1 | /** |
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2 | * @file |
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3 | * |
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4 | * @ingroup ScoreHeap |
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5 | * |
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6 | * @brief Heap Handler API |
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7 | */ |
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8 | |
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9 | /* |
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10 | * COPYRIGHT (c) 1989-2006. |
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11 | * On-Line Applications Research Corporation (OAR). |
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12 | * |
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13 | * The license and distribution terms for this file may be |
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14 | * found in the file LICENSE in this distribution or at |
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15 | * http://www.rtems.com/license/LICENSE. |
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16 | */ |
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17 | |
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18 | #ifndef _RTEMS_SCORE_HEAP_H |
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19 | #define _RTEMS_SCORE_HEAP_H |
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20 | |
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21 | #include <rtems/score/cpu.h> |
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22 | |
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23 | #ifdef __cplusplus |
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24 | extern "C" { |
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25 | #endif |
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26 | |
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27 | #ifdef RTEMS_DEBUG |
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28 | #define HEAP_PROTECTION |
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29 | #endif |
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30 | |
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31 | /** |
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32 | * @defgroup ScoreHeap Heap Handler |
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33 | * |
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34 | * @ingroup Score |
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35 | * |
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36 | * @brief The Heap Handler provides a heap. |
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37 | * |
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38 | * A heap is a doubly linked list of variable size blocks which are allocated |
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39 | * using the first fit method. Garbage collection is performed each time a |
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40 | * block is returned to the heap by coalescing neighbor blocks. Control |
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41 | * information for both allocated and free blocks is contained in the heap |
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42 | * area. A heap control structure contains control information for the heap. |
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43 | * |
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44 | * The alignment routines could be made faster should we require only powers of |
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45 | * two to be supported for page size, alignment and boundary arguments. The |
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46 | * minimum alignment requirement for pages is currently CPU_ALIGNMENT and this |
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47 | * value is only required to be multiple of two and explicitly not required to |
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48 | * be a power of two. |
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49 | * |
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50 | * There are two kinds of blocks. One sort describes a free block from which |
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51 | * we can allocate memory. The other blocks are used and provide an allocated |
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52 | * memory area. The free blocks are accessible via a list of free blocks. |
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53 | * |
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54 | * Blocks or areas cover a continuous set of memory addresses. They have a |
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55 | * begin and end address. The end address is not part of the set. The size of |
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56 | * a block or area equals the distance between the begin and end address in |
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57 | * units of bytes. |
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58 | * |
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59 | * Free blocks look like: |
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60 | * <table> |
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61 | * <tr> |
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62 | * <td rowspan=4>@ref Heap_Block</td><td>previous block size in case the |
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63 | * previous block is free, <br> otherwise it may contain data used by |
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64 | * the previous block</td> |
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65 | * </tr> |
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66 | * <tr> |
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67 | * <td>block size and a flag which indicates if the previous block is free |
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68 | * or used, <br> this field contains always valid data regardless of the |
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69 | * block usage</td> |
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70 | * </tr> |
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71 | * <tr><td>pointer to next block (this field is page size aligned)</td></tr> |
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72 | * <tr><td>pointer to previous block</td></tr> |
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73 | * <tr><td colspan=2>free space</td></tr> |
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74 | * </table> |
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75 | * |
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76 | * Used blocks look like: |
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77 | * <table> |
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78 | * <tr> |
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79 | * <td rowspan=4>@ref Heap_Block</td><td>previous block size in case the |
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80 | * previous block is free,<br>otherwise it may contain data used by |
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81 | * the previous block</td> |
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82 | * </tr> |
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83 | * <tr> |
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84 | * <td>block size and a flag which indicates if the previous block is free |
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85 | * or used, <br> this field contains always valid data regardless of the |
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86 | * block usage</td> |
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87 | * </tr> |
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88 | * <tr><td>begin of allocated area (this field is page size aligned)</td></tr> |
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89 | * <tr><td>allocated space</td></tr> |
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90 | * <tr><td colspan=2>allocated space</td></tr> |
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91 | * </table> |
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92 | * |
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93 | * The heap area after initialization contains two blocks and looks like: |
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94 | * <table> |
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95 | * <tr><th>Label</th><th colspan=2>Content</th></tr> |
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96 | * <tr><td>heap->area_begin</td><td colspan=2>heap area begin address</td></tr> |
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97 | * <tr> |
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98 | * <td>first_block->prev_size</td> |
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99 | * <td colspan=2> |
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100 | * subordinate heap area end address (this will be used to maintain a |
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101 | * linked list of scattered heap areas) |
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102 | * </td> |
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103 | * </tr> |
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104 | * <tr> |
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105 | * <td>first_block->size</td> |
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106 | * <td colspan=2>size available for allocation |
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107 | * | @c HEAP_PREV_BLOCK_USED</td> |
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108 | * </tr> |
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109 | * <tr> |
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110 | * <td>first_block->next</td><td>_Heap_Free_list_tail(heap)</td> |
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111 | * <td rowspan=3>memory area available for allocation</td> |
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112 | * </tr> |
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113 | * <tr><td>first_block->prev</td><td>_Heap_Free_list_head(heap)</td></tr> |
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114 | * <tr><td>...</td></tr> |
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115 | * <tr> |
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116 | * <td>last_block->prev_size</td><td colspan=2>size of first block</td> |
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117 | * </tr> |
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118 | * <tr> |
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119 | * <td>last_block->size</td> |
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120 | * <td colspan=2>first block begin address - last block begin address</td> |
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121 | * </tr> |
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122 | * <tr><td>heap->area_end</td><td colspan=2>heap area end address</td></tr> |
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123 | * </table> |
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124 | * The next block of the last block is the first block. Since the first |
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125 | * block indicates that the previous block is used, this ensures that the |
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126 | * last block appears as used for the _Heap_Is_used() and _Heap_Is_free() |
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127 | * functions. |
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128 | */ |
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129 | /**@{**/ |
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130 | |
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131 | typedef struct Heap_Control Heap_Control; |
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132 | |
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133 | typedef struct Heap_Block Heap_Block; |
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134 | |
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135 | #ifndef HEAP_PROTECTION |
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136 | #define HEAP_PROTECTION_HEADER_SIZE 0 |
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137 | #else |
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138 | #include <rtems/score/thread.h> |
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139 | |
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140 | #define HEAP_PROTECTOR_COUNT 2 |
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141 | |
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142 | #define HEAP_BEGIN_PROTECTOR_0 ((uintptr_t) 0xfd75a98f) |
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143 | #define HEAP_BEGIN_PROTECTOR_1 ((uintptr_t) 0xbfa1f177) |
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144 | #define HEAP_END_PROTECTOR_0 ((uintptr_t) 0xd6b8855e) |
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145 | #define HEAP_END_PROTECTOR_1 ((uintptr_t) 0x13a44a5b) |
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146 | |
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147 | #define HEAP_FREE_PATTERN ((uintptr_t) 0xe7093cdf) |
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148 | |
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149 | #define HEAP_PROTECTION_OBOLUS ((Heap_Block *) 1) |
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150 | |
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151 | typedef void (*_Heap_Protection_handler)( |
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152 | Heap_Control *heap, |
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153 | Heap_Block *block |
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154 | ); |
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155 | |
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156 | typedef struct { |
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157 | _Heap_Protection_handler block_initialize; |
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158 | _Heap_Protection_handler block_check; |
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159 | _Heap_Protection_handler block_error; |
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160 | void *handler_data; |
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161 | Heap_Block *first_delayed_free_block; |
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162 | Heap_Block *last_delayed_free_block; |
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163 | uintptr_t delayed_free_block_count; |
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164 | } Heap_Protection; |
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165 | |
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166 | typedef struct { |
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167 | uintptr_t protector [HEAP_PROTECTOR_COUNT]; |
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168 | Heap_Block *next_delayed_free_block; |
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169 | Thread_Control *task; |
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170 | void *tag; |
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171 | } Heap_Protection_block_begin; |
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172 | |
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173 | typedef struct { |
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174 | uintptr_t protector [HEAP_PROTECTOR_COUNT]; |
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175 | } Heap_Protection_block_end; |
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176 | |
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177 | #define HEAP_PROTECTION_HEADER_SIZE \ |
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178 | (sizeof(Heap_Protection_block_begin) + sizeof(Heap_Protection_block_end)) |
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179 | #endif |
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180 | |
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181 | /** |
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182 | * @brief The block header consists of the two size fields |
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183 | * (@ref Heap_Block.prev_size and @ref Heap_Block.size_and_flag). |
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184 | */ |
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185 | #define HEAP_BLOCK_HEADER_SIZE \ |
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186 | (2 * sizeof(uintptr_t) + HEAP_PROTECTION_HEADER_SIZE) |
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187 | |
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188 | /** |
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189 | * @brief Description for free or used blocks. |
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190 | */ |
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191 | struct Heap_Block { |
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192 | /** |
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193 | * @brief Size of the previous block or part of the allocated area of the |
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194 | * previous block. |
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195 | * |
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196 | * This field is only valid if the previous block is free. This case is |
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197 | * indicated by a cleared @c HEAP_PREV_BLOCK_USED flag in the |
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198 | * @a size_and_flag field of the current block. |
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199 | * |
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200 | * In a used block only the @a size_and_flag field needs to be valid. The |
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201 | * @a prev_size field of the current block is maintained by the previous |
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202 | * block. The current block can use the @a prev_size field in the next block |
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203 | * for allocation. |
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204 | */ |
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205 | uintptr_t prev_size; |
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206 | |
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207 | #ifdef HEAP_PROTECTION |
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208 | Heap_Protection_block_begin Protection_begin; |
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209 | #endif |
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210 | |
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211 | /** |
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212 | * @brief Contains the size of the current block and a flag which indicates |
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213 | * if the previous block is free or used. |
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214 | * |
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215 | * If the flag @c HEAP_PREV_BLOCK_USED is set, then the previous block is |
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216 | * used, otherwise the previous block is free. A used previous block may |
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217 | * claim the @a prev_size field for allocation. This trick allows to |
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218 | * decrease the overhead in the used blocks by the size of the @a prev_size |
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219 | * field. As sizes are required to be multiples of two, the least |
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220 | * significant bits would be always zero. We use this bit to store the flag. |
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221 | * |
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222 | * This field is always valid. |
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223 | */ |
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224 | uintptr_t size_and_flag; |
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225 | |
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226 | #ifdef HEAP_PROTECTION |
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227 | Heap_Protection_block_end Protection_end; |
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228 | #endif |
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229 | |
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230 | /** |
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231 | * @brief Pointer to the next free block or part of the allocated area. |
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232 | * |
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233 | * This field is page size aligned and begins of the allocated area in case |
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234 | * the block is used. |
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235 | * |
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236 | * This field is only valid if the block is free and thus part of the free |
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237 | * block list. |
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238 | */ |
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239 | Heap_Block *next; |
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240 | |
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241 | /** |
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242 | * @brief Pointer to the previous free block or part of the allocated area. |
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243 | * |
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244 | * This field is only valid if the block is free and thus part of the free |
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245 | * block list. |
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246 | */ |
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247 | Heap_Block *prev; |
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248 | }; |
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249 | |
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250 | /** |
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251 | * @brief Run-time heap statistics. |
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252 | * |
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253 | * The value @a searches / @a allocs gives the mean number of searches per |
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254 | * allocation, while @a max_search gives maximum number of searches ever |
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255 | * performed on a single allocation call. |
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256 | */ |
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257 | typedef struct { |
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258 | /** |
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259 | * @brief Instance number of this heap. |
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260 | */ |
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261 | uint32_t instance; |
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262 | |
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263 | /** |
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264 | * @brief Size of the allocatable area in bytes. |
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265 | * |
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266 | * This value is an integral multiple of the page size. |
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267 | */ |
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268 | uintptr_t size; |
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269 | |
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270 | /** |
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271 | * @brief Current free size in bytes. |
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272 | * |
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273 | * This value is an integral multiple of the page size. |
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274 | */ |
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275 | uintptr_t free_size; |
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276 | |
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277 | /** |
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278 | * @brief Minimum free size ever in bytes. |
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279 | * |
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280 | * This value is an integral multiple of the page size. |
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281 | */ |
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282 | uintptr_t min_free_size; |
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283 | |
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284 | /** |
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285 | * @brief Current number of free blocks. |
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286 | */ |
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287 | uint32_t free_blocks; |
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288 | |
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289 | /** |
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290 | * @brief Maximum number of free blocks ever. |
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291 | */ |
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292 | uint32_t max_free_blocks; |
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293 | |
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294 | /** |
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295 | * @brief Current number of used blocks. |
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296 | */ |
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297 | uint32_t used_blocks; |
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298 | |
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299 | /** |
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300 | * @brief Maximum number of blocks searched ever. |
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301 | */ |
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302 | uint32_t max_search; |
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303 | |
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304 | /** |
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305 | * @brief Total number of successful allocations. |
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306 | */ |
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307 | uint32_t allocs; |
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308 | |
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309 | /** |
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310 | * @brief Total number of searches ever. |
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311 | */ |
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312 | uint32_t searches; |
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313 | |
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314 | /** |
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315 | * @brief Total number of suceessful calls to free. |
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316 | */ |
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317 | uint32_t frees; |
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318 | |
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319 | /** |
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320 | * @brief Total number of successful resizes. |
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321 | */ |
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322 | uint32_t resizes; |
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323 | } Heap_Statistics; |
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324 | |
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325 | /** |
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326 | * @brief Control block used to manage a heap. |
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327 | */ |
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328 | struct Heap_Control { |
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329 | Heap_Block free_list; |
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330 | uintptr_t page_size; |
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331 | uintptr_t min_block_size; |
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332 | uintptr_t area_begin; |
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333 | uintptr_t area_end; |
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334 | Heap_Block *first_block; |
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335 | Heap_Block *last_block; |
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336 | Heap_Statistics stats; |
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337 | #ifdef HEAP_PROTECTION |
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338 | Heap_Protection Protection; |
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339 | #endif |
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340 | }; |
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341 | |
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342 | /** |
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343 | * @brief Information about blocks. |
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344 | */ |
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345 | typedef struct { |
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346 | /** |
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347 | * @brief Number of blocks of this type. |
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348 | */ |
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349 | uint32_t number; |
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350 | |
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351 | /** |
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352 | * @brief Largest block of this type. |
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353 | */ |
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354 | uint32_t largest; |
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355 | |
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356 | /** |
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357 | * @brief Total size of the blocks of this type. |
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358 | */ |
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359 | uint32_t total; |
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360 | } Heap_Information; |
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361 | |
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362 | /** |
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363 | * @brief Information block returned by _Heap_Get_information(). |
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364 | */ |
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365 | typedef struct { |
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366 | Heap_Information Free; |
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367 | Heap_Information Used; |
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368 | } Heap_Information_block; |
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369 | |
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370 | /** |
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371 | * @brief Heap area structure for table based heap initialization and |
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372 | * extension. |
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373 | * |
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374 | * @see Heap_Initialization_or_extend_handler. |
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375 | */ |
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376 | typedef struct { |
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377 | void *begin; |
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378 | uintptr_t size; |
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379 | } Heap_Area; |
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380 | |
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381 | /** |
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382 | * @brief Heap initialization and extend handler type. |
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383 | * |
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384 | * This helps to do a table based heap initialization and extension. Create a |
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385 | * table of Heap_Area elements and iterate through it. Set the handler to |
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386 | * _Heap_Initialize() in the first iteration and then to _Heap_Extend(). |
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387 | * |
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388 | * @see Heap_Area, _Heap_Initialize(), _Heap_Extend(), or _Heap_No_extend(). |
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389 | */ |
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390 | typedef uintptr_t (*Heap_Initialization_or_extend_handler)( |
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391 | Heap_Control *heap, |
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392 | void *area_begin, |
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393 | uintptr_t area_size, |
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394 | uintptr_t page_size_or_unused |
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395 | ); |
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396 | |
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397 | /** |
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398 | * @brief Extends the memory available for the heap @a heap using the memory |
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399 | * area starting at @a area_begin of size @a area_size bytes. |
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400 | * |
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401 | * There are no alignment requirements. The memory area must be big enough to |
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402 | * contain some maintainance blocks. It must not overlap parts of the current |
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403 | * heap areas. Disconnected subordinate heap areas will lead to used blocks |
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404 | * which cover the gaps. Extending with an inappropriate memory area will |
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405 | * corrupt the heap. |
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406 | * |
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407 | * The unused fourth parameter is provided to have the same signature as |
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408 | * _Heap_Initialize(). |
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409 | * |
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410 | * Returns the extended space available for allocation, or zero in case of failure. |
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411 | * |
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412 | * @see Heap_Initialization_or_extend_handler. |
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413 | */ |
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414 | uintptr_t _Heap_Extend( |
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415 | Heap_Control *heap, |
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416 | void *area_begin, |
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417 | uintptr_t area_size, |
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418 | uintptr_t unused |
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419 | ); |
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420 | |
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421 | /** |
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422 | * @brief This function returns always zero. |
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423 | * |
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424 | * This function only returns zero and does nothing else. |
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425 | * |
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426 | * Returns always zero. |
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427 | * |
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428 | * @see Heap_Initialization_or_extend_handler. |
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429 | */ |
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430 | uintptr_t _Heap_No_extend( |
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431 | Heap_Control *unused_0, |
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432 | void *unused_1, |
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433 | uintptr_t unused_2, |
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434 | uintptr_t unused_3 |
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435 | ); |
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436 | |
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437 | RTEMS_INLINE_ROUTINE uintptr_t _Heap_Align_up( |
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438 | uintptr_t value, |
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439 | uintptr_t alignment |
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440 | ) |
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441 | { |
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442 | uintptr_t remainder = value % alignment; |
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443 | |
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444 | if ( remainder != 0 ) { |
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445 | return value - remainder + alignment; |
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446 | } else { |
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447 | return value; |
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448 | } |
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449 | } |
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450 | |
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451 | /** |
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452 | * @brief Returns the worst case overhead to manage a memory area. |
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453 | */ |
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454 | RTEMS_INLINE_ROUTINE uintptr_t _Heap_Area_overhead( |
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455 | uintptr_t page_size |
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456 | ) |
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457 | { |
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458 | if ( page_size != 0 ) { |
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459 | page_size = _Heap_Align_up( page_size, CPU_ALIGNMENT ); |
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460 | } else { |
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461 | page_size = CPU_ALIGNMENT; |
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462 | } |
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463 | |
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464 | return 2 * (page_size - 1) + HEAP_BLOCK_HEADER_SIZE; |
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465 | } |
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466 | |
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467 | /** |
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468 | * @brief Returns the size with administration and alignment overhead for one |
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469 | * allocation. |
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470 | */ |
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471 | RTEMS_INLINE_ROUTINE uintptr_t _Heap_Size_with_overhead( |
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472 | uintptr_t page_size, |
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473 | uintptr_t size, |
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474 | uintptr_t alignment |
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475 | ) |
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476 | { |
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477 | if ( page_size != 0 ) { |
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478 | page_size = _Heap_Align_up( page_size, CPU_ALIGNMENT ); |
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479 | } else { |
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480 | page_size = CPU_ALIGNMENT; |
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481 | } |
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482 | |
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483 | if ( page_size < alignment ) { |
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484 | page_size = alignment; |
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485 | } |
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486 | |
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487 | return HEAP_BLOCK_HEADER_SIZE + page_size - 1 + size; |
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488 | } |
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489 | |
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490 | /** @} */ |
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491 | |
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492 | #ifdef __cplusplus |
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493 | } |
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494 | #endif |
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495 | |
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496 | #endif |
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497 | /* end of include file */ |
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