--- /dev/null
+// -*- C++ -*-
+
+// Copyright (C) 2007, 2008, 2009, 2010, 2011 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/quicksort.h
+ * @brief Implementation of a unbalanced parallel quicksort (in-place).
+ * This file is a GNU parallel extension to the Standard C++ Library.
+ */
+
+// Written by Johannes Singler.
+
+#ifndef _GLIBCXX_PARALLEL_QUICKSORT_H
+#define _GLIBCXX_PARALLEL_QUICKSORT_H 1
+
+#include <parallel/parallel.h>
+#include <parallel/partition.h>
+
+namespace __gnu_parallel
+{
+ /** @brief Unbalanced quicksort divide step.
+ * @param __begin Begin iterator of subsequence.
+ * @param __end End iterator of subsequence.
+ * @param __comp Comparator.
+ * @param __pivot_rank Desired __rank of the pivot.
+ * @param __num_samples Choose pivot from that many samples.
+ * @param __num_threads Number of threads that are allowed to work on
+ * this part.
+ */
+ template<typename _RAIter, typename _Compare>
+ typename std::iterator_traits<_RAIter>::difference_type
+ __parallel_sort_qs_divide(_RAIter __begin, _RAIter __end,
+ _Compare __comp, typename std::iterator_traits
+ <_RAIter>::difference_type __pivot_rank,
+ typename std::iterator_traits
+ <_RAIter>::difference_type
+ __num_samples, _ThreadIndex __num_threads)
+ {
+ typedef std::iterator_traits<_RAIter> _TraitsType;
+ typedef typename _TraitsType::value_type _ValueType;
+ typedef typename _TraitsType::difference_type _DifferenceType;
+
+ _DifferenceType __n = __end - __begin;
+ __num_samples = std::min(__num_samples, __n);
+
+ // Allocate uninitialized, to avoid default constructor.
+ _ValueType* __samples = static_cast<_ValueType*>
+ (::operator new(__num_samples * sizeof(_ValueType)));
+
+ for (_DifferenceType __s = 0; __s < __num_samples; ++__s)
+ {
+ const unsigned long long __index = static_cast<unsigned long long>
+ (__s) * __n / __num_samples;
+ ::new(&(__samples[__s])) _ValueType(__begin[__index]);
+ }
+
+ __gnu_sequential::sort(__samples, __samples + __num_samples, __comp);
+
+ _ValueType& __pivot = __samples[__pivot_rank * __num_samples / __n];
+
+ __gnu_parallel::__binder2nd<_Compare, _ValueType, _ValueType, bool>
+ __pred(__comp, __pivot);
+ _DifferenceType __split = __parallel_partition(__begin, __end,
+ __pred, __num_threads);
+
+ for (_DifferenceType __s = 0; __s < __num_samples; ++__s)
+ __samples[__s].~_ValueType();
+ ::operator delete(__samples);
+
+ return __split;
+ }
+
+ /** @brief Unbalanced quicksort conquer step.
+ * @param __begin Begin iterator of subsequence.
+ * @param __end End iterator of subsequence.
+ * @param __comp Comparator.
+ * @param __num_threads Number of threads that are allowed to work on
+ * this part.
+ */
+ template<typename _RAIter, typename _Compare>
+ void
+ __parallel_sort_qs_conquer(_RAIter __begin, _RAIter __end,
+ _Compare __comp,
+ _ThreadIndex __num_threads)
+ {
+ typedef std::iterator_traits<_RAIter> _TraitsType;
+ typedef typename _TraitsType::value_type _ValueType;
+ typedef typename _TraitsType::difference_type _DifferenceType;
+
+ if (__num_threads <= 1)
+ {
+ __gnu_sequential::sort(__begin, __end, __comp);
+ return;
+ }
+
+ _DifferenceType __n = __end - __begin, __pivot_rank;
+
+ if (__n <= 1)
+ return;
+
+ _ThreadIndex __num_threads_left;
+
+ if ((__num_threads % 2) == 1)
+ __num_threads_left = __num_threads / 2 + 1;
+ else
+ __num_threads_left = __num_threads / 2;
+
+ __pivot_rank = __n * __num_threads_left / __num_threads;
+
+ _DifferenceType __split = __parallel_sort_qs_divide
+ (__begin, __end, __comp, __pivot_rank,
+ _Settings::get().sort_qs_num_samples_preset, __num_threads);
+
+#pragma omp parallel sections num_threads(2)
+ {
+#pragma omp section
+ __parallel_sort_qs_conquer(__begin, __begin + __split,
+ __comp, __num_threads_left);
+#pragma omp section
+ __parallel_sort_qs_conquer(__begin + __split, __end,
+ __comp, __num_threads - __num_threads_left);
+ }
+ }
+
+
+ /** @brief Unbalanced quicksort main call.
+ * @param __begin Begin iterator of input sequence.
+ * @param __end End iterator input sequence, ignored.
+ * @param __comp Comparator.
+ * @param __num_threads Number of threads that are allowed to work on
+ * this part.
+ */
+ template<typename _RAIter, typename _Compare>
+ void
+ __parallel_sort_qs(_RAIter __begin, _RAIter __end,
+ _Compare __comp,
+ _ThreadIndex __num_threads)
+ {
+ _GLIBCXX_CALL(__n)
+
+ typedef std::iterator_traits<_RAIter> _TraitsType;
+ typedef typename _TraitsType::value_type _ValueType;
+ typedef typename _TraitsType::difference_type _DifferenceType;
+
+ _DifferenceType __n = __end - __begin;
+
+ // At least one element per processor.
+ if (__num_threads > __n)
+ __num_threads = static_cast<_ThreadIndex>(__n);
+
+ __parallel_sort_qs_conquer(
+ __begin, __begin + __n, __comp, __num_threads);
+ }
+
+} //namespace __gnu_parallel
+
+#endif /* _GLIBCXX_PARALLEL_QUICKSORT_H */
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