1 | /* |
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2 | * malloc.h - User space memory allocator. |
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3 | * |
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4 | * Author Alain Greiner (2016,2017) |
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5 | * |
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6 | * Copyright (c) UPMC Sorbonne Universites |
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7 | * |
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8 | * This file is part of ALMOS-MKH. |
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9 | * |
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10 | * ALMOS-MKH is free software; you can redistribute it and/or modify it |
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11 | * under the terms of the GNU General Public License as published by |
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12 | * the Free Software Foundation; version 2.0 of the License. |
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13 | * |
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14 | * ALMOS-MKH is distributed in the hope that it will be useful, but |
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15 | * WITHOUT ANY WARRANTY; without even the implied warranty of |
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16 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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17 | * General Public License for more details. |
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18 | * |
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19 | * You should have received a copy of the GNU General Public License |
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20 | * along with ALMOS-MKH; if not, write to the Free Software Foundation, |
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21 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA |
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22 | */ |
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23 | |
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24 | //////////////////////////////////////////////////////////////////////////////// |
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25 | // General principles: |
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26 | // - In user space this HEAP zone has a fixed size, that spread between the |
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27 | // ELF zone and the STACK zone. |
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28 | // - The malloc library uses the mmap() syscall to create - on demand - |
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29 | // up to one vseg per cluster. The size of these vsegs is defined by the |
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30 | // MALLOC_LOCAL_STORAGE_SIZE parameter. |
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31 | // - For a standard malloc(), the target cluster is the cluster of the client |
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32 | // thread. For a remote_malloc(), the target cluster is explicitely defined |
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33 | // by the arguments. |
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34 | // - In each cluster, the available storage in virtual space is handled by a |
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35 | // local allocator using the buddy algorithm. |
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36 | // TODO : introduce the possibility to use a list of vsegs in each cluster... |
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37 | //////////////////////////////////////////////////////////////////////////////// |
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38 | // Free blocks organisation in each cluster : |
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39 | // - All free blocks have a size that is a power of 2, larger or equal |
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40 | // to MALLOC_MIN_BLOCK_SIZE (typically 64 bytes). |
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41 | // - All free blocks are aligned. |
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42 | // - They are pre-classed in an array of linked lists, where all blocks in a |
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43 | // given list have the same size. |
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44 | // - The NEXT pointer implementing those linked lists is written |
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45 | // in the 4 first bytes of the block itself, using the unsigned int type. |
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46 | // - The pointers on the first free block for each size are stored in an |
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47 | // array of pointers free[32] in the stotrage(x,y) descriptor. |
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48 | //////////////////////////////////////////////////////////////////////////////// |
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49 | // Allocation policy: |
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50 | // - The block size required by the user can be any value, but the allocated |
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51 | // block size can be larger than the requested size: |
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52 | // - The allocator computes actual_size, that is the smallest power of 2 |
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53 | // value larger or equal to the requested size AND larger or equal to |
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54 | // MALLOC_MIN_BLOCK_SIZE. |
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55 | // - It pop the linked list of free blocks corresponding to actual_size, |
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56 | // and returns the block B if the list[actual_size] is not empty. |
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57 | // - If the list[actual_size] is empty, it pop the list[actual_size * 2]. |
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58 | // If a block B' is found, it break this block in 2 B/2 blocks, returns |
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59 | // the first B/2 block and push the other B/2 block into list[actual_size]. |
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60 | // - If the list[actual_size * 2] is empty, it pop the list[actual_size * 4]. |
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61 | // If a block B is found, it break this block in 3 blocks B/4, B/4 and B/2, |
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62 | // returns the first B/4 block, push the other blocks B/4 and B/2 into |
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63 | // the proper lists. etc... |
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64 | // - If no block satisfying the request is available it returns a failure |
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65 | // (NULL pointer). |
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66 | // - This allocation policy has the nice following property: |
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67 | // If the vseg is aligned (the vseg base is a multiple of the |
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68 | // vseg size), all allocated blocks are aligned on the actual_size. |
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69 | //////////////////////////////////////////////////////////////////////////////// |
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70 | // Free policy: |
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71 | // - Each allocated block is registered in an alloc[] array of unsigned char. |
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72 | // - This registration is required by the free() operation, because the size |
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73 | // of the allocated block must be obtained from the base address of the block. |
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74 | // - The number of entries in this array is equal to the max number |
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75 | // of allocated block : MALLOC_LOCAL_STORAGE_SIZE / MALLOC_MIN_BLOCK_SIZE. |
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76 | // - For each allocated block, the value registered in the alloc[] array |
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77 | // is log2( size_of_allocated_block ). |
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78 | // - The index in this array is computed from the allocated block base address: |
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79 | // index = (block_base - vseg_base) / MALLOC_MIN_BLOCK_SIZE |
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80 | // - The alloc[] array is stored at the end of heap segment. This consume |
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81 | // (1 / MALLOC_MIN_BLOCK_SIZE) of the total storage capacity. |
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82 | //////////////////////////////////////////////////////////////////////////////// |
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83 | |
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84 | #ifndef _MALLOC_H_ |
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85 | #define _MALLOC_H_ |
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86 | |
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87 | #include "pthread.h" |
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88 | |
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89 | #define MALLOC_INITIALIZED 0xBABEF00D // magic number when initialised |
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90 | #define MALLOC_MIN_BLOCK_SIZE 0x40 // 64 bytes |
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91 | #define MALLOC_LOCAL_STORE_SIZE 0x800000 // 8 Mbytes |
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92 | #define MALLOC_MAX_CLUSTERS 0x100 // 256 clusters |
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93 | |
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94 | //////////////////////////////////////////////////////////////////////////////// |
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95 | // store(x,y) descriptor (one per cluster) |
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96 | //////////////////////////////////////////////////////////////////////////////// |
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97 | |
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98 | typedef struct malloc_store_s |
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99 | { |
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100 | pthread_mutex_t mutex; // lock protecting exclusive access |
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101 | unsigned int initialized; // initialised when value == MALLOC_INITIALIZED |
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102 | unsigned int cxy; // cluster identifier |
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103 | unsigned int store_base; // store base address |
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104 | unsigned int store_size; // store size (bytes) |
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105 | unsigned int alloc_base; // alloc[] array base address |
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106 | unsigned int alloc_size; // alloc[] array size (bytes) |
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107 | unsigned int free[32]; // array of addresses of first free block |
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108 | } |
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109 | malloc_store_t; |
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110 | |
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111 | /***************************************************************************************** |
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112 | * This function allocates <size> bytes of memory in user space and returns a pointer |
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113 | * on the allocated buffer. The physical memory is allocated from store located in |
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114 | * the calling core cluster. |
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115 | ***************************************************************************************** |
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116 | * @ size : number of requested bytes. |
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117 | * @ returns a pointer on the allocated buffer if success / returns NULL if failure |
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118 | ****************************************************************************************/ |
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119 | void * malloc( unsigned int size ); |
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120 | |
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121 | /***************************************************************************************** |
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122 | * This function allocates <size> bytes of memory in user space, and returns a pointer |
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123 | * to the allocated buffer. The pysical memory is allocated from store located in |
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124 | * cluster identified by the <cxy> argument. |
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125 | ***************************************************************************************** |
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126 | * @ size : number of requested bytes. |
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127 | * @ cxy : target cluster identifier. |
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128 | * @ returns a pointer on the allocated buffer if success / returns NULL if failure |
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129 | ****************************************************************************************/ |
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130 | void * remote_malloc( unsigned int size, |
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131 | unsigned int cxy ); |
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132 | |
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133 | /***************************************************************************************** |
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134 | * This function releases the memory buffer identified by the <ptr> argument, |
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135 | * to the store located in the calling core cluster. |
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136 | * It displays an error message, but does nothing if the ptr is illegal. |
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137 | ***************************************************************************************** |
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138 | * @ ptr : pointer on the released buffer. |
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139 | ****************************************************************************************/ |
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140 | void free( void * ptr ); |
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141 | |
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142 | /***************************************************************************************** |
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143 | * This function releases the memory buffer identified by the <ptr> argument, |
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144 | * to the store identified by the <cxy> argument. |
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145 | * It displays an error message, but does nothing if the ptr is illegal. |
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146 | ***************************************************************************************** |
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147 | * @ ptr : pointer on the released buffer. |
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148 | * @ cxy : target cluster identifier. |
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149 | ****************************************************************************************/ |
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150 | void remote_free( void * ptr, |
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151 | unsigned int cxy ); |
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152 | |
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153 | /***************************************************************************************** |
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154 | * This function releases the memory buffer identified by the <ptr> argument, |
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155 | * to the store located in the calling core cluster, and allocates a new buffer |
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156 | * containing <size> bytes from this store. |
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157 | * The content of the old buffer is copied to the new buffer, up to <size> bytes. |
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158 | * It displays an error message, but does nothing if the ptr is illegal. |
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159 | ***************************************************************************************** |
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160 | * @ ptr : pointer on the released buffer. |
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161 | * @ size : new buffer requested size (bytes). |
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162 | * @ return a pointer on allocated buffer if success / return NULL if failure |
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163 | ****************************************************************************************/ |
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164 | void * realloc( void * ptr, |
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165 | unsigned int size ); |
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166 | |
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167 | /***************************************************************************************** |
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168 | * This function releases the memory buffer identified by the <ptr> argument, |
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169 | * to the store located in cluster identified by the <cxy> argument, and allocates |
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170 | * a new buffer containing <size> bytes from this store. |
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171 | * The content of the old buffer is copied to the new buffer, up to <size> bytes. |
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172 | * It displays an error message, but does nothing if the ptr is illegal. |
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173 | ***************************************************************************************** |
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174 | * @ ptr : pointer on the released buffer. |
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175 | * @ size : new buffer requested size (bytes). |
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176 | * @ cxy : target cluster identifier. |
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177 | * @ return a pointer on allocated buffer if success / return NULL if failure |
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178 | ****************************************************************************************/ |
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179 | void * remote_realloc( void * ptr, |
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180 | unsigned int size, |
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181 | unsigned int cxy ); |
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182 | |
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183 | /***************************************************************************************** |
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184 | * This function allocates enough space for <count> objects that are <size> bytes |
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185 | * of memory each from the store located in the calling core cluster. |
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186 | * The allocated memory is filled with bytes of value zero. |
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187 | ***************************************************************************************** |
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188 | * @ count : number of requested objects. |
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189 | * @ size : number of bytes per object. |
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190 | * @ returns a pointer on allocated buffer if success / returns NULL if failure |
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191 | ****************************************************************************************/ |
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192 | void * calloc( unsigned int count, |
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193 | unsigned int size ); |
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194 | |
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195 | /***************************************************************************************** |
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196 | * This function allocates enough space for <count> objects that are <size> bytes |
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197 | * of memory each from the store located in cluster identied by the <cxy> argument. |
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198 | * The allocated memory is filled with bytes of value zero. |
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199 | ***************************************************************************************** |
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200 | * @ count : number of requested objects. |
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201 | * @ size : number of bytes per object. |
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202 | * @ cxy : target cluster identifier. |
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203 | * @ returns a pointer on allocated buffer if success / returns NULL if failure |
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204 | ****************************************************************************************/ |
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205 | void * remote_calloc( unsigned int count, |
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206 | unsigned int size, |
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207 | unsigned int cxy ); |
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208 | |
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209 | #endif |
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210 | |
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211 | // Local Variables: |
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212 | // tab-width: 4 |
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213 | // c-basic-offset: 4 |
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214 | // c-file-offsets:((innamespace . 0)(inline-open . 0)) |
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215 | // indent-tabs-mode: nil |
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216 | // End: |
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217 | // vim: filetype=c:expandtab:shiftwidth=4:tabstop=4:softtabstop=4 |
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218 | |
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