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1 /* |
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2 Copyright (C) 2003, 2004, 2005, 2006, 2007 David Bateman |
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3 |
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4 This file is part of Octave. |
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5 |
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6 Octave is free software; you can redistribute it and/or modify it |
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7 under the terms of the GNU General Public License as published by the |
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8 Free Software Foundation; either version 3 of the License, or (at your |
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9 option) any later version. |
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10 |
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11 Octave is distributed in the hope that it will be useful, but WITHOUT |
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12 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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14 for more details. |
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15 |
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16 You should have received a copy of the GNU General Public License |
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17 along with Octave; see the file COPYING. If not, see |
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18 <http://www.gnu.org/licenses/>. |
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19 |
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20 Code stolen in large part from Python's, listobject.c, which itself had |
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21 no license header. However, thanks to Tim Peters for the parts of the |
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22 code I ripped-off. |
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23 |
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24 As required in the Python license the short description of the changes |
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25 made are |
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26 |
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27 * convert the sorting code in listobject.cc into a generic class, |
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28 replacing PyObject* with the type of the class T. |
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29 |
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30 The Python license is |
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31 |
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32 PSF LICENSE AGREEMENT FOR PYTHON 2.3 |
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33 -------------------------------------- |
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34 |
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35 1. This LICENSE AGREEMENT is between the Python Software Foundation |
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36 ("PSF"), and the Individual or Organization ("Licensee") accessing and |
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37 otherwise using Python 2.3 software in source or binary form and its |
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38 associated documentation. |
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39 |
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40 2. Subject to the terms and conditions of this License Agreement, PSF |
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41 hereby grants Licensee a nonexclusive, royalty-free, world-wide |
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42 license to reproduce, analyze, test, perform and/or display publicly, |
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43 prepare derivative works, distribute, and otherwise use Python 2.3 |
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44 alone or in any derivative version, provided, however, that PSF's |
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45 License Agreement and PSF's notice of copyright, i.e., "Copyright (c) |
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46 2001, 2002, 2003 Python Software Foundation; All Rights Reserved" are |
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47 retained in Python 2.3 alone or in any derivative version prepared by |
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48 Licensee. |
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49 |
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50 3. In the event Licensee prepares a derivative work that is based on |
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51 or incorporates Python 2.3 or any part thereof, and wants to make |
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52 the derivative work available to others as provided herein, then |
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53 Licensee hereby agrees to include in any such work a brief summary of |
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54 the changes made to Python 2.3. |
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55 |
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56 4. PSF is making Python 2.3 available to Licensee on an "AS IS" |
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57 basis. PSF MAKES NO REPRESENTATIONS OR WARRANTIES, EXPRESS OR |
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58 IMPLIED. BY WAY OF EXAMPLE, BUT NOT LIMITATION, PSF MAKES NO AND |
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59 DISCLAIMS ANY REPRESENTATION OR WARRANTY OF MERCHANTABILITY OR FITNESS |
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60 FOR ANY PARTICULAR PURPOSE OR THAT THE USE OF PYTHON 2.3 WILL NOT |
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61 INFRINGE ANY THIRD PARTY RIGHTS. |
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62 |
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63 5. PSF SHALL NOT BE LIABLE TO LICENSEE OR ANY OTHER USERS OF PYTHON |
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64 2.3 FOR ANY INCIDENTAL, SPECIAL, OR CONSEQUENTIAL DAMAGES OR LOSS AS |
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65 A RESULT OF MODIFYING, DISTRIBUTING, OR OTHERWISE USING PYTHON 2.3, |
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66 OR ANY DERIVATIVE THEREOF, EVEN IF ADVISED OF THE POSSIBILITY THEREOF. |
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67 |
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68 6. This License Agreement will automatically terminate upon a material |
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69 breach of its terms and conditions. |
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70 |
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71 7. Nothing in this License Agreement shall be deemed to create any |
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72 relationship of agency, partnership, or joint venture between PSF and |
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73 Licensee. This License Agreement does not grant permission to use PSF |
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74 trademarks or trade name in a trademark sense to endorse or promote |
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75 products or services of Licensee, or any third party. |
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76 |
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77 8. By copying, installing or otherwise using Python 2.3, Licensee |
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78 agrees to be bound by the terms and conditions of this License |
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79 Agreement. |
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80 */ |
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81 |
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82 #ifdef HAVE_CONFIG_H |
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83 #include <config.h> |
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84 #endif |
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85 |
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86 #include <cassert> |
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87 #include <cstdlib> |
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88 |
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89 #include "lo-mappers.h" |
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90 #include "quit.h" |
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91 #include "oct-sort.h" |
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92 |
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93 #ifndef IFLT |
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94 #define IFLT(a,b) if (compare ? compare ((a), (b)) : ((a) < (b))) |
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95 #endif |
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96 |
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97 template <class T> |
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98 octave_sort<T>::octave_sort (void) : compare (0) |
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99 { |
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100 merge_init (); |
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101 merge_getmem (1024); |
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102 } |
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103 |
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104 template <class T> |
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105 octave_sort<T>::octave_sort (bool (*comp) (T, T)) : compare (comp) |
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106 { |
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107 merge_init (); |
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108 merge_getmem (1024); |
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109 } |
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110 |
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111 /* Reverse a slice of a list in place, from lo up to (exclusive) hi. */ |
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112 template <class T> |
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113 void |
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114 octave_sort<T>::reverse_slice (T *lo, T *hi) |
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115 { |
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116 --hi; |
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117 while (lo < hi) |
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118 { |
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119 T t = *lo; |
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120 *lo = *hi; |
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121 *hi = t; |
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122 ++lo; |
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123 --hi; |
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124 } |
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125 } |
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126 |
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127 template <class T> |
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128 void |
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129 octave_sort<T>::binarysort (T *lo, T *hi, T *start) |
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130 { |
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131 T *l, *p, *r; |
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132 T pivot; |
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133 |
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134 if (lo == start) |
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135 ++start; |
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136 |
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137 for (; start < hi; ++start) |
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138 { |
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139 /* set l to where *start belongs */ |
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140 l = lo; |
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141 r = start; |
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142 pivot = *r; |
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143 /* Invariants: |
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144 * pivot >= all in [lo, l). |
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145 * pivot < all in [r, start). |
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146 * The second is vacuously true at the start. |
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147 */ |
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148 do |
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149 { |
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150 p = l + ((r - l) >> 1); |
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151 IFLT (pivot, *p) |
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152 r = p; |
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153 else |
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154 l = p+1; |
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155 } |
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156 while (l < r); |
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157 /* The invariants still hold, so pivot >= all in [lo, l) and |
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158 pivot < all in [l, start), so pivot belongs at l. Note |
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159 that if there are elements equal to pivot, l points to the |
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160 first slot after them -- that's why this sort is stable. |
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161 Slide over to make room. |
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162 Caution: using memmove is much slower under MSVC 5; |
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163 we're not usually moving many slots. */ |
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164 for (p = start; p > l; --p) |
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165 *p = *(p-1); |
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166 *l = pivot; |
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167 } |
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168 |
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169 return; |
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170 } |
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171 |
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172 /* |
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173 Return the length of the run beginning at lo, in the slice [lo, hi). lo < hi |
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174 is required on entry. "A run" is the longest ascending sequence, with |
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175 |
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176 lo[0] <= lo[1] <= lo[2] <= ... |
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177 |
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178 or the longest descending sequence, with |
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179 |
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180 lo[0] > lo[1] > lo[2] > ... |
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181 |
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182 Boolean *descending is set to 0 in the former case, or to 1 in the latter. |
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183 For its intended use in a stable mergesort, the strictness of the defn of |
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184 "descending" is needed so that the caller can safely reverse a descending |
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185 sequence without violating stability (strict > ensures there are no equal |
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186 elements to get out of order). |
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187 |
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188 Returns -1 in case of error. |
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189 */ |
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190 template <class T> |
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191 octave_idx_type |
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192 octave_sort<T>::count_run (T *lo, T *hi, int *descending) |
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193 { |
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194 octave_idx_type n; |
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195 |
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196 *descending = 0; |
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197 ++lo; |
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198 if (lo == hi) |
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199 return 1; |
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200 |
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201 n = 2; |
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202 |
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203 IFLT (*lo, *(lo-1)) |
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204 { |
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205 *descending = 1; |
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206 for (lo = lo+1; lo < hi; ++lo, ++n) |
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207 { |
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208 IFLT (*lo, *(lo-1)) |
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209 ; |
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210 else |
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211 break; |
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212 } |
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213 } |
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214 else |
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215 { |
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216 for (lo = lo+1; lo < hi; ++lo, ++n) |
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217 { |
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218 IFLT (*lo, *(lo-1)) |
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219 break; |
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220 } |
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221 } |
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222 |
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223 return n; |
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224 } |
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225 |
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226 /* |
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227 Locate the proper position of key in a sorted vector; if the vector contains |
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228 an element equal to key, return the position immediately to the left of |
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229 the leftmost equal element. [gallop_right() does the same except returns |
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230 the position to the right of the rightmost equal element (if any).] |
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231 |
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232 "a" is a sorted vector with n elements, starting at a[0]. n must be > 0. |
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233 |
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234 "hint" is an index at which to begin the search, 0 <= hint < n. The closer |
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235 hint is to the final result, the faster this runs. |
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236 |
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237 The return value is the int k in 0..n such that |
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238 |
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239 a[k-1] < key <= a[k] |
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240 |
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241 pretending that *(a-1) is minus infinity and a[n] is plus infinity. IOW, |
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242 key belongs at index k; or, IOW, the first k elements of a should precede |
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243 key, and the last n-k should follow key. |
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244 |
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245 Returns -1 on error. See listsort.txt for info on the method. |
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246 */ |
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247 template <class T> |
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248 octave_idx_type |
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249 octave_sort<T>::gallop_left (T key, T *a, octave_idx_type n, octave_idx_type hint) |
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250 { |
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251 octave_idx_type ofs; |
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252 octave_idx_type lastofs; |
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253 octave_idx_type k; |
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254 |
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255 a += hint; |
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256 lastofs = 0; |
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257 ofs = 1; |
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258 IFLT (*a, key) |
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259 { |
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260 /* a[hint] < key -- gallop right, until |
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261 * a[hint + lastofs] < key <= a[hint + ofs] |
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262 */ |
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263 const octave_idx_type maxofs = n - hint; /* &a[n-1] is highest */ |
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264 while (ofs < maxofs) |
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265 { |
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266 IFLT (a[ofs], key) |
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267 { |
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268 lastofs = ofs; |
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269 ofs = (ofs << 1) + 1; |
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270 if (ofs <= 0) /* int overflow */ |
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271 ofs = maxofs; |
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272 } |
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273 else /* key <= a[hint + ofs] */ |
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274 break; |
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275 } |
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276 if (ofs > maxofs) |
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277 ofs = maxofs; |
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278 /* Translate back to offsets relative to &a[0]. */ |
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279 lastofs += hint; |
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280 ofs += hint; |
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281 } |
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282 else |
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283 { |
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284 /* key <= a[hint] -- gallop left, until |
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285 * a[hint - ofs] < key <= a[hint - lastofs] |
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286 */ |
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287 const octave_idx_type maxofs = hint + 1; /* &a[0] is lowest */ |
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288 while (ofs < maxofs) |
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289 { |
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290 IFLT (*(a-ofs), key) |
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291 break; |
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292 /* key <= a[hint - ofs] */ |
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293 lastofs = ofs; |
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294 ofs = (ofs << 1) + 1; |
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295 if (ofs <= 0) /* int overflow */ |
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296 ofs = maxofs; |
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297 } |
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298 if (ofs > maxofs) |
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299 ofs = maxofs; |
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300 /* Translate back to positive offsets relative to &a[0]. */ |
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301 k = lastofs; |
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302 lastofs = hint - ofs; |
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303 ofs = hint - k; |
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304 } |
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305 a -= hint; |
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306 |
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307 /* Now a[lastofs] < key <= a[ofs], so key belongs somewhere to the |
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308 * right of lastofs but no farther right than ofs. Do a binary |
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309 * search, with invariant a[lastofs-1] < key <= a[ofs]. |
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310 */ |
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311 ++lastofs; |
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312 while (lastofs < ofs) |
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313 { |
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314 octave_idx_type m = lastofs + ((ofs - lastofs) >> 1); |
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315 |
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316 IFLT (a[m], key) |
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317 lastofs = m+1; /* a[m] < key */ |
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318 else |
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319 ofs = m; /* key <= a[m] */ |
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320 } |
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321 |
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322 return ofs; |
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323 } |
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324 |
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325 /* |
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326 Exactly like gallop_left(), except that if key already exists in a[0:n], |
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327 finds the position immediately to the right of the rightmost equal value. |
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328 |
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329 The return value is the int k in 0..n such that |
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330 |
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331 a[k-1] <= key < a[k] |
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332 |
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333 or -1 if error. |
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334 |
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335 The code duplication is massive, but this is enough different given that |
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336 we're sticking to "<" comparisons that it's much harder to follow if |
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337 written as one routine with yet another "left or right?" flag. |
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338 */ |
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339 template <class T> |
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340 octave_idx_type |
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341 octave_sort<T>::gallop_right (T key, T *a, octave_idx_type n, octave_idx_type hint) |
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342 { |
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343 octave_idx_type ofs; |
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344 octave_idx_type lastofs; |
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345 octave_idx_type k; |
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346 |
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347 a += hint; |
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348 lastofs = 0; |
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349 ofs = 1; |
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350 IFLT (key, *a) |
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351 { |
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352 /* key < a[hint] -- gallop left, until |
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353 * a[hint - ofs] <= key < a[hint - lastofs] |
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354 */ |
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355 const octave_idx_type maxofs = hint + 1; /* &a[0] is lowest */ |
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356 while (ofs < maxofs) |
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357 { |
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358 IFLT (key, *(a-ofs)) |
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359 { |
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360 lastofs = ofs; |
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361 ofs = (ofs << 1) + 1; |
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362 if (ofs <= 0) /* int overflow */ |
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363 ofs = maxofs; |
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364 } |
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365 else /* a[hint - ofs] <= key */ |
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366 break; |
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367 } |
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368 if (ofs > maxofs) |
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369 ofs = maxofs; |
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370 /* Translate back to positive offsets relative to &a[0]. */ |
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371 k = lastofs; |
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372 lastofs = hint - ofs; |
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373 ofs = hint - k; |
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374 } |
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375 else |
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376 { |
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377 /* a[hint] <= key -- gallop right, until |
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378 * a[hint + lastofs] <= key < a[hint + ofs] |
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379 */ |
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380 const octave_idx_type maxofs = n - hint; /* &a[n-1] is highest */ |
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381 while (ofs < maxofs) |
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382 { |
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383 IFLT (key, a[ofs]) |
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384 break; |
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385 /* a[hint + ofs] <= key */ |
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386 lastofs = ofs; |
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387 ofs = (ofs << 1) + 1; |
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388 if (ofs <= 0) /* int overflow */ |
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389 ofs = maxofs; |
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390 } |
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391 if (ofs > maxofs) |
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392 ofs = maxofs; |
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393 /* Translate back to offsets relative to &a[0]. */ |
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394 lastofs += hint; |
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395 ofs += hint; |
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396 } |
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397 a -= hint; |
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398 |
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399 /* Now a[lastofs] <= key < a[ofs], so key belongs somewhere to the |
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400 * right of lastofs but no farther right than ofs. Do a binary |
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401 * search, with invariant a[lastofs-1] <= key < a[ofs]. |
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402 */ |
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403 ++lastofs; |
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404 while (lastofs < ofs) |
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405 { |
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406 octave_idx_type m = lastofs + ((ofs - lastofs) >> 1); |
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407 |
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408 IFLT (key, a[m]) |
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409 ofs = m; /* key < a[m] */ |
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410 else |
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411 lastofs = m+1; /* a[m] <= key */ |
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412 } |
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413 |
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414 return ofs; |
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415 } |
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416 |
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417 /* Conceptually a MergeState's constructor. */ |
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418 template <class T> |
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419 void |
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420 octave_sort<T>::merge_init (void) |
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421 { |
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422 ms.a = 0; |
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423 ms.alloced = 0; |
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424 ms.n = 0; |
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425 ms.min_gallop = MIN_GALLOP; |
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426 } |
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427 |
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428 /* Free all the temp memory owned by the MergeState. This must be called |
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429 * when you're done with a MergeState, and may be called before then if |
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430 * you want to free the temp memory early. |
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431 */ |
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432 template <class T> |
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433 void |
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434 octave_sort<T>::merge_freemem (void) |
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435 { |
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436 if (ms.a) |
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437 free (ms.a); |
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438 ms.alloced = 0; |
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439 ms.a = 0; |
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440 } |
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441 |
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442 static inline octave_idx_type |
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443 roundupsize (octave_idx_type n) |
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444 { |
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445 unsigned int nbits = 3; |
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446 octave_idx_type n2 = static_cast<octave_idx_type> (n) >> 8; |
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447 |
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448 /* Round up: |
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449 * If n < 256, to a multiple of 8. |
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450 * If n < 2048, to a multiple of 64. |
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451 * If n < 16384, to a multiple of 512. |
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452 * If n < 131072, to a multiple of 4096. |
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453 * If n < 1048576, to a multiple of 32768. |
|
|
454 * If n < 8388608, to a multiple of 262144. |
|
|
455 * If n < 67108864, to a multiple of 2097152. |
|
|
456 * If n < 536870912, to a multiple of 16777216. |
|
|
457 * ... |
|
|
458 * If n < 2**(5+3*i), to a multiple of 2**(3*i). |
|
|
459 * |
|
|
460 * This over-allocates proportional to the list size, making room |
|
|
461 * for additional growth. The over-allocation is mild, but is |
|
|
462 * enough to give linear-time amortized behavior over a long |
|
|
463 * sequence of appends() in the presence of a poorly-performing |
|
|
464 * system realloc() (which is a reality, e.g., across all flavors |
|
|
465 * of Windows, with Win9x behavior being particularly bad -- and |
|
|
466 * we've still got address space fragmentation problems on Win9x |
|
|
467 * even with this scheme, although it requires much longer lists to |
|
|
468 * provoke them than it used to). |
|
|
469 */ |
|
7234
|
470 while (n2) |
|
|
471 { |
|
|
472 n2 >>= 3; |
|
|
473 nbits += 3; |
|
|
474 } |
|
|
475 |
|
4851
|
476 return ((n >> nbits) + 1) << nbits; |
|
|
477 } |
|
|
478 |
|
|
479 /* Ensure enough temp memory for 'need' array slots is available. |
|
|
480 * Returns 0 on success and -1 if the memory can't be gotten. |
|
|
481 */ |
|
|
482 template <class T> |
|
|
483 int |
|
7433
|
484 octave_sort<T>::merge_getmem (octave_idx_type need) |
|
4851
|
485 { |
|
|
486 if (need <= ms.alloced) |
|
|
487 return 0; |
|
|
488 |
|
7234
|
489 need = roundupsize (need); |
|
4851
|
490 /* Don't realloc! That can cost cycles to copy the old data, but |
|
|
491 * we don't care what's in the block. |
|
|
492 */ |
|
7234
|
493 merge_freemem (); |
|
5760
|
494 ms.a = static_cast <T *> (malloc (need * sizeof (T))); |
|
7234
|
495 if (ms.a) |
|
|
496 { |
|
|
497 ms.alloced = need; |
|
|
498 return 0; |
|
|
499 } |
|
|
500 merge_freemem (); /* reset to sane state */ |
|
|
501 |
|
4851
|
502 return -1; |
|
|
503 } |
|
|
504 |
|
7234
|
505 #define MERGE_GETMEM(NEED) ((NEED) <= ms.alloced ? 0 : merge_getmem (NEED)) |
|
4851
|
506 |
|
|
507 /* Merge the na elements starting at pa with the nb elements starting at pb |
|
|
508 * in a stable way, in-place. na and nb must be > 0, and pa + na == pb. |
|
|
509 * Must also have that *pb < *pa, that pa[na-1] belongs at the end of the |
|
|
510 * merge, and should have na <= nb. See listsort.txt for more info. |
|
|
511 * Return 0 if successful, -1 if error. |
|
|
512 */ |
|
|
513 template <class T> |
|
|
514 int |
|
7433
|
515 octave_sort<T>::merge_lo (T *pa, octave_idx_type na, T *pb, octave_idx_type nb) |
|
4851
|
516 { |
|
7433
|
517 octave_idx_type k; |
|
4851
|
518 T *dest; |
|
|
519 int result = -1; /* guilty until proved innocent */ |
|
7433
|
520 octave_idx_type min_gallop = ms.min_gallop; |
|
4851
|
521 |
|
7234
|
522 if (MERGE_GETMEM (na) < 0) |
|
4851
|
523 return -1; |
|
7234
|
524 memcpy (ms.a, pa, na * sizeof (T)); |
|
4851
|
525 dest = pa; |
|
|
526 pa = ms.a; |
|
|
527 |
|
|
528 *dest++ = *pb++; |
|
|
529 --nb; |
|
|
530 if (nb == 0) |
|
|
531 goto Succeed; |
|
|
532 if (na == 1) |
|
|
533 goto CopyB; |
|
|
534 |
|
7234
|
535 for (;;) |
|
|
536 { |
|
7433
|
537 octave_idx_type acount = 0; /* # of times A won in a row */ |
|
|
538 octave_idx_type bcount = 0; /* # of times B won in a row */ |
|
7234
|
539 |
|
|
540 /* Do the straightforward thing until (if ever) one run |
|
|
541 * appears to win consistently. |
|
|
542 */ |
|
|
543 for (;;) |
|
|
544 { |
|
4851
|
545 |
|
7234
|
546 IFLT (*pb, *pa) |
|
|
547 { |
|
|
548 *dest++ = *pb++; |
|
|
549 ++bcount; |
|
|
550 acount = 0; |
|
|
551 --nb; |
|
|
552 if (nb == 0) |
|
|
553 goto Succeed; |
|
|
554 if (bcount >= min_gallop) |
|
|
555 break; |
|
|
556 } |
|
|
557 else |
|
|
558 { |
|
|
559 *dest++ = *pa++; |
|
|
560 ++acount; |
|
|
561 bcount = 0; |
|
|
562 --na; |
|
|
563 if (na == 1) |
|
|
564 goto CopyB; |
|
|
565 if (acount >= min_gallop) |
|
|
566 break; |
|
|
567 } |
|
|
568 } |
|
4851
|
569 |
|
7234
|
570 /* One run is winning so consistently that galloping may |
|
|
571 * be a huge win. So try that, and continue galloping until |
|
|
572 * (if ever) neither run appears to be winning consistently |
|
|
573 * anymore. |
|
|
574 */ |
|
|
575 ++min_gallop; |
|
|
576 do |
|
4851
|
577 { |
|
7234
|
578 min_gallop -= min_gallop > 1; |
|
|
579 ms.min_gallop = min_gallop; |
|
|
580 k = gallop_right (*pb, pa, na, 0); |
|
|
581 acount = k; |
|
|
582 if (k) |
|
|
583 { |
|
|
584 if (k < 0) |
|
|
585 goto Fail; |
|
|
586 memcpy (dest, pa, k * sizeof (T)); |
|
|
587 dest += k; |
|
|
588 pa += k; |
|
|
589 na -= k; |
|
|
590 if (na == 1) |
|
|
591 goto CopyB; |
|
|
592 /* na==0 is impossible now if the comparison |
|
|
593 * function is consistent, but we can't assume |
|
|
594 * that it is. |
|
|
595 */ |
|
|
596 if (na == 0) |
|
|
597 goto Succeed; |
|
|
598 } |
|
4851
|
599 *dest++ = *pb++; |
|
|
600 --nb; |
|
|
601 if (nb == 0) |
|
|
602 goto Succeed; |
|
7234
|
603 |
|
|
604 k = gallop_left (*pa, pb, nb, 0); |
|
|
605 bcount = k; |
|
|
606 if (k) |
|
|
607 { |
|
|
608 if (k < 0) |
|
|
609 goto Fail; |
|
|
610 memmove (dest, pb, k * sizeof (T)); |
|
|
611 dest += k; |
|
|
612 pb += k; |
|
|
613 nb -= k; |
|
|
614 if (nb == 0) |
|
|
615 goto Succeed; |
|
|
616 } |
|
4851
|
617 *dest++ = *pa++; |
|
|
618 --na; |
|
|
619 if (na == 1) |
|
|
620 goto CopyB; |
|
|
621 } |
|
7234
|
622 while (acount >= MIN_GALLOP || bcount >= MIN_GALLOP); |
|
|
623 |
|
|
624 ++min_gallop; /* penalize it for leaving galloping mode */ |
|
|
625 ms.min_gallop = min_gallop; |
|
4851
|
626 } |
|
|
627 |
|
|
628 Succeed: |
|
|
629 result = 0; |
|
7234
|
630 |
|
4851
|
631 Fail: |
|
|
632 if (na) |
|
7234
|
633 memcpy (dest, pa, na * sizeof (T)); |
|
4851
|
634 return result; |
|
7234
|
635 |
|
4851
|
636 CopyB: |
|
|
637 /* The last element of pa belongs at the end of the merge. */ |
|
7234
|
638 memmove (dest, pb, nb * sizeof (T)); |
|
4851
|
639 dest[nb] = *pa; |
|
7234
|
640 |
|
4851
|
641 return 0; |
|
|
642 } |
|
|
643 |
|
|
644 /* Merge the na elements starting at pa with the nb elements starting at pb |
|
|
645 * in a stable way, in-place. na and nb must be > 0, and pa + na == pb. |
|
|
646 * Must also have that *pb < *pa, that pa[na-1] belongs at the end of the |
|
|
647 * merge, and should have na >= nb. See listsort.txt for more info. |
|
|
648 * Return 0 if successful, -1 if error. |
|
|
649 */ |
|
|
650 template <class T> |
|
|
651 int |
|
7433
|
652 octave_sort<T>::merge_hi (T *pa, octave_idx_type na, T *pb, octave_idx_type nb) |
|
4851
|
653 { |
|
7433
|
654 octave_idx_type k; |
|
4851
|
655 T *dest; |
|
|
656 int result = -1; /* guilty until proved innocent */ |
|
|
657 T *basea; |
|
|
658 T *baseb; |
|
7433
|
659 octave_idx_type min_gallop = ms.min_gallop; |
|
4851
|
660 |
|
7234
|
661 if (MERGE_GETMEM (nb) < 0) |
|
4851
|
662 return -1; |
|
|
663 dest = pb + nb - 1; |
|
7234
|
664 memcpy (ms.a, pb, nb * sizeof (T)); |
|
4851
|
665 basea = pa; |
|
|
666 baseb = ms.a; |
|
|
667 pb = ms.a + nb - 1; |
|
|
668 pa += na - 1; |
|
|
669 |
|
|
670 *dest-- = *pa--; |
|
|
671 --na; |
|
|
672 if (na == 0) |
|
|
673 goto Succeed; |
|
|
674 if (nb == 1) |
|
|
675 goto CopyA; |
|
|
676 |
|
|
677 for (;;) |
|
|
678 { |
|
7433
|
679 octave_idx_type acount = 0; /* # of times A won in a row */ |
|
|
680 octave_idx_type bcount = 0; /* # of times B won in a row */ |
|
4851
|
681 |
|
|
682 /* Do the straightforward thing until (if ever) one run |
|
|
683 * appears to win consistently. |
|
|
684 */ |
|
|
685 for (;;) |
|
|
686 { |
|
|
687 IFLT (*pb, *pa) |
|
|
688 { |
|
|
689 *dest-- = *pa--; |
|
|
690 ++acount; |
|
|
691 bcount = 0; |
|
|
692 --na; |
|
|
693 if (na == 0) |
|
|
694 goto Succeed; |
|
|
695 if (acount >= min_gallop) |
|
|
696 break; |
|
|
697 } |
|
|
698 else |
|
|
699 { |
|
|
700 *dest-- = *pb--; |
|
|
701 ++bcount; |
|
|
702 acount = 0; |
|
|
703 --nb; |
|
|
704 if (nb == 1) |
|
|
705 goto CopyA; |
|
|
706 if (bcount >= min_gallop) |
|
|
707 break; |
|
|
708 } |
|
|
709 } |
|
|
710 |
|
|
711 /* One run is winning so consistently that galloping may |
|
|
712 * be a huge win. So try that, and continue galloping until |
|
|
713 * (if ever) neither run appears to be winning consistently |
|
|
714 * anymore. |
|
|
715 */ |
|
|
716 ++min_gallop; |
|
|
717 do |
|
|
718 { |
|
|
719 min_gallop -= min_gallop > 1; |
|
|
720 ms.min_gallop = min_gallop; |
|
7234
|
721 k = gallop_right (*pb, basea, na, na-1); |
|
4851
|
722 if (k < 0) |
|
|
723 goto Fail; |
|
|
724 k = na - k; |
|
|
725 acount = k; |
|
|
726 if (k) |
|
|
727 { |
|
|
728 dest -= k; |
|
|
729 pa -= k; |
|
7234
|
730 memmove (dest+1, pa+1, k * sizeof (T)); |
|
4851
|
731 na -= k; |
|
|
732 if (na == 0) |
|
|
733 goto Succeed; |
|
|
734 } |
|
|
735 *dest-- = *pb--; |
|
|
736 --nb; |
|
|
737 if (nb == 1) |
|
|
738 goto CopyA; |
|
|
739 |
|
7234
|
740 k = gallop_left (*pa, baseb, nb, nb-1); |
|
4851
|
741 if (k < 0) |
|
|
742 goto Fail; |
|
|
743 k = nb - k; |
|
|
744 bcount = k; |
|
|
745 if (k) |
|
|
746 { |
|
|
747 dest -= k; |
|
|
748 pb -= k; |
|
7234
|
749 memcpy (dest+1, pb+1, k * sizeof (T)); |
|
4851
|
750 nb -= k; |
|
|
751 if (nb == 1) |
|
|
752 goto CopyA; |
|
|
753 /* nb==0 is impossible now if the comparison |
|
|
754 * function is consistent, but we can't assume |
|
|
755 * that it is. |
|
|
756 */ |
|
|
757 if (nb == 0) |
|
|
758 goto Succeed; |
|
|
759 } |
|
|
760 *dest-- = *pa--; |
|
|
761 --na; |
|
|
762 if (na == 0) |
|
|
763 goto Succeed; |
|
|
764 } while (acount >= MIN_GALLOP || bcount >= MIN_GALLOP); |
|
|
765 ++min_gallop; /* penalize it for leaving galloping mode */ |
|
|
766 ms.min_gallop = min_gallop; |
|
|
767 } |
|
7234
|
768 |
|
4851
|
769 Succeed: |
|
|
770 result = 0; |
|
7234
|
771 |
|
4851
|
772 Fail: |
|
|
773 if (nb) |
|
7234
|
774 memcpy (dest-(nb-1), baseb, nb * sizeof (T)); |
|
4851
|
775 return result; |
|
7234
|
776 |
|
4851
|
777 CopyA: |
|
|
778 /* The first element of pb belongs at the front of the merge. */ |
|
|
779 dest -= na; |
|
|
780 pa -= na; |
|
7234
|
781 memmove (dest+1, pa+1, na * sizeof (T)); |
|
4851
|
782 *dest = *pb; |
|
7234
|
783 |
|
4851
|
784 return 0; |
|
|
785 } |
|
|
786 |
|
|
787 /* Merge the two runs at stack indices i and i+1. |
|
|
788 * Returns 0 on success, -1 on error. |
|
|
789 */ |
|
|
790 template <class T> |
|
|
791 int |
|
7433
|
792 octave_sort<T>::merge_at (octave_idx_type i) |
|
4851
|
793 { |
|
|
794 T *pa, *pb; |
|
7433
|
795 octave_idx_type na, nb; |
|
|
796 octave_idx_type k; |
|
4851
|
797 |
|
|
798 pa = ms.pending[i].base; |
|
|
799 na = ms.pending[i].len; |
|
|
800 pb = ms.pending[i+1].base; |
|
|
801 nb = ms.pending[i+1].len; |
|
|
802 |
|
|
803 /* Record the length of the combined runs; if i is the 3rd-last |
|
|
804 * run now, also slide over the last run (which isn't involved |
|
|
805 * in this merge). The current run i+1 goes away in any case. |
|
|
806 */ |
|
|
807 ms.pending[i].len = na + nb; |
|
|
808 if (i == ms.n - 3) |
|
|
809 ms.pending[i+1] = ms.pending[i+2]; |
|
|
810 --ms.n; |
|
|
811 |
|
|
812 /* Where does b start in a? Elements in a before that can be |
|
|
813 * ignored (already in place). |
|
|
814 */ |
|
7234
|
815 k = gallop_right (*pb, pa, na, 0); |
|
4851
|
816 if (k < 0) |
|
|
817 return -1; |
|
|
818 pa += k; |
|
|
819 na -= k; |
|
|
820 if (na == 0) |
|
|
821 return 0; |
|
|
822 |
|
|
823 /* Where does a end in b? Elements in b after that can be |
|
|
824 * ignored (already in place). |
|
|
825 */ |
|
7234
|
826 nb = gallop_left (pa[na-1], pb, nb, nb-1); |
|
4851
|
827 if (nb <= 0) |
|
|
828 return nb; |
|
|
829 |
|
|
830 /* Merge what remains of the runs, using a temp array with |
|
|
831 * min(na, nb) elements. |
|
|
832 */ |
|
|
833 if (na <= nb) |
|
7234
|
834 return merge_lo (pa, na, pb, nb); |
|
4851
|
835 else |
|
7234
|
836 return merge_hi (pa, na, pb, nb); |
|
4851
|
837 } |
|
|
838 |
|
|
839 /* Examine the stack of runs waiting to be merged, merging adjacent runs |
|
|
840 * until the stack invariants are re-established: |
|
|
841 * |
|
|
842 * 1. len[-3] > len[-2] + len[-1] |
|
|
843 * 2. len[-2] > len[-1] |
|
|
844 * |
|
|
845 * See listsort.txt for more info. |
|
|
846 * |
|
|
847 * Returns 0 on success, -1 on error. |
|
|
848 */ |
|
|
849 template <class T> |
|
|
850 int |
|
7234
|
851 octave_sort<T>::merge_collapse (void) |
|
4851
|
852 { |
|
|
853 struct s_slice *p = ms.pending; |
|
|
854 |
|
|
855 while (ms.n > 1) |
|
|
856 { |
|
7433
|
857 octave_idx_type n = ms.n - 2; |
|
4851
|
858 if (n > 0 && p[n-1].len <= p[n].len + p[n+1].len) |
|
|
859 { |
|
|
860 if (p[n-1].len < p[n+1].len) |
|
|
861 --n; |
|
7234
|
862 if (merge_at (n) < 0) |
|
4851
|
863 return -1; |
|
|
864 } |
|
|
865 else if (p[n].len <= p[n+1].len) |
|
|
866 { |
|
7234
|
867 if (merge_at (n) < 0) |
|
4851
|
868 return -1; |
|
|
869 } |
|
|
870 else |
|
|
871 break; |
|
|
872 } |
|
7234
|
873 |
|
4851
|
874 return 0; |
|
|
875 } |
|
|
876 |
|
|
877 /* Regardless of invariants, merge all runs on the stack until only one |
|
|
878 * remains. This is used at the end of the mergesort. |
|
|
879 * |
|
|
880 * Returns 0 on success, -1 on error. |
|
|
881 */ |
|
|
882 template <class T> |
|
|
883 int |
|
7234
|
884 octave_sort<T>::merge_force_collapse (void) |
|
4851
|
885 { |
|
|
886 struct s_slice *p = ms.pending; |
|
|
887 |
|
|
888 while (ms.n > 1) |
|
|
889 { |
|
7433
|
890 octave_idx_type n = ms.n - 2; |
|
4851
|
891 if (n > 0 && p[n-1].len < p[n+1].len) |
|
|
892 --n; |
|
7234
|
893 if (merge_at (n) < 0) |
|
4851
|
894 return -1; |
|
|
895 } |
|
7234
|
896 |
|
4851
|
897 return 0; |
|
|
898 } |
|
|
899 |
|
|
900 /* Compute a good value for the minimum run length; natural runs shorter |
|
|
901 * than this are boosted artificially via binary insertion. |
|
|
902 * |
|
|
903 * If n < 64, return n (it's too small to bother with fancy stuff). |
|
|
904 * Else if n is an exact power of 2, return 32. |
|
|
905 * Else return an int k, 32 <= k <= 64, such that n/k is close to, but |
|
|
906 * strictly less than, an exact power of 2. |
|
|
907 * |
|
|
908 * See listsort.txt for more info. |
|
|
909 */ |
|
|
910 template <class T> |
|
7433
|
911 octave_idx_type |
|
|
912 octave_sort<T>::merge_compute_minrun (octave_idx_type n) |
|
4851
|
913 { |
|
7433
|
914 octave_idx_type r = 0; /* becomes 1 if any 1 bits are shifted off */ |
|
4851
|
915 |
|
7234
|
916 while (n >= 64) |
|
|
917 { |
|
|
918 r |= n & 1; |
|
|
919 n >>= 1; |
|
|
920 } |
|
|
921 |
|
4851
|
922 return n + r; |
|
|
923 } |
|
|
924 |
|
|
925 template <class T> |
|
|
926 void |
|
7433
|
927 octave_sort<T>::sort (T *v, octave_idx_type elements) |
|
4851
|
928 { |
|
|
929 /* Re-initialize the Mergestate as this might be the second time called */ |
|
|
930 ms.n = 0; |
|
|
931 ms.min_gallop = MIN_GALLOP; |
|
|
932 |
|
|
933 if (elements > 1) |
|
|
934 { |
|
7433
|
935 octave_idx_type nremaining = elements; |
|
4851
|
936 T *lo = v; |
|
|
937 T *hi = v + elements; |
|
|
938 |
|
|
939 /* March over the array once, left to right, finding natural runs, |
|
|
940 * and extending short natural runs to minrun elements. |
|
|
941 */ |
|
7433
|
942 octave_idx_type minrun = merge_compute_minrun (nremaining); |
|
4851
|
943 do |
|
|
944 { |
|
|
945 int descending; |
|
7433
|
946 octave_idx_type n; |
|
4851
|
947 |
|
|
948 /* Identify next run. */ |
|
7234
|
949 n = count_run (lo, hi, &descending); |
|
4851
|
950 if (n < 0) |
|
|
951 goto fail; |
|
|
952 if (descending) |
|
7234
|
953 reverse_slice (lo, lo + n); |
|
4851
|
954 /* If short, extend to min(minrun, nremaining). */ |
|
|
955 if (n < minrun) |
|
|
956 { |
|
7433
|
957 const octave_idx_type force = nremaining <= minrun ? nremaining : minrun; |
|
7234
|
958 binarysort (lo, lo + force, lo + n); |
|
4851
|
959 n = force; |
|
|
960 } |
|
|
961 /* Push run onto pending-runs stack, and maybe merge. */ |
|
7234
|
962 assert (ms.n < MAX_MERGE_PENDING); |
|
4851
|
963 ms.pending[ms.n].base = lo; |
|
|
964 ms.pending[ms.n].len = n; |
|
|
965 ++ms.n; |
|
7234
|
966 if (merge_collapse () < 0) |
|
4851
|
967 goto fail; |
|
|
968 /* Advance to find next run. */ |
|
|
969 lo += n; |
|
|
970 nremaining -= n; |
|
7234
|
971 } |
|
|
972 while (nremaining); |
|
4851
|
973 |
|
7234
|
974 merge_force_collapse (); |
|
4851
|
975 } |
|
|
976 |
|
|
977 fail: |
|
|
978 return; |
|
|
979 } |
|
|
980 |
|
|
981 /* |
|
|
982 ;;; Local Variables: *** |
|
|
983 ;;; mode: C++ *** |
|
|
984 ;;; End: *** |
|
|
985 */ |
