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