1 | /** |
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2 | * @file |
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3 | * |
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4 | * @ingroup ClassicUserExtensions |
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5 | * |
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6 | * @brief User Extensions API. |
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7 | */ |
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8 | |
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9 | /* |
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10 | * COPYRIGHT (c) 1989-2008. |
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11 | * On-Line Applications Research Corporation (OAR). |
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12 | * |
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13 | * The license and distribution terms for this file may be |
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14 | * found in the file LICENSE in this distribution or at |
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15 | * http://www.rtems.com/license/LICENSE. |
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16 | */ |
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17 | |
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18 | #ifndef _RTEMS_EXTENSION_H |
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19 | #define _RTEMS_EXTENSION_H |
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20 | |
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21 | #ifndef SAPI_EXT_EXTERN |
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22 | #define SAPI_EXT_EXTERN extern |
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23 | #endif |
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24 | |
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25 | #ifdef __cplusplus |
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26 | extern "C" { |
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27 | #endif |
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28 | |
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29 | #include <rtems/score/object.h> |
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30 | #include <rtems/score/userext.h> |
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31 | #include <rtems/rtems/status.h> |
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32 | #include <rtems/rtems/types.h> |
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33 | |
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34 | SAPI_EXT_EXTERN Objects_Information _Extension_Information; |
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35 | |
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36 | typedef struct { |
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37 | Objects_Control Object; |
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38 | User_extensions_Control Extension; |
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39 | } Extension_Control; |
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40 | |
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41 | void _Extension_Manager_initialization(void); |
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42 | |
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43 | typedef User_extensions_routine |
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44 | rtems_extension RTEMS_COMPILER_DEPRECATED_ATTRIBUTE; |
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45 | |
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46 | /** |
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47 | * @defgroup ClassicUserExtensions User Extensions |
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48 | * |
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49 | * @ingroup ClassicRTEMS |
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50 | * |
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51 | * @brief The User Extensions Manager allows the application developer to |
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52 | * augment the executive by allowing them to supply extension routines which |
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53 | * are invoked at critical system events. |
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54 | * |
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55 | * @section ClassicUserExtensionsSets Extension Sets |
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56 | * |
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57 | * An @ref User_extensions_Table "extension set" is defined as a set of |
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58 | * routines which are invoked at each of the critical system events at which |
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59 | * user extension routines are invoked. Together a set of these routines |
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60 | * typically perform a specific functionality such as performance monitoring or |
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61 | * debugger support. |
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62 | * |
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63 | * RTEMS allows the user to have multiple extension sets active at the same |
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64 | * time. First, a single static extension set may be defined as the |
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65 | * application's User Extension Table which is included as part of the |
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66 | * Configuration Table. This extension set is active for the entire life of the |
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67 | * system and may not be deleted. This extension set is especially important |
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68 | * because it is the only way the application can provided a fatal error |
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69 | * extension which is invoked if RTEMS fails during the |
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70 | * rtems_initialize_data_structures() directive. The static extension set is |
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71 | * optional and may be configured as @c NULL if no static extension set is |
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72 | * required. |
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73 | * |
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74 | * Second, the user can install dynamic extensions using the |
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75 | * rtems_extension_create() directive. These extensions are RTEMS objects in |
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76 | * that they have a name, an ID, and can be dynamically created and deleted. In |
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77 | * contrast to the static extension set, these extensions can only be created |
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78 | * and installed after the rtems_initialize_data_structures() directive |
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79 | * successfully completes execution. Dynamic extensions are useful for |
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80 | * encapsulating the functionality of an extension set. For example, the |
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81 | * application could use extensions to manage a special coprocessor, do |
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82 | * performance monitoring, and to do stack bounds checking. Each of these |
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83 | * extension sets could be written and installed independently of the others. |
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84 | * |
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85 | * All user extensions are optional and RTEMS places no naming restrictions on |
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86 | * the user. The user extension entry points are copied into an internal RTEMS |
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87 | * structure. This means the user does not need to keep the table after |
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88 | * creating it, and changing the handler entry points dynamically in a table |
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89 | * once created has no effect. Creating a table local to a function can save |
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90 | * space in space limited applications. |
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91 | * |
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92 | * Extension switches do not effect the context switch overhead if no switch |
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93 | * handler is installed. |
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94 | * |
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95 | * @section ClassicUserExtensionsTCB Task Control Block Area |
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96 | * |
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97 | * RTEMS provides for a pointer to a user-defined data area for each extension |
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98 | * set to be linked to each task's control block (TCB). This area is only |
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99 | * available for the dynamic extensions. This set of pointers is an extension |
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100 | * of the TCB and can be used to store additional data required by the user's |
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101 | * extension functions. It is also possible for a user extension to utilize the |
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102 | * notepad locations associated with each task although this may conflict with |
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103 | * application usage of those particular notepads. |
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104 | * |
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105 | * The TCB extension is an array of pointers in the TCB. The index into the |
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106 | * table can be obtained from the extension identifier returned when the |
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107 | * extension is created: |
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108 | * |
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109 | * @code |
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110 | * rtems_tcb *task = some_task; |
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111 | * size_t index = rtems_object_id_get_index(extension_id); |
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112 | * void *extension_data = task->extensions [index]; |
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113 | * @endcode |
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114 | * |
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115 | * The number of pointers in the area is the same as the number of user |
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116 | * extension sets configured. This allows an application to augment the TCB |
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117 | * with user-defined information. For example, an application could implement |
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118 | * task profiling by storing timing statistics in the TCB's extended memory |
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119 | * area. When a task context switch is being executed, the task switch |
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120 | * extension could read a real-time clock to calculate how long the task being |
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121 | * swapped out has run as well as timestamp the starting time for the task |
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122 | * being swapped in. |
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123 | * |
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124 | * If used, the extended memory area for the TCB should be allocated and the |
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125 | * TCB extension pointer should be set at the time the task is created or |
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126 | * started by either the task create or task start extension. The application |
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127 | * is responsible for managing this extended memory area for the TCBs. The |
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128 | * memory may be reinitialized by the task restart extension and should be |
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129 | * deallocated by the task delete extension when the task is deleted. Since the |
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130 | * TCB extension buffers would most likely be of a fixed size, the RTEMS |
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131 | * partition manager could be used to manage the application's extended memory |
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132 | * area. The application could create a partition of fixed size TCB extension |
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133 | * buffers and use the partition manager's allocation and deallocation |
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134 | * directives to obtain and release the extension buffers. |
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135 | * |
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136 | * @section ClassicUserExtensionsOrder Order of Invokation |
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137 | * |
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138 | * When one of the critical system events occur, the user extensions are |
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139 | * invoked in either @a forward or @a reverse order. Forward order indicates |
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140 | * that the static extension set is invoked followed by the dynamic extension |
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141 | * sets in the order in which they were created. Reverse order means that the |
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142 | * dynamic extension sets are invoked in the opposite of the order in which |
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143 | * they were created followed by the static extension set. By invoking the |
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144 | * extension sets in this order, extensions can be built upon one another. At |
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145 | * the following system events, the extensions are invoked in forward order: |
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146 | * |
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147 | * - Task creation |
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148 | * - Task start |
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149 | * - Task restart |
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150 | * - Task context switch |
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151 | * - Post task context switch |
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152 | * - Task begins to execute |
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153 | * |
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154 | * At the following system events, the extensions are invoked in reverse order: |
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155 | * |
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156 | * - Task exit |
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157 | * - Task deletion |
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158 | * - Fatal error detection |
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159 | * |
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160 | * At these system events, the extensions are invoked in reverse order to |
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161 | * insure that if an extension set is built upon another, the more complicated |
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162 | * extension is invoked before the extension set it is built upon. For example, |
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163 | * by invoking the static extension set last it is known that the "system" |
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164 | * fatal error extension will be the last fatal error extension executed. |
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165 | * Another example is use of the task delete extension by the Standard C |
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166 | * Library. Extension sets which are installed after the Standard C Library |
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167 | * will operate correctly even if they utilize the C Library because the C |
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168 | * Library's task delete extension is invoked after that of the other |
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169 | * extensions. |
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170 | * |
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171 | * @{ |
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172 | */ |
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173 | |
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174 | typedef User_extensions_thread_create_extension rtems_task_create_extension; |
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175 | typedef User_extensions_thread_delete_extension rtems_task_delete_extension; |
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176 | typedef User_extensions_thread_start_extension rtems_task_start_extension; |
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177 | typedef User_extensions_thread_restart_extension rtems_task_restart_extension; |
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178 | typedef User_extensions_thread_switch_extension rtems_task_switch_extension; |
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179 | typedef User_extensions_thread_begin_extension rtems_task_begin_extension; |
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180 | typedef User_extensions_thread_exitted_extension rtems_task_exitted_extension; |
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181 | typedef User_extensions_fatal_extension rtems_fatal_extension; |
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182 | |
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183 | typedef User_extensions_Table rtems_extensions_table; |
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184 | |
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185 | /** |
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186 | * @brief Creates an extension set object. |
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187 | * |
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188 | * This directive creates a extension set object from the extension table |
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189 | * @a extension_table. The assigned extension set identifier is returned in |
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190 | * @a id. The identifier is used to access this extension set in other |
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191 | * extension set related directives. The name @a name will be assigned to the |
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192 | * extension set object. |
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193 | * |
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194 | * Newly created extension sets are immediately installed and are invoked upon |
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195 | * the next system event supporting an extension. |
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196 | * |
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197 | * This directive will not cause the calling task to be preempted. |
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198 | * |
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199 | * @retval RTEMS_SUCCESSFUL Extension set created successfully. |
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200 | * @retval RTEMS_INVALID_ADDRESS Identifier pointer is @c NULL. |
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201 | * @retval RTEMS_INVALID_NAME Invalid extension set name. |
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202 | * @retval RTEMS_TOO_MANY Too many extension sets created. |
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203 | */ |
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204 | rtems_status_code rtems_extension_create( |
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205 | rtems_name name, |
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206 | const rtems_extensions_table *extension_table, |
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207 | rtems_id *id |
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208 | ); |
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209 | |
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210 | /** |
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211 | * @brief Identifies an extension set object by a name. |
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212 | * |
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213 | * This directive obtains an extension set identifier in @a id associated with |
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214 | * the extension set name @a name. If the extension set name is not unique, |
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215 | * then the extension set identifier will match one of the extension sets with |
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216 | * that name. However, this extension set identifier is not guaranteed to |
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217 | * correspond to the desired extension set. The extension set identifier is |
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218 | * used to access this extension set in other extension set related directives. |
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219 | * |
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220 | * This directive will not cause the calling task to be preempted. |
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221 | * |
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222 | * @retval RTEMS_SUCCESSFUL Extension set identified successfully. |
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223 | * @retval RTEMS_INVALID_ADDRESS Identifier pointer is @c NULL. |
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224 | * @retval RTEMS_INVALID_NAME Extension set name not found or invalid name. |
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225 | */ |
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226 | rtems_status_code rtems_extension_ident( |
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227 | rtems_name name, |
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228 | rtems_id *id |
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229 | ); |
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230 | |
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231 | /** |
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232 | * @brief Deletes an extension set object specified by the identifier @a id. |
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233 | * |
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234 | * Any subsequent references to the extension's name and identifier are |
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235 | * invalid. |
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236 | * |
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237 | * This directive will not cause the calling task to be preempted. |
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238 | * |
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239 | * @retval RTEMS_SUCCESSFUL Extension set deleted successfully. |
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240 | * @retval RTEMS_INVALID_ID Invalid extension set identifier. |
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241 | */ |
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242 | rtems_status_code rtems_extension_delete( |
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243 | rtems_id id |
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244 | ); |
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245 | |
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246 | /** @} */ |
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247 | |
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248 | #ifndef __RTEMS_APPLICATION__ |
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249 | #include <rtems/extension.inl> |
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250 | #endif |
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251 | |
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252 | #ifdef __cplusplus |
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253 | } |
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254 | #endif |
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255 | |
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256 | #endif |
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257 | /* end of include file */ |
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