1 | /** |
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2 | * @file |
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3 | * |
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4 | * @ingroup RTEMSScorePriority |
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5 | * |
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6 | * @brief Priority Handler API |
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7 | */ |
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8 | |
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9 | /* |
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10 | * COPYRIGHT (c) 1989-2011. |
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11 | * On-Line Applications Research Corporation (OAR). |
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12 | * |
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13 | * Copyright (c) 2016, 2017 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.org/license/LICENSE. |
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18 | */ |
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19 | |
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20 | #ifndef _RTEMS_SCORE_PRIORITY_H |
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21 | #define _RTEMS_SCORE_PRIORITY_H |
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22 | |
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23 | #include <rtems/score/chain.h> |
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24 | #include <rtems/score/cpu.h> |
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25 | #include <rtems/score/rbtree.h> |
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26 | |
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27 | #ifdef __cplusplus |
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28 | extern "C" { |
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29 | #endif |
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30 | |
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31 | struct _Scheduler_Control; |
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32 | |
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33 | /** |
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34 | * @defgroup RTEMSScorePriority Priority Handler |
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35 | * |
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36 | * @ingroup RTEMSScore |
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37 | * |
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38 | * @brief Priority Handler |
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39 | * |
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40 | * This handler encapsulates functionality which is used to manage thread |
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41 | * priorities. The actual priority of a thread is an aggregation of priority |
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42 | * nodes. The thread priority aggregation for the home scheduler instance of a |
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43 | * thread consists of at least one priority node, which is normally the real |
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44 | * priority of the thread. The locking protocols (e.g. priority ceiling and |
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45 | * priority inheritance), rate-monotonic period objects and the POSIX sporadic |
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46 | * server add, change and remove priority nodes. |
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47 | * |
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48 | * @{ |
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49 | */ |
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50 | |
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51 | /** |
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52 | * @brief The thread priority control. |
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53 | * |
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54 | * Lower values represent higher priorities. So, a priority value of zero |
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55 | * represents the highest priority thread. This value is reserved for internal |
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56 | * threads and the priority ceiling protocol. |
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57 | * |
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58 | * The format of the thread priority control depends on the context. A thread |
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59 | * priority control may contain a user visible priority for API import/export. |
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60 | * It may also contain a scheduler internal priority value. Values are |
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61 | * translated via the scheduler map/unmap priority operations. The format of |
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62 | * scheduler interal values depend on the particular scheduler implementation. |
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63 | * It may for example encode a deadline in case of the EDF scheduler. |
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64 | * |
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65 | * The thread priority control value contained in the scheduler node |
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66 | * (Scheduler_Node::Priority::value) uses the least-significant bit to indicate |
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67 | * if the thread should be appended or prepended to its priority group, see |
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68 | * SCHEDULER_PRIORITY_APPEND(). |
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69 | */ |
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70 | typedef uint64_t Priority_Control; |
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71 | |
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72 | /** |
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73 | * @brief The highest (most important) thread priority value. |
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74 | */ |
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75 | #define PRIORITY_MINIMUM 0 |
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76 | |
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77 | /** |
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78 | * @brief The priority value of pseudo-ISR threads. |
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79 | * |
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80 | * Examples are the MPCI and timer server threads. |
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81 | */ |
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82 | #define PRIORITY_PSEUDO_ISR PRIORITY_MINIMUM |
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83 | |
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84 | /** |
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85 | * @brief The default lowest (least important) thread priority value. |
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86 | * |
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87 | * This value is CPU port dependent. |
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88 | */ |
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89 | #if defined (CPU_PRIORITY_MAXIMUM) |
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90 | #define PRIORITY_DEFAULT_MAXIMUM CPU_PRIORITY_MAXIMUM |
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91 | #else |
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92 | #define PRIORITY_DEFAULT_MAXIMUM 255 |
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93 | #endif |
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94 | |
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95 | /** |
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96 | * @brief The priority node to build up a priority aggregation. |
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97 | */ |
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98 | typedef struct { |
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99 | /** |
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100 | * @brief Node component for a chain or red-black tree. |
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101 | */ |
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102 | union { |
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103 | Chain_Node Chain; |
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104 | RBTree_Node RBTree; |
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105 | } Node; |
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106 | |
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107 | /** |
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108 | * @brief The priority value of this node. |
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109 | */ |
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110 | Priority_Control priority; |
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111 | } Priority_Node; |
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112 | |
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113 | /** |
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114 | * @brief The priority action type. |
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115 | */ |
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116 | typedef enum { |
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117 | PRIORITY_ACTION_ADD, |
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118 | PRIORITY_ACTION_CHANGE, |
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119 | PRIORITY_ACTION_REMOVE, |
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120 | PRIORITY_ACTION_INVALID |
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121 | } Priority_Action_type; |
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122 | |
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123 | typedef struct Priority_Aggregation Priority_Aggregation; |
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124 | |
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125 | /** |
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126 | * @brief The priority aggregation. |
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127 | * |
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128 | * This structure serves two purposes. Firstly, it provides a place to |
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129 | * register priority nodes and reflects the overall priority of its |
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130 | * contributors. Secondly, it provides an action block to signal addition, |
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131 | * change and removal of a priority node. |
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132 | */ |
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133 | struct Priority_Aggregation { |
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134 | /** |
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135 | * @brief This priority node reflects the overall priority of the aggregation. |
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136 | * |
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137 | * The overall priority of the aggregation is the minimum priority of the |
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138 | * priority nodes in the contributors tree. |
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139 | * |
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140 | * This priority node may be used to add this aggregation to another |
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141 | * aggregation to build up a recursive priority scheme. |
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142 | * |
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143 | * In case priority nodes of the contributors tree are added, changed or |
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144 | * removed the priority of this node may change. To signal such changes to a |
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145 | * priority aggregation the action block may be used. |
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146 | */ |
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147 | Priority_Node Node; |
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148 | |
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149 | /** |
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150 | * @brief A red-black tree to contain priority nodes contributing to the |
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151 | * overall priority of this priority aggregation. |
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152 | */ |
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153 | RBTree_Control Contributors; |
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154 | |
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155 | #if defined(RTEMS_SMP) |
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156 | /** |
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157 | * @brief The scheduler instance of this priority aggregation. |
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158 | */ |
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159 | const struct _Scheduler_Control *scheduler; |
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160 | #endif |
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161 | |
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162 | /** |
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163 | * @brief A priority action block to manage priority node additions, changes |
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164 | * and removals. |
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165 | */ |
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166 | struct { |
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167 | #if defined(RTEMS_SMP) |
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168 | /** |
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169 | * @brief The next priority aggregation in the action list. |
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170 | */ |
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171 | Priority_Aggregation *next; |
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172 | #endif |
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173 | |
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174 | /** |
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175 | * @brief The priority node of the action. |
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176 | */ |
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177 | Priority_Node *node; |
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178 | |
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179 | /** |
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180 | * @brief The type of the action. |
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181 | */ |
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182 | Priority_Action_type type; |
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183 | } Action; |
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184 | }; |
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185 | |
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186 | /** |
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187 | * @brief A list of priority actions. |
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188 | * |
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189 | * Actions are only added to the list. The action lists reside on the stack |
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190 | * and have a short life-time. They are moved, processed or destroyed as a |
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191 | * whole. |
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192 | */ |
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193 | typedef struct { |
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194 | /** |
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195 | * @brief The first action of a priority action list. |
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196 | */ |
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197 | Priority_Aggregation *actions; |
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198 | } Priority_Actions; |
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199 | |
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200 | #ifdef __cplusplus |
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201 | } |
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202 | #endif |
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203 | |
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204 | /** @} */ |
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205 | |
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206 | #endif |
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207 | /* end of include file */ |
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