1 // -*- C++ -*- 2 3 // Copyright (C) 2007-2018 Free Software Foundation, Inc. 4 // 5 // This file is part of the GNU ISO C++ Library. This library is free 6 // software; you can redistribute it and/or modify it under the terms 7 // of the GNU General Public License as published by the Free Software 8 // Foundation; either version 3, or (at your option) any later 9 // version. 10 11 // This library is distributed in the hope that it will be useful, but 12 // WITHOUT ANY WARRANTY; without even the implied warranty of 13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14 // General Public License for more details. 15 16 // Under Section 7 of GPL version 3, you are granted additional 17 // permissions described in the GCC Runtime Library Exception, version 18 // 3.1, as published by the Free Software Foundation. 19 20 // You should have received a copy of the GNU General Public License and 21 // a copy of the GCC Runtime Library Exception along with this program; 22 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 23 // <http://www.gnu.org/licenses/>. 24 25 /** @file parallel/compatibility.h 26 * @brief Compatibility layer, mostly concerned with atomic operations. 27 * 28 * This file is a GNU parallel extension to the Standard C++ Library 29 * and contains implementation details for the library's internal use. 30 */ 31 32 // Written by Felix Putze. 33 34 #ifndef _GLIBCXX_PARALLEL_COMPATIBILITY_H 35 #define _GLIBCXX_PARALLEL_COMPATIBILITY_H 1 36 37 #include <parallel/types.h> 38 #include <parallel/base.h> 39 40 #if !defined(_WIN32) || defined (__CYGWIN__) 41 #include <sched.h> 42 #endif 43 44 #ifdef __MINGW32__ 45 // Including <windows.h> will drag in all the windows32 names. Since 46 // that can cause user code portability problems, we just declare the 47 // one needed function here. 48 extern "C" 49 __attribute((dllimport)) void __attribute__((stdcall)) Sleep (unsigned long); 50 #endif 51 52 namespace __gnu_parallel 53 { 54 template<typename _Tp> 55 inline _Tp __add_omp(volatile _Tp * __ptr,_Tp __addend)56 __add_omp(volatile _Tp* __ptr, _Tp __addend) 57 { 58 int64_t __res; 59 #pragma omp critical 60 { 61 __res = *__ptr; 62 *(__ptr) += __addend; 63 } 64 return __res; 65 } 66 67 /** @brief Add a value to a variable, atomically. 68 * 69 * @param __ptr Pointer to a signed integer. 70 * @param __addend Value to add. 71 */ 72 template<typename _Tp> 73 inline _Tp __fetch_and_add(volatile _Tp * __ptr,_Tp __addend)74 __fetch_and_add(volatile _Tp* __ptr, _Tp __addend) 75 { 76 if (__atomic_always_lock_free(sizeof(_Tp), __ptr)) 77 return __atomic_fetch_add(__ptr, __addend, __ATOMIC_ACQ_REL); 78 return __add_omp(__ptr, __addend); 79 } 80 81 template<typename _Tp> 82 inline bool __cas_omp(volatile _Tp * __ptr,_Tp __comparand,_Tp __replacement)83 __cas_omp(volatile _Tp* __ptr, _Tp __comparand, _Tp __replacement) 84 { 85 bool __res = false; 86 #pragma omp critical 87 { 88 if (*__ptr == __comparand) 89 { 90 *__ptr = __replacement; 91 __res = true; 92 } 93 } 94 return __res; 95 } 96 97 /** @brief Compare-and-swap 98 * 99 * Compare @c *__ptr and @c __comparand. If equal, let @c 100 * *__ptr=__replacement and return @c true, return @c false otherwise. 101 * 102 * @param __ptr Pointer to signed integer. 103 * @param __comparand Compare value. 104 * @param __replacement Replacement value. 105 */ 106 template<typename _Tp> 107 inline bool __compare_and_swap(volatile _Tp * __ptr,_Tp __comparand,_Tp __replacement)108 __compare_and_swap(volatile _Tp* __ptr, _Tp __comparand, _Tp __replacement) 109 { 110 if (__atomic_always_lock_free(sizeof(_Tp), __ptr)) 111 return __atomic_compare_exchange_n(__ptr, &__comparand, __replacement, 112 false, __ATOMIC_ACQ_REL, 113 __ATOMIC_RELAXED); 114 return __cas_omp(__ptr, __comparand, __replacement); 115 } 116 117 /** @brief Yield control to another thread, without waiting for 118 * the end of the time slice. 119 */ 120 inline void __yield()121 __yield() 122 { 123 #if defined (_WIN32) && !defined (__CYGWIN__) 124 Sleep(0); 125 #else 126 sched_yield(); 127 #endif 128 } 129 } // end namespace 130 131 #endif /* _GLIBCXX_PARALLEL_COMPATIBILITY_H */ 132