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2128 jermar 1 
/*
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 * Copyright (c) 2007 Michal Kebrt
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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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/** @addtogroup arm32
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 * @{
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 */
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/** @file
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 *  @brief Atomic operations.
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 */
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#ifndef KERN_arm32_ATOMIC_H_
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#define KERN_arm32_ATOMIC_H_
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/** Atomic addition.
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 *
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 * @param val Where to add.
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 * @param i   Value to be added.
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 *
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 * @return Value after addition.
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 *
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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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    int ret;
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    volatile long *mem = &(val->count);
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    asm volatile (
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        "1:\n"
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            "ldr r2, [%[mem]]\n"
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            "add r3, r2, %[i]\n"
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            "str r3, %[ret]\n"
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            "swp r3, r3, [%[mem]]\n"
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            "cmp r3, r2\n"
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            "bne 1b\n"
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        : [ret] "=m" (ret)
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        : [mem] "r" (mem), [i] "r" (i)
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        : "r3", "r2"
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    );
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    return ret;
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}
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/** Atomic increment.
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 *
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 * @param val Variable to be incremented.
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 */
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static inline void atomic_inc(atomic_t *val)
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{
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    atomic_add(val, 1);
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}
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/** Atomic decrement.
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 *
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 * @param val Variable to be decremented.
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 */
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static inline void atomic_dec(atomic_t *val) {
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    atomic_add(val, -1);
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}
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/** Atomic pre-increment.
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 *
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 * @param val Variable to be incremented.
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 * @return    Value after incrementation.
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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);
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}
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/** Atomic pre-decrement.
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 *
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 * @param val Variable to be decremented.
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 * @return    Value after decrementation.
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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);
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}
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/** Atomic post-increment.
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 *
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 * @param val Variable to be incremented.
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 * @return    Value before incrementation.
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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) - 1;
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}
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/** Atomic post-decrement.
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 *
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 * @param val Variable to be decremented.
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 * @return    Value before decrementation.
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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) + 1;
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}
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#endif
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/** @}
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 */