libstdc++
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