8d9254fc8a
From-SVN: r279813
198 lines
6.0 KiB
C++
198 lines
6.0 KiB
C++
// -*- C++ -*-
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// Copyright (C) 2007-2020 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 3, 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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// Under Section 7 of GPL version 3, you are granted additional
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// permissions described in the GCC Runtime Library Exception, version
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// 3.1, as published by the Free Software Foundation.
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// You should have received a copy of the GNU General Public License and
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// a copy of the GCC Runtime Library Exception along with this program;
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// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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// <http://www.gnu.org/licenses/>.
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/** @file parallel/unique_copy.h
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* @brief Parallel implementations of std::unique_copy().
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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 Robert Geisberger and Robin Dapp.
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#ifndef _GLIBCXX_PARALLEL_UNIQUE_COPY_H
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#define _GLIBCXX_PARALLEL_UNIQUE_COPY_H 1
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#include <parallel/parallel.h>
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#include <parallel/multiseq_selection.h>
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namespace __gnu_parallel
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{
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/** @brief Parallel std::unique_copy(), w/__o explicit equality predicate.
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* @param __first Begin iterator of input sequence.
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* @param __last End iterator of input sequence.
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* @param __result Begin iterator of result __sequence.
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* @param __binary_pred Equality predicate.
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* @return End iterator of result __sequence. */
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template<typename _IIter,
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class _OutputIterator,
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class _BinaryPredicate>
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_OutputIterator
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__parallel_unique_copy(_IIter __first, _IIter __last,
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_OutputIterator __result,
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_BinaryPredicate __binary_pred)
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{
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_GLIBCXX_CALL(__last - __first)
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typedef std::iterator_traits<_IIter> _TraitsType;
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typedef typename _TraitsType::value_type _ValueType;
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typedef typename _TraitsType::difference_type _DifferenceType;
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_DifferenceType __size = __last - __first;
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if (__size == 0)
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return __result;
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// Let the first thread process two parts.
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_DifferenceType *__counter;
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_DifferenceType *__borders;
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_ThreadIndex __num_threads = __get_max_threads();
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// First part contains at least one element.
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# pragma omp parallel num_threads(__num_threads)
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{
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# pragma omp single
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{
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__num_threads = omp_get_num_threads();
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__borders = new _DifferenceType[__num_threads + 2];
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__equally_split(__size, __num_threads + 1, __borders);
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__counter = new _DifferenceType[__num_threads + 1];
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}
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_ThreadIndex __iam = omp_get_thread_num();
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_DifferenceType __begin, __end;
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// Check for length without duplicates
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// Needed for position in output
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_DifferenceType __i = 0;
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_OutputIterator __out = __result;
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if (__iam == 0)
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{
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__begin = __borders[0] + 1; // == 1
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__end = __borders[__iam + 1];
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++__i;
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*__out++ = *__first;
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for (_IIter __iter = __first + __begin; __iter < __first + __end;
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++__iter)
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{
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if (!__binary_pred(*__iter, *(__iter - 1)))
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{
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++__i;
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*__out++ = *__iter;
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}
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}
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}
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else
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{
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__begin = __borders[__iam]; //one part
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__end = __borders[__iam + 1];
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for (_IIter __iter = __first + __begin; __iter < __first + __end;
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++__iter)
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{
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if (!__binary_pred(*__iter, *(__iter - 1)))
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++__i;
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}
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}
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__counter[__iam] = __i;
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// Last part still untouched.
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_DifferenceType __begin_output;
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# pragma omp barrier
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// Store result in output on calculated positions.
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__begin_output = 0;
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if (__iam == 0)
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{
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for (_ThreadIndex __t = 0; __t < __num_threads; ++__t)
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__begin_output += __counter[__t];
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__i = 0;
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_OutputIterator __iter_out = __result + __begin_output;
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__begin = __borders[__num_threads];
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__end = __size;
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for (_IIter __iter = __first + __begin; __iter < __first + __end;
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++__iter)
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{
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if (__iter == __first
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|| !__binary_pred(*__iter, *(__iter - 1)))
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{
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++__i;
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*__iter_out++ = *__iter;
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}
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}
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__counter[__num_threads] = __i;
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}
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else
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{
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for (_ThreadIndex __t = 0; __t < __iam; __t++)
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__begin_output += __counter[__t];
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_OutputIterator __iter_out = __result + __begin_output;
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for (_IIter __iter = __first + __begin; __iter < __first + __end;
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++__iter)
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{
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if (!__binary_pred(*__iter, *(__iter - 1)))
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*__iter_out++ = *__iter;
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}
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}
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}
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_DifferenceType __end_output = 0;
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for (_ThreadIndex __t = 0; __t < __num_threads + 1; __t++)
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__end_output += __counter[__t];
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delete[] __borders;
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return __result + __end_output;
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}
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/** @brief Parallel std::unique_copy(), without explicit equality predicate
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* @param __first Begin iterator of input sequence.
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* @param __last End iterator of input sequence.
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* @param __result Begin iterator of result __sequence.
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* @return End iterator of result __sequence. */
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template<typename _IIter, class _OutputIterator>
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inline _OutputIterator
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__parallel_unique_copy(_IIter __first, _IIter __last,
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_OutputIterator __result)
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{
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typedef typename std::iterator_traits<_IIter>::value_type
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_ValueType;
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return __parallel_unique_copy(__first, __last, __result,
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std::equal_to<_ValueType>());
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}
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}//namespace __gnu_parallel
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#endif /* _GLIBCXX_PARALLEL_UNIQUE_COPY_H */
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