libstdc++
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00001 // Support for atomic operations -*- C++ -*- 00002 00003 // Copyright (C) 2004, 2005, 2006, 2008, 2009, 2010, 2011, 2012 00004 // Free Software Foundation, Inc. 00005 // 00006 // This file is part of the GNU ISO C++ Library. This library is free 00007 // software; you can redistribute it and/or modify it under the 00008 // terms of the GNU General Public License as published by the 00009 // Free Software Foundation; either version 3, or (at your option) 00010 // any later version. 00011 00012 // This library is distributed in the hope that it will be useful, 00013 // but WITHOUT ANY WARRANTY; without even the implied warranty of 00014 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 00015 // GNU General Public License for more details. 00016 00017 // Under Section 7 of GPL version 3, you are granted additional 00018 // permissions described in the GCC Runtime Library Exception, version 00019 // 3.1, as published by the Free Software Foundation. 00020 00021 // You should have received a copy of the GNU General Public License and 00022 // a copy of the GCC Runtime Library Exception along with this program; 00023 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 00024 // <http://www.gnu.org/licenses/>. 00025 00026 /** @file ext/atomicity.h 00027 * This file is a GNU extension to the Standard C++ Library. 00028 */ 00029 00030 #ifndef _GLIBCXX_ATOMICITY_H 00031 #define _GLIBCXX_ATOMICITY_H 1 00032 00033 #include <bits/c++config.h> 00034 #include <bits/gthr.h> 00035 #include <bits/atomic_word.h> 00036 00037 namespace __gnu_cxx _GLIBCXX_VISIBILITY(default) 00038 { 00039 _GLIBCXX_BEGIN_NAMESPACE_VERSION 00040 00041 // Functions for portable atomic access. 00042 // To abstract locking primitives across all thread policies, use: 00043 // __exchange_and_add_dispatch 00044 // __atomic_add_dispatch 00045 #ifdef _GLIBCXX_ATOMIC_BUILTINS 00046 static inline _Atomic_word 00047 __exchange_and_add(volatile _Atomic_word* __mem, int __val) 00048 { return __atomic_fetch_add(__mem, __val, __ATOMIC_ACQ_REL); } 00049 00050 static inline void 00051 __atomic_add(volatile _Atomic_word* __mem, int __val) 00052 { __atomic_fetch_add(__mem, __val, __ATOMIC_ACQ_REL); } 00053 #else 00054 _Atomic_word 00055 __attribute__ ((__unused__)) 00056 __exchange_and_add(volatile _Atomic_word*, int) throw (); 00057 00058 void 00059 __attribute__ ((__unused__)) 00060 __atomic_add(volatile _Atomic_word*, int) throw (); 00061 #endif 00062 00063 static inline _Atomic_word 00064 __exchange_and_add_single(_Atomic_word* __mem, int __val) 00065 { 00066 _Atomic_word __result = *__mem; 00067 *__mem += __val; 00068 return __result; 00069 } 00070 00071 static inline void 00072 __atomic_add_single(_Atomic_word* __mem, int __val) 00073 { *__mem += __val; } 00074 00075 static inline _Atomic_word 00076 __attribute__ ((__unused__)) 00077 __exchange_and_add_dispatch(_Atomic_word* __mem, int __val) 00078 { 00079 #ifdef __GTHREADS 00080 if (__gthread_active_p()) 00081 return __exchange_and_add(__mem, __val); 00082 else 00083 return __exchange_and_add_single(__mem, __val); 00084 #else 00085 return __exchange_and_add_single(__mem, __val); 00086 #endif 00087 } 00088 00089 static inline void 00090 __attribute__ ((__unused__)) 00091 __atomic_add_dispatch(_Atomic_word* __mem, int __val) 00092 { 00093 #ifdef __GTHREADS 00094 if (__gthread_active_p()) 00095 __atomic_add(__mem, __val); 00096 else 00097 __atomic_add_single(__mem, __val); 00098 #else 00099 __atomic_add_single(__mem, __val); 00100 #endif 00101 } 00102 00103 _GLIBCXX_END_NAMESPACE_VERSION 00104 } // namespace 00105 00106 // Even if the CPU doesn't need a memory barrier, we need to ensure 00107 // that the compiler doesn't reorder memory accesses across the 00108 // barriers. 00109 #ifndef _GLIBCXX_READ_MEM_BARRIER 00110 #define _GLIBCXX_READ_MEM_BARRIER __asm __volatile ("":::"memory") 00111 #endif 00112 #ifndef _GLIBCXX_WRITE_MEM_BARRIER 00113 #define _GLIBCXX_WRITE_MEM_BARRIER __asm __volatile ("":::"memory") 00114 #endif 00115 00116 #endif