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/usr/include/c++/8/parallel/omp_loop.h

// -*- C++ -*-

// Copyright (C) 2007-2018 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 */

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algo.h	78.15 KB	lrw-r--r--	2025-08-26 09:45:05	Edit Download recursive recursive
algobase.h	16.75 KB	lrw-r--r--	2025-08-26 09:45:05	Edit Download recursive recursive
algorithm	1.35 KB	lrw-r--r--	2025-08-26 09:45:05	Edit Download recursive recursive
algorithmfwd.h	31.45 KB	lrw-r--r--	2025-08-26 09:45:05	Edit Download recursive recursive
balanced_quicksort.h	16.55 KB	lrw-r--r--	2025-08-26 09:45:05	Edit Download recursive recursive
base.h	12.08 KB	lrw-r--r--	2025-08-26 09:45:05	Edit Download recursive recursive
basic_iterator.h	1.55 KB	lrw-r--r--	2025-08-26 09:45:05	Edit Download recursive recursive
checkers.h	2.25 KB	lrw-r--r--	2025-08-26 09:45:05	Edit Download recursive recursive
compatibility.h	3.70 KB	lrw-r--r--	2025-08-26 09:45:05	Edit Download recursive recursive
compiletime_settings.h	2.80 KB	lrw-r--r--	2025-08-26 09:45:05	Edit Download recursive recursive
equally_split.h	3.28 KB	lrw-r--r--	2025-08-26 09:45:05	Edit Download recursive recursive
features.h	3.46 KB	lrw-r--r--	2025-08-26 09:45:05	Edit Download recursive recursive
find.h	13.27 KB	lrw-r--r--	2025-08-26 09:45:05	Edit Download recursive recursive
find_selectors.h	6.83 KB	lrw-r--r--	2025-08-26 09:45:05	Edit Download recursive recursive
for_each.h	3.85 KB	lrw-r--r--	2025-08-26 09:45:05	Edit Download recursive recursive
for_each_selectors.h	10.32 KB	lrw-r--r--	2025-08-26 09:45:05	Edit Download recursive recursive
iterator.h	5.54 KB	lrw-r--r--	2025-08-26 09:45:05	Edit Download recursive recursive
list_partition.h	6.39 KB	lrw-r--r--	2025-08-26 09:45:05	Edit Download recursive recursive
losertree.h	27.92 KB	lrw-r--r--	2025-08-26 09:45:05	Edit Download recursive recursive
merge.h	9.35 KB	lrw-r--r--	2025-08-26 09:45:05	Edit Download recursive recursive
multiseq_selection.h	21.56 KB	lrw-r--r--	2025-08-26 09:45:05	Edit Download recursive recursive
multiway_merge.h	68.88 KB	lrw-r--r--	2025-08-26 09:45:05	Edit Download recursive recursive
multiway_mergesort.h	14.91 KB	lrw-r--r--	2025-08-26 09:45:05	Edit Download recursive recursive
numeric	20.23 KB	lrw-r--r--	2025-08-26 09:45:05	Edit Download recursive recursive
numericfwd.h	7.32 KB	lrw-r--r--	2025-08-26 09:45:05	Edit Download recursive recursive
omp_loop.h	3.94 KB	lrw-r--r--	2025-08-26 09:45:05	Edit Download recursive recursive
omp_loop_static.h	4.01 KB	lrw-r--r--	2025-08-26 09:45:05	Edit Download recursive recursive
parallel.h	1.54 KB	lrw-r--r--	2025-08-26 09:45:05	Edit Download recursive recursive
partial_sum.h	7.30 KB	lrw-r--r--	2025-08-26 09:45:05	Edit Download recursive recursive
partition.h	14.61 KB	lrw-r--r--	2025-08-26 09:45:05	Edit Download recursive recursive
par_loop.h	4.45 KB	lrw-r--r--	2025-08-26 09:45:05	Edit Download recursive recursive
queue.h	5.41 KB	lrw-r--r--	2025-08-26 09:45:05	Edit Download recursive recursive
quicksort.h	5.98 KB	lrw-r--r--	2025-08-26 09:45:05	Edit Download recursive recursive
random_number.h	4.13 KB	lrw-r--r--	2025-08-26 09:45:05	Edit Download recursive recursive
random_shuffle.h	18.24 KB	lrw-r--r--	2025-08-26 09:45:05	Edit Download recursive recursive
search.h	5.26 KB	lrw-r--r--	2025-08-26 09:45:05	Edit Download recursive recursive
settings.h	12.17 KB	lrw-r--r--	2025-08-26 09:45:05	Edit Download recursive recursive
set_operations.h	14.25 KB	lrw-r--r--	2025-08-26 09:45:05	Edit Download recursive recursive
sort.h	7.53 KB	lrw-r--r--	2025-08-26 09:45:05	Edit Download recursive recursive
tags.h	5.84 KB	lrw-r--r--	2025-08-26 09:45:05	Edit Download recursive recursive
types.h	3.63 KB	lrw-r--r--	2025-08-26 09:45:05	Edit Download recursive recursive
unique_copy.h	6.02 KB	lrw-r--r--	2025-08-26 09:45:05	Edit Download recursive recursive
workstealing.h	9.39 KB	lrw-r--r--	2025-08-26 09:45:05	Edit Download recursive recursive