1// Low-level functions 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 atomicity.h 31 * This is an internal header file, included by other library headers. 32 * You should not attempt to use it directly. 33 */ 34 35#ifndef _GLIBCXX_ATOMICITY_H 36#define _GLIBCXX_ATOMICITY_H 1 37 38#include <bits/atomic_word.h> 39 40namespace __gnu_cxx 41{ 42 _Atomic_word 43 __attribute__ ((__unused__)) 44 __exchange_and_add(volatile _Atomic_word* __mem, int __val); 45 46 void 47 __attribute__ ((__unused__)) 48 __atomic_add(volatile _Atomic_word* __mem, int __val); 49} // namespace __gnu_cxx 50 51/* Even if the CPU doesn't need a memory barrier, we need to ensure that 52 the compiler doesn't reorder memory accesses across the barriers. */ 53#ifndef _GLIBCXX_READ_MEM_BARRIER 54#define _GLIBCXX_READ_MEM_BARRIER __asm __volatile ("":::"memory") 55#endif 56#ifndef _GLIBCXX_WRITE_MEM_BARRIER 57#define _GLIBCXX_WRITE_MEM_BARRIER __asm __volatile ("":::"memory") 58#endif 59 60#endif 61