(val, 1);
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}
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static inline long atomic_predec(atomic_t *val)
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{
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    return atomic_add(val, -1) - 1;
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}
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static inline long atomic_postdec(atomic_t *val)
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{
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    return atomic_add(val, -1);
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}
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static inline void atomic_inc(atomic_t *val)
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{
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    (void) atomic_add(val, 1);
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}
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static inline void atomic_dec(atomic_t *val)
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{
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    (void) atomic_add(val, -1);
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}
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#endif