<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "https://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/xhtml;charset=UTF-8"/> <meta http-equiv="X-UA-Compatible" content="IE=9"/> <meta name="generator" content="Doxygen 1.8.15"/> <meta name="viewport" content="width=device-width, initial-scale=1"/> <title>libstdc++: equally_split.h Source File</title> <link href="tabs.css" rel="stylesheet" type="text/css"/> <script type="text/javascript" src="jquery.js"></script> <script type="text/javascript" src="dynsections.js"></script> <link href="navtree.css" rel="stylesheet" type="text/css"/> <script type="text/javascript" src="resize.js"></script> <script type="text/javascript" src="navtreedata.js"></script> <script type="text/javascript" src="navtree.js"></script> <script type="text/javascript"> /* @license magnet:?xt=urn:btih:cf05388f2679ee054f2beb29a391d25f4e673ac3&dn=gpl-2.0.txt GPL-v2 */ $(document).ready(initResizable); /* @license-end */</script> <link href="doxygen.css" rel="stylesheet" type="text/css" /> </head> <body> <div id="top"><!-- do not remove this div, it is closed by doxygen! --> <div id="titlearea"> <table cellspacing="0" cellpadding="0"> <tbody> <tr style="height: 56px;"> <td id="projectalign" style="padding-left: 0.5em;"> <div id="projectname">libstdc++ </div> </td> </tr> </tbody> </table> </div> <!-- end header part --> <!-- Generated by Doxygen 1.8.15 --> </div><!-- top --> <div id="side-nav" class="ui-resizable side-nav-resizable"> <div id="nav-tree"> <div id="nav-tree-contents"> <div id="nav-sync" class="sync"></div> </div> </div> <div id="splitbar" style="-moz-user-select:none;" class="ui-resizable-handle"> </div> </div> <script type="text/javascript"> /* @license magnet:?xt=urn:btih:cf05388f2679ee054f2beb29a391d25f4e673ac3&dn=gpl-2.0.txt GPL-v2 */ $(document).ready(function(){initNavTree('a00881_source.html','');}); /* @license-end */ </script> <div id="doc-content"> <div class="header"> <div class="headertitle"> <div class="title">equally_split.h</div> </div> </div><!--header--> <div class="contents"> <a href="a00881.html">Go to the documentation of this file.</a><div class="fragment"><div class="line"><a name="l00001"></a><span class="lineno"> 1</span> <span class="comment">// -*- C++ -*-</span></div><div class="line"><a name="l00002"></a><span class="lineno"> 2</span> </div><div class="line"><a name="l00003"></a><span class="lineno"> 3</span> <span class="comment">// Copyright (C) 2007-2018 Free Software Foundation, Inc.</span></div><div class="line"><a name="l00004"></a><span class="lineno"> 4</span> <span class="comment">//</span></div><div class="line"><a name="l00005"></a><span class="lineno"> 5</span> <span class="comment">// This file is part of the GNU ISO C++ Library. This library is free</span></div><div class="line"><a name="l00006"></a><span class="lineno"> 6</span> <span class="comment">// software; you can redistribute it and/or modify it under the terms</span></div><div class="line"><a name="l00007"></a><span class="lineno"> 7</span> <span class="comment">// of the GNU General Public License as published by the Free Software</span></div><div class="line"><a name="l00008"></a><span class="lineno"> 8</span> <span class="comment">// Foundation; either version 3, or (at your option) any later</span></div><div class="line"><a name="l00009"></a><span class="lineno"> 9</span> <span class="comment">// version.</span></div><div class="line"><a name="l00010"></a><span class="lineno"> 10</span> </div><div class="line"><a name="l00011"></a><span class="lineno"> 11</span> <span class="comment">// This library is distributed in the hope that it will be useful, but</span></div><div class="line"><a name="l00012"></a><span class="lineno"> 12</span> <span class="comment">// WITHOUT ANY WARRANTY; without even the implied warranty of</span></div><div class="line"><a name="l00013"></a><span class="lineno"> 13</span> <span class="comment">// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU</span></div><div class="line"><a name="l00014"></a><span class="lineno"> 14</span> <span class="comment">// General Public License for more details.</span></div><div class="line"><a name="l00015"></a><span class="lineno"> 15</span> </div><div class="line"><a name="l00016"></a><span class="lineno"> 16</span> <span class="comment">// Under Section 7 of GPL version 3, you are granted additional</span></div><div class="line"><a name="l00017"></a><span class="lineno"> 17</span> <span class="comment">// permissions described in the GCC Runtime Library Exception, version</span></div><div class="line"><a name="l00018"></a><span class="lineno"> 18</span> <span class="comment">// 3.1, as published by the Free Software Foundation.</span></div><div class="line"><a name="l00019"></a><span class="lineno"> 19</span> </div><div class="line"><a name="l00020"></a><span class="lineno"> 20</span> <span class="comment">// You should have received a copy of the GNU General Public License and</span></div><div class="line"><a name="l00021"></a><span class="lineno"> 21</span> <span class="comment">// a copy of the GCC Runtime Library Exception along with this program;</span></div><div class="line"><a name="l00022"></a><span class="lineno"> 22</span> <span class="comment">// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see</span></div><div class="line"><a name="l00023"></a><span class="lineno"> 23</span> <span class="comment">// <http://www.gnu.org/licenses/>.</span></div><div class="line"><a name="l00024"></a><span class="lineno"> 24</span> <span class="comment"></span></div><div class="line"><a name="l00025"></a><span class="lineno"> 25</span> <span class="comment">/** @file parallel/equally_split.h</span></div><div class="line"><a name="l00026"></a><span class="lineno"> 26</span> <span class="comment"> * This file is a GNU parallel extension to the Standard C++ Library.</span></div><div class="line"><a name="l00027"></a><span class="lineno"> 27</span> <span class="comment"> */</span></div><div class="line"><a name="l00028"></a><span class="lineno"> 28</span> </div><div class="line"><a name="l00029"></a><span class="lineno"> 29</span> <span class="comment">// Written by Johannes Singler.</span></div><div class="line"><a name="l00030"></a><span class="lineno"> 30</span> </div><div class="line"><a name="l00031"></a><span class="lineno"> 31</span> <span class="preprocessor">#ifndef _GLIBCXX_PARALLEL_EQUALLY_SPLIT_H</span></div><div class="line"><a name="l00032"></a><span class="lineno"> 32</span> <span class="preprocessor">#define _GLIBCXX_PARALLEL_EQUALLY_SPLIT_H 1</span></div><div class="line"><a name="l00033"></a><span class="lineno"> 33</span> </div><div class="line"><a name="l00034"></a><span class="lineno"> 34</span> <span class="keyword">namespace </span><a class="code" href="a01572.html">__gnu_parallel</a></div><div class="line"><a name="l00035"></a><span class="lineno"> 35</span> {<span class="comment"></span></div><div class="line"><a name="l00036"></a><span class="lineno"> 36</span> <span class="comment"> /** @brief function to split a sequence into parts of almost equal size.</span></div><div class="line"><a name="l00037"></a><span class="lineno"> 37</span> <span class="comment"> *</span></div><div class="line"><a name="l00038"></a><span class="lineno"> 38</span> <span class="comment"> * The resulting sequence __s of length __num_threads+1 contains the</span></div><div class="line"><a name="l00039"></a><span class="lineno"> 39</span> <span class="comment"> * splitting positions when splitting the range [0,__n) into parts of</span></div><div class="line"><a name="l00040"></a><span class="lineno"> 40</span> <span class="comment"> * almost equal size (plus minus 1). The first entry is 0, the last</span></div><div class="line"><a name="l00041"></a><span class="lineno"> 41</span> <span class="comment"> * one n. There may result empty parts.</span></div><div class="line"><a name="l00042"></a><span class="lineno"> 42</span> <span class="comment"> * @param __n Number of elements</span></div><div class="line"><a name="l00043"></a><span class="lineno"> 43</span> <span class="comment"> * @param __num_threads Number of parts</span></div><div class="line"><a name="l00044"></a><span class="lineno"> 44</span> <span class="comment"> * @param __s Splitters</span></div><div class="line"><a name="l00045"></a><span class="lineno"> 45</span> <span class="comment"> * @returns End of __splitter sequence, i.e. @c __s+__num_threads+1 */</span></div><div class="line"><a name="l00046"></a><span class="lineno"> 46</span>  <span class="keyword">template</span><<span class="keyword">typename</span> _DifferenceType, <span class="keyword">typename</span> _OutputIterator></div><div class="line"><a name="l00047"></a><span class="lineno"> 47</span>  _OutputIterator</div><div class="line"><a name="l00048"></a><span class="lineno"><a class="line" href="a01572.html#ac799255921e70b0378d145924d673f9c"> 48</a></span>  <a class="code" href="a01572.html#ac799255921e70b0378d145924d673f9c">__equally_split</a>(_DifferenceType __n, <a class="code" href="a01572.html#a05e502e51bfc3233671730f74a44dc6a">_ThreadIndex</a> __num_threads,</div><div class="line"><a name="l00049"></a><span class="lineno"> 49</span>  _OutputIterator __s)</div><div class="line"><a name="l00050"></a><span class="lineno"> 50</span>  {</div><div class="line"><a name="l00051"></a><span class="lineno"> 51</span>  _DifferenceType __chunk_length = __n / __num_threads;</div><div class="line"><a name="l00052"></a><span class="lineno"> 52</span>  _DifferenceType __num_longer_chunks = __n % __num_threads;</div><div class="line"><a name="l00053"></a><span class="lineno"> 53</span>  _DifferenceType __pos = 0;</div><div class="line"><a name="l00054"></a><span class="lineno"> 54</span>  <span class="keywordflow">for</span> (<a class="code" href="a01572.html#a05e502e51bfc3233671730f74a44dc6a">_ThreadIndex</a> __i = 0; __i < __num_threads; ++__i)</div><div class="line"><a name="l00055"></a><span class="lineno"> 55</span>  {</div><div class="line"><a name="l00056"></a><span class="lineno"> 56</span>  *__s++ = __pos;</div><div class="line"><a name="l00057"></a><span class="lineno"> 57</span>  __pos += ((__i < __num_longer_chunks)</div><div class="line"><a name="l00058"></a><span class="lineno"> 58</span>  ? (__chunk_length + 1) : __chunk_length);</div><div class="line"><a name="l00059"></a><span class="lineno"> 59</span>  }</div><div class="line"><a name="l00060"></a><span class="lineno"> 60</span>  *__s++ = __n;</div><div class="line"><a name="l00061"></a><span class="lineno"> 61</span>  <span class="keywordflow">return</span> __s;</div><div class="line"><a name="l00062"></a><span class="lineno"> 62</span>  }</div><div class="line"><a name="l00063"></a><span class="lineno"> 63</span> <span class="comment"></span></div><div class="line"><a name="l00064"></a><span class="lineno"> 64</span> <span class="comment"> /** @brief function to split a sequence into parts of almost equal size.</span></div><div class="line"><a name="l00065"></a><span class="lineno"> 65</span> <span class="comment"> *</span></div><div class="line"><a name="l00066"></a><span class="lineno"> 66</span> <span class="comment"> * Returns the position of the splitting point between</span></div><div class="line"><a name="l00067"></a><span class="lineno"> 67</span> <span class="comment"> * thread number __thread_no (included) and</span></div><div class="line"><a name="l00068"></a><span class="lineno"> 68</span> <span class="comment"> * thread number __thread_no+1 (excluded).</span></div><div class="line"><a name="l00069"></a><span class="lineno"> 69</span> <span class="comment"> * @param __n Number of elements</span></div><div class="line"><a name="l00070"></a><span class="lineno"> 70</span> <span class="comment"> * @param __num_threads Number of parts</span></div><div class="line"><a name="l00071"></a><span class="lineno"> 71</span> <span class="comment"> * @param __thread_no Number of threads</span></div><div class="line"><a name="l00072"></a><span class="lineno"> 72</span> <span class="comment"> * @returns splitting point */</span></div><div class="line"><a name="l00073"></a><span class="lineno"> 73</span>  <span class="keyword">template</span><<span class="keyword">typename</span> _DifferenceType></div><div class="line"><a name="l00074"></a><span class="lineno"> 74</span>  _DifferenceType</div><div class="line"><a name="l00075"></a><span class="lineno"><a class="line" href="a01572.html#a8e3a77cb920e419144b72d6d20167dfd"> 75</a></span>  <a class="code" href="a01572.html#a8e3a77cb920e419144b72d6d20167dfd">__equally_split_point</a>(_DifferenceType __n,</div><div class="line"><a name="l00076"></a><span class="lineno"> 76</span>  <a class="code" href="a01572.html#a05e502e51bfc3233671730f74a44dc6a">_ThreadIndex</a> __num_threads,</div><div class="line"><a name="l00077"></a><span class="lineno"> 77</span>  <a class="code" href="a01572.html#a05e502e51bfc3233671730f74a44dc6a">_ThreadIndex</a> __thread_no)</div><div class="line"><a name="l00078"></a><span class="lineno"> 78</span>  {</div><div class="line"><a name="l00079"></a><span class="lineno"> 79</span>  _DifferenceType __chunk_length = __n / __num_threads;</div><div class="line"><a name="l00080"></a><span class="lineno"> 80</span>  _DifferenceType __num_longer_chunks = __n % __num_threads;</div><div class="line"><a name="l00081"></a><span class="lineno"> 81</span>  <span class="keywordflow">if</span> (__thread_no < __num_longer_chunks)</div><div class="line"><a name="l00082"></a><span class="lineno"> 82</span>  <span class="keywordflow">return</span> __thread_no * (__chunk_length + 1);</div><div class="line"><a name="l00083"></a><span class="lineno"> 83</span>  <span class="keywordflow">else</span></div><div class="line"><a name="l00084"></a><span class="lineno"> 84</span>  <span class="keywordflow">return</span> __num_longer_chunks * (__chunk_length + 1)</div><div class="line"><a name="l00085"></a><span class="lineno"> 85</span>  + (__thread_no - __num_longer_chunks) * __chunk_length;</div><div class="line"><a name="l00086"></a><span class="lineno"> 86</span>  }</div><div class="line"><a name="l00087"></a><span class="lineno"> 87</span> }</div><div class="line"><a name="l00088"></a><span class="lineno"> 88</span> </div><div class="line"><a name="l00089"></a><span class="lineno"> 89</span> <span class="preprocessor">#endif </span><span class="comment">/* _GLIBCXX_PARALLEL_EQUALLY_SPLIT_H */</span><span class="preprocessor"></span></div><div class="ttc" id="a01572_html_ac799255921e70b0378d145924d673f9c"><div class="ttname"><a href="a01572.html#ac799255921e70b0378d145924d673f9c">__gnu_parallel::__equally_split</a></div><div class="ttdeci">_OutputIterator __equally_split(_DifferenceType __n, _ThreadIndex __num_threads, _OutputIterator __s)</div><div class="ttdoc">function to split a sequence into parts of almost equal size.</div><div class="ttdef"><b>Definition:</b> <a href="a00881_source.html#l00048">equally_split.h:48</a></div></div> <div class="ttc" id="a01572_html_a05e502e51bfc3233671730f74a44dc6a"><div class="ttname"><a href="a01572.html#a05e502e51bfc3233671730f74a44dc6a">__gnu_parallel::_ThreadIndex</a></div><div class="ttdeci">uint16_t _ThreadIndex</div><div class="ttdoc">Unsigned integer to index a thread number. The maximum thread number (for each processor) must fit in...</div><div class="ttdef"><b>Definition:</b> <a href="a00968_source.html#l00123">types.h:123</a></div></div> <div class="ttc" id="a01572_html_a8e3a77cb920e419144b72d6d20167dfd"><div class="ttname"><a href="a01572.html#a8e3a77cb920e419144b72d6d20167dfd">__gnu_parallel::__equally_split_point</a></div><div class="ttdeci">_DifferenceType __equally_split_point(_DifferenceType __n, _ThreadIndex __num_threads, _ThreadIndex __thread_no)</div><div class="ttdoc">function to split a sequence into parts of almost equal size.</div><div class="ttdef"><b>Definition:</b> <a href="a00881_source.html#l00075">equally_split.h:75</a></div></div> <div class="ttc" id="a01572_html"><div class="ttname"><a href="a01572.html">__gnu_parallel</a></div><div class="ttdoc">GNU parallel code for public use.</div><div class="ttdef"><b>Definition:</b> <a href="a00869_source.html#l00061">balanced_quicksort.h:61</a></div></div> </div><!-- fragment --></div><!-- contents --> </div><!-- doc-content --> <!-- start footer part --> <div id="nav-path" class="navpath"><!-- id is needed for treeview function! --> <ul> <li class="navelem"><a class="el" href="dir_e0ca5f9b79afec9781b100dc0e5c7504.html">include</a></li><li class="navelem"><a class="el" href="dir_d2331c0d6b7f7f8ed85dc9efb934eb07.html">parallel</a></li><li class="navelem"><a class="el" href="a00881.html">equally_split.h</a></li> <li class="footer">Generated by <a href="http://www.doxygen.org/index.html"> <img class="footer" src="doxygen.png" alt="doxygen"/></a> 1.8.15 </li> </ul> </div> </body> </html>