atomic_word.h revision 303975
1// Low-level type for atomic operations -*- C++ -*- 2 3// Copyright (C) 2004 Free Software Foundation, Inc. 4// 5// This file is part of the GNU ISO C++ Library. This library is free 6// software; you can redistribute it and/or modify it under the 7// terms of the GNU General Public License as published by the 8// Free Software Foundation; either version 2, or (at your option) 9// any later version. 10 11// This library is distributed in the hope that it will be useful, 12// but WITHOUT ANY WARRANTY; without even the implied warranty of 13// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14// GNU General Public License for more details. 15 16// You should have received a copy of the GNU General Public License along 17// with this library; see the file COPYING. If not, write to the Free 18// Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, 19// USA. 20 21// As a special exception, you may use this file as part of a free software 22// library without restriction. Specifically, if other files instantiate 23// templates or use macros or inline functions from this file, or you compile 24// this file and link it with other files to produce an executable, this 25// file does not by itself cause the resulting executable to be covered by 26// the GNU General Public License. This exception does not however 27// invalidate any other reasons why the executable file might be covered by 28// the GNU General Public License. 29 30/** @file atomic_word.h 31 * This file is a GNU extension to the Standard C++ Library. 32 */ 33 34#ifndef _GLIBCXX_ATOMIC_WORD_H 35#define _GLIBCXX_ATOMIC_WORD_H 1 36 37typedef int _Atomic_word; 38 39// Define these two macros using the appropriate memory barrier for the target. 40// The commented out versions below are the defaults. 41// See ia64/atomic_word.h for an alternative approach. 42 43// This one prevents loads from being hoisted across the barrier; 44// in other words, this is a Load-Load acquire barrier. 45// This is necessary iff TARGET_RELAXED_ORDERING is defined in tm.h. 46// #define _GLIBCXX_READ_MEM_BARRIER __asm __volatile ("":::"memory") 47 48// This one prevents stores from being sunk across the barrier; in other 49// words, a Store-Store release barrier. 50// #define _GLIBCXX_WRITE_MEM_BARRIER __asm __volatile ("":::"memory") 51 52#endif 53