1 | /** |
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2 | * @file timerserver.c |
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3 | * |
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4 | * Timer Manager - rtems_timer_initiate_server directive along with |
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5 | * the Timer Server Body and support routines |
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6 | * |
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7 | * @note Data specific to the Timer Server is declared in this |
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8 | * file as the Timer Server so it does not have to be in the |
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9 | * minimum footprint. It is only really required when |
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10 | * task-based timers are used. Since task-based timers can |
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11 | * not be started until the server is initiated, this structure |
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12 | * does not have to be initialized until then. |
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13 | */ |
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14 | |
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15 | /* COPYRIGHT (c) 1989-2008. |
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16 | * On-Line Applications Research Corporation (OAR). |
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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.com/license/LICENSE. |
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21 | * |
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22 | * $Id$ |
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23 | */ |
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24 | |
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25 | #if HAVE_CONFIG_H |
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26 | #include "config.h" |
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27 | #endif |
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28 | |
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29 | #include <rtems/system.h> |
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30 | #include <rtems/rtems/status.h> |
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31 | #include <rtems/rtems/support.h> |
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32 | #include <rtems/score/object.h> |
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33 | #include <rtems/score/thread.h> |
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34 | #include <rtems/rtems/timer.h> |
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35 | #include <rtems/score/tod.h> |
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36 | #include <rtems/score/watchdog.h> |
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37 | |
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38 | #include <rtems/rtems/tasks.h> |
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39 | #include <rtems/rtems/support.h> |
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40 | #include <rtems/score/thread.h> |
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41 | |
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42 | /** |
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43 | * This chain contains the list of interval timers that are |
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44 | * executed in the context of the Timer Server. |
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45 | */ |
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46 | Chain_Control _Timer_Ticks_chain; |
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47 | |
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48 | /** |
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49 | * This chain contains the list of time of day timers that are |
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50 | * executed in the context of the Timer Server. |
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51 | */ |
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52 | Chain_Control _Timer_Seconds_chain; |
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53 | |
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54 | /** |
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55 | * This chain holds the set of timers to be inserted when the |
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56 | * server runs again. |
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57 | */ |
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58 | Chain_Control _Timer_To_be_inserted; |
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59 | |
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60 | /** |
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61 | * This variables keeps track of the last time the Timer Server actually |
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62 | * processed the ticks chain. |
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63 | */ |
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64 | Watchdog_Interval _Timer_Server_ticks_last_time; |
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65 | |
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66 | /** |
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67 | * This variable keeps track of the last time the Timer Server actually |
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68 | * processed the seconds chain. |
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69 | */ |
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70 | Watchdog_Interval _Timer_Server_seconds_last_time; |
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71 | |
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72 | /** |
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73 | * This is the timer used to control when the Timer Server wakes up to |
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74 | * service "when" timers. |
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75 | * |
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76 | * @note The timer in the Timer Server TCB is used for ticks timer. |
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77 | */ |
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78 | Watchdog_Control _Timer_Seconds_timer; |
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79 | |
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80 | /** |
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81 | * This method is used to temporarily disable updates to the |
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82 | * Ticks Timer Chain managed by the Timer Server. |
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83 | */ |
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84 | #define _Timer_Server_stop_ticks_timer() \ |
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85 | _Watchdog_Remove( &_Timer_Server->Timer ) |
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86 | |
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87 | /** |
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88 | * This method is used to temporarily disable updates to the |
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89 | * Seconds Timer Chain managed by the Timer Server. |
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90 | */ |
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91 | #define _Timer_Server_stop_seconds_timer() \ |
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92 | _Watchdog_Remove( &_Timer_Seconds_timer ); |
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93 | |
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94 | /** |
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95 | * This method resets a timer and places it on the Ticks chain. It |
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96 | * is assumed that the timer has already been canceled. |
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97 | */ |
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98 | #define _Timer_Server_reset_ticks_timer() \ |
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99 | do { \ |
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100 | if ( !_Chain_Is_empty( &_Timer_Ticks_chain ) ) { \ |
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101 | _Watchdog_Insert_ticks( &_Timer_Server->Timer, \ |
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102 | ((Watchdog_Control *)_Timer_Ticks_chain.first)->delta_interval ); \ |
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103 | } \ |
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104 | } while (0) |
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105 | |
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106 | /** |
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107 | * This method resets a timer and places it on the Seconds chain. It |
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108 | * is assumed that the timer has already been canceled. |
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109 | */ |
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110 | #define _Timer_Server_reset_seconds_timer() \ |
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111 | do { \ |
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112 | if ( !_Chain_Is_empty( &_Timer_Seconds_chain ) ) { \ |
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113 | _Watchdog_Insert_seconds( &_Timer_Seconds_timer, \ |
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114 | ((Watchdog_Control *)_Timer_Seconds_chain.first)->delta_interval ); \ |
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115 | } \ |
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116 | } while (0) |
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117 | |
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118 | /** |
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119 | * @brief _Timer_Server_process_insertions |
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120 | * |
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121 | * This method processes the set of timers scheduled for insertion |
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122 | * onto one of the Timer Server chains. |
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123 | * |
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124 | * @note It is only to be called from the Timer Server task. |
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125 | */ |
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126 | static void _Timer_Server_process_insertions(void) |
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127 | { |
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128 | Timer_Control *the_timer; |
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129 | |
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130 | while ( 1 ) { |
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131 | the_timer = (Timer_Control *) _Chain_Get( &_Timer_To_be_inserted ); |
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132 | if ( the_timer == NULL ) |
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133 | break; |
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134 | |
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135 | if ( the_timer->the_class == TIMER_INTERVAL_ON_TASK ) { |
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136 | _Watchdog_Insert( &_Timer_Ticks_chain, &the_timer->Ticker ); |
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137 | } else if ( the_timer->the_class == TIMER_TIME_OF_DAY_ON_TASK ) { |
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138 | _Watchdog_Insert( &_Timer_Seconds_chain, &the_timer->Ticker ); |
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139 | } |
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140 | } |
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141 | } |
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142 | |
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143 | /** |
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144 | * @brief _Timer_Server_process_ticks_chain |
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145 | * |
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146 | * This routine is responsible for adjusting the list of task-based |
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147 | * interval timers to reflect the passage of time. |
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148 | * |
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149 | * @param[in] to_fire will contain the set of timers that are to be fired. |
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150 | * |
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151 | * @note It is only to be called from the Timer Server task. |
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152 | */ |
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153 | static void _Timer_Server_process_ticks_chain( |
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154 | Chain_Control *to_fire |
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155 | ) |
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156 | { |
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157 | Watchdog_Interval snapshot; |
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158 | Watchdog_Interval ticks; |
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159 | |
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160 | snapshot = _Watchdog_Ticks_since_boot; |
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161 | if ( snapshot >= _Timer_Server_ticks_last_time ) |
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162 | ticks = snapshot - _Timer_Server_ticks_last_time; |
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163 | else |
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164 | ticks = (0xFFFFFFFF - _Timer_Server_ticks_last_time) + snapshot; |
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165 | |
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166 | _Timer_Server_ticks_last_time = snapshot; |
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167 | _Watchdog_Adjust_to_chain( &_Timer_Ticks_chain, ticks, to_fire ); |
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168 | } |
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169 | |
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170 | /** |
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171 | * @brief _Timer_Server_process_seconds_chain |
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172 | * |
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173 | * This routine is responsible for adjusting the list of task-based |
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174 | * time of day timers to reflect the passage of time. |
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175 | * |
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176 | * @param[in] to_fire will contain the set of timers that are to be fired. |
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177 | * |
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178 | * @note It is only to be called from the Timer Server task. |
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179 | */ |
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180 | static void _Timer_Server_process_seconds_chain( |
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181 | Chain_Control *to_fire |
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182 | ) |
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183 | { |
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184 | Watchdog_Interval snapshot; |
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185 | Watchdog_Interval ticks; |
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186 | |
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187 | /* |
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188 | * Process the seconds chain. Start by checking that the Time |
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189 | * of Day (TOD) has not been set backwards. If it has then |
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190 | * we want to adjust the _Timer_Seconds_chain to indicate this. |
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191 | */ |
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192 | snapshot = _TOD_Seconds_since_epoch(); |
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193 | if ( snapshot > _Timer_Server_seconds_last_time ) { |
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194 | /* |
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195 | * This path is for normal forward movement and cases where the |
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196 | * TOD has been set forward. |
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197 | */ |
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198 | ticks = snapshot - _Timer_Server_seconds_last_time; |
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199 | _Watchdog_Adjust_to_chain( &_Timer_Seconds_chain, ticks, to_fire ); |
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200 | |
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201 | } else if ( snapshot < _Timer_Server_seconds_last_time ) { |
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202 | /* |
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203 | * The current TOD is before the last TOD which indicates that |
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204 | * TOD has been set backwards. |
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205 | */ |
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206 | ticks = _Timer_Server_seconds_last_time - snapshot; |
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207 | _Watchdog_Adjust( &_Timer_Seconds_chain, WATCHDOG_BACKWARD, ticks ); |
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208 | } |
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209 | _Timer_Server_seconds_last_time = snapshot; |
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210 | } |
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211 | |
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212 | /** |
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213 | * @brief _Timer_Server_body |
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214 | * |
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215 | * This is the server for task based timers. This task executes whenever |
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216 | * a task-based timer should fire. It services both "after" and "when" |
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217 | * timers. It is not created automatically but must be created explicitly |
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218 | * by the application before task-based timers may be initiated. |
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219 | * |
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220 | * @param[in] ignored is the the task argument that is ignored |
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221 | */ |
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222 | Thread _Timer_Server_body( |
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223 | uint32_t ignored |
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224 | ) |
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225 | { |
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226 | Chain_Control to_fire; |
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227 | |
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228 | _Chain_Initialize_empty( &to_fire ); |
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229 | |
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230 | /* |
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231 | * Initialize the "last time" markers to indicate the timer that |
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232 | * the server was initiated. |
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233 | */ |
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234 | _Timer_Server_ticks_last_time = _Watchdog_Ticks_since_boot; |
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235 | _Timer_Server_seconds_last_time = _TOD_Seconds_since_epoch(); |
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236 | |
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237 | /* |
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238 | * Insert the timers that were inserted before we got to run. |
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239 | * This should be done with dispatching disabled. |
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240 | */ |
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241 | _Thread_Disable_dispatch(); |
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242 | _Timer_Server_process_insertions(); |
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243 | _Thread_Enable_dispatch(); |
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244 | |
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245 | while(1) { |
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246 | |
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247 | /* |
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248 | * Block until there is something to do. |
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249 | */ |
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250 | _Thread_Disable_dispatch(); |
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251 | _Thread_Set_state( _Timer_Server, STATES_DELAYING ); |
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252 | _Timer_Server_reset_ticks_timer(); |
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253 | _Timer_Server_reset_seconds_timer(); |
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254 | _Thread_Enable_dispatch(); |
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255 | |
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256 | /******************************************************************** |
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257 | ******************************************************************** |
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258 | **** TIMER SERVER BLOCKS HERE **** |
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259 | ******************************************************************** |
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260 | ********************************************************************/ |
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261 | |
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262 | /* |
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263 | * Disable dispatching while processing the timers since we want |
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264 | * the removal of the timers from the chain to be atomic. |
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265 | * |
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266 | * NOTE: Dispatching is disabled for interrupt based TSRs. |
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267 | * Dispatching is enabled for task based TSRs so they |
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268 | * can temporarily malloc memory or block. |
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269 | * _ISR_Nest_level is 0 for task-based TSRs and non-zero |
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270 | * for the others. |
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271 | */ |
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272 | _Thread_Disable_dispatch(); |
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273 | |
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274 | /* |
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275 | * At this point, at least one of the timers this task relies |
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276 | * upon has fired. Stop them both while we process any outstanding |
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277 | * timers. Before we block, we will restart them. |
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278 | */ |
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279 | _Timer_Server_stop_ticks_timer(); |
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280 | _Timer_Server_stop_seconds_timer(); |
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281 | |
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282 | /* |
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283 | * Remove all the timers that need to fire so we can invoke them |
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284 | * outside the critical section. |
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285 | */ |
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286 | _Timer_Server_process_ticks_chain( &to_fire ); |
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287 | _Timer_Server_process_seconds_chain( &to_fire ); |
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288 | |
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289 | /* |
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290 | * Insert the timers that have been requested to be inserted. |
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291 | */ |
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292 | _Timer_Server_process_insertions(); |
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293 | |
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294 | /* |
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295 | * Enable dispatching to process the set that are ready "to fire." |
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296 | */ |
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297 | _Thread_Enable_dispatch(); |
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298 | |
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299 | /* |
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300 | * Now we actually invoke the TSR for all the timers that fired. |
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301 | * This is done with dispatching |
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302 | */ |
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303 | while (1) { |
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304 | Watchdog_Control *watch; |
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305 | ISR_Level level; |
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306 | |
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307 | _ISR_Disable( level ); |
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308 | watch = (Watchdog_Control *) _Chain_Get_unprotected( &to_fire ); |
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309 | if ( watch == NULL ) { |
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310 | _ISR_Enable( level ); |
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311 | break; |
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312 | } |
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313 | |
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314 | watch->state = WATCHDOG_INACTIVE; |
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315 | _ISR_Enable( level ); |
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316 | |
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317 | (*watch->routine)( watch->id, watch->user_data ); |
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318 | } |
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319 | } |
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320 | |
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321 | return 0; /* unreached - only to remove warnings */ |
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322 | } |
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323 | |
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324 | /** |
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325 | * This method schedules the insertion of timers on the proper list. It |
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326 | * wakes up the Timer Server task to process the insertion. |
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327 | * |
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328 | * @param[in] the_timer is the timer to insert |
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329 | * |
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330 | * @note It is highly likely the executing task will be preempted after |
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331 | * the directive invoking this is executed. |
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332 | */ |
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333 | static void _Timer_Server_schedule_operation_method( |
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334 | Timer_Control *the_timer |
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335 | ) |
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336 | { |
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337 | _Chain_Append( &_Timer_To_be_inserted, &the_timer->Object.Node ); |
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338 | _Watchdog_Remove( &_Timer_Server->Timer ); |
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339 | _Thread_Delay_ended( _Timer_Server->Object.id, NULL ); |
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340 | } |
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341 | |
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342 | /** |
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343 | * @brief rtems_timer_initiate_server |
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344 | * |
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345 | * This directive creates and starts the server for task-based timers. |
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346 | * It must be invoked before any task-based timers can be initiated. |
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347 | * |
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348 | * @param[in] priority is the timer server priority |
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349 | * @param[in] stack_size is the stack size in bytes |
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350 | * @param[in] attribute_set is the timer server attributes |
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351 | * |
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352 | * @return This method returns RTEMS_SUCCESSFUL if successful and an |
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353 | * error code otherwise. |
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354 | */ |
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355 | rtems_status_code rtems_timer_initiate_server( |
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356 | uint32_t priority, |
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357 | uint32_t stack_size, |
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358 | rtems_attribute attribute_set |
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359 | ) |
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360 | { |
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361 | rtems_id id; |
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362 | rtems_status_code status; |
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363 | rtems_task_priority _priority; |
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364 | static bool initialized = false; |
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365 | bool tmpInitialized; |
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366 | |
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367 | /* |
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368 | * Make sure the requested priority is valid. The if is |
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369 | * structured so we check it is invalid before looking for |
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370 | * a specific invalid value as the default. |
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371 | */ |
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372 | _priority = priority; |
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373 | if ( !_RTEMS_tasks_Priority_is_valid( priority ) ) { |
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374 | if ( priority != RTEMS_TIMER_SERVER_DEFAULT_PRIORITY ) |
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375 | return RTEMS_INVALID_PRIORITY; |
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376 | _priority = 0; |
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377 | } |
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378 | |
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379 | /* |
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380 | * Just to make sure this is only called once. |
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381 | */ |
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382 | _Thread_Disable_dispatch(); |
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383 | tmpInitialized = initialized; |
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384 | initialized = true; |
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385 | _Thread_Enable_dispatch(); |
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386 | |
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387 | if ( tmpInitialized ) |
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388 | return RTEMS_INCORRECT_STATE; |
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389 | |
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390 | /* |
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391 | * Initialize the set of timers to be inserted by the server. |
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392 | */ |
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393 | _Chain_Initialize_empty( &_Timer_To_be_inserted ); |
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394 | |
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395 | /* |
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396 | * Create the Timer Server with the name the name of "TIME". The attribute |
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397 | * RTEMS_SYSTEM_TASK allows us to set a priority to 0 which will makes it |
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398 | * higher than any other task in the system. It can be viewed as a low |
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399 | * priority interrupt. It is also always NO_PREEMPT so it looks like |
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400 | * an interrupt to other tasks. |
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401 | * |
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402 | * We allow the user to override the default priority because the Timer |
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403 | * Server can invoke TSRs which must adhere to language run-time or |
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404 | * other library rules. For example, if using a TSR written in Ada the |
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405 | * Server should run at the same priority as the priority Ada task. |
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406 | * Otherwise, the priority ceiling for the mutex used to protect the |
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407 | * GNAT run-time is violated. |
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408 | */ |
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409 | status = rtems_task_create( |
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410 | _Objects_Build_name('T','I','M','E'), /* "TIME" */ |
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411 | _priority, /* create with priority 1 since 0 is illegal */ |
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412 | stack_size, /* let user specify stack size */ |
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413 | RTEMS_NO_PREEMPT, /* no preempt is like an interrupt */ |
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414 | /* user may want floating point but we need */ |
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415 | /* system task specified for 0 priority */ |
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416 | attribute_set | RTEMS_SYSTEM_TASK, |
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417 | &id /* get the id back */ |
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418 | ); |
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419 | if (status) { |
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420 | initialized = false; |
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421 | return status; |
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422 | } |
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423 | |
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424 | /* |
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425 | * Do all the data structure initialization before starting the |
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426 | * Timer Server so we do not have to have a critical section. |
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427 | */ |
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428 | |
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429 | /* |
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430 | * We work with the TCB pointer, not the ID, so we need to convert |
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431 | * to a TCB pointer from here out. |
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432 | * |
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433 | * NOTE: Setting the pointer to the Timer Server TCB to a value other than |
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434 | * NULL indicates that task-based timer support is initialized. |
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435 | */ |
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436 | _Timer_Server = (Thread_Control *)_Objects_Get_local_object( |
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437 | &_RTEMS_tasks_Information, |
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438 | _Objects_Get_index(id) |
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439 | ); |
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440 | |
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441 | /* |
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442 | * Initialize the timer lists that the server will manage. |
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443 | */ |
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444 | _Chain_Initialize_empty( &_Timer_Ticks_chain ); |
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445 | _Chain_Initialize_empty( &_Timer_Seconds_chain ); |
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446 | |
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447 | /* |
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448 | * Initialize the timers that will be used to control when the |
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449 | * Timer Server wakes up and services the task-based timers. |
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450 | */ |
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451 | _Watchdog_Initialize( &_Timer_Server->Timer, _Thread_Delay_ended, id, NULL ); |
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452 | _Watchdog_Initialize( &_Timer_Seconds_timer, _Thread_Delay_ended, id, NULL ); |
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453 | |
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454 | /* |
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455 | * Initialize the pointer to the timer reset method so applications |
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456 | * that do not use the Timer Server do not have to pull it in. |
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457 | */ |
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458 | _Timer_Server_schedule_operation = _Timer_Server_schedule_operation_method; |
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459 | |
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460 | /* |
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461 | * Start the timer server |
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462 | */ |
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463 | status = rtems_task_start( |
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464 | id, /* the id from create */ |
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465 | (rtems_task_entry) _Timer_Server_body, /* the timer server entry point */ |
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466 | 0 /* there is no argument */ |
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467 | ); |
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468 | |
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469 | #if defined(RTEMS_DEBUG) |
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470 | /* |
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471 | * One would expect a call to rtems_task_delete() here to clean up |
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472 | * but there is actually no way (in normal circumstances) that the |
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473 | * start can fail. The id and starting address are known to be |
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474 | * be good. If this service fails, something is weirdly wrong on the |
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475 | * target such as a stray write in an ISR or incorrect memory layout. |
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476 | */ |
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477 | if (status) { |
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478 | initialized = false; |
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479 | } |
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480 | #endif |
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481 | |
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482 | return status; |
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483 | } |
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