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.org/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 | #include <rtems/score/heapinfo.h> |
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23 | |
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24 | #ifdef __cplusplus |
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25 | extern "C" { |
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26 | #endif |
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27 | |
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28 | #ifdef RTEMS_DEBUG |
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29 | #define HEAP_PROTECTION |
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30 | #endif |
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31 | |
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32 | /** |
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33 | * @defgroup ScoreHeap Heap Handler |
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34 | * |
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35 | * @ingroup Score |
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36 | * |
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37 | * @brief The Heap Handler provides a heap. |
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38 | * |
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39 | * A heap is a doubly linked list of variable size blocks which are allocated |
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40 | * using the first fit method. Garbage collection is performed each time a |
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41 | * block is returned to the heap by coalescing neighbor blocks. Control |
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42 | * information for both allocated and free blocks is contained in the heap |
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43 | * area. A heap control structure contains control information for the heap. |
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44 | * |
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45 | * The alignment routines could be made faster should we require only powers of |
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46 | * two to be supported for page size, alignment and boundary arguments. The |
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47 | * minimum alignment requirement for pages is currently CPU_ALIGNMENT and this |
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48 | * value is only required to be multiple of two and explicitly not required to |
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49 | * be a power of two. |
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50 | * |
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51 | * There are two kinds of blocks. One sort describes a free block from which |
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52 | * we can allocate memory. The other blocks are used and provide an allocated |
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53 | * memory area. The free blocks are accessible via a list of free blocks. |
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54 | * |
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55 | * Blocks or areas cover a continuous set of memory addresses. They have a |
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56 | * begin and end address. The end address is not part of the set. The size of |
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57 | * a block or area equals the distance between the begin and end address in |
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58 | * units of bytes. |
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59 | * |
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60 | * Free blocks look like: |
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61 | * <table> |
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62 | * <tr> |
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63 | * <td rowspan=4>@ref Heap_Block</td><td>previous block size in case the |
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64 | * previous block is free, <br> otherwise it may contain data used by |
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65 | * the previous block</td> |
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66 | * </tr> |
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67 | * <tr> |
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68 | * <td>block size and a flag which indicates if the previous block is free |
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69 | * or used, <br> this field contains always valid data regardless of the |
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70 | * block usage</td> |
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71 | * </tr> |
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72 | * <tr><td>pointer to next block (this field is page size aligned)</td></tr> |
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73 | * <tr><td>pointer to previous block</td></tr> |
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74 | * <tr><td colspan=2>free space</td></tr> |
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75 | * </table> |
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76 | * |
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77 | * Used blocks look like: |
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78 | * <table> |
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79 | * <tr> |
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80 | * <td rowspan=4>@ref Heap_Block</td><td>previous block size in case the |
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81 | * previous block is free,<br>otherwise it may contain data used by |
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82 | * the previous block</td> |
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83 | * </tr> |
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84 | * <tr> |
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85 | * <td>block size and a flag which indicates if the previous block is free |
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86 | * or used, <br> this field contains always valid data regardless of the |
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87 | * block usage</td> |
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88 | * </tr> |
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89 | * <tr><td>begin of allocated area (this field is page size aligned)</td></tr> |
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90 | * <tr><td>allocated space</td></tr> |
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91 | * <tr><td colspan=2>allocated space</td></tr> |
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92 | * </table> |
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93 | * |
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94 | * The heap area after initialization contains two blocks and looks like: |
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95 | * <table> |
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96 | * <tr><th>Label</th><th colspan=2>Content</th></tr> |
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97 | * <tr><td>heap->area_begin</td><td colspan=2>heap area begin address</td></tr> |
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98 | * <tr> |
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99 | * <td>first_block->prev_size</td> |
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100 | * <td colspan=2> |
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101 | * subordinate heap area end address (this will be used to maintain a |
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102 | * linked list of scattered heap areas) |
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103 | * </td> |
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104 | * </tr> |
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105 | * <tr> |
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106 | * <td>first_block->size</td> |
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107 | * <td colspan=2>size available for allocation |
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108 | * | @c HEAP_PREV_BLOCK_USED</td> |
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109 | * </tr> |
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110 | * <tr> |
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111 | * <td>first_block->next</td><td>_Heap_Free_list_tail(heap)</td> |
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112 | * <td rowspan=3>memory area available for allocation</td> |
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113 | * </tr> |
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114 | * <tr><td>first_block->prev</td><td>_Heap_Free_list_head(heap)</td></tr> |
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115 | * <tr><td>...</td></tr> |
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116 | * <tr> |
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117 | * <td>last_block->prev_size</td><td colspan=2>size of first block</td> |
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118 | * </tr> |
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119 | * <tr> |
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120 | * <td>last_block->size</td> |
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121 | * <td colspan=2>first block begin address - last block begin address</td> |
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122 | * </tr> |
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123 | * <tr><td>heap->area_end</td><td colspan=2>heap area end address</td></tr> |
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124 | * </table> |
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125 | * The next block of the last block is the first block. Since the first |
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126 | * block indicates that the previous block is used, this ensures that the |
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127 | * last block appears as used for the _Heap_Is_used() and _Heap_Is_free() |
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128 | * functions. |
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129 | */ |
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130 | /**@{**/ |
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131 | |
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132 | typedef struct Heap_Control Heap_Control; |
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133 | |
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134 | typedef struct Heap_Block Heap_Block; |
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135 | |
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136 | #ifndef HEAP_PROTECTION |
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137 | #define HEAP_PROTECTION_HEADER_SIZE 0 |
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138 | #else |
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139 | #define HEAP_PROTECTOR_COUNT 2 |
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140 | |
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141 | #define HEAP_BEGIN_PROTECTOR_0 ((uintptr_t) 0xfd75a98f) |
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142 | #define HEAP_BEGIN_PROTECTOR_1 ((uintptr_t) 0xbfa1f177) |
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143 | #define HEAP_END_PROTECTOR_0 ((uintptr_t) 0xd6b8855e) |
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144 | #define HEAP_END_PROTECTOR_1 ((uintptr_t) 0x13a44a5b) |
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145 | |
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146 | #define HEAP_FREE_PATTERN ((uintptr_t) 0xe7093cdf) |
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147 | |
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148 | #define HEAP_PROTECTION_OBOLUS ((Heap_Block *) 1) |
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149 | |
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150 | typedef void (*_Heap_Protection_handler)( |
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151 | Heap_Control *heap, |
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152 | Heap_Block *block |
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153 | ); |
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154 | |
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155 | typedef struct { |
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156 | _Heap_Protection_handler block_initialize; |
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157 | _Heap_Protection_handler block_check; |
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158 | _Heap_Protection_handler block_error; |
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159 | void *handler_data; |
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160 | Heap_Block *first_delayed_free_block; |
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161 | Heap_Block *last_delayed_free_block; |
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162 | uintptr_t delayed_free_block_count; |
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163 | uintptr_t delayed_free_fraction; |
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164 | } Heap_Protection; |
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165 | |
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166 | struct _Thread_Control; |
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167 | |
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168 | typedef struct { |
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169 | uintptr_t protector [HEAP_PROTECTOR_COUNT]; |
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170 | Heap_Block *next_delayed_free_block; |
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171 | struct _Thread_Control *task; |
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172 | void *tag; |
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173 | } Heap_Protection_block_begin; |
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174 | |
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175 | typedef struct { |
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176 | uintptr_t protector [HEAP_PROTECTOR_COUNT]; |
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177 | } Heap_Protection_block_end; |
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178 | |
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179 | #define HEAP_PROTECTION_HEADER_SIZE \ |
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180 | (sizeof(Heap_Protection_block_begin) + sizeof(Heap_Protection_block_end)) |
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181 | #endif |
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182 | |
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183 | /** |
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184 | * @brief The block header consists of the two size fields |
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185 | * (@ref Heap_Block.prev_size and @ref Heap_Block.size_and_flag). |
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186 | */ |
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187 | #define HEAP_BLOCK_HEADER_SIZE \ |
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188 | (2 * sizeof(uintptr_t) + HEAP_PROTECTION_HEADER_SIZE) |
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189 | |
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190 | /** |
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191 | * @brief Description for free or used blocks. |
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192 | */ |
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193 | struct Heap_Block { |
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194 | /** |
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195 | * @brief Size of the previous block or part of the allocated area of the |
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196 | * previous block. |
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197 | * |
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198 | * This field is only valid if the previous block is free. This case is |
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199 | * indicated by a cleared @c HEAP_PREV_BLOCK_USED flag in the |
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200 | * @a size_and_flag field of the current block. |
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201 | * |
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202 | * In a used block only the @a size_and_flag field needs to be valid. The |
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203 | * @a prev_size field of the current block is maintained by the previous |
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204 | * block. The current block can use the @a prev_size field in the next block |
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205 | * for allocation. |
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206 | */ |
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207 | uintptr_t prev_size; |
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208 | |
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209 | #ifdef HEAP_PROTECTION |
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210 | Heap_Protection_block_begin Protection_begin; |
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211 | #endif |
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212 | |
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213 | /** |
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214 | * @brief Contains the size of the current block and a flag which indicates |
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215 | * if the previous block is free or used. |
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216 | * |
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217 | * If the flag @c HEAP_PREV_BLOCK_USED is set, then the previous block is |
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218 | * used, otherwise the previous block is free. A used previous block may |
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219 | * claim the @a prev_size field for allocation. This trick allows to |
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220 | * decrease the overhead in the used blocks by the size of the @a prev_size |
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221 | * field. As sizes are required to be multiples of two, the least |
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222 | * significant bits would be always zero. We use this bit to store the flag. |
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223 | * |
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224 | * This field is always valid. |
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225 | */ |
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226 | uintptr_t size_and_flag; |
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227 | |
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228 | #ifdef HEAP_PROTECTION |
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229 | Heap_Protection_block_end Protection_end; |
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230 | #endif |
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231 | |
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232 | /** |
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233 | * @brief Pointer to the next free block or part of the allocated area. |
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234 | * |
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235 | * This field is page size aligned and begins of the allocated area in case |
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236 | * the block is used. |
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237 | * |
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238 | * This field is only valid if the block is free and thus part of the free |
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239 | * block list. |
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240 | */ |
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241 | Heap_Block *next; |
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242 | |
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243 | /** |
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244 | * @brief Pointer to the previous free block or part of the allocated area. |
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245 | * |
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246 | * This field is only valid if the block is free and thus part of the free |
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247 | * block list. |
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248 | */ |
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249 | Heap_Block *prev; |
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250 | }; |
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251 | |
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252 | /** |
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253 | * @brief Control block used to manage a heap. |
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254 | */ |
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255 | struct Heap_Control { |
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256 | Heap_Block free_list; |
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257 | uintptr_t page_size; |
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258 | uintptr_t min_block_size; |
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259 | uintptr_t area_begin; |
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260 | uintptr_t area_end; |
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261 | Heap_Block *first_block; |
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262 | Heap_Block *last_block; |
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263 | Heap_Statistics stats; |
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264 | #ifdef HEAP_PROTECTION |
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265 | Heap_Protection Protection; |
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266 | #endif |
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267 | }; |
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268 | |
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269 | /** |
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270 | * @brief Heap area structure for table based heap initialization and |
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271 | * extension. |
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272 | * |
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273 | * @see Heap_Initialization_or_extend_handler. |
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274 | */ |
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275 | typedef struct { |
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276 | void *begin; |
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277 | uintptr_t size; |
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278 | } Heap_Area; |
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279 | |
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280 | /** |
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281 | * @brief Heap initialization and extend handler type. |
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282 | * |
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283 | * This helps to do a table based heap initialization and extension. Create a |
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284 | * table of Heap_Area elements and iterate through it. Set the handler to |
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285 | * _Heap_Initialize() in the first iteration and then to _Heap_Extend(). |
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286 | * |
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287 | * @see Heap_Area, _Heap_Initialize(), _Heap_Extend(), or _Heap_No_extend(). |
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288 | */ |
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289 | typedef uintptr_t (*Heap_Initialization_or_extend_handler)( |
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290 | Heap_Control *heap, |
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291 | void *area_begin, |
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292 | uintptr_t area_size, |
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293 | uintptr_t page_size_or_unused |
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294 | ); |
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295 | |
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296 | /** |
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297 | * @brief Extends the memory available for the heap @a heap using the memory |
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298 | * area starting at @a area_begin of size @a area_size bytes. |
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299 | * |
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300 | * There are no alignment requirements for the memory area. The memory area |
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301 | * must be big enough to contain some maintenance blocks. It must not overlap |
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302 | * parts of the current heap memory areas. Disconnected memory areas added to |
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303 | * the heap will lead to used blocks which cover the gaps. Extending with an |
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304 | * inappropriate memory area will corrupt the heap resulting in undefined |
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305 | * behaviour. |
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306 | * |
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307 | * The unused fourth parameter is provided to have the same signature as |
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308 | * _Heap_Initialize(). |
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309 | * |
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310 | * Returns the extended space available for allocation, or zero in case of failure. |
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311 | * |
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312 | * @see Heap_Initialization_or_extend_handler. |
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313 | */ |
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314 | uintptr_t _Heap_Extend( |
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315 | Heap_Control *heap, |
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316 | void *area_begin, |
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317 | uintptr_t area_size, |
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318 | uintptr_t unused |
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319 | ); |
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320 | |
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321 | /** |
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322 | * @brief This function returns always zero. |
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323 | * |
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324 | * This function only returns zero and does nothing else. |
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325 | * |
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326 | * Returns always zero. |
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327 | * |
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328 | * @see Heap_Initialization_or_extend_handler. |
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329 | */ |
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330 | uintptr_t _Heap_No_extend( |
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331 | Heap_Control *unused_0, |
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332 | void *unused_1, |
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333 | uintptr_t unused_2, |
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334 | uintptr_t unused_3 |
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335 | ); |
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336 | |
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337 | RTEMS_INLINE_ROUTINE uintptr_t _Heap_Align_up( |
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338 | uintptr_t value, |
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339 | uintptr_t alignment |
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340 | ) |
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341 | { |
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342 | uintptr_t remainder = value % alignment; |
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343 | |
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344 | if ( remainder != 0 ) { |
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345 | return value - remainder + alignment; |
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346 | } else { |
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347 | return value; |
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348 | } |
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349 | } |
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350 | |
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351 | RTEMS_INLINE_ROUTINE uintptr_t _Heap_Min_block_size( uintptr_t page_size ) |
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352 | { |
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353 | return _Heap_Align_up( sizeof( Heap_Block ), page_size ); |
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354 | } |
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355 | |
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356 | /** |
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357 | * @brief Returns the worst case overhead to manage a memory area. |
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358 | */ |
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359 | RTEMS_INLINE_ROUTINE uintptr_t _Heap_Area_overhead( |
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360 | uintptr_t page_size |
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361 | ) |
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362 | { |
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363 | if ( page_size != 0 ) { |
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364 | page_size = _Heap_Align_up( page_size, CPU_ALIGNMENT ); |
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365 | } else { |
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366 | page_size = CPU_ALIGNMENT; |
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367 | } |
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368 | |
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369 | return 2 * (page_size - 1) + HEAP_BLOCK_HEADER_SIZE; |
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370 | } |
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371 | |
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372 | /** |
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373 | * @brief Returns the size with administration and alignment overhead for one |
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374 | * allocation. |
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375 | */ |
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376 | RTEMS_INLINE_ROUTINE uintptr_t _Heap_Size_with_overhead( |
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377 | uintptr_t page_size, |
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378 | uintptr_t size, |
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379 | uintptr_t alignment |
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380 | ) |
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381 | { |
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382 | if ( page_size != 0 ) { |
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383 | page_size = _Heap_Align_up( page_size, CPU_ALIGNMENT ); |
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384 | } else { |
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385 | page_size = CPU_ALIGNMENT; |
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386 | } |
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387 | |
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388 | if ( page_size < alignment ) { |
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389 | page_size = alignment; |
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390 | } |
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391 | |
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392 | return HEAP_BLOCK_HEADER_SIZE + page_size - 1 + size; |
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393 | } |
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394 | |
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395 | /** @} */ |
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396 | |
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397 | #ifdef __cplusplus |
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398 | } |
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399 | #endif |
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400 | |
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401 | #endif |
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402 | /* end of include file */ |
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