1 | /* -*- C++ -*- */ |
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2 | |
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3 | /* |
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4 | |
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5 | Heap Layers: An Extensible Memory Allocation Infrastructure |
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6 | |
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7 | Copyright (C) 2000-2005 by Emery Berger |
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8 | http://www.cs.umass.edu/~emery |
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9 | emery@cs.umass.edu |
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10 | |
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11 | This program is free software; you can redistribute it and/or modify |
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12 | it under the terms of the GNU General Public License as published by |
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13 | the Free Software Foundation; either version 2 of the License, or |
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14 | (at your option) any later version. |
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15 | |
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16 | This program is distributed in the hope that it will be useful, |
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17 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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18 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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19 | GNU General Public License for more details. |
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20 | |
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21 | You should have received a copy of the GNU General Public License |
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22 | along with this program; if not, write to the Free Software |
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23 | Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
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24 | |
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25 | */ |
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26 | |
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27 | /** |
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28 | * @file segheap.h |
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29 | * @brief Definitions of SegHeap and StrictSegHeap. |
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30 | */ |
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31 | |
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32 | #ifndef _SEGHEAP_H_ |
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33 | #define _SEGHEAP_H_ |
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34 | |
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35 | /** |
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36 | * @class SegHeap |
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37 | * @brief A segregated-fits collection of (homogeneous) heaps. |
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38 | * @author Emery Berger |
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39 | * |
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40 | * Note that one extra heap is used for objects that are "too big". |
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41 | * |
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42 | * @param NumBins The number of bins (subheaps). |
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43 | * @param getSizeClass Function to compute size class from size. |
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44 | * @param getClassMaxSize Function to compute the largest size for a given size class. |
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45 | * @param LittleHeap The subheap class. |
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46 | * @param BigHeap The parent class, used for "big" objects. |
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47 | * |
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48 | * Example:<BR> |
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49 | * <TT> |
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50 | * int myFunc (size_t sz); // The size-to-class function.<BR> |
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51 | * size_t myFunc2 (int); // The class-to-size function.<P> |
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52 | * // The heap. Use freelists for these small objects,<BR> |
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53 | * // but defer to malloc for large objects.<P> |
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54 | * |
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55 | * SegHeap<4, myFunc, myFunc2, freelistHeap<mallocHeap>, mallocHeap> mySegHeap; |
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56 | * </TT> |
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57 | **/ |
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58 | |
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59 | #include <assert.h> |
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60 | #include "bitstring.h" |
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61 | |
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62 | namespace HL { |
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63 | |
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64 | template <int NumBins, |
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65 | int (*getSizeClass) (const size_t), |
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66 | size_t (*getClassMaxSize) (const int), |
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67 | class LittleHeap, |
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68 | class BigHeap> |
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69 | class SegHeap : public LittleHeap { |
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70 | private: |
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71 | |
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72 | typedef int (*scFunction) (const size_t); |
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73 | typedef size_t (*csFunction) (const int); |
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74 | |
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75 | public: |
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76 | |
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77 | inline SegHeap (void) |
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78 | : memoryHeld (0), |
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79 | maxObjectSize (((csFunction) getClassMaxSize) (NumBins - 1)) |
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80 | { |
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81 | for (int i = 0; i < NUM_ULONGS; i++) { |
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82 | binmap[i] = 0; |
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83 | } |
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84 | } |
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85 | |
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86 | inline ~SegHeap (void) {} |
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87 | |
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88 | inline size_t getMemoryHeld (void) const { |
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89 | return memoryHeld; |
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90 | } |
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91 | |
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92 | // new... |
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93 | size_t getSize (void * ptr) { |
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94 | return LittleHeap::getSize (ptr); |
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95 | } |
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96 | |
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97 | inline void * malloc (const size_t sz) { |
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98 | void * ptr = NULL; |
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99 | if (sz > maxObjectSize) { |
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100 | goto GET_MEMORY; |
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101 | } |
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102 | |
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103 | { |
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104 | const int sc = ((scFunction) getSizeClass)(sz); |
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105 | assert (sc >= 0); |
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106 | assert (sc < NumBins); |
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107 | int idx = sc; |
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108 | int block = idx2block (idx); |
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109 | unsigned long map = binmap[block]; |
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110 | unsigned long bit = idx2bit (idx); |
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111 | |
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112 | for (;;) { |
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113 | if (bit > map || bit == 0) { |
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114 | do { |
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115 | if (++block >= NUM_ULONGS) { |
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116 | goto GET_MEMORY; |
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117 | // return bigheap.malloc (sz); |
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118 | } |
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119 | } while ( (map = binmap[block]) == 0); |
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120 | |
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121 | idx = block << SHIFTS_PER_ULONG; |
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122 | bit = 1; |
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123 | } |
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124 | |
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125 | while ((bit & map) == 0) { |
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126 | bit <<= 1; |
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127 | assert(bit != 0); |
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128 | idx++; |
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129 | } |
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130 | |
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131 | assert (idx < NumBins); |
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132 | ptr = myLittleHeap[idx].malloc (sz); |
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133 | |
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134 | if (ptr == NULL) { |
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135 | binmap[block] = map &= ~bit; // Write through |
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136 | idx++; |
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137 | bit <<= 1; |
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138 | } else { |
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139 | return ptr; |
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140 | } |
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141 | } |
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142 | } |
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143 | |
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144 | GET_MEMORY: |
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145 | if (ptr == NULL) { |
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146 | // There was no free memory in any of the bins. |
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147 | // Get some memory. |
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148 | ptr = bigheap.malloc (sz); |
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149 | } |
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150 | |
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151 | return ptr; |
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152 | } |
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153 | |
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154 | |
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155 | inline void free (void * ptr) { |
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156 | // printf ("Free: %x (%d bytes)\n", ptr, getSize(ptr)); |
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157 | const size_t objectSize = getSize(ptr); // was bigheap.getSize(ptr) |
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158 | if (objectSize > maxObjectSize) { |
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159 | // printf ("free up! (size class = %d)\n", objectSizeClass); |
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160 | bigheap.free (ptr); |
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161 | } else { |
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162 | int objectSizeClass = ((scFunction) getSizeClass) (objectSize); |
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163 | assert (objectSizeClass >= 0); |
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164 | assert (objectSizeClass < NumBins); |
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165 | // Put the freed object into the right sizeclass heap. |
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166 | assert (getClassMaxSize(objectSizeClass) >= objectSize); |
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167 | #if 1 |
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168 | while (((csFunction) getClassMaxSize)(objectSizeClass) > objectSize) { |
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169 | objectSizeClass--; |
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170 | } |
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171 | #endif |
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172 | assert (((csFunction) getClassMaxSize)(objectSizeClass) <= objectSize); |
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173 | if (objectSizeClass > 0) { |
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174 | assert (objectSize >= ((csFunction) getClassMaxSize)(objectSizeClass - 1)); |
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175 | } |
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176 | |
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177 | |
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178 | myLittleHeap[objectSizeClass].free (ptr); |
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179 | mark_bin (objectSizeClass); |
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180 | memoryHeld += objectSize; |
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181 | } |
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182 | } |
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183 | |
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184 | |
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185 | void clear (void) { |
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186 | int i; |
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187 | for (i = 0; i < NumBins; i++) { |
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188 | myLittleHeap[i].clear(); |
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189 | } |
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190 | for (int j = 0; j < NUM_ULONGS; j++) { |
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191 | binmap[j] = 0; |
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192 | } |
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193 | // bitstring.clear(); |
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194 | bigheap.clear(); |
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195 | memoryHeld = 0; |
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196 | } |
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197 | |
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198 | private: |
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199 | |
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200 | enum { BITS_PER_ULONG = 32 }; |
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201 | enum { SHIFTS_PER_ULONG = 5 }; |
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202 | enum { MAX_BITS = (NumBins + BITS_PER_ULONG - 1) & ~(BITS_PER_ULONG - 1) }; |
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203 | |
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204 | |
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205 | private: |
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206 | |
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207 | static inline int idx2block (int i) { |
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208 | int blk = i >> SHIFTS_PER_ULONG; |
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209 | assert (blk < NUM_ULONGS); |
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210 | assert (blk >= 0); |
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211 | return blk; |
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212 | } |
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213 | |
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214 | static inline unsigned long idx2bit (int i) { |
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215 | unsigned long bit = ((1U << ((i) & ((1U << SHIFTS_PER_ULONG)-1)))); |
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216 | return bit; |
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217 | } |
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218 | |
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219 | |
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220 | protected: |
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221 | |
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222 | BigHeap bigheap; |
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223 | |
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224 | enum { NUM_ULONGS = MAX_BITS / BITS_PER_ULONG }; |
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225 | unsigned long binmap[NUM_ULONGS]; |
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226 | |
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227 | inline int get_binmap (int i) const { |
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228 | return binmap[i >> SHIFTS_PER_ULONG] & idx2bit(i); |
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229 | } |
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230 | |
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231 | inline void mark_bin (int i) { |
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232 | binmap[i >> SHIFTS_PER_ULONG] |= idx2bit(i); |
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233 | } |
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234 | |
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235 | inline void unmark_bin (int i) { |
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236 | binmap[i >> SHIFTS_PER_ULONG] &= ~(idx2bit(i)); |
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237 | } |
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238 | |
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239 | size_t memoryHeld; |
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240 | |
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241 | const size_t maxObjectSize; |
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242 | |
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243 | // The little heaps. |
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244 | LittleHeap myLittleHeap[NumBins]; |
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245 | |
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246 | }; |
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247 | |
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248 | }; |
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249 | |
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250 | |
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251 | /** |
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252 | * @class StrictSegHeap |
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253 | * @brief A "strict" segregated-fits collection of (homogeneous) heaps. |
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254 | * |
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255 | * One extra heap is used for objects that are "too big". Unlike |
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256 | * SegHeap, StrictSegHeap does not perform splitting to satisfy memory |
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257 | * requests. If no memory is available from the appropriate bin, |
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258 | * malloc returns NULL. |
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259 | * |
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260 | * @sa SegHeap |
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261 | * |
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262 | * @param NumBins The number of bins (subheaps). |
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263 | * @param getSizeClass Function to compute size class from size. |
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264 | * @param getClassMaxSize Function to compute the largest size for a given size class. |
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265 | * @param LittleHeap The subheap class. |
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266 | * @param BigHeap The parent class, used for "big" objects. |
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267 | */ |
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268 | |
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269 | namespace HL { |
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270 | |
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271 | template <int NumBins, |
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272 | int (*getSizeClass) (const size_t), |
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273 | size_t (*getClassMaxSize) (const int), |
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274 | class LittleHeap, |
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275 | class BigHeap> |
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276 | class StrictSegHeap : |
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277 | public SegHeap<NumBins, getSizeClass, getClassMaxSize, LittleHeap, BigHeap> |
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278 | { |
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279 | private: |
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280 | |
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281 | typedef SegHeap<NumBins, getSizeClass, getClassMaxSize, LittleHeap, BigHeap> super; |
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282 | |
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283 | typedef int (*scFunction) (const size_t); |
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284 | typedef size_t (*csFunction) (const int); |
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285 | |
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286 | public: |
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287 | |
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288 | void freeAll (void) { |
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289 | int i; |
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290 | for (i = 0; i < NumBins; i++) { |
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291 | const size_t sz = ((csFunction) getClassMaxSize)(i); |
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292 | void * ptr; |
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293 | while ((ptr = super::myLittleHeap[i].malloc (sz)) != NULL) { |
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294 | super::bigheap.free (ptr); |
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295 | } |
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296 | } |
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297 | for (int j = 0; j < super::NUM_ULONGS; j++) { |
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298 | super::binmap[j] = 0; |
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299 | } |
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300 | super::memoryHeld = 0; |
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301 | } |
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302 | |
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303 | |
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304 | /** |
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305 | * Malloc from exactly one available size. |
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306 | * (don't look in every small heap, as in SegHeap). |
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307 | */ |
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308 | |
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309 | inline void * malloc (const size_t sz) { |
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310 | void * ptr = NULL; |
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311 | if (sz <= super::maxObjectSize) { |
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312 | const int sizeClass = ((scFunction) getSizeClass) (sz); |
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313 | assert (sizeClass >= 0); |
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314 | assert (sizeClass < NumBins); |
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315 | ptr = super::myLittleHeap[sizeClass].malloc (sz); |
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316 | } |
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317 | if (!ptr) { |
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318 | ptr = super::bigheap.malloc (sz); |
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319 | } |
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320 | return ptr; |
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321 | } |
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322 | |
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323 | inline void free (void * ptr) { |
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324 | const size_t objectSize = super::getSize(ptr); |
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325 | if (objectSize > super::maxObjectSize) { |
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326 | super::bigheap.free (ptr); |
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327 | } else { |
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328 | int objectSizeClass = ((scFunction) getSizeClass) (objectSize); |
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329 | assert (objectSizeClass >= 0); |
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330 | assert (objectSizeClass < NumBins); |
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331 | // Put the freed object into the right sizeclass heap. |
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332 | assert (getClassMaxSize(objectSizeClass) >= objectSize); |
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333 | while (((csFunction) getClassMaxSize)(objectSizeClass) > objectSize) { |
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334 | objectSizeClass--; |
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335 | } |
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336 | assert (((csFunction) getClassMaxSize)(objectSizeClass) <= objectSize); |
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337 | if (objectSizeClass > 0) { |
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338 | assert (objectSize >= ((csFunction) getClassMaxSize)(objectSizeClass - 1)); |
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339 | } |
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340 | |
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341 | super::myLittleHeap[objectSizeClass].free (ptr); |
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342 | super::memoryHeld += objectSize; |
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343 | } |
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344 | } |
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345 | |
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346 | }; |
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347 | |
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348 | }; |
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349 | |
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350 | |
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351 | #endif |
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