// Support for atomic operations -*- C++ -*- // Copyright (C) 2004, 2005, 2006 Free Software Foundation, Inc. // // This file is part of the GNU ISO C++ Library. This library is free // software; you can redistribute it and/or modify it under the // terms of the GNU General Public License as published by the // Free Software Foundation; either version 2, or (at your option) // any later version. // This library is distributed in the hope that it will be useful, // but WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the // GNU General Public License for more details. // You should have received a copy of the GNU General Public License along // with this library; see the file COPYING. If not, write to the Free // Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, // USA. // As a special exception, you may use this file as part of a free software // library without restriction. Specifically, if other files instantiate // templates or use macros or inline functions from this file, or you compile // this file and link it with other files to produce an executable, this // file does not by itself cause the resulting executable to be covered by // the GNU General Public License. This exception does not however // invalidate any other reasons why the executable file might be covered by // the GNU General Public License. /** @file atomicity.h * This is an internal header file, included by other library headers. * You should not attempt to use it directly. */ #ifndef _GLIBCXX_ATOMICITY_H #define _GLIBCXX_ATOMICITY_H 1 #include <bits/c++config.h> #include <bits/gthr.h> #include <bits/atomic_word.h> _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx) // Functions for portable atomic access. // To abstract locking primatives across all thread policies, use: // __exchange_and_add_dispatch // __atomic_add_dispatch #ifdef _GLIBCXX_ATOMIC_BUILTINS static inline _Atomic_word __exchange_and_add(volatile _Atomic_word* __mem, int __val) { return __sync_fetch_and_add(__mem, __val); } static inline void __atomic_add(volatile _Atomic_word* __mem, int __val) { __sync_fetch_and_add(__mem, __val); } #else _Atomic_word __attribute__ ((__unused__)) __exchange_and_add(volatile _Atomic_word*, int); void __attribute__ ((__unused__)) __atomic_add(volatile _Atomic_word*, int); #endif static inline _Atomic_word __exchange_and_add_single(_Atomic_word* __mem, int __val) { _Atomic_word __result = *__mem; *__mem += __val; return __result; } static inline void __atomic_add_single(_Atomic_word* __mem, int __val) { *__mem += __val; } static inline _Atomic_word __attribute__ ((__unused__)) __exchange_and_add_dispatch(_Atomic_word* __mem, int __val) { #ifdef __GTHREADS if (__gthread_active_p()) return __exchange_and_add(__mem, __val); else return __exchange_and_add_single(__mem, __val); #else return __exchange_and_add_single(__mem, __val); #endif } static inline void __attribute__ ((__unused__)) __atomic_add_dispatch(_Atomic_word* __mem, int __val) { #ifdef __GTHREADS if (__gthread_active_p()) __atomic_add(__mem, __val); else __atomic_add_single(__mem, __val); #else __atomic_add_single(__mem, __val); #endif } _GLIBCXX_END_NAMESPACE // Even if the CPU doesn't need a memory barrier, we need to ensure // that the compiler doesn't reorder memory accesses across the // barriers. #ifndef _GLIBCXX_READ_MEM_BARRIER #define _GLIBCXX_READ_MEM_BARRIER __asm __volatile ("":::"memory") #endif #ifndef _GLIBCXX_WRITE_MEM_BARRIER #define _GLIBCXX_WRITE_MEM_BARRIER __asm __volatile ("":::"memory") #endif #endif