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| // Support for atomic operations -*- C++ -*- |
| |
| // Copyright (C) 2004-2013 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 3, 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. |
| |
| // Under Section 7 of GPL version 3, you are granted additional |
| // permissions described in the GCC Runtime Library Exception, version |
| // 3.1, as published by the Free Software Foundation. |
| |
| // You should have received a copy of the GNU General Public License and |
| // a copy of the GCC Runtime Library Exception along with this program; |
| // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see |
| // <http://www.gnu.org/licenses/>. |
| |
| /** @file ext/atomicity.h |
| * This file is a GNU extension to the Standard C++ Library. |
| */ |
| |
| #ifndef _GLIBCXX_ATOMICITY_H |
| #define _GLIBCXX_ATOMICITY_H 1 |
| |
| #pragma GCC system_header |
| |
| #include <bits/c++config.h> |
| #include <bits/gthr.h> |
| #include <bits/atomic_word.h> |
| |
| namespace __gnu_cxx _GLIBCXX_VISIBILITY(default) |
| { |
| _GLIBCXX_BEGIN_NAMESPACE_VERSION |
| |
| // Functions for portable atomic access. |
| // To abstract locking primitives 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 __atomic_fetch_add(__mem, __val, __ATOMIC_ACQ_REL); } |
| |
| static inline void |
| __atomic_add(volatile _Atomic_word* __mem, int __val) |
| { __atomic_fetch_add(__mem, __val, __ATOMIC_ACQ_REL); } |
| #else |
| _Atomic_word |
| __attribute__ ((__unused__)) |
| __exchange_and_add(volatile _Atomic_word*, int) throw (); |
| |
| void |
| __attribute__ ((__unused__)) |
| __atomic_add(volatile _Atomic_word*, int) throw (); |
| #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_VERSION |
| } // 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 |