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 implementation. |
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7 | */ |
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8 | |
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9 | /* |
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10 | * COPYRIGHT (c) 1989-2009. |
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11 | * On-Line Applications Research Corporation (OAR). |
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12 | * |
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13 | * Copyright (c) 2009 embedded brains GmbH. |
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14 | * |
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15 | * The license and distribution terms for this file may be |
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16 | * found in the file LICENSE in this distribution or at |
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17 | * http://www.rtems.com/license/LICENSE. |
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18 | * |
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19 | * $Id$ |
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20 | */ |
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21 | |
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22 | #if HAVE_CONFIG_H |
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23 | #include "config.h" |
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24 | #endif |
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25 | |
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26 | #include <rtems/system.h> |
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27 | #include <rtems/score/heap.h> |
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28 | |
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29 | #if CPU_ALIGNMENT == 0 || CPU_ALIGNMENT % 4 != 0 |
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30 | #error "invalid CPU_ALIGNMENT value" |
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31 | #endif |
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32 | |
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33 | static uint32_t instance = 0; |
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34 | |
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35 | /*PAGE |
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36 | * |
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37 | * _Heap_Initialize |
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38 | * |
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39 | * This kernel routine initializes a heap. |
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40 | * |
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41 | * Input parameters: |
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42 | * heap - pointer to heap header |
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43 | * area_begin - starting address of heap |
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44 | * size - size of heap |
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45 | * page_size - allocatable unit of memory |
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46 | * |
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47 | * Output parameters: |
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48 | * returns - maximum memory available if RTEMS_SUCCESSFUL |
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49 | * 0 - otherwise |
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50 | * |
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51 | * This is what a heap looks like in memory immediately after initialization: |
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52 | * |
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53 | * |
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54 | * +--------------------------------+ <- begin = area_begin |
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55 | * | unused space due to alignment | |
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56 | * | size < page_size | |
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57 | * 0 +--------------------------------+ <- first block |
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58 | * | prev_size = page_size | |
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59 | * 4 +--------------------------------+ |
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60 | * | size = size0 | 1 | |
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61 | * 8 +---------------------+----------+ <- aligned on page_size |
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62 | * | next = HEAP_TAIL | | |
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63 | * 12 +---------------------+ | |
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64 | * | prev = HEAP_HEAD | memory | |
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65 | * +---------------------+ | |
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66 | * | available | |
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67 | * | | |
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68 | * | for allocation | |
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69 | * | | |
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70 | * size0 +--------------------------------+ <- last dummy block |
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71 | * | prev_size = size0 | |
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72 | * +4 +--------------------------------+ |
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73 | * | size = page_size | 0 | <- prev block is free |
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74 | * +8 +--------------------------------+ <- aligned on page_size |
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75 | * | unused space due to alignment | |
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76 | * | size < page_size | |
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77 | * +--------------------------------+ <- end = begin + size |
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78 | * |
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79 | * Below is what a heap looks like after first allocation of SIZE bytes using |
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80 | * _Heap_allocate(). BSIZE stands for SIZE + 4 aligned up on 'page_size' |
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81 | * boundary. |
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82 | * [NOTE: If allocation were performed by _Heap_Allocate_aligned(), the |
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83 | * block size BSIZE is defined differently, and previously free block will |
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84 | * be split so that upper part of it will become used block (see |
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85 | * 'heapallocatealigned.c' for details).] |
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86 | * |
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87 | * +--------------------------------+ <- begin = area_begin |
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88 | * | unused space due to alignment | |
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89 | * | size < page_size | |
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90 | * 0 +--------------------------------+ <- used block |
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91 | * | prev_size = page_size | |
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92 | * 4 +--------------------------------+ |
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93 | * | size = BSIZE | 1 | <- prev block is used |
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94 | * 8 +--------------------------------+ <- aligned on page_size |
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95 | * | . | Pointer returned to the user |
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96 | * | . | is 8 for _Heap_Allocate() |
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97 | * | . | and is in range |
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98 | * 8 + | user-accessible | [8,8+page_size) for |
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99 | * page_size +- - - - - -+ _Heap_Allocate_aligned() |
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100 | * | area | |
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101 | * | . | |
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102 | * BSIZE +- - - - - . - - - - -+ <- free block |
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103 | * | . | |
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104 | * BSIZE +4 +--------------------------------+ |
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105 | * | size = S = size0 - BSIZE | 1 | <- prev block is used |
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106 | * BSIZE +8 +-------------------+------------+ <- aligned on page_size |
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107 | * | next = HEAP_TAIL | | |
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108 | * BSIZE +12 +-------------------+ | |
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109 | * | prev = HEAP_HEAD | memory | |
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110 | * +-------------------+ | |
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111 | * | . available | |
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112 | * | . | |
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113 | * | . for | |
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114 | * | . | |
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115 | * BSIZE +S+0 +-------------------+ allocation + <- last dummy block |
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116 | * | prev_size = S | | |
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117 | * +S+4 +-------------------+------------+ |
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118 | * | size = page_size | 0 | <- prev block is free |
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119 | * +S+8 +--------------------------------+ <- aligned on page_size |
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120 | * | unused space due to alignment | |
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121 | * | size < page_size | |
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122 | * +--------------------------------+ <- end = begin + size |
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123 | * |
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124 | */ |
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125 | |
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126 | uintptr_t _Heap_Initialize( |
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127 | Heap_Control *heap, |
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128 | void *heap_area_begin_ptr, |
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129 | uintptr_t heap_area_size, |
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130 | uintptr_t page_size |
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131 | ) |
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132 | { |
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133 | Heap_Statistics *const stats = &heap->stats; |
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134 | uintptr_t const heap_area_begin = (uintptr_t) heap_area_begin_ptr; |
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135 | uintptr_t const heap_area_end = heap_area_begin + heap_area_size; |
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136 | uintptr_t alloc_area_begin = heap_area_begin + HEAP_BLOCK_HEADER_SIZE; |
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137 | uintptr_t alloc_area_size = 0; |
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138 | uintptr_t first_block_begin = 0; |
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139 | uintptr_t first_block_size = 0; |
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140 | uintptr_t min_block_size = 0; |
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141 | uintptr_t overhead = 0; |
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142 | Heap_Block *first_block = NULL; |
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143 | Heap_Block *last_block = NULL; |
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144 | |
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145 | if ( page_size == 0 ) { |
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146 | page_size = CPU_ALIGNMENT; |
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147 | } else { |
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148 | page_size = _Heap_Align_up( page_size, CPU_ALIGNMENT ); |
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149 | |
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150 | if ( page_size < CPU_ALIGNMENT ) { |
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151 | /* Integer overflow */ |
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152 | return 0; |
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153 | } |
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154 | } |
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155 | min_block_size = _Heap_Align_up( sizeof( Heap_Block ), page_size ); |
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156 | |
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157 | alloc_area_begin = _Heap_Align_up( alloc_area_begin, page_size ); |
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158 | first_block_begin = alloc_area_begin - HEAP_BLOCK_HEADER_SIZE; |
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159 | overhead = HEAP_BLOCK_HEADER_SIZE + (first_block_begin - heap_area_begin); |
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160 | first_block_size = heap_area_size - overhead; |
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161 | first_block_size = _Heap_Align_down ( first_block_size, page_size ); |
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162 | alloc_area_size = first_block_size - HEAP_BLOCK_HEADER_SIZE; |
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163 | |
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164 | if ( |
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165 | heap_area_end < heap_area_begin |
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166 | || heap_area_size <= overhead |
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167 | || first_block_size < min_block_size |
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168 | ) { |
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169 | /* Invalid area or area too small */ |
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170 | return 0; |
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171 | } |
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172 | |
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173 | /* First block */ |
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174 | first_block = (Heap_Block *) first_block_begin; |
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175 | first_block->prev_size = page_size; |
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176 | first_block->size_and_flag = first_block_size | HEAP_PREV_BLOCK_USED; |
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177 | first_block->next = _Heap_Free_list_tail( heap ); |
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178 | first_block->prev = _Heap_Free_list_head( heap ); |
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179 | |
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180 | /* |
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181 | * Last block. |
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182 | * |
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183 | * The next block of the last block is the first block. Since the first |
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184 | * block indicates that the previous block is used, this ensures that the |
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185 | * last block appears as used for the _Heap_Is_used() and _Heap_Is_free() |
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186 | * functions. |
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187 | */ |
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188 | last_block = _Heap_Block_at( first_block, first_block_size ); |
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189 | last_block->prev_size = first_block_size; |
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190 | last_block->size_and_flag = first_block_begin - (uintptr_t) last_block; |
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191 | |
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192 | /* Heap control */ |
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193 | heap->page_size = page_size; |
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194 | heap->min_block_size = min_block_size; |
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195 | heap->area_begin = heap_area_begin; |
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196 | heap->area_end = heap_area_end; |
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197 | heap->first_block = first_block; |
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198 | heap->last_block = last_block; |
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199 | _Heap_Free_list_head( heap )->next = first_block; |
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200 | _Heap_Free_list_tail( heap )->prev = first_block; |
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201 | |
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202 | /* Statistics */ |
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203 | stats->size = first_block_size; |
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204 | stats->free_size = first_block_size; |
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205 | stats->min_free_size = first_block_size; |
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206 | stats->free_blocks = 1; |
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207 | stats->max_free_blocks = 1; |
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208 | stats->used_blocks = 0; |
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209 | stats->max_search = 0; |
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210 | stats->allocs = 0; |
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211 | stats->searches = 0; |
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212 | stats->frees = 0; |
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213 | stats->resizes = 0; |
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214 | stats->instance = instance++; |
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215 | |
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216 | _HAssert( _Heap_Is_aligned( CPU_ALIGNMENT, 4 ) ); |
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217 | _HAssert( _Heap_Is_aligned( heap->page_size, CPU_ALIGNMENT ) ); |
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218 | _HAssert( _Heap_Is_aligned( heap->min_block_size, page_size ) ); |
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219 | _HAssert( |
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220 | _Heap_Is_aligned( _Heap_Alloc_area_of_block( first_block ), page_size ) |
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221 | ); |
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222 | _HAssert( |
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223 | _Heap_Is_aligned( _Heap_Alloc_area_of_block( last_block ), page_size ) |
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224 | ); |
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225 | |
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226 | return alloc_area_size; |
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227 | } |
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228 | |
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229 | void _Heap_Block_split( |
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230 | Heap_Control *heap, |
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231 | Heap_Block *block, |
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232 | Heap_Block *free_list_anchor, |
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233 | uintptr_t alloc_size |
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234 | ) |
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235 | { |
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236 | Heap_Statistics *const stats = &heap->stats; |
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237 | |
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238 | uintptr_t const page_size = heap->page_size; |
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239 | uintptr_t const min_block_size = heap->min_block_size; |
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240 | uintptr_t const min_alloc_size = min_block_size - HEAP_BLOCK_HEADER_SIZE; |
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241 | |
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242 | uintptr_t const block_size = _Heap_Block_size( block ); |
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243 | |
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244 | uintptr_t const used_size = |
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245 | _Heap_Max( alloc_size, min_alloc_size ) + HEAP_BLOCK_HEADER_SIZE; |
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246 | uintptr_t const used_block_size = _Heap_Align_up( used_size, page_size ); |
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247 | |
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248 | uintptr_t const free_size = block_size + HEAP_BLOCK_SIZE_OFFSET - used_size; |
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249 | uintptr_t const free_size_limit = min_block_size + HEAP_BLOCK_SIZE_OFFSET; |
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250 | |
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251 | Heap_Block *next_block = _Heap_Block_at( block, block_size ); |
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252 | |
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253 | _HAssert( used_size <= block_size + HEAP_BLOCK_SIZE_OFFSET ); |
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254 | _HAssert( used_size + free_size == block_size + HEAP_BLOCK_SIZE_OFFSET ); |
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255 | |
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256 | if ( free_size >= free_size_limit ) { |
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257 | Heap_Block *const free_block = _Heap_Block_at( block, used_block_size ); |
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258 | uintptr_t free_block_size = block_size - used_block_size; |
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259 | |
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260 | _HAssert( used_block_size + free_block_size == block_size ); |
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261 | |
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262 | _Heap_Block_set_size( block, used_block_size ); |
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263 | |
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264 | /* Statistics */ |
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265 | stats->free_size += free_block_size; |
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266 | |
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267 | if ( _Heap_Is_used( next_block ) ) { |
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268 | _Heap_Free_list_insert_after( free_list_anchor, free_block ); |
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269 | |
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270 | /* Statistics */ |
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271 | ++stats->free_blocks; |
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272 | } else { |
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273 | uintptr_t const next_block_size = _Heap_Block_size( next_block ); |
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274 | |
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275 | _Heap_Free_list_replace( next_block, free_block ); |
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276 | |
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277 | free_block_size += next_block_size; |
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278 | |
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279 | next_block = _Heap_Block_at( free_block, free_block_size ); |
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280 | } |
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281 | |
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282 | free_block->size_and_flag = free_block_size | HEAP_PREV_BLOCK_USED; |
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283 | |
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284 | next_block->prev_size = free_block_size; |
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285 | next_block->size_and_flag &= ~HEAP_PREV_BLOCK_USED; |
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286 | } else { |
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287 | next_block->size_and_flag |= HEAP_PREV_BLOCK_USED; |
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288 | } |
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289 | } |
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290 | |
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291 | static Heap_Block *_Heap_Block_allocate_from_begin( |
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292 | Heap_Control *heap, |
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293 | Heap_Block *block, |
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294 | Heap_Block *free_list_anchor, |
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295 | uintptr_t alloc_size |
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296 | ) |
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297 | { |
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298 | _Heap_Block_split( heap, block, free_list_anchor, alloc_size ); |
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299 | |
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300 | return block; |
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301 | } |
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302 | |
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303 | static Heap_Block *_Heap_Block_allocate_from_end( |
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304 | Heap_Control *heap, |
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305 | Heap_Block *block, |
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306 | Heap_Block *free_list_anchor, |
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307 | uintptr_t alloc_begin, |
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308 | uintptr_t alloc_size |
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309 | ) |
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310 | { |
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311 | Heap_Statistics *const stats = &heap->stats; |
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312 | |
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313 | uintptr_t block_begin = (uintptr_t) block; |
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314 | uintptr_t block_size = _Heap_Block_size( block ); |
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315 | uintptr_t block_end = block_begin + block_size; |
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316 | |
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317 | Heap_Block *const new_block = |
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318 | _Heap_Block_of_alloc_area( alloc_begin, heap->page_size ); |
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319 | uintptr_t const new_block_begin = (uintptr_t) new_block; |
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320 | uintptr_t const new_block_size = block_end - new_block_begin; |
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321 | |
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322 | block_end = new_block_begin; |
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323 | block_size = block_end - block_begin; |
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324 | |
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325 | _HAssert( block_size >= heap->min_block_size ); |
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326 | _HAssert( new_block_size >= heap->min_block_size ); |
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327 | |
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328 | /* Statistics */ |
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329 | stats->free_size += block_size; |
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330 | |
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331 | if ( _Heap_Is_prev_used( block ) ) { |
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332 | _Heap_Free_list_insert_after( free_list_anchor, block ); |
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333 | |
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334 | free_list_anchor = block; |
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335 | |
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336 | /* Statistics */ |
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337 | ++stats->free_blocks; |
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338 | } else { |
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339 | Heap_Block *const prev_block = _Heap_Prev_block( block ); |
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340 | uintptr_t const prev_block_size = _Heap_Block_size( prev_block ); |
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341 | |
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342 | block = prev_block; |
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343 | block_begin = (uintptr_t) block; |
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344 | block_size += prev_block_size; |
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345 | } |
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346 | |
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347 | block->size_and_flag = block_size | HEAP_PREV_BLOCK_USED; |
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348 | |
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349 | new_block->prev_size = block_size; |
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350 | new_block->size_and_flag = new_block_size; |
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351 | |
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352 | _Heap_Block_split( heap, new_block, free_list_anchor, alloc_size ); |
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353 | |
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354 | return new_block; |
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355 | } |
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356 | |
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357 | Heap_Block *_Heap_Block_allocate( |
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358 | Heap_Control *heap, |
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359 | Heap_Block *block, |
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360 | uintptr_t alloc_begin, |
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361 | uintptr_t alloc_size |
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362 | ) |
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363 | { |
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364 | Heap_Statistics *const stats = &heap->stats; |
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365 | |
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366 | uintptr_t const alloc_area_begin = _Heap_Alloc_area_of_block( block ); |
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367 | uintptr_t const alloc_area_offset = alloc_begin - alloc_area_begin; |
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368 | |
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369 | Heap_Block *free_list_anchor = NULL; |
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370 | |
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371 | _HAssert( alloc_area_begin <= alloc_begin ); |
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372 | |
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373 | if ( _Heap_Is_free( block ) ) { |
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374 | free_list_anchor = block->prev; |
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375 | |
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376 | _Heap_Free_list_remove( block ); |
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377 | |
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378 | /* Statistics */ |
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379 | --stats->free_blocks; |
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380 | ++stats->used_blocks; |
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381 | stats->free_size -= _Heap_Block_size( block ); |
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382 | } else { |
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383 | free_list_anchor = _Heap_Free_list_head( heap ); |
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384 | } |
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385 | |
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386 | if ( alloc_area_offset < heap->page_size ) { |
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387 | alloc_size += alloc_area_offset; |
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388 | |
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389 | block = _Heap_Block_allocate_from_begin( |
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390 | heap, |
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391 | block, |
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392 | free_list_anchor, |
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393 | alloc_size |
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394 | ); |
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395 | } else { |
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396 | block = _Heap_Block_allocate_from_end( |
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397 | heap, |
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398 | block, |
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399 | free_list_anchor, |
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400 | alloc_begin, |
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401 | alloc_size |
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402 | ); |
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403 | } |
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404 | |
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405 | /* Statistics */ |
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406 | if ( stats->min_free_size > stats->free_size ) { |
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407 | stats->min_free_size = stats->free_size; |
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408 | } |
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409 | |
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410 | return block; |
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411 | } |
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