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 | * Copyright (c) 2009 embedded brains GmbH. |
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19 | * |
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20 | * The license and distribution terms for this file may be |
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21 | * found in the file LICENSE in this distribution or at |
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22 | * http://www.rtems.org/license/LICENSE. |
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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/rtems/timerimpl.h> |
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30 | #include <rtems/rtems/tasksimpl.h> |
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31 | #include <rtems/score/isrlevel.h> |
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32 | #include <rtems/score/threadimpl.h> |
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33 | #include <rtems/score/todimpl.h> |
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34 | #include <rtems/score/watchdogimpl.h> |
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35 | |
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36 | static Timer_server_Control _Timer_server_Default; |
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37 | |
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38 | static void _Timer_server_Stop_interval_system_watchdog( |
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39 | Timer_server_Control *ts |
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40 | ) |
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41 | { |
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42 | _Watchdog_Remove( &ts->Interval_watchdogs.System_watchdog ); |
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43 | } |
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44 | |
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45 | static void _Timer_server_Reset_interval_system_watchdog( |
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46 | Timer_server_Control *ts |
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47 | ) |
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48 | { |
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49 | ISR_Level level; |
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50 | |
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51 | _Timer_server_Stop_interval_system_watchdog( ts ); |
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52 | |
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53 | _ISR_Disable( level ); |
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54 | if ( !_Chain_Is_empty( &ts->Interval_watchdogs.Chain ) ) { |
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55 | Watchdog_Interval delta_interval = |
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56 | _Watchdog_First( &ts->Interval_watchdogs.Chain )->delta_interval; |
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57 | _ISR_Enable( level ); |
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58 | |
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59 | /* |
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60 | * The unit is TICKS here. |
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61 | */ |
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62 | _Watchdog_Insert_ticks( |
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63 | &ts->Interval_watchdogs.System_watchdog, |
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64 | delta_interval |
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65 | ); |
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66 | } else { |
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67 | _ISR_Enable( level ); |
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68 | } |
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69 | } |
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70 | |
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71 | static void _Timer_server_Stop_tod_system_watchdog( |
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72 | Timer_server_Control *ts |
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73 | ) |
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74 | { |
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75 | _Watchdog_Remove( &ts->TOD_watchdogs.System_watchdog ); |
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76 | } |
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77 | |
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78 | static void _Timer_server_Reset_tod_system_watchdog( |
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79 | Timer_server_Control *ts |
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80 | ) |
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81 | { |
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82 | ISR_Level level; |
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83 | |
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84 | _Timer_server_Stop_tod_system_watchdog( ts ); |
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85 | |
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86 | _ISR_Disable( level ); |
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87 | if ( !_Chain_Is_empty( &ts->TOD_watchdogs.Chain ) ) { |
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88 | Watchdog_Interval delta_interval = |
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89 | _Watchdog_First( &ts->TOD_watchdogs.Chain )->delta_interval; |
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90 | _ISR_Enable( level ); |
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91 | |
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92 | /* |
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93 | * The unit is SECONDS here. |
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94 | */ |
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95 | _Watchdog_Insert_seconds( |
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96 | &ts->TOD_watchdogs.System_watchdog, |
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97 | delta_interval |
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98 | ); |
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99 | } else { |
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100 | _ISR_Enable( level ); |
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101 | } |
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102 | } |
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103 | |
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104 | static void _Timer_server_Insert_timer( |
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105 | Timer_server_Control *ts, |
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106 | Timer_Control *timer |
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107 | ) |
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108 | { |
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109 | if ( timer->the_class == TIMER_INTERVAL_ON_TASK ) { |
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110 | _Watchdog_Insert( &ts->Interval_watchdogs.Chain, &timer->Ticker ); |
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111 | } else if ( timer->the_class == TIMER_TIME_OF_DAY_ON_TASK ) { |
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112 | _Watchdog_Insert( &ts->TOD_watchdogs.Chain, &timer->Ticker ); |
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113 | } |
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114 | } |
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115 | |
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116 | static void _Timer_server_Insert_timer_and_make_snapshot( |
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117 | Timer_server_Control *ts, |
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118 | Timer_Control *timer |
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119 | ) |
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120 | { |
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121 | Watchdog_Control *first_watchdog; |
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122 | Watchdog_Interval delta_interval; |
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123 | Watchdog_Interval last_snapshot; |
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124 | Watchdog_Interval snapshot; |
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125 | Watchdog_Interval delta; |
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126 | ISR_Level level; |
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127 | |
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128 | /* |
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129 | * We have to update the time snapshots here, because otherwise we may have |
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130 | * problems with the integer range of the delta values. The time delta DT |
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131 | * from the last snapshot to now may be arbitrarily long. The last snapshot |
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132 | * is the reference point for the delta chain. Thus if we do not update the |
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133 | * reference point we have to add DT to the initial delta of the watchdog |
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134 | * being inserted. This could result in an integer overflow. |
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135 | */ |
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136 | |
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137 | _Thread_Disable_dispatch(); |
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138 | |
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139 | if ( timer->the_class == TIMER_INTERVAL_ON_TASK ) { |
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140 | /* |
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141 | * We have to advance the last known ticks value of the server and update |
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142 | * the watchdog chain accordingly. |
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143 | */ |
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144 | _ISR_Disable( level ); |
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145 | snapshot = _Watchdog_Ticks_since_boot; |
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146 | last_snapshot = ts->Interval_watchdogs.last_snapshot; |
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147 | if ( !_Chain_Is_empty( &ts->Interval_watchdogs.Chain ) ) { |
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148 | first_watchdog = _Watchdog_First( &ts->Interval_watchdogs.Chain ); |
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149 | |
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150 | /* |
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151 | * We assume adequate unsigned arithmetic here. |
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152 | */ |
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153 | delta = snapshot - last_snapshot; |
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154 | |
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155 | delta_interval = first_watchdog->delta_interval; |
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156 | if (delta_interval > delta) { |
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157 | delta_interval -= delta; |
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158 | } else { |
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159 | delta_interval = 0; |
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160 | } |
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161 | first_watchdog->delta_interval = delta_interval; |
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162 | } |
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163 | ts->Interval_watchdogs.last_snapshot = snapshot; |
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164 | _ISR_Enable( level ); |
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165 | |
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166 | _Watchdog_Insert( &ts->Interval_watchdogs.Chain, &timer->Ticker ); |
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167 | |
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168 | if ( !ts->active ) { |
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169 | _Timer_server_Reset_interval_system_watchdog( ts ); |
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170 | } |
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171 | } else if ( timer->the_class == TIMER_TIME_OF_DAY_ON_TASK ) { |
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172 | /* |
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173 | * We have to advance the last known seconds value of the server and update |
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174 | * the watchdog chain accordingly. |
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175 | */ |
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176 | _ISR_Disable( level ); |
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177 | snapshot = (Watchdog_Interval) _TOD_Seconds_since_epoch(); |
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178 | last_snapshot = ts->TOD_watchdogs.last_snapshot; |
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179 | if ( !_Chain_Is_empty( &ts->TOD_watchdogs.Chain ) ) { |
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180 | first_watchdog = _Watchdog_First( &ts->TOD_watchdogs.Chain ); |
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181 | delta_interval = first_watchdog->delta_interval; |
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182 | if ( snapshot > last_snapshot ) { |
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183 | /* |
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184 | * We advanced in time. |
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185 | */ |
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186 | delta = snapshot - last_snapshot; |
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187 | if (delta_interval > delta) { |
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188 | delta_interval -= delta; |
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189 | } else { |
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190 | delta_interval = 0; |
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191 | } |
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192 | } else { |
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193 | /* |
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194 | * Someone put us in the past. |
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195 | */ |
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196 | delta = last_snapshot - snapshot; |
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197 | delta_interval += delta; |
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198 | } |
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199 | first_watchdog->delta_interval = delta_interval; |
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200 | } |
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201 | ts->TOD_watchdogs.last_snapshot = snapshot; |
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202 | _ISR_Enable( level ); |
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203 | |
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204 | _Watchdog_Insert( &ts->TOD_watchdogs.Chain, &timer->Ticker ); |
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205 | |
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206 | if ( !ts->active ) { |
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207 | _Timer_server_Reset_tod_system_watchdog( ts ); |
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208 | } |
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209 | } |
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210 | |
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211 | _Thread_Enable_dispatch(); |
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212 | } |
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213 | |
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214 | static void _Timer_server_Schedule_operation_method( |
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215 | Timer_server_Control *ts, |
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216 | Timer_Control *timer |
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217 | ) |
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218 | { |
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219 | if ( ts->insert_chain == NULL ) { |
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220 | _Timer_server_Insert_timer_and_make_snapshot( ts, timer ); |
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221 | } else { |
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222 | /* |
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223 | * We interrupted a critical section of the timer server. The timer |
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224 | * server is not preemptible, so we must be in interrupt context here. No |
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225 | * thread dispatch will happen until the timer server finishes its |
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226 | * critical section. We have to use the protected chain methods because |
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227 | * we may be interrupted by a higher priority interrupt. |
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228 | */ |
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229 | _Chain_Append( ts->insert_chain, &timer->Object.Node ); |
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230 | } |
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231 | } |
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232 | |
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233 | static void _Timer_server_Process_interval_watchdogs( |
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234 | Timer_server_Watchdogs *watchdogs, |
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235 | Chain_Control *fire_chain |
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236 | ) |
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237 | { |
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238 | Watchdog_Interval snapshot = _Watchdog_Ticks_since_boot; |
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239 | |
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240 | /* |
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241 | * We assume adequate unsigned arithmetic here. |
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242 | */ |
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243 | Watchdog_Interval delta = snapshot - watchdogs->last_snapshot; |
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244 | |
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245 | watchdogs->last_snapshot = snapshot; |
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246 | |
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247 | _Watchdog_Adjust_to_chain( &watchdogs->Chain, delta, fire_chain ); |
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248 | } |
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249 | |
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250 | static void _Timer_server_Process_tod_watchdogs( |
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251 | Timer_server_Watchdogs *watchdogs, |
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252 | Chain_Control *fire_chain |
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253 | ) |
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254 | { |
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255 | Watchdog_Interval snapshot = (Watchdog_Interval) _TOD_Seconds_since_epoch(); |
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256 | Watchdog_Interval last_snapshot = watchdogs->last_snapshot; |
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257 | Watchdog_Interval delta; |
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258 | |
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259 | /* |
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260 | * Process the seconds chain. Start by checking that the Time |
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261 | * of Day (TOD) has not been set backwards. If it has then |
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262 | * we want to adjust the watchdogs->Chain to indicate this. |
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263 | */ |
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264 | if ( snapshot > last_snapshot ) { |
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265 | /* |
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266 | * This path is for normal forward movement and cases where the |
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267 | * TOD has been set forward. |
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268 | */ |
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269 | delta = snapshot - last_snapshot; |
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270 | _Watchdog_Adjust_to_chain( &watchdogs->Chain, delta, fire_chain ); |
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271 | |
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272 | } else if ( snapshot < last_snapshot ) { |
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273 | /* |
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274 | * The current TOD is before the last TOD which indicates that |
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275 | * TOD has been set backwards. |
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276 | */ |
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277 | delta = last_snapshot - snapshot; |
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278 | _Watchdog_Adjust( &watchdogs->Chain, WATCHDOG_BACKWARD, delta ); |
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279 | } |
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280 | |
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281 | watchdogs->last_snapshot = snapshot; |
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282 | } |
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283 | |
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284 | static void _Timer_server_Process_insertions( Timer_server_Control *ts ) |
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285 | { |
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286 | while ( true ) { |
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287 | Timer_Control *timer = (Timer_Control *) _Chain_Get( ts->insert_chain ); |
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288 | |
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289 | if ( timer == NULL ) { |
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290 | break; |
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291 | } |
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292 | |
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293 | _Timer_server_Insert_timer( ts, timer ); |
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294 | } |
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295 | } |
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296 | |
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297 | static void _Timer_server_Get_watchdogs_that_fire_now( |
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298 | Timer_server_Control *ts, |
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299 | Chain_Control *insert_chain, |
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300 | Chain_Control *fire_chain |
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301 | ) |
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302 | { |
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303 | /* |
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304 | * Afterwards all timer inserts are directed to this chain and the interval |
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305 | * and TOD chains will be no more modified by other parties. |
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306 | */ |
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307 | ts->insert_chain = insert_chain; |
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308 | |
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309 | while ( true ) { |
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310 | ISR_Level level; |
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311 | |
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312 | /* |
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313 | * Remove all the watchdogs that need to fire so we can invoke them. |
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314 | */ |
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315 | _Timer_server_Process_interval_watchdogs( |
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316 | &ts->Interval_watchdogs, |
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317 | fire_chain |
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318 | ); |
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319 | _Timer_server_Process_tod_watchdogs( &ts->TOD_watchdogs, fire_chain ); |
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320 | |
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321 | /* |
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322 | * The insertions have to take place here, because they reference the |
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323 | * current time. The previous process methods take a snapshot of the |
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324 | * current time. In case someone inserts a watchdog with an initial value |
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325 | * of zero it will be processed in the next iteration of the timer server |
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326 | * body loop. |
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327 | */ |
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328 | _Timer_server_Process_insertions( ts ); |
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329 | |
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330 | _ISR_Disable( level ); |
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331 | if ( _Chain_Is_empty( insert_chain ) ) { |
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332 | ts->insert_chain = NULL; |
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333 | _ISR_Enable( level ); |
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334 | |
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335 | break; |
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336 | } else { |
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337 | _ISR_Enable( level ); |
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338 | } |
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339 | } |
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340 | } |
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341 | |
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342 | /* FIXME: This locking approach for SMP is improvable! */ |
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343 | |
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344 | static void _Timer_server_SMP_lock_aquire( void ) |
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345 | { |
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346 | #if defined( RTEMS_SMP ) |
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347 | _Thread_Disable_dispatch(); |
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348 | #endif |
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349 | } |
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350 | |
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351 | static void _Timer_server_SMP_lock_release( void ) |
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352 | { |
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353 | #if defined( RTEMS_SMP ) |
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354 | _Thread_Enable_dispatch(); |
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355 | #endif |
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356 | } |
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357 | |
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358 | /** |
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359 | * @brief Timer server body. |
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360 | * |
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361 | * This is the server for task based timers. This task executes whenever a |
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362 | * task-based timer should fire. It services both "after" and "when" timers. |
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363 | * It is not created automatically but must be created explicitly by the |
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364 | * application before task-based timers may be initiated. The parameter |
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365 | * @a arg points to the corresponding timer server control block. |
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366 | */ |
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367 | static rtems_task _Timer_server_Body( |
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368 | rtems_task_argument arg |
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369 | ) |
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370 | { |
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371 | Timer_server_Control *ts = (Timer_server_Control *) arg; |
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372 | Chain_Control insert_chain; |
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373 | Chain_Control fire_chain; |
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374 | |
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375 | _Chain_Initialize_empty( &insert_chain ); |
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376 | _Chain_Initialize_empty( &fire_chain ); |
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377 | |
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378 | _Timer_server_SMP_lock_aquire(); |
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379 | |
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380 | while ( true ) { |
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381 | _Timer_server_Get_watchdogs_that_fire_now( ts, &insert_chain, &fire_chain ); |
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382 | |
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383 | if ( !_Chain_Is_empty( &fire_chain ) ) { |
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384 | /* |
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385 | * Fire the watchdogs. |
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386 | */ |
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387 | while ( true ) { |
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388 | Watchdog_Control *watchdog; |
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389 | ISR_Level level; |
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390 | |
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391 | /* |
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392 | * It is essential that interrupts are disable here since an interrupt |
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393 | * service routine may remove a watchdog from the chain. |
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394 | */ |
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395 | _ISR_Disable( level ); |
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396 | watchdog = (Watchdog_Control *) _Chain_Get_unprotected( &fire_chain ); |
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397 | if ( watchdog != NULL ) { |
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398 | watchdog->state = WATCHDOG_INACTIVE; |
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399 | _ISR_Enable( level ); |
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400 | } else { |
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401 | _ISR_Enable( level ); |
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402 | |
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403 | break; |
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404 | } |
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405 | |
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406 | _Timer_server_SMP_lock_release(); |
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407 | |
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408 | /* |
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409 | * The timer server may block here and wait for resources or time. |
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410 | * The system watchdogs are inactive and will remain inactive since |
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411 | * the active flag of the timer server is true. |
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412 | */ |
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413 | (*watchdog->routine)( watchdog->id, watchdog->user_data ); |
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414 | |
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415 | _Timer_server_SMP_lock_aquire(); |
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416 | } |
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417 | } else { |
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418 | ts->active = false; |
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419 | |
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420 | /* |
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421 | * Block until there is something to do. |
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422 | */ |
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423 | #if !defined( RTEMS_SMP ) |
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424 | _Thread_Disable_dispatch(); |
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425 | #endif |
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426 | _Thread_Set_state( ts->thread, STATES_DELAYING ); |
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427 | _Timer_server_Reset_interval_system_watchdog( ts ); |
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428 | _Timer_server_Reset_tod_system_watchdog( ts ); |
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429 | #if !defined( RTEMS_SMP ) |
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430 | _Thread_Enable_dispatch(); |
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431 | #endif |
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432 | |
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433 | _Timer_server_SMP_lock_release(); |
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434 | _Timer_server_SMP_lock_aquire(); |
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435 | |
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436 | ts->active = true; |
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437 | |
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438 | /* |
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439 | * Maybe an interrupt did reset the system timers, so we have to stop |
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440 | * them here. Since we are active now, there will be no more resets |
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441 | * until we are inactive again. |
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442 | */ |
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443 | _Timer_server_Stop_interval_system_watchdog( ts ); |
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444 | _Timer_server_Stop_tod_system_watchdog( ts ); |
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445 | } |
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446 | } |
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447 | } |
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448 | |
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449 | /** |
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450 | * @brief rtems_timer_initiate_server |
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451 | * |
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452 | * This directive creates and starts the server for task-based timers. |
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453 | * It must be invoked before any task-based timers can be initiated. |
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454 | * |
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455 | * @param[in] priority is the timer server priority |
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456 | * @param[in] stack_size is the stack size in bytes |
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457 | * @param[in] attribute_set is the timer server attributes |
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458 | * |
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459 | * @return This method returns RTEMS_SUCCESSFUL if successful and an |
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460 | * error code otherwise. |
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461 | */ |
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462 | rtems_status_code rtems_timer_initiate_server( |
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463 | uint32_t priority, |
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464 | uint32_t stack_size, |
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465 | rtems_attribute attribute_set |
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466 | ) |
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467 | { |
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468 | rtems_id id; |
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469 | rtems_status_code status; |
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470 | rtems_task_priority _priority; |
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471 | static bool initialized = false; |
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472 | bool tmpInitialized; |
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473 | Timer_server_Control *ts = &_Timer_server_Default; |
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474 | |
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475 | /* |
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476 | * Make sure the requested priority is valid. The if is |
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477 | * structured so we check it is invalid before looking for |
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478 | * a specific invalid value as the default. |
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479 | */ |
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480 | _priority = priority; |
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481 | if ( !_RTEMS_tasks_Priority_is_valid( priority ) ) { |
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482 | if ( priority != RTEMS_TIMER_SERVER_DEFAULT_PRIORITY ) |
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483 | return RTEMS_INVALID_PRIORITY; |
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484 | _priority = 0; |
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485 | } |
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486 | |
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487 | /* |
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488 | * Just to make sure this is only called once. |
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489 | */ |
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490 | _Thread_Disable_dispatch(); |
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491 | tmpInitialized = initialized; |
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492 | initialized = true; |
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493 | _Thread_Enable_dispatch(); |
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494 | |
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495 | if ( tmpInitialized ) |
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496 | return RTEMS_INCORRECT_STATE; |
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497 | |
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498 | /* |
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499 | * Create the Timer Server with the name the name of "TIME". The attribute |
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500 | * RTEMS_SYSTEM_TASK allows us to set a priority to 0 which will makes it |
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501 | * higher than any other task in the system. It can be viewed as a low |
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502 | * priority interrupt. It is also always NO_PREEMPT so it looks like |
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503 | * an interrupt to other tasks. |
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504 | * |
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505 | * We allow the user to override the default priority because the Timer |
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506 | * Server can invoke TSRs which must adhere to language run-time or |
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507 | * other library rules. For example, if using a TSR written in Ada the |
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508 | * Server should run at the same priority as the priority Ada task. |
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509 | * Otherwise, the priority ceiling for the mutex used to protect the |
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510 | * GNAT run-time is violated. |
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511 | */ |
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512 | status = rtems_task_create( |
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513 | _Objects_Build_name('T','I','M','E'), /* "TIME" */ |
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514 | _priority, /* create with priority 1 since 0 is illegal */ |
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515 | stack_size, /* let user specify stack size */ |
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516 | rtems_configuration_is_smp_enabled() ? |
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517 | RTEMS_DEFAULT_MODES : /* no preempt is not supported for SMP */ |
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518 | RTEMS_NO_PREEMPT, /* no preempt is like an interrupt */ |
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519 | /* user may want floating point but we need */ |
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520 | /* system task specified for 0 priority */ |
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521 | attribute_set | RTEMS_SYSTEM_TASK, |
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522 | &id /* get the id back */ |
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523 | ); |
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524 | if (status) { |
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525 | initialized = false; |
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526 | return status; |
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527 | } |
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528 | |
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529 | /* |
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530 | * Do all the data structure initialization before starting the |
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531 | * Timer Server so we do not have to have a critical section. |
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532 | */ |
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533 | |
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534 | /* |
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535 | * We work with the TCB pointer, not the ID, so we need to convert |
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536 | * to a TCB pointer from here out. |
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537 | */ |
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538 | ts->thread = (Thread_Control *)_Objects_Get_local_object( |
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539 | &_RTEMS_tasks_Information, |
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540 | _Objects_Get_index(id) |
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541 | ); |
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542 | |
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543 | /* |
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544 | * Initialize the timer lists that the server will manage. |
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545 | */ |
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546 | _Chain_Initialize_empty( &ts->Interval_watchdogs.Chain ); |
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547 | _Chain_Initialize_empty( &ts->TOD_watchdogs.Chain ); |
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548 | |
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549 | /* |
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550 | * Initialize the timers that will be used to control when the |
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551 | * Timer Server wakes up and services the task-based timers. |
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552 | */ |
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553 | _Watchdog_Initialize( |
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554 | &ts->Interval_watchdogs.System_watchdog, |
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555 | _Thread_Delay_ended, |
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556 | 0, |
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557 | ts->thread |
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558 | ); |
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559 | _Watchdog_Initialize( |
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560 | &ts->TOD_watchdogs.System_watchdog, |
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561 | _Thread_Delay_ended, |
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562 | 0, |
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563 | ts->thread |
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564 | ); |
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565 | |
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566 | /* |
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567 | * Initialize the pointer to the timer schedule method so applications that |
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568 | * do not use the Timer Server do not have to pull it in. |
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569 | */ |
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570 | ts->schedule_operation = _Timer_server_Schedule_operation_method; |
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571 | |
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572 | ts->Interval_watchdogs.last_snapshot = _Watchdog_Ticks_since_boot; |
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573 | ts->TOD_watchdogs.last_snapshot = (Watchdog_Interval) _TOD_Seconds_since_epoch(); |
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574 | |
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575 | ts->insert_chain = NULL; |
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576 | ts->active = false; |
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577 | |
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578 | /* |
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579 | * The default timer server is now available. |
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580 | */ |
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581 | _Timer_server = ts; |
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582 | |
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583 | /* |
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584 | * Start the timer server |
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585 | */ |
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586 | status = rtems_task_start( |
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587 | id, |
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588 | _Timer_server_Body, |
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589 | (rtems_task_argument) ts |
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590 | ); |
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591 | |
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592 | #if defined(RTEMS_DEBUG) |
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593 | /* |
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594 | * One would expect a call to rtems_task_delete() here to clean up |
---|
595 | * but there is actually no way (in normal circumstances) that the |
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596 | * start can fail. The id and starting address are known to be |
---|
597 | * be good. If this service fails, something is weirdly wrong on the |
---|
598 | * target such as a stray write in an ISR or incorrect memory layout. |
---|
599 | */ |
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600 | if (status) { |
---|
601 | initialized = false; |
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602 | } |
---|
603 | #endif |
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604 | |
---|
605 | return status; |
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606 | } |
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