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+// -*- C++ -*-
+
+// Copyright (C) 2007, 2008, 2009 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/par_loop.h
+ * @brief Parallelization of embarrassingly parallel execution by
+ * means of equal splitting.
+ * This file is a GNU parallel extension to the Standard C++ Library.
+ */
+
+// Written by Felix Putze.
+
+#ifndef _GLIBCXX_PARALLEL_PAR_LOOP_H
+#define _GLIBCXX_PARALLEL_PAR_LOOP_H 1
+
+#include <omp.h>
+#include <parallel/settings.h>
+#include <parallel/base.h>
+#include <parallel/equally_split.h>
+
+namespace __gnu_parallel
+{
+
+/** @brief Embarrassingly parallel algorithm for random access
+ * iterators, using hand-crafted parallelization by equal splitting
+ * the work.
+ *
+ * @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 "process" an element with op (depends on
+ * desired functionality, e. g. for std::for_each(), ...).
+ * @param r Functor to "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 RandomAccessIterator,
+ typename Op,
+ typename Fu,
+ typename Red,
+ typename Result>
+ Op
+ for_each_template_random_access_ed(RandomAccessIterator begin,
+ RandomAccessIterator end,
+ Op o, Fu& f, Red r, Result base,
+ Result& output,
+ typename std::iterator_traits
+ <RandomAccessIterator>::
+ difference_type bound)
+ {
+ typedef std::iterator_traits<RandomAccessIterator> traits_type;
+ typedef typename traits_type::difference_type difference_type;
+ const difference_type length = end - begin;
+ Result *thread_results;
+ bool* constructed;
+
+ thread_index_t num_threads =
+ __gnu_parallel::min<difference_type>(get_max_threads(), length);
+
+# pragma omp parallel num_threads(num_threads)
+ {
+# pragma omp single
+ {
+ num_threads = omp_get_num_threads();
+ thread_results = static_cast<Result*>(
+ ::operator new(num_threads * sizeof(Result)));
+ constructed = new bool[num_threads];
+ }
+
+ thread_index_t iam = omp_get_thread_num();
+
+ // Neutral element.
+ Result* reduct = static_cast<Result*>(::operator new(sizeof(Result)));
+
+ difference_type
+ start = equally_split_point(length, num_threads, iam),
+ stop = equally_split_point(length, num_threads, iam + 1);
+
+ if (start < stop)
+ {
+ new(reduct) Result(f(o, begin + start));
+ ++start;
+ constructed[iam] = true;
+ }
+ else
+ constructed[iam] = false;
+
+ for (; start < stop; ++start)
+ *reduct = r(*reduct, f(o, begin + start));
+
+ thread_results[iam] = *reduct;
+ } //parallel
+
+ for (thread_index_t i = 0; i < num_threads; ++i)
+ if (constructed[i])
+ output = r(output, thread_results[i]);
+
+ // Points to last element processed (needed as return value for
+ // some algorithms like transform).
+ f.finish_iterator = begin + length;
+
+ delete[] thread_results;
+ delete[] constructed;
+
+ return o;
+ }
+
+} // end namespace
+
+#endif /* _GLIBCXX_PARALLEL_PAR_LOOP_H */