| // 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 |