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Diffstat (limited to 'libstdc++-v3/include/parallel/omp_loop.h')
| -rw-r--r-- | libstdc++-v3/include/parallel/omp_loop.h | 115 |
1 files changed, 115 insertions, 0 deletions
diff --git a/libstdc++-v3/include/parallel/omp_loop.h b/libstdc++-v3/include/parallel/omp_loop.h new file mode 100644 index 000000000..94f9e6bba --- /dev/null +++ b/libstdc++-v3/include/parallel/omp_loop.h @@ -0,0 +1,115 @@ +// -*- C++ -*- + +// Copyright (C) 2007, 2008, 2009, 2010 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.h + * @brief Parallelization of embarrassingly parallel execution by + * means of an OpenMP for loop. + * This file is a GNU parallel extension to the Standard C++ Library. + */ + +// Written by Felix Putze. + +#ifndef _GLIBCXX_PARALLEL_OMP_LOOP_H +#define _GLIBCXX_PARALLEL_OMP_LOOP_H 1 + +#include <omp.h> + +#include <parallel/settings.h> +#include <parallel/basic_iterator.h> +#include <parallel/base.h> + +namespace __gnu_parallel +{ + /** @brief Embarrassingly parallel algorithm for random access + * iterators, using an OpenMP for loop. + * + * @param __begin Begin iterator of element sequence. + * @param __end End iterator of element sequence. + * @param __o User-supplied functor (comparator, predicate, adding + * functor, etc.). + * @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(_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 = __gnu_parallel::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(dynamic, _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._M_finish_iterator = __begin + __length; + + return __o; + } + +} // end namespace + +#endif /* _GLIBCXX_PARALLEL_OMP_LOOP_H */ |