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c2ba9709 JS |
1 | // -*- C++ -*- |
2 | ||
748086b7 | 3 | // Copyright (C) 2007, 2008, 2009 Free Software Foundation, Inc. |
c2ba9709 JS |
4 | // |
5 | // This file is part of the GNU ISO C++ Library. This library is free | |
6 | // software; you can redistribute it and/or modify it under the terms | |
7 | // of the GNU General Public License as published by the Free Software | |
748086b7 | 8 | // Foundation; either version 3, or (at your option) any later |
c2ba9709 JS |
9 | // version. |
10 | ||
11 | // This library is distributed in the hope that it will be useful, but | |
12 | // WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
14 | // General Public License for more details. | |
15 | ||
748086b7 JJ |
16 | // Under Section 7 of GPL version 3, you are granted additional |
17 | // permissions described in the GCC Runtime Library Exception, version | |
18 | // 3.1, as published by the Free Software Foundation. | |
c2ba9709 | 19 | |
748086b7 JJ |
20 | // You should have received a copy of the GNU General Public License and |
21 | // a copy of the GCC Runtime Library Exception along with this program; | |
22 | // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see | |
23 | // <http://www.gnu.org/licenses/>. | |
c2ba9709 JS |
24 | |
25 | /** @file parallel/multiway_mergesort.h | |
26 | * @brief Parallel multiway merge sort. | |
27 | * This file is a GNU parallel extension to the Standard C++ Library. | |
28 | */ | |
29 | ||
30 | // Written by Johannes Singler. | |
31 | ||
cbcd1e45 JS |
32 | #ifndef _GLIBCXX_PARALLEL_MULTIWAY_MERGESORT_H |
33 | #define _GLIBCXX_PARALLEL_MULTIWAY_MERGESORT_H 1 | |
c2ba9709 JS |
34 | |
35 | #include <vector> | |
36 | ||
37 | #include <parallel/basic_iterator.h> | |
38 | #include <bits/stl_algo.h> | |
39 | #include <parallel/parallel.h> | |
40 | #include <parallel/multiway_merge.h> | |
c2ba9709 JS |
41 | |
42 | namespace __gnu_parallel | |
43 | { | |
44 | ||
e683ee2a JS |
45 | /** @brief Subsequence description. */ |
46 | template<typename _DifferenceTp> | |
1acba85b | 47 | struct _Piece |
c2ba9709 | 48 | { |
1acba85b | 49 | typedef _DifferenceTp _DifferenceType; |
c2ba9709 JS |
50 | |
51 | /** @brief Begin of subsequence. */ | |
54384f7f | 52 | _DifferenceType _M_begin; |
c2ba9709 JS |
53 | |
54 | /** @brief End of subsequence. */ | |
54384f7f | 55 | _DifferenceType _M_end; |
c2ba9709 JS |
56 | }; |
57 | ||
e683ee2a JS |
58 | /** @brief Data accessed by all threads. |
59 | * | |
60 | * PMWMS = parallel multiway mergesort */ | |
1acba85b JS |
61 | template<typename _RAIter> |
62 | struct _PMWMSSortingData | |
c2ba9709 | 63 | { |
1acba85b JS |
64 | typedef std::iterator_traits<_RAIter> _TraitsType; |
65 | typedef typename _TraitsType::value_type _ValueType; | |
66 | typedef typename _TraitsType::difference_type _DifferenceType; | |
c2ba9709 | 67 | |
e683ee2a | 68 | /** @brief Number of threads involved. */ |
54384f7f | 69 | _ThreadIndex _M_num_threads; |
e683ee2a | 70 | |
1acba85b JS |
71 | /** @brief Input __begin. */ |
72 | _RAIter _M_source; | |
c2ba9709 JS |
73 | |
74 | /** @brief Start indices, per thread. */ | |
1acba85b | 75 | _DifferenceType* _M_starts; |
c2ba9709 | 76 | |
c2ba9709 | 77 | /** @brief Storage in which to sort. */ |
1acba85b | 78 | _ValueType** _M_temporary; |
c2ba9709 | 79 | |
c2ba9709 | 80 | /** @brief Samples. */ |
1acba85b | 81 | _ValueType* _M_samples; |
c2ba9709 JS |
82 | |
83 | /** @brief Offsets to add to the found positions. */ | |
1acba85b | 84 | _DifferenceType* _M_offsets; |
c2ba9709 | 85 | |
1acba85b JS |
86 | /** @brief Pieces of data to merge @__c [thread][__sequence] */ |
87 | std::vector<_Piece<_DifferenceType> >* _M_pieces; | |
e683ee2a JS |
88 | }; |
89 | ||
90 | /** | |
1acba85b JS |
91 | * @brief Select _M_samples from a sequence. |
92 | * @param __sd Pointer to algorithm data. _Result will be placed in | |
93 | * @__c __sd->_M_samples. | |
94 | * @param __num_samples Number of _M_samples to select. | |
e683ee2a | 95 | */ |
1acba85b | 96 | template<typename _RAIter, typename _DifferenceTp> |
5817ff8e | 97 | void |
1acba85b JS |
98 | __determine_samples(_PMWMSSortingData<_RAIter>* __sd, |
99 | _DifferenceTp __num_samples) | |
c2ba9709 | 100 | { |
1acba85b JS |
101 | typedef std::iterator_traits<_RAIter> _TraitsType; |
102 | typedef typename _TraitsType::value_type _ValueType; | |
103 | typedef _DifferenceTp _DifferenceType; | |
c2ba9709 | 104 | |
1acba85b | 105 | _ThreadIndex __iam = omp_get_thread_num(); |
c2ba9709 | 106 | |
1acba85b | 107 | _DifferenceType* __es = new _DifferenceType[__num_samples + 2]; |
c891154f | 108 | |
1acba85b JS |
109 | equally_split(__sd->_M_starts[__iam + 1] - __sd->_M_starts[__iam], |
110 | __num_samples + 1, __es); | |
c2ba9709 | 111 | |
1acba85b JS |
112 | for (_DifferenceType __i = 0; __i < __num_samples; ++__i) |
113 | ::new(&(__sd->_M_samples[__iam * __num_samples + __i])) | |
15ac3c72 | 114 | _ValueType(__sd->_M_source[__sd->_M_starts[__iam] + __es[__i + 1]]); |
e683ee2a | 115 | |
1acba85b | 116 | delete[] __es; |
c2ba9709 JS |
117 | } |
118 | ||
f9985df5 | 119 | /** @brief Split consistently. */ |
1acba85b JS |
120 | template<bool __exact, typename _RAIter, |
121 | typename _Compare, typename _SortingPlacesIterator> | |
122 | struct _SplitConsistently | |
f9985df5 JS |
123 | { |
124 | }; | |
125 | ||
126 | /** @brief Split by exact splitting. */ | |
1acba85b JS |
127 | template<typename _RAIter, typename _Compare, |
128 | typename _SortingPlacesIterator> | |
129 | struct _SplitConsistently | |
130 | <true, _RAIter, _Compare, _SortingPlacesIterator> | |
f9985df5 JS |
131 | { |
132 | void operator()( | |
1acba85b JS |
133 | const _ThreadIndex __iam, |
134 | _PMWMSSortingData<_RAIter>* __sd, | |
135 | _Compare& __comp, | |
f9985df5 | 136 | const typename |
1acba85b JS |
137 | std::iterator_traits<_RAIter>::difference_type |
138 | __num_samples) | |
f9985df5 JS |
139 | const |
140 | { | |
141 | # pragma omp barrier | |
142 | ||
1acba85b | 143 | std::vector<std::pair<_SortingPlacesIterator, _SortingPlacesIterator> > |
54384f7f JS |
144 | seqs(__sd->_M_num_threads); |
145 | for (_ThreadIndex __s = 0; __s < __sd->_M_num_threads; __s++) | |
1acba85b | 146 | seqs[__s] = std::make_pair(__sd->_M_temporary[__s], |
15ac3c72 JS |
147 | __sd->_M_temporary[__s] |
148 | + (__sd->_M_starts[__s + 1] | |
149 | - __sd->_M_starts[__s])); | |
f9985df5 | 150 | |
54384f7f | 151 | std::vector<_SortingPlacesIterator> _M_offsets(__sd->_M_num_threads); |
f9985df5 JS |
152 | |
153 | // if not last thread | |
54384f7f | 154 | if (__iam < __sd->_M_num_threads - 1) |
f9985df5 | 155 | multiseq_partition(seqs.begin(), seqs.end(), |
15ac3c72 JS |
156 | __sd->_M_starts[__iam + 1], _M_offsets.begin(), |
157 | __comp); | |
f9985df5 | 158 | |
54384f7f | 159 | for (int __seq = 0; __seq < __sd->_M_num_threads; __seq++) |
f9985df5 JS |
160 | { |
161 | // for each sequence | |
54384f7f | 162 | if (__iam < (__sd->_M_num_threads - 1)) |
15ac3c72 JS |
163 | __sd->_M_pieces[__iam][__seq]._M_end |
164 | = _M_offsets[__seq] - seqs[__seq].first; | |
f9985df5 JS |
165 | else |
166 | // very end of this sequence | |
54384f7f | 167 | __sd->_M_pieces[__iam][__seq]._M_end = |
15ac3c72 | 168 | __sd->_M_starts[__seq + 1] - __sd->_M_starts[__seq]; |
f9985df5 JS |
169 | } |
170 | ||
171 | # pragma omp barrier | |
172 | ||
54384f7f | 173 | for (_ThreadIndex __seq = 0; __seq < __sd->_M_num_threads; __seq++) |
f9985df5 JS |
174 | { |
175 | // For each sequence. | |
1acba85b | 176 | if (__iam > 0) |
15ac3c72 JS |
177 | __sd->_M_pieces[__iam][__seq]._M_begin = |
178 | __sd->_M_pieces[__iam - 1][__seq]._M_end; | |
f9985df5 JS |
179 | else |
180 | // Absolute beginning. | |
54384f7f | 181 | __sd->_M_pieces[__iam][__seq]._M_begin = 0; |
f9985df5 JS |
182 | } |
183 | } | |
184 | }; | |
185 | ||
186 | /** @brief Split by sampling. */ | |
1acba85b JS |
187 | template<typename _RAIter, typename _Compare, |
188 | typename _SortingPlacesIterator> | |
189 | struct _SplitConsistently<false, _RAIter, _Compare, | |
190 | _SortingPlacesIterator> | |
f9985df5 JS |
191 | { |
192 | void operator()( | |
1acba85b JS |
193 | const _ThreadIndex __iam, |
194 | _PMWMSSortingData<_RAIter>* __sd, | |
195 | _Compare& __comp, | |
f9985df5 | 196 | const typename |
1acba85b JS |
197 | std::iterator_traits<_RAIter>::difference_type |
198 | __num_samples) | |
f9985df5 JS |
199 | const |
200 | { | |
1acba85b JS |
201 | typedef std::iterator_traits<_RAIter> _TraitsType; |
202 | typedef typename _TraitsType::value_type _ValueType; | |
203 | typedef typename _TraitsType::difference_type _DifferenceType; | |
f9985df5 | 204 | |
1acba85b | 205 | __determine_samples(__sd, __num_samples); |
f9985df5 JS |
206 | |
207 | # pragma omp barrier | |
208 | ||
209 | # pragma omp single | |
1acba85b | 210 | __gnu_sequential::sort(__sd->_M_samples, |
15ac3c72 JS |
211 | __sd->_M_samples |
212 | + (__num_samples * __sd->_M_num_threads), | |
1acba85b | 213 | __comp); |
f9985df5 JS |
214 | |
215 | # pragma omp barrier | |
216 | ||
54384f7f | 217 | for (_ThreadIndex __s = 0; __s < __sd->_M_num_threads; ++__s) |
f9985df5 JS |
218 | { |
219 | // For each sequence. | |
1acba85b | 220 | if (__num_samples * __iam > 0) |
54384f7f | 221 | __sd->_M_pieces[__iam][__s]._M_begin = |
1acba85b JS |
222 | std::lower_bound(__sd->_M_temporary[__s], |
223 | __sd->_M_temporary[__s] | |
224 | + (__sd->_M_starts[__s + 1] - __sd->_M_starts[__s]), | |
225 | __sd->_M_samples[__num_samples * __iam], | |
226 | __comp) | |
227 | - __sd->_M_temporary[__s]; | |
f9985df5 JS |
228 | else |
229 | // Absolute beginning. | |
54384f7f | 230 | __sd->_M_pieces[__iam][__s]._M_begin = 0; |
1acba85b | 231 | |
15ac3c72 JS |
232 | if ((__num_samples * (__iam + 1)) < |
233 | (__num_samples * __sd->_M_num_threads)) | |
54384f7f | 234 | __sd->_M_pieces[__iam][__s]._M_end = |
1acba85b JS |
235 | std::lower_bound(__sd->_M_temporary[__s], |
236 | __sd->_M_temporary[__s] | |
15ac3c72 | 237 | + (__sd->_M_starts[__s + 1] - __sd->_M_starts[__s]), |
1acba85b JS |
238 | __sd->_M_samples[__num_samples * (__iam + 1)], |
239 | __comp) | |
240 | - __sd->_M_temporary[__s]; | |
f9985df5 | 241 | else |
721641c4 | 242 | // Absolute end. |
15ac3c72 JS |
243 | __sd->_M_pieces[__iam][__s]._M_end = __sd->_M_starts[__s + 1] |
244 | - __sd->_M_starts[__s]; | |
f9985df5 JS |
245 | } |
246 | } | |
247 | }; | |
248 | ||
1acba85b JS |
249 | template<bool __stable, typename _RAIter, typename _Compare> |
250 | struct __possibly_stable_sort | |
f9985df5 JS |
251 | { |
252 | }; | |
253 | ||
1acba85b JS |
254 | template<typename _RAIter, typename _Compare> |
255 | struct __possibly_stable_sort<true, _RAIter, _Compare> | |
f9985df5 | 256 | { |
1acba85b JS |
257 | void operator()(const _RAIter& __begin, |
258 | const _RAIter& __end, _Compare& __comp) const | |
f9985df5 | 259 | { |
1acba85b | 260 | __gnu_sequential::stable_sort(__begin, __end, __comp); |
f9985df5 JS |
261 | } |
262 | }; | |
263 | ||
1acba85b JS |
264 | template<typename _RAIter, typename _Compare> |
265 | struct __possibly_stable_sort<false, _RAIter, _Compare> | |
f9985df5 | 266 | { |
1acba85b JS |
267 | void operator()(const _RAIter __begin, |
268 | const _RAIter __end, _Compare& __comp) const | |
f9985df5 | 269 | { |
1acba85b | 270 | __gnu_sequential::sort(__begin, __end, __comp); |
f9985df5 JS |
271 | } |
272 | }; | |
273 | ||
1acba85b JS |
274 | template<bool __stable, typename Seq_RAIter, |
275 | typename _RAIter, typename _Compare, | |
f9985df5 | 276 | typename DiffType> |
1acba85b | 277 | struct __possibly_stable_multiway_merge |
f9985df5 JS |
278 | { |
279 | }; | |
280 | ||
1acba85b JS |
281 | template<typename Seq_RAIter, typename _RAIter, |
282 | typename _Compare, typename DiffType> | |
283 | struct __possibly_stable_multiway_merge | |
284 | <true, Seq_RAIter, _RAIter, _Compare, | |
f9985df5 JS |
285 | DiffType> |
286 | { | |
1acba85b JS |
287 | void operator()(const Seq_RAIter& __seqs_begin, |
288 | const Seq_RAIter& __seqs_end, | |
289 | const _RAIter& __target, | |
290 | _Compare& __comp, | |
291 | DiffType __length_am) const | |
f9985df5 | 292 | { |
15ac3c72 JS |
293 | stable_multiway_merge(__seqs_begin, __seqs_end, __target, __length_am, |
294 | __comp, sequential_tag()); | |
f9985df5 JS |
295 | } |
296 | }; | |
297 | ||
1acba85b JS |
298 | template<typename Seq_RAIter, typename _RAIter, |
299 | typename _Compare, typename DiffType> | |
300 | struct __possibly_stable_multiway_merge | |
301 | <false, Seq_RAIter, _RAIter, _Compare, | |
f9985df5 JS |
302 | DiffType> |
303 | { | |
1acba85b JS |
304 | void operator()(const Seq_RAIter& __seqs_begin, |
305 | const Seq_RAIter& __seqs_end, | |
306 | const _RAIter& __target, | |
307 | _Compare& __comp, | |
308 | DiffType __length_am) const | |
f9985df5 | 309 | { |
1acba85b | 310 | multiway_merge(__seqs_begin, __seqs_end, __target, __length_am, __comp, |
36fc5958 | 311 | sequential_tag()); |
f9985df5 JS |
312 | } |
313 | }; | |
314 | ||
e683ee2a | 315 | /** @brief PMWMS code executed by each thread. |
1acba85b JS |
316 | * @param __sd Pointer to algorithm data. |
317 | * @param __comp Comparator. | |
e683ee2a | 318 | */ |
1acba85b JS |
319 | template<bool __stable, bool __exact, typename _RAIter, |
320 | typename _Compare> | |
5817ff8e | 321 | void |
1acba85b JS |
322 | parallel_sort_mwms_pu(_PMWMSSortingData<_RAIter>* __sd, |
323 | _Compare& __comp) | |
c2ba9709 | 324 | { |
1acba85b JS |
325 | typedef std::iterator_traits<_RAIter> _TraitsType; |
326 | typedef typename _TraitsType::value_type _ValueType; | |
327 | typedef typename _TraitsType::difference_type _DifferenceType; | |
c2ba9709 | 328 | |
1acba85b | 329 | _ThreadIndex __iam = omp_get_thread_num(); |
c2ba9709 JS |
330 | |
331 | // Length of this thread's chunk, before merging. | |
15ac3c72 JS |
332 | _DifferenceType __length_local |
333 | = __sd->_M_starts[__iam + 1] - __sd->_M_starts[__iam]; | |
c2ba9709 | 334 | |
f9985df5 | 335 | // Sort in temporary storage, leave space for sentinel. |
c2ba9709 | 336 | |
1acba85b | 337 | typedef _ValueType* _SortingPlacesIterator; |
c2ba9709 | 338 | |
1acba85b JS |
339 | __sd->_M_temporary[__iam] = |
340 | static_cast<_ValueType*>( | |
341 | ::operator new(sizeof(_ValueType) * (__length_local + 1))); | |
c2ba9709 JS |
342 | |
343 | // Copy there. | |
15ac3c72 JS |
344 | std::uninitialized_copy( |
345 | __sd->_M_source + __sd->_M_starts[__iam], | |
346 | __sd->_M_source + __sd->_M_starts[__iam] + __length_local, | |
347 | __sd->_M_temporary[__iam]); | |
e683ee2a | 348 | |
1acba85b | 349 | __possibly_stable_sort<__stable, _SortingPlacesIterator, _Compare>() |
15ac3c72 JS |
350 | (__sd->_M_temporary[__iam], |
351 | __sd->_M_temporary[__iam] + __length_local, | |
352 | __comp); | |
e683ee2a | 353 | |
1acba85b JS |
354 | // Invariant: locally sorted subsequence in sd->_M_temporary[__iam], |
355 | // __sd->_M_temporary[__iam] + __length_local. | |
e683ee2a | 356 | |
f9985df5 | 357 | // No barrier here: Synchronization is done by the splitting routine. |
e683ee2a | 358 | |
1acba85b | 359 | _DifferenceType __num_samples = |
54384f7f | 360 | _Settings::get().sort_mwms_oversampling * __sd->_M_num_threads - 1; |
1acba85b JS |
361 | _SplitConsistently |
362 | <__exact, _RAIter, _Compare, _SortingPlacesIterator>() | |
363 | (__iam, __sd, __comp, __num_samples); | |
c2ba9709 | 364 | |
1acba85b JS |
365 | // Offset from __target __begin, __length after merging. |
366 | _DifferenceType __offset = 0, __length_am = 0; | |
54384f7f | 367 | for (_ThreadIndex __s = 0; __s < __sd->_M_num_threads; __s++) |
c2ba9709 | 368 | { |
15ac3c72 JS |
369 | __length_am += __sd->_M_pieces[__iam][__s]._M_end |
370 | - __sd->_M_pieces[__iam][__s]._M_begin; | |
54384f7f | 371 | __offset += __sd->_M_pieces[__iam][__s]._M_begin; |
c2ba9709 JS |
372 | } |
373 | ||
f9985df5 | 374 | typedef std::vector< |
1acba85b | 375 | std::pair<_SortingPlacesIterator, _SortingPlacesIterator> > |
4459d22e JS |
376 | _SeqVector; |
377 | _SeqVector seqs(__sd->_M_num_threads); | |
c2ba9709 | 378 | |
54384f7f | 379 | for (int __s = 0; __s < __sd->_M_num_threads; ++__s) |
c2ba9709 | 380 | { |
1acba85b | 381 | seqs[__s] = |
15ac3c72 JS |
382 | std::make_pair( |
383 | __sd->_M_temporary[__s] + __sd->_M_pieces[__iam][__s]._M_begin, | |
384 | __sd->_M_temporary[__s] + __sd->_M_pieces[__iam][__s]._M_end); | |
c2ba9709 JS |
385 | } |
386 | ||
1acba85b JS |
387 | __possibly_stable_multiway_merge< |
388 | __stable, | |
4459d22e | 389 | typename _SeqVector::iterator, |
1acba85b JS |
390 | _RAIter, |
391 | _Compare, _DifferenceType>() | |
f9985df5 | 392 | (seqs.begin(), seqs.end(), |
1acba85b JS |
393 | __sd->_M_source + __offset, __comp, |
394 | __length_am); | |
c2ba9709 | 395 | |
e683ee2a | 396 | # pragma omp barrier |
c2ba9709 | 397 | |
1acba85b | 398 | ::operator delete(__sd->_M_temporary[__iam]); |
c2ba9709 JS |
399 | } |
400 | ||
e683ee2a | 401 | /** @brief PMWMS main call. |
1acba85b JS |
402 | * @param __begin Begin iterator of sequence. |
403 | * @param __end End iterator of sequence. | |
404 | * @param __comp Comparator. | |
405 | * @param __n Length of sequence. | |
406 | * @param __num_threads Number of threads to use. | |
e683ee2a | 407 | */ |
1acba85b JS |
408 | template<bool __stable, bool __exact, typename _RAIter, |
409 | typename _Compare> | |
5817ff8e | 410 | void |
1acba85b JS |
411 | parallel_sort_mwms(_RAIter __begin, _RAIter __end, |
412 | _Compare __comp, | |
413 | _ThreadIndex __num_threads) | |
c2ba9709 | 414 | { |
1acba85b | 415 | _GLIBCXX_CALL(__end - __begin) |
e683ee2a | 416 | |
1acba85b JS |
417 | typedef std::iterator_traits<_RAIter> _TraitsType; |
418 | typedef typename _TraitsType::value_type _ValueType; | |
419 | typedef typename _TraitsType::difference_type _DifferenceType; | |
c2ba9709 | 420 | |
1acba85b | 421 | _DifferenceType __n = __end - __begin; |
f9985df5 | 422 | |
1acba85b | 423 | if (__n <= 1) |
c2ba9709 JS |
424 | return; |
425 | ||
e683ee2a | 426 | // at least one element per thread |
1acba85b JS |
427 | if (__num_threads > __n) |
428 | __num_threads = static_cast<_ThreadIndex>(__n); | |
c2ba9709 | 429 | |
e683ee2a | 430 | // shared variables |
1acba85b JS |
431 | _PMWMSSortingData<_RAIter> __sd; |
432 | _DifferenceType* _M_starts; | |
c2ba9709 | 433 | |
1acba85b | 434 | # pragma omp parallel num_threads(__num_threads) |
e683ee2a | 435 | { |
15ac3c72 | 436 | __num_threads = omp_get_num_threads(); //no more threads than requested |
e683ee2a JS |
437 | |
438 | # pragma omp single | |
439 | { | |
54384f7f | 440 | __sd._M_num_threads = __num_threads; |
1acba85b | 441 | __sd._M_source = __begin; |
c2ba9709 | 442 | |
1acba85b | 443 | __sd._M_temporary = new _ValueType*[__num_threads]; |
f9985df5 | 444 | |
1acba85b | 445 | if (!__exact) |
e683ee2a | 446 | { |
4459d22e | 447 | _DifferenceType __size = |
15ac3c72 | 448 | (_Settings::get().sort_mwms_oversampling * __num_threads - 1) |
1acba85b JS |
449 | * __num_threads; |
450 | __sd._M_samples = static_cast<_ValueType*>( | |
4459d22e | 451 | ::operator new(__size * sizeof(_ValueType))); |
e683ee2a JS |
452 | } |
453 | else | |
1acba85b JS |
454 | __sd._M_samples = NULL; |
455 | ||
456 | __sd._M_offsets = new _DifferenceType[__num_threads - 1]; | |
15ac3c72 JS |
457 | __sd._M_pieces |
458 | = new std::vector<_Piece<_DifferenceType> >[__num_threads]; | |
1acba85b JS |
459 | for (int __s = 0; __s < __num_threads; ++__s) |
460 | __sd._M_pieces[__s].resize(__num_threads); | |
15ac3c72 JS |
461 | _M_starts = __sd._M_starts |
462 | = new _DifferenceType[__num_threads + 1]; | |
1acba85b JS |
463 | |
464 | _DifferenceType __chunk_length = __n / __num_threads; | |
465 | _DifferenceType __split = __n % __num_threads; | |
466 | _DifferenceType __pos = 0; | |
467 | for (int __i = 0; __i < __num_threads; ++__i) | |
e683ee2a | 468 | { |
1acba85b | 469 | _M_starts[__i] = __pos; |
15ac3c72 JS |
470 | __pos += (__i < __split) |
471 | ? (__chunk_length + 1) : __chunk_length; | |
e683ee2a | 472 | } |
1acba85b | 473 | _M_starts[__num_threads] = __pos; |
f9985df5 | 474 | } //single |
e683ee2a JS |
475 | |
476 | // Now sort in parallel. | |
1acba85b | 477 | parallel_sort_mwms_pu<__stable, __exact>(&__sd, __comp); |
e683ee2a | 478 | } //parallel |
c2ba9709 | 479 | |
1acba85b JS |
480 | delete[] _M_starts; |
481 | delete[] __sd._M_temporary; | |
c2ba9709 | 482 | |
1acba85b JS |
483 | if (!__exact) |
484 | ::operator delete(__sd._M_samples); | |
c2ba9709 | 485 | |
1acba85b JS |
486 | delete[] __sd._M_offsets; |
487 | delete[] __sd._M_pieces; | |
c2ba9709 | 488 | } |
e683ee2a | 489 | } //namespace __gnu_parallel |
c2ba9709 | 490 | |
cbcd1e45 | 491 | #endif /* _GLIBCXX_PARALLEL_MULTIWAY_MERGESORT_H */ |