132 lines
3.7 KiB
C++
132 lines
3.7 KiB
C++
// -*- C++ -*-
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// Copyright (C) 2007-2019 Free Software Foundation, Inc.
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//
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// This file is part of the GNU ISO C++ Library. This library is free
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// software; you can redistribute it and/or modify it under the terms
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// of the GNU General Public License as published by the Free Software
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// Foundation; either version 3, or (at your option) any later
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// version.
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// This library is distributed in the hope that it will be useful, but
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// WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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// General Public License for more details.
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// Under Section 7 of GPL version 3, you are granted additional
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// permissions described in the GCC Runtime Library Exception, version
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// 3.1, as published by the Free Software Foundation.
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// You should have received a copy of the GNU General Public License and
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// a copy of the GCC Runtime Library Exception along with this program;
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// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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// <http://www.gnu.org/licenses/>.
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/** @file parallel/compatibility.h
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* @brief Compatibility layer, mostly concerned with atomic operations.
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*
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* This file is a GNU parallel extension to the Standard C++ Library
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* and contains implementation details for the library's internal use.
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*/
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// Written by Felix Putze.
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#ifndef _GLIBCXX_PARALLEL_COMPATIBILITY_H
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#define _GLIBCXX_PARALLEL_COMPATIBILITY_H 1
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#include <parallel/types.h>
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#include <parallel/base.h>
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#if !defined(_WIN32) || defined (__CYGWIN__)
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#include <sched.h>
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#endif
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#ifdef __MINGW32__
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// Including <windows.h> will drag in all the windows32 names. Since
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// that can cause user code portability problems, we just declare the
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// one needed function here.
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extern "C"
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__attribute((dllimport)) void __attribute__((stdcall)) Sleep (unsigned long);
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#endif
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namespace __gnu_parallel
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{
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template<typename _Tp>
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inline _Tp
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__add_omp(volatile _Tp* __ptr, _Tp __addend)
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{
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int64_t __res;
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#pragma omp critical
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{
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__res = *__ptr;
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*(__ptr) += __addend;
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}
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return __res;
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}
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/** @brief Add a value to a variable, atomically.
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*
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* @param __ptr Pointer to a signed integer.
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* @param __addend Value to add.
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*/
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template<typename _Tp>
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inline _Tp
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__fetch_and_add(volatile _Tp* __ptr, _Tp __addend)
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{
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if (__atomic_always_lock_free(sizeof(_Tp), __ptr))
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return __atomic_fetch_add(__ptr, __addend, __ATOMIC_ACQ_REL);
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return __add_omp(__ptr, __addend);
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}
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template<typename _Tp>
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inline bool
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__cas_omp(volatile _Tp* __ptr, _Tp __comparand, _Tp __replacement)
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{
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bool __res = false;
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#pragma omp critical
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{
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if (*__ptr == __comparand)
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{
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*__ptr = __replacement;
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__res = true;
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}
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}
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return __res;
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}
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/** @brief Compare-and-swap
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*
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* Compare @c *__ptr and @c __comparand. If equal, let @c
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* *__ptr=__replacement and return @c true, return @c false otherwise.
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*
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* @param __ptr Pointer to signed integer.
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* @param __comparand Compare value.
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* @param __replacement Replacement value.
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*/
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template<typename _Tp>
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inline bool
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__compare_and_swap(volatile _Tp* __ptr, _Tp __comparand, _Tp __replacement)
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{
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if (__atomic_always_lock_free(sizeof(_Tp), __ptr))
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return __atomic_compare_exchange_n(__ptr, &__comparand, __replacement,
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false, __ATOMIC_ACQ_REL,
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__ATOMIC_RELAXED);
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return __cas_omp(__ptr, __comparand, __replacement);
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}
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/** @brief Yield control to another thread, without waiting for
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* the end of the time slice.
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*/
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inline void
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__yield()
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{
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#if defined (_WIN32) && !defined (__CYGWIN__)
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Sleep(0);
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#else
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sched_yield();
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#endif
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}
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} // end namespace
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#endif /* _GLIBCXX_PARALLEL_COMPATIBILITY_H */
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