1 | /* -*- C++ -*- */ |
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2 | |
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3 | #ifndef _BIGCHUNK_H_ |
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4 | #define _BIGCHUNK_H_ |
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5 | |
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6 | #include <assert.h> |
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7 | |
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8 | template <int chunkSize, int slotSize, class Super> |
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9 | class BigChunk { |
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10 | public: |
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11 | |
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12 | inline BigChunk (void); |
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13 | |
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14 | // Get and put slots. |
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15 | // Get returns NULL if there are no slots available. |
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16 | inline void * getSlot (void); |
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17 | inline void putSlot (void *); |
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18 | |
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19 | // How many slots are there in total? |
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20 | inline static int getNumSlots (void); |
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21 | |
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22 | // How many slots are available? |
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23 | inline int getNumSlotsFree (void); |
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24 | |
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25 | // How many slots are available? |
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26 | inline int getNumSlotsInUse (void); |
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27 | |
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28 | // Find a chunk given its slot. |
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29 | inline static BigChunk * getChunk (void *); |
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30 | |
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31 | class ChunkBlock { |
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32 | public: |
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33 | void setChunk (BigChunk * ch) { _myChunk = ch; } |
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34 | BigChunk * getChunk (void) { return _myChunk; } |
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35 | void setNext (ChunkBlock * n) { _next = n; } |
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36 | ChunkBlock * getNext (void) { return _next; } |
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37 | private: |
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38 | BigChunk * _myChunk; // If allocated, point to the chunk. |
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39 | ChunkBlock * _next; // If not allocated, point to the next chunk block. |
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40 | }; |
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41 | |
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42 | // Find a chunk block for a given pointer. |
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43 | static inline ChunkBlock * getChunkBlock (void * ptr) { |
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44 | assert (ptr != NULL); |
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45 | return (ChunkBlock *) ptr - 1; |
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46 | } |
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47 | |
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48 | void setHeap (Super * h) { |
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49 | heap = h; |
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50 | } |
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51 | |
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52 | inline Super * getHeap (void) { |
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53 | return heap; |
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54 | } |
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55 | |
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56 | // Add doubly linked-list operations. |
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57 | inline BigChunk * getNext (void); |
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58 | inline BigChunk * getPrev (void); |
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59 | inline void setNext (BigChunk *); |
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60 | inline void setPrev (BigChunk *); |
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61 | |
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62 | private: |
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63 | |
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64 | static inline size_t align (size_t sz) { |
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65 | return (sz + (sizeof(double) - 1)) & ~(sizeof(double) - 1); |
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66 | } |
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67 | |
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68 | ChunkBlock * freeSlots; |
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69 | int numSlotsAvailable; |
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70 | Super * heap; |
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71 | BigChunk * prev; |
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72 | BigChunk * next; |
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73 | }; |
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74 | |
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75 | |
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76 | template <int chunkSize, int slotSize, class Super> |
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77 | BigChunk<chunkSize, slotSize, Super> * BigChunk<chunkSize, slotSize, Super>::getNext (void) |
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78 | { |
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79 | return next; |
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80 | } |
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81 | |
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82 | |
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83 | template <int chunkSize, int slotSize, class Super> |
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84 | BigChunk<chunkSize, slotSize, Super> * BigChunk<chunkSize, slotSize, Super>::getPrev (void) |
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85 | { |
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86 | return prev; |
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87 | } |
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88 | |
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89 | |
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90 | template <int chunkSize, int slotSize, class Super> |
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91 | void BigChunk<chunkSize, slotSize, Super>::setNext (BigChunk<chunkSize, slotSize, Super> * ptr) |
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92 | { |
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93 | next = ptr; |
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94 | } |
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95 | |
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96 | |
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97 | template <int chunkSize, int slotSize, class Super> |
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98 | void BigChunk<chunkSize, slotSize, Super>::setPrev (BigChunk<chunkSize, slotSize, Super> * ptr) |
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99 | { |
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100 | prev = ptr; |
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101 | } |
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102 | |
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103 | |
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104 | template <int chunkSize, int slotSize, class Super> |
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105 | BigChunk<chunkSize, slotSize, Super>::BigChunk (void) |
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106 | : freeSlots (NULL), |
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107 | numSlotsAvailable (getNumSlots()), |
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108 | prev (NULL), |
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109 | next (NULL) |
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110 | { |
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111 | //printf ("numSlots = %d\n", numSlots); |
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112 | int numSlots = getNumSlots(); |
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113 | assert (numSlots > 0); |
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114 | const int blksize = align(sizeof(ChunkBlock) + slotSize); |
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115 | //printf ("blksize = %d\n", blksize); |
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116 | // Carve up the chunk into a number of slots. |
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117 | ChunkBlock * b = (ChunkBlock *) (this + 1); |
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118 | for (int i = 0; i < numSlots; i++) { |
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119 | assert ((unsigned long) b < ((unsigned long) (this + 1) + blksize * numSlots)); |
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120 | new (b) ChunkBlock; |
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121 | b->setChunk (this); |
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122 | assert (b->getChunk() == this); |
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123 | b->setNext (freeSlots); |
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124 | freeSlots = b; |
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125 | b = (ChunkBlock *) ((char *) b + blksize); |
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126 | } |
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127 | } |
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128 | |
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129 | |
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130 | template <int chunkSize, int slotSize, class Super> |
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131 | void * BigChunk<chunkSize, slotSize, Super>::getSlot (void) |
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132 | { |
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133 | if (freeSlots == NULL) { |
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134 | assert (numSlotsAvailable == 0); |
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135 | return NULL; |
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136 | } |
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137 | assert (numSlotsAvailable > 0); |
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138 | assert (numSlotsAvailable <= getNumSlots()); |
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139 | ChunkBlock * b = freeSlots; |
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140 | freeSlots = freeSlots->getNext(); |
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141 | numSlotsAvailable--; |
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142 | b->setChunk (this); // FIX ME -- this should be unnecessary. |
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143 | b->setNext (NULL); |
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144 | void * ptr = (void *) (b + 1); |
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145 | BigChunk<chunkSize, slotSize, Super> * bch = getChunk(ptr); |
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146 | assert (bch == this); |
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147 | return (void *) (b + 1); |
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148 | } |
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149 | |
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150 | |
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151 | template <int chunkSize, int slotSize, class Super> |
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152 | void BigChunk<chunkSize, slotSize, Super>::putSlot (void * ptr) |
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153 | { |
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154 | assert (numSlotsAvailable >= 0); |
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155 | assert (numSlotsAvailable <= getNumSlots()); |
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156 | ChunkBlock * b = getChunkBlock (ptr); |
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157 | assert (b->getChunk() == this); |
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158 | b->setNext (freeSlots); |
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159 | freeSlots = b; |
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160 | numSlotsAvailable++; |
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161 | assert (numSlotsAvailable > 0); |
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162 | assert (numSlotsAvailable <= getNumSlots()); |
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163 | } |
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164 | |
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165 | |
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166 | template <int chunkSize, int slotSize, class Super> |
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167 | int BigChunk<chunkSize, slotSize, Super>::getNumSlots (void) |
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168 | { |
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169 | return ((chunkSize - sizeof(BigChunk)) / align (sizeof(ChunkBlock) + slotSize)); |
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170 | } |
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171 | |
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172 | |
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173 | template <int chunkSize, int slotSize, class Super> |
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174 | int BigChunk<chunkSize, slotSize, Super>::getNumSlotsFree (void) |
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175 | { |
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176 | return numSlotsAvailable; |
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177 | } |
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178 | |
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179 | |
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180 | template <int chunkSize, int slotSize, class Super> |
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181 | int BigChunk<chunkSize, slotSize, Super>::getNumSlotsInUse (void) |
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182 | { |
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183 | return getNumSlots() - numSlotsAvailable; |
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184 | } |
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185 | |
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186 | |
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187 | template <int chunkSize, int slotSize, class Super> |
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188 | BigChunk<chunkSize, slotSize, Super> * BigChunk<chunkSize, slotSize, Super>::getChunk (void * ptr) |
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189 | { |
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190 | ChunkBlock * ch = getChunkBlock (ptr); |
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191 | return ch->getChunk(); |
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192 | } |
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193 | |
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194 | #endif |
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