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// -*- C++ -*- |
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// Copyright (C) 2007-2013 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. |
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// 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. |
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// 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. |
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// 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/>. |
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/** @file parallel/omp_loop_static.h |
* @brief Parallelization of embarrassingly parallel execution by |
* means of an OpenMP for loop with static scheduling. |
* This file is a GNU parallel extension to the Standard C++ Library. |
*/ |
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// Written by Felix Putze. |
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#ifndef _GLIBCXX_PARALLEL_OMP_LOOP_STATIC_H |
#define _GLIBCXX_PARALLEL_OMP_LOOP_STATIC_H 1 |
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#include <omp.h> |
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#include <parallel/settings.h> |
#include <parallel/basic_iterator.h> |
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namespace __gnu_parallel |
{ |
/** @brief Embarrassingly parallel algorithm for random access |
* iterators, using an OpenMP for loop with static scheduling. |
* |
* @param __begin Begin iterator of element sequence. |
* @param __end End iterator of element sequence. |
* @param __o User-supplied functor (comparator, predicate, adding |
* functor, ...). |
* @param __f Functor to @a process an element with __op (depends on |
* desired functionality, e. g. for std::for_each(), ...). |
* @param __r Functor to @a add a single __result to the already processed |
* __elements (depends on functionality). |
* @param __base Base value for reduction. |
* @param __output Pointer to position where final result is written to |
* @param __bound Maximum number of elements processed (e. g. for |
* std::count_n()). |
* @return User-supplied functor (that may contain a part of the result). |
*/ |
template<typename _RAIter, |
typename _Op, |
typename _Fu, |
typename _Red, |
typename _Result> |
_Op |
__for_each_template_random_access_omp_loop_static(_RAIter __begin, |
_RAIter __end, _Op __o, |
_Fu& __f, _Red __r, |
_Result __base, |
_Result& __output, |
typename std::iterator_traits<_RAIter>::difference_type __bound) |
{ |
typedef typename std::iterator_traits<_RAIter>::difference_type |
_DifferenceType; |
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_DifferenceType __length = __end - __begin; |
_ThreadIndex __num_threads = std::min<_DifferenceType> |
(__get_max_threads(), __length); |
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_Result *__thread_results; |
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# pragma omp parallel num_threads(__num_threads) |
{ |
# pragma omp single |
{ |
__num_threads = omp_get_num_threads(); |
__thread_results = new _Result[__num_threads]; |
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for (_ThreadIndex __i = 0; __i < __num_threads; ++__i) |
__thread_results[__i] = _Result(); |
} |
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_ThreadIndex __iam = omp_get_thread_num(); |
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#pragma omp for schedule(static, _Settings::get().workstealing_chunk_size) |
for (_DifferenceType __pos = 0; __pos < __length; ++__pos) |
__thread_results[__iam] = __r(__thread_results[__iam], |
__f(__o, __begin+__pos)); |
} //parallel |
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for (_ThreadIndex __i = 0; __i < __num_threads; ++__i) |
__output = __r(__output, __thread_results[__i]); |
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delete [] __thread_results; |
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// Points to last element processed (needed as return value for |
// some algorithms like transform). |
__f.finish_iterator = __begin + __length; |
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return __o; |
} |
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} // end namespace |
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#endif /* _GLIBCXX_PARALLEL_OMP_LOOP_STATIC_H */ |