1169691Skan// Support for atomic operations -*- C++ -*- 2169691Skan 3169691Skan// Copyright (C) 2004, 2005, 2006 Free Software Foundation, Inc. 4169691Skan// 5169691Skan// This file is part of the GNU ISO C++ Library. This library is free 6169691Skan// software; you can redistribute it and/or modify it under the 7169691Skan// terms of the GNU General Public License as published by the 8169691Skan// Free Software Foundation; either version 2, or (at your option) 9169691Skan// any later version. 10169691Skan 11169691Skan// This library is distributed in the hope that it will be useful, 12169691Skan// but WITHOUT ANY WARRANTY; without even the implied warranty of 13169691Skan// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14169691Skan// GNU General Public License for more details. 15169691Skan 16169691Skan// You should have received a copy of the GNU General Public License along 17169691Skan// with this library; see the file COPYING. If not, write to the Free 18169691Skan// Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, 19169691Skan// USA. 20169691Skan 21169691Skan// As a special exception, you may use this file as part of a free software 22169691Skan// library without restriction. Specifically, if other files instantiate 23169691Skan// templates or use macros or inline functions from this file, or you compile 24169691Skan// this file and link it with other files to produce an executable, this 25169691Skan// file does not by itself cause the resulting executable to be covered by 26169691Skan// the GNU General Public License. This exception does not however 27169691Skan// invalidate any other reasons why the executable file might be covered by 28169691Skan// the GNU General Public License. 29169691Skan 30169691Skan/** @file atomicity.h 31169691Skan * This is an internal header file, included by other library headers. 32169691Skan * You should not attempt to use it directly. 33169691Skan */ 34169691Skan 35169691Skan#ifndef _GLIBCXX_ATOMICITY_H 36169691Skan#define _GLIBCXX_ATOMICITY_H 1 37169691Skan 38169691Skan#include <bits/c++config.h> 39169691Skan#include <bits/gthr.h> 40169691Skan#include <bits/atomic_word.h> 41169691Skan 42169691Skan_GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx) 43169691Skan 44169691Skan // Functions for portable atomic access. 45228780Spfg // To abstract locking primitives across all thread policies, use: 46169691Skan // __exchange_and_add_dispatch 47169691Skan // __atomic_add_dispatch 48169691Skan#ifdef _GLIBCXX_ATOMIC_BUILTINS 49169691Skan static inline _Atomic_word 50169691Skan __exchange_and_add(volatile _Atomic_word* __mem, int __val) 51169691Skan { return __sync_fetch_and_add(__mem, __val); } 52169691Skan 53169691Skan static inline void 54169691Skan __atomic_add(volatile _Atomic_word* __mem, int __val) 55169691Skan { __sync_fetch_and_add(__mem, __val); } 56169691Skan#else 57169691Skan _Atomic_word 58169691Skan __attribute__ ((__unused__)) 59169691Skan __exchange_and_add(volatile _Atomic_word*, int); 60169691Skan 61169691Skan void 62169691Skan __attribute__ ((__unused__)) 63169691Skan __atomic_add(volatile _Atomic_word*, int); 64169691Skan#endif 65169691Skan 66169691Skan static inline _Atomic_word 67169691Skan __exchange_and_add_single(_Atomic_word* __mem, int __val) 68169691Skan { 69169691Skan _Atomic_word __result = *__mem; 70169691Skan *__mem += __val; 71169691Skan return __result; 72169691Skan } 73169691Skan 74169691Skan static inline void 75169691Skan __atomic_add_single(_Atomic_word* __mem, int __val) 76169691Skan { *__mem += __val; } 77169691Skan 78169691Skan static inline _Atomic_word 79169691Skan __attribute__ ((__unused__)) 80169691Skan __exchange_and_add_dispatch(_Atomic_word* __mem, int __val) 81169691Skan { 82169691Skan#ifdef __GTHREADS 83169691Skan if (__gthread_active_p()) 84169691Skan return __exchange_and_add(__mem, __val); 85169691Skan else 86169691Skan return __exchange_and_add_single(__mem, __val); 87169691Skan#else 88169691Skan return __exchange_and_add_single(__mem, __val); 89169691Skan#endif 90169691Skan } 91169691Skan 92169691Skan static inline void 93169691Skan __attribute__ ((__unused__)) 94169691Skan __atomic_add_dispatch(_Atomic_word* __mem, int __val) 95169691Skan { 96169691Skan#ifdef __GTHREADS 97169691Skan if (__gthread_active_p()) 98169691Skan __atomic_add(__mem, __val); 99169691Skan else 100169691Skan __atomic_add_single(__mem, __val); 101169691Skan#else 102169691Skan __atomic_add_single(__mem, __val); 103169691Skan#endif 104169691Skan } 105169691Skan 106169691Skan_GLIBCXX_END_NAMESPACE 107169691Skan 108169691Skan// Even if the CPU doesn't need a memory barrier, we need to ensure 109169691Skan// that the compiler doesn't reorder memory accesses across the 110169691Skan// barriers. 111169691Skan#ifndef _GLIBCXX_READ_MEM_BARRIER 112169691Skan#define _GLIBCXX_READ_MEM_BARRIER __asm __volatile ("":::"memory") 113169691Skan#endif 114169691Skan#ifndef _GLIBCXX_WRITE_MEM_BARRIER 115169691Skan#define _GLIBCXX_WRITE_MEM_BARRIER __asm __volatile ("":::"memory") 116169691Skan#endif 117169691Skan 118169691Skan#endif 119