1 | /** |
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2 | * @file |
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3 | * |
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4 | * @ingroup RTEMSAPIRBHeap |
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5 | * |
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6 | * @brief This header file provides the Red-Black Tree Heap API. |
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7 | */ |
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8 | |
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9 | /* |
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10 | * Copyright (c) 2012 embedded brains GmbH. All rights reserved. |
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11 | * |
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12 | * embedded brains GmbH |
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13 | * Obere Lagerstr. 30 |
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14 | * 82178 Puchheim |
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15 | * Germany |
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16 | * <rtems@embedded-brains.de> |
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17 | * |
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18 | * The license and distribution terms for this file may be |
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19 | * found in the file LICENSE in this distribution or at |
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20 | * http://www.rtems.org/license/LICENSE. |
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21 | */ |
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22 | |
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23 | #ifndef _RTEMS_RBHEAP_H |
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24 | #define _RTEMS_RBHEAP_H |
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25 | |
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26 | #include <rtems.h> |
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27 | #include <rtems/chain.h> |
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28 | #include <rtems/rbtree.h> |
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29 | |
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30 | #ifdef __cplusplus |
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31 | extern "C" { |
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32 | #endif |
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33 | |
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34 | /** |
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35 | * @defgroup RTEMSAPIRBHeap Red-Black Tree Heap |
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36 | * |
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37 | * @ingroup RTEMSAPI |
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38 | * |
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39 | * @brief The red-black tree heap provides a memory allocator using a red-black |
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40 | * tree to maintain blocks of memory. |
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41 | * |
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42 | * The red-black tree heap provides a memory allocator suitable to implement |
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43 | * the malloc() and free() interface. It uses a first-fit allocation strategy. |
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44 | * In the red-black tree heap the administration data structures are not |
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45 | * contained in the managed memory area. Thus writing beyond the boundaries of |
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46 | * a chunk does not damage the data to maintain the heap. This can be used for |
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47 | * example in a task stack allocator which protects the task stacks from access |
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48 | * by other tasks. The allocated and free memory parts of the managed area are |
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49 | * called chunks. Each chunk needs a descriptor which is stored outside of the |
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50 | * managed area. |
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51 | */ |
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52 | /**@{*/ |
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53 | |
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54 | /** |
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55 | * @brief Red-black heap chunk descriptor. |
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56 | */ |
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57 | typedef struct { |
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58 | /** |
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59 | * This chain node can be used in two chains |
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60 | * - the chain of spare chunk descriptors and |
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61 | * - the chain of free chunks in the managed memory area. |
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62 | * |
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63 | * In case this chain node is not part of a chain, the chunk represents a |
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64 | * used chunk in the managed memory area. |
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65 | */ |
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66 | rtems_chain_node chain_node; |
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67 | |
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68 | /** |
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69 | * Tree node for chunks that represent a part of the managed memory area. |
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70 | * These chunks are either free or used. |
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71 | */ |
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72 | rtems_rbtree_node tree_node; |
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73 | |
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74 | /** |
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75 | * Begin address of the chunk. The address alignment it specified in the |
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76 | * @ref rtems_rbheap_control. |
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77 | */ |
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78 | uintptr_t begin; |
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79 | |
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80 | /** |
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81 | * Size of the chunk in bytes. |
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82 | */ |
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83 | uintptr_t size; |
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84 | } rtems_rbheap_chunk; |
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85 | |
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86 | typedef struct rtems_rbheap_control rtems_rbheap_control; |
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87 | |
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88 | /** |
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89 | * @brief Handler to extend the available chunk descriptors. |
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90 | * |
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91 | * This handler is called when no more chunk descriptors are available. An |
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92 | * example implementation is this: |
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93 | * |
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94 | * @code |
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95 | * void extend_descriptors_with_malloc(rtems_rbheap_control *control) |
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96 | * { |
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97 | * rtems_rbheap_chunk *chunk = malloc(sizeof(*chunk)); |
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98 | * |
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99 | * if (chunk != NULL) { |
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100 | * rtems_rbheap_add_to_spare_descriptor_chain(control, chunk); |
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101 | * } |
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102 | * } |
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103 | * @endcode |
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104 | * |
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105 | * @see rtems_rbheap_extend_descriptors_never() and |
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106 | * rtems_rbheap_extend_descriptors_with_malloc(). |
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107 | */ |
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108 | typedef void (*rtems_rbheap_extend_descriptors)(rtems_rbheap_control *control); |
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109 | |
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110 | /** |
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111 | * @brief Red-black heap control. |
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112 | */ |
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113 | struct rtems_rbheap_control { |
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114 | /** |
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115 | * Chain of free chunks in the managed memory area. |
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116 | */ |
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117 | rtems_chain_control free_chunk_chain; |
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118 | |
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119 | /** |
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120 | * Chain of free chunk descriptors. Descriptors are consumed during |
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121 | * allocation and may be produced during free if contiguous chunks can be |
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122 | * coalesced. In case of descriptor starvation the @ref extend_descriptors |
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123 | * handler will be called. |
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124 | */ |
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125 | rtems_chain_control spare_descriptor_chain; |
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126 | |
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127 | /** |
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128 | * Tree of chunks representing the state of the managed memory area. |
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129 | */ |
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130 | rtems_rbtree_control chunk_tree; |
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131 | |
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132 | /** |
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133 | * Minimum chunk begin alignment in bytes. |
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134 | */ |
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135 | uintptr_t alignment; |
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136 | |
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137 | /** |
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138 | * Handler to extend the available chunk descriptors. |
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139 | */ |
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140 | rtems_rbheap_extend_descriptors extend_descriptors; |
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141 | |
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142 | /** |
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143 | * User specified argument handler for private handler data. |
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144 | */ |
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145 | void *handler_arg; |
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146 | }; |
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147 | |
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148 | /** |
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149 | * @brief Initializes the red-black tree heap @a control. |
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150 | * |
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151 | * @param[in, out] control The red-black tree heap. |
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152 | * @param[in] area_begin The managed memory area begin. |
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153 | * @param[in] area_size The managed memory area size. |
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154 | * @param[in] alignment The minimum chunk alignment. |
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155 | * @param[in] extend_descriptors The handler to extend the available chunk |
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156 | * descriptors. |
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157 | * @param[in] handler_arg The handler argument. |
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158 | * |
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159 | * @retval RTEMS_SUCCESSFUL Successful operation. |
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160 | * @retval RTEMS_INVALID_ADDRESS The memory area is invalid. |
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161 | * @retval RTEMS_NO_MEMORY Not enough chunk descriptors. |
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162 | */ |
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163 | rtems_status_code rtems_rbheap_initialize( |
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164 | rtems_rbheap_control *control, |
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165 | void *area_begin, |
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166 | uintptr_t area_size, |
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167 | uintptr_t alignment, |
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168 | rtems_rbheap_extend_descriptors extend_descriptors, |
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169 | void *handler_arg |
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170 | ); |
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171 | |
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172 | /** |
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173 | * @brief Allocates a chunk of memory of at least @a size bytes from the |
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174 | * red-black tree heap @a control. |
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175 | * |
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176 | * The chunk begin is aligned by the value specified in |
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177 | * rtems_rbheap_initialize(). |
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178 | * |
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179 | * @param[in, out] control The red-black tree heap. |
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180 | * @param[in] size The requested chunk size in bytes. |
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181 | * |
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182 | * @retval NULL Not enough free space in the heap. |
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183 | * @retval otherwise Pointer to allocated chunk of memory. |
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184 | */ |
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185 | void *rtems_rbheap_allocate(rtems_rbheap_control *control, size_t size); |
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186 | |
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187 | /** |
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188 | * @brief Frees a chunk of memory @a ptr allocated from the red-black tree heap |
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189 | * @a control. |
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190 | * |
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191 | * @param[in, out] control The red-black tree heap. |
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192 | * @param[in] ptr The pointer to the chunk of memory. |
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193 | * |
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194 | * @retval RTEMS_SUCCESSFUL Successful operation. |
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195 | * @retval RTEMS_INVALID_ID The chunk of memory is not a valid chunk in the |
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196 | * red-black tree heap. |
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197 | * @retval RTEMS_INCORRECT_STATE The chunk of memory is not in the right state. |
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198 | */ |
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199 | rtems_status_code rtems_rbheap_free(rtems_rbheap_control *control, void *ptr); |
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200 | |
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201 | static inline rtems_chain_control *rtems_rbheap_get_spare_descriptor_chain( |
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202 | rtems_rbheap_control *control |
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203 | ) |
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204 | { |
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205 | return &control->spare_descriptor_chain; |
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206 | } |
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207 | |
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208 | static inline void rtems_rbheap_add_to_spare_descriptor_chain( |
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209 | rtems_rbheap_control *control, |
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210 | rtems_rbheap_chunk *chunk |
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211 | ) |
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212 | { |
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213 | rtems_chain_control *chain = |
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214 | rtems_rbheap_get_spare_descriptor_chain(control); |
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215 | |
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216 | rtems_chain_initialize_node(&chunk->chain_node); |
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217 | rtems_chain_prepend_unprotected(chain, &chunk->chain_node); |
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218 | } |
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219 | |
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220 | static inline void rtems_rbheap_set_extend_descriptors( |
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221 | rtems_rbheap_control *control, |
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222 | rtems_rbheap_extend_descriptors extend_descriptors |
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223 | ) |
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224 | { |
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225 | control->extend_descriptors = extend_descriptors; |
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226 | } |
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227 | |
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228 | static inline void *rtems_rbheap_get_handler_arg( |
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229 | const rtems_rbheap_control *control |
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230 | ) |
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231 | { |
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232 | return control->handler_arg; |
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233 | } |
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234 | |
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235 | static inline void rtems_rbheap_set_handler_arg( |
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236 | rtems_rbheap_control *control, |
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237 | void *handler_arg |
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238 | ) |
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239 | { |
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240 | control->handler_arg = handler_arg; |
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241 | } |
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242 | |
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243 | /** |
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244 | * @brief Chunk descriptor extend handler that does nothing. |
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245 | */ |
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246 | void rtems_rbheap_extend_descriptors_never(rtems_rbheap_control *control); |
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247 | |
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248 | /** |
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249 | * @brief Chunk descriptor extend handler that uses malloc(). |
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250 | */ |
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251 | void rtems_rbheap_extend_descriptors_with_malloc( |
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252 | rtems_rbheap_control *control |
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253 | ); |
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254 | |
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255 | /** @} */ |
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256 | |
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257 | /* Private API */ |
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258 | |
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259 | #define rtems_rbheap_chunk_of_node(node) \ |
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260 | RTEMS_CONTAINER_OF(node, rtems_rbheap_chunk, tree_node) |
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261 | |
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262 | static inline bool rtems_rbheap_is_chunk_free(const rtems_rbheap_chunk *chunk) |
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263 | { |
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264 | return !rtems_chain_is_node_off_chain(&chunk->chain_node); |
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265 | } |
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266 | |
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267 | #ifdef __cplusplus |
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268 | } |
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269 | #endif |
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270 | |
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271 | #endif /* _RTEMS_RBHEAP_H */ |
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