md-atomic.hpp

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/* src/vm/jit/arm/atomic.hpp - ARM atomic instructions

   Copyright (C) 1996-2013
   CACAOVM - Verein zur Foerderung der freien virtuellen Maschine CACAO

   This file is part of CACAO.

   This program is free software; you can redistribute it and/or
   modify it under the terms of the GNU General Public License as
   published by the Free Software Foundation; either version 2, or (at
   your option) any later version.

   This program is distributed in the hope that it will be useful, but
   WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
   02110-1301, USA.

*/


#ifndef MD_ATOMIC_HPP_
#define MD_ATOMIC_HPP_ 1

#include "config.h"

#include <stdint.h>

#include "threads/atomic.hpp"

/* Apparently, this is the best way to define a memory barrier on Linux.
 * See for example: http://icedtea.classpath.org/hg/icedtea6/file/7c7835fceadc/ports/hotspot/src/os_cpu/linux_zero/vm/orderAccess_linux_zero.inline.hpp#l29
 */
typedef void (__kernel_dmb_t)(void);
#define __kernel_dmb (*(__kernel_dmb_t *)0xffff0fa0)

namespace Atomic_md {

/**
 * An atomic compare and swap for 32-bit integer values.
 *
 * @param p      Pointer to memory address.
 * @param oldval Old value to be expected.
 * @param newval New value to be stored.
 *
 * @return value of the memory location before the store
 */
inline uint32_t compare_and_swap(volatile uint32_t *p, uint32_t oldval, uint32_t newval)
{
    return __sync_val_compare_and_swap(p, oldval, newval);
}


/**
 * An atomic compare and swap for 64-bit integer values.
 *
 * @param p      Pointer to memory address.
 * @param oldval Old value to be expected.
 * @param newval New value to be stored.
 *
 * @return value of the memory location before the store
 */
inline uint64_t compare_and_swap(volatile uint64_t *p, uint64_t oldval, uint64_t newval)
{
    return Atomic::generic_compare_and_swap(p, oldval, newval);
}


/**
 * A memory barrier.
 */
inline void memory_barrier(void)
{
    __kernel_dmb();
}


/**
 * A write memory barrier.
 */
inline void write_memory_barrier(void)
{
    __kernel_dmb();
}


/**
 * An instruction barrier.
 */
inline void instruction_barrier(void)
{
    __asm__ __volatile__ ("" : : : "memory");
}

}

#endif // MD_ATOMIC_HPP_


/*
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