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1 jermar 1 
/*
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 * Copyright (c) 2001-2004 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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/** @addtogroup ia32
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 * @{
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 */
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/** @file
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 */
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#ifndef KERN_ia32_ATOMIC_H_
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#define KERN_ia32_ATOMIC_H_
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#include <arch/types.h>
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#include <arch/barrier.h>
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#include <preemption.h>
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static inline void atomic_inc(atomic_t *val) {
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#ifdef CONFIG_SMP
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    asm volatile (
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        "lock incl %[count]\n"
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        : [count] "+m" (val->count)
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    );
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#else
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    asm volatile (
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        "incl %[count]\n"
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        : [count] "+m" (val->count)
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    );
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#endif /* CONFIG_SMP */
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}
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static inline void atomic_dec(atomic_t *val) {
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#ifdef CONFIG_SMP
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    asm volatile (
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        "lock decl %[count]\n"
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        : [count] "+m" (val->count)
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    );
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#else
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    asm volatile (
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        "decl %[count]\n"
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        : [count] "+m" (val->count)
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    );
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#endif /* CONFIG_SMP */
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}
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static inline long atomic_postinc(atomic_t *val)
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{
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    long r = 1;
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    asm volatile (
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        "lock xaddl %[r], %[count]\n"
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        : [count] "+m" (val->count), [r] "+r" (r)
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    );
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    return r;
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}
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static inline long atomic_postdec(atomic_t *val)
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{
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    long r = -1;
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    asm volatile (
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        "lock xaddl %[r], %[count]\n"
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        : [count] "+m" (val->count), [r] "+r"(r)
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    );
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    return r;
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}
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#define atomic_preinc(val)  (atomic_postinc(val) + 1)
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#define atomic_predec(val)  (atomic_postdec(val) - 1)
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static inline uint32_t test_and_set(atomic_t *val) {
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    uint32_t v;
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    asm volatile (
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        "movl $1, %[v]\n"
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        "xchgl %[v], %[count]\n"
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        : [v] "=r" (v), [count] "+m" (val->count)
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    );
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    return v;
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}
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/** ia32 specific fast spinlock */
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static inline void atomic_lock_arch(atomic_t *val)
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{
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    uint32_t tmp;
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    preemption_disable();
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    asm volatile (
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        "0:\n"
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        "pause\n"        /* Pentium 4's HT love this instruction */
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        "mov %[count], %[tmp]\n"
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        "testl %[tmp], %[tmp]\n"
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        "jnz 0b\n"       /* lightweight looping on locked spinlock */
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        "incl %[tmp]\n"  /* now use the atomic operation */
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        "xchgl %[count], %[tmp]\n"
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        "testl %[tmp], %[tmp]\n"
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        "jnz 0b\n"
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        : [count] "+m" (val->count), [tmp] "=&r" (tmp)
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    );
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    /*
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     * Prevent critical section code from bleeding out this way up.
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     */
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    CS_ENTER_BARRIER();
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}
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#endif
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/** @}
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 */