1 | /** |
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2 | * @file rtems/score/heap.h |
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3 | * |
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4 | * This include file contains the information pertaining to the Heap |
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5 | * Handler. A heap is a doubly linked list of variable size |
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6 | * blocks which are allocated using the first fit method. Garbage |
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7 | * collection is performed each time a block is returned to the heap by |
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8 | * coalescing neighbor blocks. Control information for both allocated |
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9 | * and unallocated blocks is contained in the heap space. A heap control |
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10 | * structure contains control information for the heap. |
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11 | * |
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12 | * FIXME: the alignment routines could be made faster should we require only |
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13 | * powers of two to be supported both for 'page_size' and for |
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14 | * 'alignment' arguments. However, both workspace and malloc heaps are |
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15 | * initialized with CPU_HEAP_ALIGNMENT as 'page_size', and while all |
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16 | * the BSPs seem to use CPU_ALIGNMENT (that is power of two) as |
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17 | * CPU_HEAP_ALIGNMENT, for whatever reason CPU_HEAP_ALIGNMENT is only |
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18 | * required to be multiple of CPU_ALIGNMENT and explicitly not |
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19 | * required to be a power of two. |
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20 | * |
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21 | * COPYRIGHT (c) 1989-2004. |
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22 | * On-Line Applications Research Corporation (OAR). |
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23 | * |
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24 | * The license and distribution terms for this file may be |
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25 | * found in the file LICENSE in this distribution or at |
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26 | * http://www.rtems.com/license/LICENSE. |
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27 | * |
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28 | * $Id$ |
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29 | */ |
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30 | |
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31 | #ifndef __RTEMS_HEAP_h |
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32 | #define __RTEMS_HEAP_h |
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33 | |
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34 | /** |
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35 | * @defgroup ScoreHeap Heap Handler |
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36 | * |
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37 | * This group contains functionality which provides the foundation |
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38 | * Heap services used in all of the APIs supported by RTEMS. |
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39 | */ |
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40 | /**@{*/ |
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41 | |
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42 | #ifdef __cplusplus |
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43 | extern "C" { |
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44 | #endif |
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45 | |
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46 | /** |
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47 | * This type defines unsigned integer type to store 'void*'. Analog of C99 |
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48 | * 'uintptr_t'. This should work on 16/32/64 bit architectures. |
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49 | * |
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50 | * FIXME: Something like this should better be defined by |
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51 | * 'rtems/score/types.h' and used here. |
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52 | */ |
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53 | |
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54 | typedef unsigned long int _H_uptr_t; |
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55 | |
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56 | /** |
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57 | * Forward reference |
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58 | * |
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59 | * @ref Heap_Block |
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60 | */ |
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61 | typedef struct Heap_Block_struct Heap_Block; |
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62 | |
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63 | /** |
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64 | * The following defines the data structure used to manage individual blocks |
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65 | * in a heap. When the block is allocated, the 'next' and 'prev' fields, as |
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66 | * well as 'prev_size' field of the next block, are not used by the heap |
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67 | * manager and thus the address returned for the block starts at the address |
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68 | * of the 'next' field and the size of the user accessible area includes the |
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69 | * size of the 'prev_size' field. |
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70 | * |
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71 | * @note The 'next' and 'prev' pointers are only valid when the block is free. |
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72 | * Caution must be taken to ensure that every block is large enough to |
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73 | * hold them and that they are not accessed while the block is actually |
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74 | * allocated (i.e., not free). |
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75 | * |
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76 | * @note The 'prev_size' field is only valid when HEAP_PREV_USED bit is clear |
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77 | * in the 'size' field indicating that previous block is not allocated. |
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78 | * If the bit is set, the 'prev_size' field is part of user-accessible |
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79 | * space of the previous allocated block and thus shouldn't be accessed |
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80 | * by the heap manager code. This trick allows to further decrease |
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81 | * overhead in the used blocks to the size of 'size' field (4 bytes). |
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82 | * |
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83 | */ |
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84 | |
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85 | struct Heap_Block_struct { |
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86 | /** size of prev block (if prev block is free) */ |
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87 | uint32_t prev_size; |
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88 | /** size of block in bytes and status of prev block */ |
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89 | uint32_t size; |
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90 | /** pointer to the next free block */ |
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91 | Heap_Block *next; |
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92 | /** pointer to the previous free block */ |
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93 | Heap_Block *prev; |
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94 | }; |
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95 | |
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96 | /** |
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97 | * This flag used in the 'size' field of each heap block to indicate |
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98 | * if previous block is free or in use. As sizes are always multiples of |
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99 | * 4, the 2 least significant bits would always be 0, and we use one of them |
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100 | * to store the flag. |
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101 | */ |
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102 | |
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103 | #define HEAP_PREV_USED 1 /* indicates previous block is in use */ |
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104 | |
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105 | /** |
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106 | * The following constants reflect various requirements of the |
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107 | * heap data structures which impact the management of a heap. |
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108 | */ |
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109 | |
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110 | #define HEAP_MIN_BLOCK_SIZE (sizeof(Heap_Block)) |
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111 | |
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112 | /** |
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113 | * Offset of the block header from the block pointer. Equal to the |
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114 | * offsetof(Heap_Block.size). |
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115 | */ |
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116 | #define HEAP_BLOCK_HEADER_OFFSET (sizeof(uint32_t)) |
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117 | |
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118 | /** |
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119 | * Offset of user data pointer from the block pointer. Equal to the |
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120 | * offsetof(Heap_Block.next). |
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121 | */ |
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122 | #define HEAP_BLOCK_USER_OFFSET (sizeof(uint32_t) * 2) |
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123 | |
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124 | /** |
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125 | * Num bytes of overhead in used block. Equal to the sizeof(Heap_Block.size). |
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126 | */ |
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127 | #define HEAP_BLOCK_USED_OVERHEAD \ |
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128 | (HEAP_BLOCK_USER_OFFSET - HEAP_BLOCK_HEADER_OFFSET) |
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129 | |
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130 | /** Size of the permanent dummy last block. */ |
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131 | #define HEAP_OVERHEAD HEAP_BLOCK_USER_OFFSET |
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132 | |
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133 | /** |
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134 | * Run-time heap statistics. |
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135 | * |
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136 | * @note (double)searches/allocs gives mean number of searches per alloc while |
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137 | * max_search gives maximum number of searches ever performed on a |
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138 | * single call to alloc. |
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139 | * |
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140 | * @note the statistics is always gathered. I believe the imposed overhead is |
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141 | * rather small. Feel free to make it compile-time option if you think |
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142 | * the overhead is too high for your application. |
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143 | */ |
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144 | |
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145 | typedef struct Heap_Statistics_tag { |
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146 | /** instance number of this heap */ |
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147 | uint32_t instance; |
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148 | /** the size of the memory for heap */ |
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149 | uint32_t size; |
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150 | /** current free size */ |
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151 | uint32_t free_size; |
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152 | /** minimum free size ever */ |
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153 | uint32_t min_free_size; |
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154 | /** current number of free blocks */ |
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155 | uint32_t free_blocks; |
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156 | /** maximum number of free blocks ever */ |
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157 | uint32_t max_free_blocks; |
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158 | /** current number of used blocks */ |
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159 | uint32_t used_blocks; |
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160 | /** maximum number of blocks searched ever */ |
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161 | uint32_t max_search; |
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162 | /** total number of successful calls to alloc */ |
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163 | uint32_t allocs; |
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164 | /** total number of searches ever */ |
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165 | uint32_t searches; |
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166 | /** total number of suceessful calls to free */ |
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167 | uint32_t frees; |
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168 | } Heap_Statistics; |
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169 | |
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170 | /** |
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171 | * Control block used to manage each heap. |
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172 | */ |
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173 | typedef struct { |
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174 | /** head and tail of circular list of free blocks */ |
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175 | Heap_Block free_list; |
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176 | /** allocation unit and alignment */ |
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177 | uint32_t page_size; |
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178 | /** minimum block size aligned on page_size */ |
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179 | uint32_t min_block_size; |
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180 | /** first address of memory for the heap */ |
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181 | void *begin; |
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182 | /** first address past end of memory for the heap */ |
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183 | void *end; |
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184 | /** first valid block address in the heap */ |
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185 | Heap_Block *start; |
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186 | /** last valid block address in the heap */ |
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187 | Heap_Block *final; |
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188 | /** run-time statistics */ |
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189 | Heap_Statistics stats; |
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190 | } Heap_Control; |
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191 | |
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192 | /** |
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193 | * Status codes for heap_extend |
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194 | */ |
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195 | |
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196 | typedef enum { |
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197 | HEAP_EXTEND_SUCCESSFUL, |
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198 | HEAP_EXTEND_ERROR, |
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199 | HEAP_EXTEND_NOT_IMPLEMENTED |
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200 | } Heap_Extend_status; |
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201 | |
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202 | /** |
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203 | * Status codes for _Heap_Get_information |
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204 | */ |
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205 | |
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206 | typedef enum { |
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207 | HEAP_GET_INFORMATION_SUCCESSFUL = 0, |
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208 | HEAP_GET_INFORMATION_BLOCK_ERROR |
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209 | } Heap_Get_information_status; |
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210 | |
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211 | /** |
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212 | * Information block returned by the Heap routines used to |
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213 | * obtain heap information. This information is returned about |
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214 | * either free or used blocks. |
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215 | */ |
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216 | typedef struct { |
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217 | /** Number of blocks of this type. */ |
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218 | uint32_t number; |
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219 | /** Largest blocks of this type. */ |
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220 | uint32_t largest; |
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221 | /** Total size of the blocks of this type. */ |
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222 | uint32_t total; |
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223 | } Heap_Information; |
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224 | |
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225 | /** |
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226 | * Information block returned by _Heap_Get_information |
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227 | */ |
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228 | typedef struct { |
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229 | /** This field is information on the used blocks in the heap. */ |
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230 | Heap_Information Free; |
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231 | /** This field is information on the used blocks in the heap. */ |
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232 | Heap_Information Used; |
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233 | } Heap_Information_block; |
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234 | |
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235 | /** |
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236 | * This routine initializes @a the_heap record to manage the |
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237 | * contiguous heap of @a size bytes which starts at @a starting_address. |
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238 | * Blocks of memory are allocated from the heap in multiples of |
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239 | * @a page_size byte units. If @a page_size is 0 or is not multiple of |
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240 | * CPU_ALIGNMENT, it's aligned up to the nearest CPU_ALIGNMENT boundary. |
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241 | * |
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242 | * @param the_heap (in) is the heap to operate upon |
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243 | * @param starting_address (in) is the starting address of the memory for |
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244 | * the heap |
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245 | * @param size (in) is the size in bytes of the memory area for the heap |
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246 | * @param page_size (in) is the size in bytes of the allocation unit |
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247 | * @return XXX |
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248 | */ |
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249 | uint32_t _Heap_Initialize( |
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250 | Heap_Control *the_heap, |
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251 | void *starting_address, |
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252 | uint32_t size, |
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253 | uint32_t page_size |
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254 | ); |
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255 | |
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256 | /** |
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257 | * This routine grows @a the_heap memory area using the size bytes which |
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258 | * begin at @a starting_address. |
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259 | * |
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260 | * @param the_heap (in) is the heap to operate upon |
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261 | * @param starting_address (in) is the starting address of the memory |
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262 | * to add to the heap |
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263 | * @param size (in) is the size in bytes of the memory area to add |
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264 | * @param amount_extended (in) points to a user area to return the |
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265 | * @return a status indicating success or the reason for failure |
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266 | * @return *size filled in with the amount of memory added to the heap |
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267 | */ |
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268 | Heap_Extend_status _Heap_Extend( |
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269 | Heap_Control *the_heap, |
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270 | void *starting_address, |
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271 | uint32_t size, |
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272 | uint32_t *amount_extended |
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273 | ); |
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274 | |
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275 | /** |
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276 | * This function attempts to allocate a block of @a size bytes from |
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277 | * @a the_heap. If insufficient memory is free in @a the_heap to allocate |
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278 | * a block of the requested size, then NULL is returned. |
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279 | * |
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280 | * @param the_heap (in) is the heap to operate upon |
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281 | * @param size (in) is the amount of memory to allocate in bytes |
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282 | * @return NULL if unsuccessful and a pointer to the block if successful |
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283 | */ |
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284 | void *_Heap_Allocate( |
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285 | Heap_Control *the_heap, |
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286 | uint32_t size |
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287 | ); |
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288 | |
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289 | /** |
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290 | * This function attempts to allocate a memory block of @a size bytes from |
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291 | * @a the_heap so that the start of the user memory is aligned on the |
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292 | * @a alignment boundary. If @a alignment is 0, it is set to CPU_ALIGNMENT. |
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293 | * Any other value of @a alignment is taken "as is", i.e., even odd |
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294 | * alignments are possible. |
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295 | * Returns pointer to the start of the memory block if success, NULL if |
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296 | * failure. |
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297 | * |
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298 | * @param the_heap (in) is the heap to operate upon |
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299 | * @param size (in) is the amount of memory to allocate in bytes |
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300 | * @param alignment (in) the required alignment |
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301 | * @return NULL if unsuccessful and a pointer to the block if successful |
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302 | */ |
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303 | void *_Heap_Allocate_aligned( |
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304 | Heap_Control *the_heap, |
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305 | uint32_t size, |
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306 | uint32_t alignment |
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307 | ); |
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308 | |
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309 | /** |
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310 | * This function sets @a *size to the size of the block of user memory |
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311 | * which begins at @a starting_address. The size returned in @a *size could |
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312 | * be greater than the size requested for allocation. |
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313 | * Returns TRUE if the @a starting_address is in the heap, and FALSE |
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314 | * otherwise. |
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315 | * |
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316 | * @param the_heap (in) is the heap to operate upon |
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317 | * @param starting_address (in) is the starting address of the user block |
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318 | * to obtain the size of |
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319 | * @param size (in) points to a user area to return the size in |
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320 | * @return TRUE if successfully able to determine the size, FALSE otherwise |
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321 | * @return *size filled in with the size of the user area for this block |
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322 | */ |
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323 | boolean _Heap_Size_of_user_area( |
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324 | Heap_Control *the_heap, |
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325 | void *starting_address, |
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326 | size_t *size |
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327 | ); |
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328 | |
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329 | /** |
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330 | * This routine returns the block of memory which begins |
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331 | * at @a starting_address to @a the_heap. Any coalescing which is |
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332 | * possible with the freeing of this routine is performed. |
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333 | * |
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334 | * @param the_heap (in) is the heap to operate upon |
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335 | * @param starting_address (in) is the starting address of the user block |
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336 | * to free |
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337 | * @return TRUE if successfully freed, FALSE otherwise |
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338 | */ |
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339 | boolean _Heap_Free( |
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340 | Heap_Control *the_heap, |
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341 | void *start_address |
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342 | ); |
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343 | |
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344 | /** |
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345 | * This routine walks the heap to verify its integrity. |
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346 | * |
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347 | * @param the_heap (in) is the heap to operate upon |
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348 | * @param source (in) XXX |
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349 | * @param do_dump (in) is set to TRUE if errors should be printed |
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350 | * @return TRUE if the test passed fine, FALSE otherwise. |
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351 | */ |
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352 | |
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353 | boolean _Heap_Walk( |
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354 | Heap_Control *the_heap, |
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355 | int source, |
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356 | boolean do_dump |
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357 | ); |
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358 | |
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359 | /** |
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360 | * This routine walks the heap and tots up the free and allocated |
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361 | * sizes. |
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362 | * |
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363 | * @param the_heap (in) pointer to heap header |
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364 | * @param the_info (in) pointer to a status information area |
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365 | * @return *the_info is filled with status information |
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366 | * @return 0=success, otherwise heap is corrupt. |
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367 | */ |
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368 | Heap_Get_information_status _Heap_Get_information( |
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369 | Heap_Control *the_heap, |
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370 | Heap_Information_block *the_info |
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371 | ); |
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372 | |
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373 | /** |
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374 | * This heap routine returns information about the free blocks |
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375 | * in the specified heap. |
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376 | * |
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377 | * @param the_heap (in) pointer to heap header. |
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378 | * @param info (in) pointer to the free block information. |
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379 | * |
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380 | * @return free block information filled in. |
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381 | */ |
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382 | |
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383 | void _Heap_Get_free_information( |
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384 | Heap_Control *the_heap, |
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385 | Heap_Information *info |
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386 | ); |
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387 | |
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388 | #if !defined(__RTEMS_APPLICATION__) |
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389 | |
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390 | /* |
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391 | * A pointer to unsigned integer conversion. |
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392 | */ |
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393 | #define _H_p2u(_p) ((_H_uptr_t)(_p)) |
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394 | |
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395 | #include <rtems/score/heap.inl> |
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396 | |
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397 | /* |
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398 | * Internal routines shared by _Heap_Allocate() and _Heap_Allocate_aligned(). |
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399 | * Refer to 'heap.c' for details. |
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400 | */ |
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401 | |
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402 | extern uint32_t _Heap_Calc_block_size( |
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403 | uint32_t size, |
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404 | uint32_t page_size, |
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405 | uint32_t min_size); |
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406 | |
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407 | extern Heap_Block* _Heap_Block_allocate( |
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408 | Heap_Control* the_heap, |
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409 | Heap_Block* the_block, |
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410 | uint32_t alloc_size); |
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411 | |
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412 | /* |
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413 | * Debug support |
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414 | */ |
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415 | |
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416 | #if defined(RTEMS_DEBUG) |
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417 | #define RTEMS_HEAP_DEBUG |
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418 | #endif |
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419 | |
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420 | #if defined(RTEMS_HEAP_DEBUG) |
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421 | |
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422 | #include <assert.h> |
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423 | |
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424 | /* |
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425 | * We do asserts only for heaps with instance number greater than 0 assuming |
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426 | * that the heap used for malloc is initialized first and thus has instance |
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427 | * number 0. Asserting malloc heap may lead to troubles as printf may invoke |
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428 | * malloc thus probably leading to infinite recursion. |
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429 | */ |
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430 | |
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431 | #define _HAssert(cond_) \ |
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432 | do { \ |
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433 | if(the_heap->stats.instance && !(cond_)) \ |
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434 | __assert(__FILE__, __LINE__, #cond_); \ |
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435 | } while(0) |
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436 | |
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437 | #else /* !defined(RTEMS_HEAP_DEBUG) */ |
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438 | |
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439 | #define _HAssert(cond_) ((void)0) |
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440 | |
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441 | #endif /* !defined(RTEMS_HEAP_DEBUG) */ |
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442 | |
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443 | #endif /* !defined(__RTEMS_APPLICATION__) */ |
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444 | |
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445 | #ifdef __cplusplus |
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446 | } |
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447 | #endif |
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448 | |
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449 | /**@}*/ |
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450 | |
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451 | #endif |
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452 | /* end of include file */ |
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