1// Low-level type for atomic operations -*- C++ -*-
2
3// Copyright (C) 2004-2015 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 3, 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// Under Section 7 of GPL version 3, you are granted additional
17// permissions described in the GCC Runtime Library Exception, version
18// 3.1, as published by the Free Software Foundation.
19
20// You should have received a copy of the GNU General Public License and
21// a copy of the GCC Runtime Library Exception along with this program;
22// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23// <http://www.gnu.org/licenses/>.
24
25/** @file atomic_word.h
26 * This file is a GNU extension to the Standard C++ Library.
27 */
28
29#ifndef _GLIBCXX_ATOMIC_WORD_H
30#define _GLIBCXX_ATOMIC_WORD_H 1
31
32typedef int _Atomic_word;
33
34// Define these two macros using the appropriate memory barrier for the target.
35// The commented out versions below are the defaults.
36// See ia64/atomic_word.h for an alternative approach.
37
38// This one prevents loads from being hoisted across the barrier;
39// in other words, this is a Load-Load acquire barrier.
40// This is necessary iff TARGET_RELAXED_ORDERING is defined in tm.h.
41// #define _GLIBCXX_READ_MEM_BARRIER __asm __volatile ("":::"memory")
42
43// This one prevents stores from being sunk across the barrier; in other
44// words, a Store-Store release barrier.
45// #define _GLIBCXX_WRITE_MEM_BARRIER __asm __volatile ("":::"memory")
46
47#endif
48