1 | /** |
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2 | * @brief Constants and Structures Related with Thread Dispatch |
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3 | */ |
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4 | |
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5 | /* |
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6 | * COPYRIGHT (c) 1989-2009. |
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7 | * On-Line Applications Research Corporation (OAR). |
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8 | * |
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9 | * The license and distribution terms for this file may be |
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10 | * found in the file LICENSE in this distribution or at |
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11 | * http://www.rtems.org/license/LICENSE. |
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12 | */ |
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13 | |
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14 | #ifndef _RTEMS_SCORE_THREADDISPATCH_H |
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15 | #define _RTEMS_SCORE_THREADDISPATCH_H |
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16 | |
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17 | #include <rtems/score/percpu.h> |
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18 | #include <rtems/score/smplock.h> |
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19 | #include <rtems/score/profiling.h> |
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20 | |
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21 | #ifdef __cplusplus |
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22 | extern "C" { |
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23 | #endif /* __cplusplus */ |
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24 | |
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25 | #if defined(RTEMS_SMP) || \ |
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26 | defined(RTEMS_HEAVY_STACK_DEBUG) || \ |
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27 | defined(RTEMS_HEAVY_MALLOC_DEBUG) |
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28 | #define __THREAD_DO_NOT_INLINE_DISABLE_DISPATCH__ |
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29 | #endif |
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30 | |
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31 | #if defined(RTEMS_SMP) || \ |
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32 | (CPU_INLINE_ENABLE_DISPATCH == FALSE) || \ |
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33 | (__RTEMS_DO_NOT_INLINE_THREAD_ENABLE_DISPATCH__ == 1) |
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34 | #define __THREAD_DO_NOT_INLINE_ENABLE_DISPATCH__ |
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35 | #endif |
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36 | |
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37 | /** |
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38 | * @addtogroup ScoreThread |
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39 | * |
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40 | * @{ |
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41 | */ |
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42 | |
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43 | /** |
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44 | * @brief Indicates if the executing thread is inside a thread dispatch |
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45 | * critical section. |
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46 | * |
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47 | * @retval true Thread dispatching is enabled. |
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48 | * @retval false The executing thread is inside a thread dispatch critical |
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49 | * section and dispatching is not allowed. |
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50 | */ |
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51 | RTEMS_INLINE_ROUTINE bool _Thread_Dispatch_is_enabled(void) |
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52 | { |
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53 | bool enabled; |
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54 | |
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55 | #if defined(RTEMS_SMP) |
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56 | ISR_Level level; |
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57 | |
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58 | _ISR_Disable_without_giant( level ); |
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59 | #endif |
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60 | |
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61 | enabled = _Thread_Dispatch_disable_level == 0; |
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62 | |
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63 | #if defined(RTEMS_SMP) |
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64 | _ISR_Enable_without_giant( level ); |
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65 | #endif |
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66 | |
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67 | return enabled; |
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68 | } |
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69 | |
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70 | /** |
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71 | * @briefs Gets thread dispatch disable level. |
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72 | * |
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73 | * @return The value of the thread dispatch level. |
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74 | */ |
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75 | RTEMS_INLINE_ROUTINE uint32_t _Thread_Dispatch_get_disable_level(void) |
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76 | { |
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77 | return _Thread_Dispatch_disable_level; |
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78 | } |
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79 | |
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80 | /** |
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81 | * @brief Thread dispatch initialization. |
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82 | * |
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83 | * This routine initializes the thread dispatching subsystem. |
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84 | */ |
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85 | RTEMS_INLINE_ROUTINE void _Thread_Dispatch_initialization( void ) |
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86 | { |
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87 | _Thread_Dispatch_disable_level = 1; |
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88 | } |
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89 | |
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90 | #if defined(RTEMS_SMP) |
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91 | /** |
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92 | * @brief Acquires the giant lock. |
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93 | * |
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94 | * The giant lock is a recursive SMP lock protecting nearly all operating |
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95 | * system services. |
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96 | * |
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97 | * This lock is implicitly acquired in |
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98 | * _Thread_Dispatch_increment_disable_level(). |
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99 | * |
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100 | * Thread dispatching must be disabled before this lock can be acquired. |
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101 | */ |
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102 | void _Giant_Acquire( void ); |
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103 | |
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104 | /** |
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105 | * @brief Releases the giant lock. |
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106 | * |
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107 | * This lock is implicitly released in |
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108 | * _Thread_Dispatch_decrement_disable_level(). |
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109 | */ |
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110 | void _Giant_Release( void ); |
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111 | |
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112 | /** |
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113 | * @brief Releases the giant lock completely if held by the executing processor. |
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114 | * |
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115 | * The thread dispatch disable level is not altered by this function. |
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116 | * |
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117 | * The only use case for this operation is in _SMP_Request_shutdown(). |
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118 | * |
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119 | * @param[in] self_cpu The current processor. |
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120 | */ |
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121 | void _Giant_Drop( Per_CPU_Control *self_cpu ); |
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122 | |
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123 | /** |
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124 | * @brief Increments the thread dispatch level. |
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125 | * |
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126 | * This rountine increments the thread dispatch level |
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127 | */ |
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128 | uint32_t _Thread_Dispatch_increment_disable_level(void); |
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129 | |
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130 | /** |
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131 | * @brief Decrements the thread dispatch level. |
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132 | * |
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133 | * This routine decrements the thread dispatch level. |
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134 | */ |
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135 | uint32_t _Thread_Dispatch_decrement_disable_level(void); |
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136 | #else /* RTEMS_SMP */ |
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137 | /** |
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138 | * @brief Increase thread dispatch disable level. |
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139 | * |
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140 | * This rountine increments the thread dispatch level |
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141 | */ |
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142 | RTEMS_INLINE_ROUTINE uint32_t _Thread_Dispatch_increment_disable_level(void) |
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143 | { |
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144 | uint32_t disable_level = _Thread_Dispatch_disable_level; |
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145 | #if defined( RTEMS_PROFILING ) |
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146 | ISR_Level level; |
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147 | |
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148 | _ISR_Disable( level ); |
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149 | _Profiling_Thread_dispatch_disable( _Per_CPU_Get(), disable_level ); |
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150 | #endif |
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151 | |
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152 | ++disable_level; |
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153 | _Thread_Dispatch_disable_level = disable_level; |
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154 | |
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155 | #if defined( RTEMS_PROFILING ) |
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156 | _ISR_Enable( level ); |
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157 | #endif |
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158 | |
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159 | return disable_level; |
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160 | } |
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161 | |
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162 | /** |
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163 | * @brief Decrease thread dispatch disable level. |
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164 | * |
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165 | * This routine decrements the thread dispatch level. |
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166 | */ |
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167 | RTEMS_INLINE_ROUTINE uint32_t _Thread_Dispatch_decrement_disable_level(void) |
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168 | { |
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169 | uint32_t disable_level = _Thread_Dispatch_disable_level; |
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170 | #if defined( RTEMS_PROFILING ) |
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171 | ISR_Level level; |
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172 | |
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173 | _ISR_Disable( level ); |
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174 | #endif |
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175 | |
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176 | --disable_level; |
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177 | _Thread_Dispatch_disable_level = disable_level; |
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178 | |
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179 | #if defined( RTEMS_PROFILING ) |
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180 | _Profiling_Thread_dispatch_enable( _Per_CPU_Get(), disable_level ); |
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181 | _ISR_Enable( level ); |
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182 | #endif |
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183 | |
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184 | return disable_level; |
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185 | } |
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186 | #endif /* RTEMS_SMP */ |
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187 | |
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188 | /** |
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189 | * @brief Dispatch thread. |
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190 | * |
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191 | * This routine is responsible for transferring control of the |
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192 | * processor from the executing thread to the heir thread. Once the |
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193 | * heir is running an attempt is made to dispatch any ASRs. |
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194 | * As part of this process, it is responsible for the following actions: |
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195 | * + saving the context of the executing thread |
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196 | * + restoring the context of the heir thread |
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197 | * + dispatching any signals for the resulting executing thread |
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198 | |
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199 | * ALTERNATE ENTRY POINTS: |
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200 | * void _Thread_Enable_dispatch(); |
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201 | * |
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202 | * - INTERRUPT LATENCY: |
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203 | * + dispatch thread |
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204 | * + no dispatch thread |
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205 | */ |
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206 | void _Thread_Dispatch( void ); |
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207 | |
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208 | /** |
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209 | * This routine prevents dispatching. |
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210 | */ |
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211 | |
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212 | #if defined ( __THREAD_DO_NOT_INLINE_DISABLE_DISPATCH__ ) |
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213 | void _Thread_Disable_dispatch( void ); |
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214 | #else |
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215 | RTEMS_INLINE_ROUTINE void _Thread_Disable_dispatch( void ) |
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216 | { |
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217 | _Thread_Dispatch_increment_disable_level(); |
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218 | RTEMS_COMPILER_MEMORY_BARRIER(); |
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219 | } |
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220 | #endif |
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221 | |
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222 | /** |
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223 | * This routine allows dispatching to occur again. If this is |
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224 | * the outer most dispatching critical section, then a dispatching |
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225 | * operation will be performed and, if necessary, control of the |
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226 | * processor will be transferred to the heir thread. |
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227 | */ |
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228 | |
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229 | #if defined ( __THREAD_DO_NOT_INLINE_ENABLE_DISPATCH__ ) |
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230 | void _Thread_Enable_dispatch( void ); |
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231 | #else |
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232 | /* inlining of enable dispatching must be true */ |
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233 | RTEMS_INLINE_ROUTINE void _Thread_Enable_dispatch( void ) |
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234 | { |
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235 | RTEMS_COMPILER_MEMORY_BARRIER(); |
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236 | if ( _Thread_Dispatch_decrement_disable_level() == 0 ) |
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237 | _Thread_Dispatch(); |
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238 | } |
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239 | #endif |
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240 | |
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241 | /** |
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242 | * This routine allows dispatching to occur again. However, |
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243 | * no dispatching operation is performed even if this is the outer |
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244 | * most dispatching critical section. |
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245 | */ |
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246 | |
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247 | RTEMS_INLINE_ROUTINE void _Thread_Unnest_dispatch( void ) |
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248 | { |
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249 | RTEMS_COMPILER_MEMORY_BARRIER(); |
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250 | _Thread_Dispatch_decrement_disable_level(); |
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251 | } |
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252 | |
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253 | /** @} */ |
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254 | |
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255 | #ifdef __cplusplus |
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256 | } |
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257 | #endif /* __cplusplus */ |
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258 | |
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259 | #endif /* _RTEMS_SCORE_THREADDISPATCH_H */ |
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