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- // -*- C++ -*-
- // Copyright (C) 2007-2022 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 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.
- */
- // Written by Felix Putze.
- #ifndef _GLIBCXX_PARALLEL_OMP_LOOP_STATIC_H
- #define _GLIBCXX_PARALLEL_OMP_LOOP_STATIC_H 1
- #include <omp.h>
- #include <parallel/settings.h>
- #include <parallel/basic_iterator.h>
- 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;
- _DifferenceType __length = __end - __begin;
- _ThreadIndex __num_threads = std::min<_DifferenceType>
- (__get_max_threads(), __length);
- _Result *__thread_results;
- # pragma omp parallel num_threads(__num_threads)
- {
- # pragma omp single
- {
- __num_threads = omp_get_num_threads();
- __thread_results = new _Result[__num_threads];
- for (_ThreadIndex __i = 0; __i < __num_threads; ++__i)
- __thread_results[__i] = _Result();
- }
- _ThreadIndex __iam = omp_get_thread_num();
- #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
- for (_ThreadIndex __i = 0; __i < __num_threads; ++__i)
- __output = __r(__output, __thread_results[__i]);
- delete [] __thread_results;
- // Points to last element processed (needed as return value for
- // some algorithms like transform).
- __f.finish_iterator = __begin + __length;
- return __o;
- }
- } // end namespace
- #endif /* _GLIBCXX_PARALLEL_OMP_LOOP_STATIC_H */
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