# atomic_word.h

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    00001 // Low-level type for atomic operations -*- C++ -*-
    00002
    00003 // Copyright (C) 2004, 2009 Free Software Foundation, Inc.
    00004 //
    00005 // This file is part of the GNU ISO C++ Library.  This library is free
    00006 // software; you can redistribute it and/or modify it under the
    00007 // terms of the GNU General Public License as published by the
    00008 // Free Software Foundation; either version 3, or (at your option)
    00009 // any later version.
    00010
    00011 // This library is distributed in the hope that it will be useful,
    00012 // but WITHOUT ANY WARRANTY; without even the implied warranty of
    00013 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    00014 // GNU General Public License for more details.
    00015
    00016 // Under Section 7 of GPL version 3, you are granted additional
    00017 // permissions described in the GCC Runtime Library Exception, version
    00018 // 3.1, as published by the Free Software Foundation.
    00019
    00020 // You should have received a copy of the GNU General Public License and
    00021 // a copy of the GCC Runtime Library Exception along with this program;
    00022 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
    00023 // <http://www.gnu.org/licenses/>.
    00024
    00025 /** @file atomic_word.h
    00026  *  This file is a GNU extension to the Standard C++ Library.
    00027  */
    00028
    00029 #ifndef _GLIBCXX_ATOMIC_WORD_H
    00030 #define _GLIBCXX_ATOMIC_WORD_H  1
    00031
    00032 typedef int _Atomic_word;
    00033
    00034 // Define these two macros using the appropriate memory barrier for the target.
    00035 // The commented out versions below are the defaults.
    00036 // See ia64/atomic_word.h for an alternative approach.
    00037
    00038 // This one prevents loads from being hoisted across the barrier;
    00039 // in other words, this is a Load-Load acquire barrier.
    00040 // This is necessary iff TARGET_RELAXED_ORDERING is defined in tm.h.
    00041 // #define _GLIBCXX_READ_MEM_BARRIER __asm __volatile ("":::"memory")
    00042
    00043 // This one prevents stores from being sunk across the barrier; in other
    00044 // words, a Store-Store release barrier.
    00045 // #define _GLIBCXX_WRITE_MEM_BARRIER __asm __volatile ("":::"memory")
    00046
    00047 #endif