cbcd1e4520
2008-07-15 Johannes Singler <singler@ira.uka.de>
* include/parallel/find_selectors.h:
Correct name for include guard #ifndef.
* include/parallel/balanced_quicksort.h: Likewise.
* include/parallel/unique_copy.h: Likewise.
* include/parallel/multiway_mergesort.h: Likewise.
* include/parallel/checkers.h: Likewise.
* include/parallel/[various files]:
Add/correct comment for #endif of include guard (at end of file)
From-SVN: r137827
94 lines
3.4 KiB
C++
94 lines
3.4 KiB
C++
// -*- C++ -*-
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// Copyright (C) 2007 Free Software Foundation, Inc.
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//
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// This file is part of the GNU ISO C++ Library. This library is free
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// software; you can redistribute it and/or modify it under the terms
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// of the GNU General Public License as published by the Free Software
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// Foundation; either version 2, or (at your option) any later
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// version.
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// This library is distributed in the hope that it will be useful, but
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// WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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// General Public License for more details.
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// You should have received a copy of the GNU General Public License
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// along with this library; see the file COPYING. If not, write to
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// the Free Software Foundation, 59 Temple Place - Suite 330, Boston,
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// MA 02111-1307, USA.
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// As a special exception, you may use this file as part of a free
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// software library without restriction. Specifically, if other files
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// instantiate templates or use macros or inline functions from this
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// file, or you compile this file and link it with other files to
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// produce an executable, this file does not by itself cause the
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// resulting executable to be covered by the GNU General Public
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// License. This exception does not however invalidate any other
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// reasons why the executable file might be covered by the GNU General
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// Public License.
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/** @file parallel/equally_split.h
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* This file is a GNU parallel extension to the Standard C++ Library.
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*/
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// Written by Johannes Singler.
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#ifndef _GLIBCXX_PARALLEL_EQUALLY_SPLIT_H
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#define _GLIBCXX_PARALLEL_EQUALLY_SPLIT_H 1
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namespace __gnu_parallel
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{
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/** @brief Function to split a sequence into parts of almost equal size.
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*
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* The resulting sequence s of length num_threads+1 contains the splitting
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* positions when splitting the range [0,n) into parts of almost
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* equal size (plus minus 1). The first entry is 0, the last one
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* n. There may result empty parts.
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* @param n Number of elements
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* @param num_threads Number of parts
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* @param s Splitters
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* @returns End of splitter sequence, i. e. @c s+num_threads+1 */
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template<typename difference_type, typename OutputIterator>
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OutputIterator
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equally_split(difference_type n, thread_index_t num_threads, OutputIterator s)
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{
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difference_type chunk_length = n / num_threads;
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difference_type num_longer_chunks = n % num_threads;
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difference_type pos = 0;
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for (thread_index_t i = 0; i < num_threads; ++i)
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{
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*s++ = pos;
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pos += (i < num_longer_chunks) ? (chunk_length + 1) : chunk_length;
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}
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*s++ = n;
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return s;
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}
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/** @brief Function to split a sequence into parts of almost equal size.
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*
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* Returns the position of the splitting point between
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* thread number thread_no (included) and
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* thread number thread_no+1 (excluded).
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* @param n Number of elements
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* @param num_threads Number of parts
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* @returns _SplittingAlgorithm point */
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template<typename difference_type>
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difference_type
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equally_split_point(difference_type n,
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thread_index_t num_threads,
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thread_index_t thread_no)
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{
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difference_type chunk_length = n / num_threads;
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difference_type num_longer_chunks = n % num_threads;
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if (thread_no < num_longer_chunks)
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return thread_no * (chunk_length + 1);
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else
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return num_longer_chunks * (chunk_length + 1)
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+ (thread_no - num_longer_chunks) * chunk_length;
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}
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}
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#endif /* _GLIBCXX_PARALLEL_EQUALLY_SPLIT_H */
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