1 | @c |
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2 | @c COPYRIGHT (c) 1988-1998. |
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3 | @c On-Line Applications Research Corporation (OAR). |
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4 | @c All rights reserved. |
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5 | @c |
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6 | @c $Id$ |
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7 | @c |
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8 | |
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9 | @ifinfo |
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10 | @node Timer Manager, Timer Manager Introduction, CLOCK_TICK - Announce a clock tick, Top |
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11 | @end ifinfo |
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12 | @chapter Timer Manager |
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13 | @ifinfo |
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14 | @menu |
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15 | * Timer Manager Introduction:: |
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16 | * Timer Manager Background:: |
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17 | * Timer Manager Operations:: |
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18 | * Timer Manager Directives:: |
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19 | @end menu |
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20 | @end ifinfo |
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21 | |
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22 | @ifinfo |
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23 | @node Timer Manager Introduction, Timer Manager Background, Timer Manager, Timer Manager |
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24 | @end ifinfo |
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25 | @section Introduction |
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26 | |
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27 | The timer manager provides support for timer |
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28 | facilities. The directives provided by the timer manager are: |
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29 | |
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30 | @itemize @bullet |
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31 | @item @code{timer_create} - Create a timer |
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32 | @item @code{timer_ident} - Get ID of a timer |
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33 | @item @code{timer_cancel} - Cancel a timer |
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34 | @item @code{timer_delete} - Delete a timer |
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35 | @item @code{timer_fire_after} - Fire timer after interval |
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36 | @item @code{timer_fire_when} - Fire timer when specified |
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37 | @item @code{timer_reset} - Reset an interval timer |
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38 | @end itemize |
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39 | |
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40 | |
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41 | @ifinfo |
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42 | @node Timer Manager Background, Timer Manager Required Support, Timer Manager Introduction, Timer Manager |
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43 | @end ifinfo |
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44 | @section Background |
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45 | @ifinfo |
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46 | @menu |
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47 | * Timer Manager Required Support:: |
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48 | * Timers:: |
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49 | * Timer Service Routines:: |
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50 | @end menu |
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51 | @end ifinfo |
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52 | |
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53 | @ifinfo |
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54 | @node Timer Manager Required Support, Timers, Timer Manager Background, Timer Manager Background |
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55 | @end ifinfo |
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56 | @subsection Required Support |
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57 | |
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58 | A clock tick is required to support the functionality provided by this manager. |
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59 | |
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60 | @ifinfo |
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61 | @node Timers, Timer Service Routines, Timer Manager Required Support, Timer Manager Background |
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62 | @end ifinfo |
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63 | @subsection Timers |
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64 | |
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65 | A timer is an RTEMS object which allows the |
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66 | application to schedule operations to occur at specific times in |
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67 | the future. User supplied timer service routines are invoked by |
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68 | the clock_tick directive when the timer fires. Timer service |
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69 | routines may perform any operations or directives which normally |
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70 | would be performed by the application code which invoked the |
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71 | clock_tick directive. |
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72 | |
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73 | The timer can be used to implement watchdog routines |
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74 | which only fire to denote that an application error has |
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75 | occurred. The timer is reset at specific points in the |
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76 | application to insure that the watchdog does not fire. Thus, if |
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77 | the application does not reset the watchdog timer, then the |
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78 | timer service routine will fire to indicate that the application |
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79 | has failed to reach a reset point. This use of a timer is |
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80 | sometimes referred to as a "keep alive" or a "deadman" timer. |
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81 | |
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82 | @ifinfo |
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83 | @node Timer Service Routines, Timer Manager Operations, Timers, Timer Manager Background |
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84 | @end ifinfo |
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85 | @subsection Timer Service Routines |
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86 | |
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87 | The timer service routine should adhere to @value{LANGUAGE} calling |
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88 | conventions and have a prototype similar to the following: |
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89 | |
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90 | @ifset is-C |
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91 | @example |
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92 | rtems_timer_service_routine user_routine( |
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93 | rtems_id timer_id, |
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94 | void *user_data |
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95 | ); |
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96 | @end example |
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97 | @end ifset |
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98 | |
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99 | @ifset is-Ada |
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100 | @example |
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101 | procedure User_Routine( |
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102 | Timer_ID : in RTEMS.ID; |
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103 | User_Data : in System.Address |
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104 | ); |
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105 | @end example |
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106 | @end ifset |
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107 | |
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108 | Where the timer_id parameter is the RTEMS object ID |
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109 | of the timer which is being fired and user_data is a pointer to |
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110 | user-defined information which may be utilized by the timer |
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111 | service routine. The argument user_data may be NULL. |
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112 | |
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113 | @ifinfo |
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114 | @node Timer Manager Operations, Creating a Timer, Timer Service Routines, Timer Manager |
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115 | @end ifinfo |
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116 | @section Operations |
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117 | @ifinfo |
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118 | @menu |
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119 | * Creating a Timer:: |
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120 | * Obtaining Timer IDs:: |
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121 | * Initiating an Interval Timer:: |
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122 | * Initiating a Time of Day Timer:: |
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123 | * Canceling a Timer:: |
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124 | * Resetting a Timer:: |
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125 | * Deleting a Timer:: |
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126 | @end menu |
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127 | @end ifinfo |
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128 | |
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129 | @ifinfo |
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130 | @node Creating a Timer, Obtaining Timer IDs, Timer Manager Operations, Timer Manager Operations |
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131 | @end ifinfo |
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132 | @subsection Creating a Timer |
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133 | |
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134 | The timer_create directive creates a timer by |
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135 | allocating a Timer Control Block (TMCB), assigning the timer a |
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136 | user-specified name, and assigning it a timer ID. Newly created |
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137 | timers do not have a timer service routine associated with them |
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138 | and are not active. |
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139 | |
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140 | @ifinfo |
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141 | @node Obtaining Timer IDs, Initiating an Interval Timer, Creating a Timer, Timer Manager Operations |
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142 | @end ifinfo |
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143 | @subsection Obtaining Timer IDs |
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144 | |
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145 | When a timer is created, RTEMS generates a unique |
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146 | timer ID and assigns it to the created timer until it is |
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147 | deleted. The timer ID may be obtained by either of two methods. |
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148 | First, as the result of an invocation of the timer_create |
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149 | directive, the timer ID is stored in a user provided location. |
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150 | Second, the timer ID may be obtained later using the timer_ident |
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151 | directive. The timer ID is used by other directives to |
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152 | manipulate this timer. |
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153 | |
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154 | @ifinfo |
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155 | @node Initiating an Interval Timer, Initiating a Time of Day Timer, Obtaining Timer IDs, Timer Manager Operations |
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156 | @end ifinfo |
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157 | @subsection Initiating an Interval Timer |
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158 | |
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159 | The timer_fire_after directive initiates a timer to |
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160 | fire a user provided timer service routine after the specified |
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161 | number of clock ticks have elapsed. When the interval has |
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162 | elapsed, the timer service routine will be invoked from the |
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163 | clock_tick directive. |
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164 | |
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165 | @ifinfo |
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166 | @node Initiating a Time of Day Timer, Canceling a Timer, Initiating an Interval Timer, Timer Manager Operations |
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167 | @end ifinfo |
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168 | @subsection Initiating a Time of Day Timer |
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169 | |
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170 | The timer_fire_when directive initiates a timer to |
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171 | fire a user provided timer service routine when the specified |
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172 | time of day has been reached. When the interval has elapsed, |
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173 | the timer service routine will be invoked from the clock_tick |
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174 | directive. |
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175 | |
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176 | @ifinfo |
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177 | @node Canceling a Timer, Resetting a Timer, Initiating a Time of Day Timer, Timer Manager Operations |
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178 | @end ifinfo |
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179 | @subsection Canceling a Timer |
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180 | |
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181 | The timer_cancel directive is used to halt the |
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182 | specified timer. Once canceled, the timer service routine will |
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183 | not fire unless the timer is reinitiated. The timer can be |
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184 | reinitiated using the timer_reset, timer_fire_after, and |
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185 | timer_fire_when directives. |
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186 | |
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187 | @ifinfo |
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188 | @node Resetting a Timer, Deleting a Timer, Canceling a Timer, Timer Manager Operations |
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189 | @end ifinfo |
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190 | @subsection Resetting a Timer |
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191 | |
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192 | The timer_reset directive is used to restore an |
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193 | interval timer initiated by a previous invocation of |
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194 | timer_fire_after to its original interval length. If the |
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195 | timer has not been used or the last usage of this timer |
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196 | was by a timer_fire_when directive, then an error is |
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197 | returned. The timer service routine is not changed or |
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198 | fired by this directive. |
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199 | |
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200 | @ifinfo |
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201 | @node Deleting a Timer, Timer Manager Directives, Resetting a Timer, Timer Manager Operations |
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202 | @end ifinfo |
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203 | @subsection Deleting a Timer |
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204 | |
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205 | The timer_delete directive is used to delete a timer. |
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206 | If the timer is running and has not expired, the timer is |
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207 | automatically canceled. The timer's control block is returned |
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208 | to the TMCB free list when it is deleted. A timer can be |
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209 | deleted by a task other than the task which created the timer. |
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210 | Any subsequent references to the timer's name and ID are invalid. |
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211 | |
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212 | @ifinfo |
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213 | @node Timer Manager Directives, TIMER_CREATE - Create a timer, Deleting a Timer, Timer Manager |
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214 | @end ifinfo |
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215 | @section Directives |
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216 | @ifinfo |
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217 | @menu |
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218 | * TIMER_CREATE - Create a timer:: |
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219 | * TIMER_IDENT - Get ID of a timer:: |
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220 | * TIMER_CANCEL - Cancel a timer:: |
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221 | * TIMER_DELETE - Delete a timer:: |
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222 | * TIMER_FIRE_AFTER - Fire timer after interval:: |
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223 | * TIMER_FIRE_WHEN - Fire timer when specified:: |
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224 | * TIMER_RESET - Reset an interval timer:: |
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225 | @end menu |
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226 | @end ifinfo |
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227 | |
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228 | This section details the timer manager's directives. |
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229 | A subsection is dedicated to each of this manager's directives |
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230 | and describes the calling sequence, related constants, usage, |
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231 | and status codes. |
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232 | |
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233 | @page |
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234 | @ifinfo |
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235 | @node TIMER_CREATE - Create a timer, TIMER_IDENT - Get ID of a timer, Timer Manager Directives, Timer Manager Directives |
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236 | @end ifinfo |
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237 | @subsection TIMER_CREATE - Create a timer |
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238 | |
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239 | @subheading CALLING SEQUENCE: |
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240 | |
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241 | @ifset is-C |
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242 | @example |
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243 | rtems_status_code rtems_timer_create( |
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244 | rtems_name name, |
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245 | rtems_id *id |
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246 | ); |
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247 | @end example |
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248 | @end ifset |
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249 | |
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250 | @ifset is-Ada |
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251 | @example |
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252 | procedure Timer_Create ( |
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253 | Name : in RTEMS.Name; |
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254 | ID : out RTEMS.ID; |
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255 | Result : out RTEMS.Status_Codes |
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256 | ); |
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257 | @end example |
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258 | @end ifset |
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259 | |
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260 | @subheading DIRECTIVE STATUS CODES: |
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261 | @code{SUCCESSFUL} - timer created successfully@* |
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262 | @code{INVALID_NAME} - invalid timer name@* |
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263 | @code{TOO_MANY} - too many timers created |
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264 | |
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265 | @subheading DESCRIPTION: |
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266 | |
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267 | This directive creates a timer. The assigned timer |
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268 | id is returned in id. This id is used to access the timer with |
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269 | other timer manager directives. For control and maintenance of |
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270 | the timer, RTEMS allocates a TMCB from the local TMCB free pool |
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271 | and initializes it. |
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272 | |
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273 | @subheading NOTES: |
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274 | |
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275 | This directive will not cause the calling task to be |
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276 | preempted. |
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277 | |
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278 | @page |
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279 | @ifinfo |
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280 | @node TIMER_IDENT - Get ID of a timer, TIMER_CANCEL - Cancel a timer, TIMER_CREATE - Create a timer, Timer Manager Directives |
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281 | @end ifinfo |
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282 | @subsection TIMER_IDENT - Get ID of a timer |
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283 | |
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284 | @subheading CALLING SEQUENCE: |
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285 | |
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286 | @ifset is-C |
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287 | @example |
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288 | rtems_status_code rtems_timer_ident( |
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289 | rtems_name name, |
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290 | rtems_id *id |
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291 | ); |
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292 | @end example |
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293 | @end ifset |
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294 | |
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295 | @ifset is-Ada |
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296 | @example |
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297 | procedure Timer_Ident ( |
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298 | Name : in RTEMS.Name; |
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299 | ID : out RTEMS.ID; |
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300 | Result : out RTEMS.Status_Codes |
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301 | ); |
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302 | @end example |
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303 | @end ifset |
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304 | |
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305 | @subheading DIRECTIVE STATUS CODES: |
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306 | @code{SUCCESSFUL} - timer identified successfully@* |
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307 | @code{INVALID_NAME} - timer name not found |
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308 | |
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309 | @subheading DESCRIPTION: |
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310 | |
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311 | This directive obtains the timer id associated with |
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312 | the timer name to be acquired. If the timer name is not unique, |
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313 | then the timer id will match one of the timers with that name. |
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314 | However, this timer id is not guaranteed to correspond to the |
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315 | desired timer. The timer id is used to access this timer in |
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316 | other timer related directives. |
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317 | |
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318 | @subheading NOTES: |
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319 | |
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320 | This directive will not cause the running task to be |
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321 | preempted. |
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322 | |
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323 | @page |
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324 | @ifinfo |
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325 | @node TIMER_CANCEL - Cancel a timer, TIMER_DELETE - Delete a timer, TIMER_IDENT - Get ID of a timer, Timer Manager Directives |
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326 | @end ifinfo |
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327 | @subsection TIMER_CANCEL - Cancel a timer |
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328 | |
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329 | @subheading CALLING SEQUENCE: |
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330 | |
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331 | @ifset is-C |
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332 | @example |
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333 | rtems_status_code rtems_timer_cancel( |
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334 | rtems_id id |
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335 | ); |
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336 | @end example |
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337 | @end ifset |
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338 | |
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339 | @ifset is-Ada |
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340 | @example |
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341 | procedure Timer_Cancel ( |
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342 | ID : in RTEMS.ID; |
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343 | Result : out RTEMS.Status_Codes |
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344 | ); |
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345 | @end example |
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346 | @end ifset |
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347 | |
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348 | @subheading DIRECTIVE STATUS CODES: |
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349 | @code{SUCCESSFUL} - timer canceled successfully@* |
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350 | @code{INVALID_ID} - invalid timer id |
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351 | |
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352 | @subheading DESCRIPTION: |
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353 | |
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354 | This directive cancels the timer id. This timer will |
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355 | be reinitiated by the next invocation of timer_reset, |
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356 | timer_fire_after, or timer_fire_when with id. |
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357 | |
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358 | @subheading NOTES: |
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359 | |
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360 | This directive will not cause the running task to be preempted. |
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361 | |
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362 | @page |
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363 | @ifinfo |
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364 | @node TIMER_DELETE - Delete a timer, TIMER_FIRE_AFTER - Fire timer after interval, TIMER_CANCEL - Cancel a timer, Timer Manager Directives |
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365 | @end ifinfo |
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366 | @subsection TIMER_DELETE - Delete a timer |
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367 | |
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368 | @subheading CALLING SEQUENCE: |
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369 | |
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370 | @ifset is-C |
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371 | @example |
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372 | rtems_status_code rtems_timer_delete( |
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373 | rtems_id id |
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374 | ); |
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375 | @end example |
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376 | @end ifset |
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377 | |
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378 | @ifset is-Ada |
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379 | @example |
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380 | procedure Timer_Delete ( |
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381 | ID : in RTEMS.ID; |
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382 | Result : out RTEMS.Status_Codes |
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383 | ); |
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384 | @end example |
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385 | @end ifset |
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386 | |
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387 | @subheading DIRECTIVE STATUS CODES: |
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388 | @code{SUCCESSFUL} - timer deleted successfully@* |
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389 | @code{INVALID_ID} - invalid timer id |
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390 | |
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391 | @subheading DESCRIPTION: |
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392 | |
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393 | This directive deletes the timer specified by id. If |
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394 | the timer is running, it is automatically canceled. The TMCB |
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395 | for the deleted timer is reclaimed by RTEMS. |
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396 | |
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397 | @subheading NOTES: |
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398 | |
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399 | This directive will not cause the running task to be |
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400 | preempted. |
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401 | |
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402 | A timer can be deleted by a task other than the task |
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403 | which created the timer. |
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404 | |
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405 | @page |
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406 | @ifinfo |
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407 | @node TIMER_FIRE_AFTER - Fire timer after interval, TIMER_FIRE_WHEN - Fire timer when specified, TIMER_DELETE - Delete a timer, Timer Manager Directives |
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408 | @end ifinfo |
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409 | @subsection TIMER_FIRE_AFTER - Fire timer after interval |
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410 | |
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411 | @subheading CALLING SEQUENCE: |
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412 | |
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413 | @ifset is-C |
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414 | @example |
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415 | rtems_status_code rtems_timer_fire_after( |
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416 | rtems_id id, |
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417 | rtems_interval ticks, |
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418 | rtems_timer_service_routine_entry routine, |
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419 | void *user_data |
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420 | ); |
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421 | @end example |
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422 | @end ifset |
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423 | |
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424 | @ifset is-Ada |
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425 | @example |
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426 | procedure Timer_Fire_After ( |
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427 | ID : in RTEMS.ID; |
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428 | Ticks : in RTEMS.Interval; |
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429 | Routine : in RTEMS.Timer_Service_Routine; |
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430 | User_Data : in RTEMS.Address; |
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431 | Result : out RTEMS.Status_Codes |
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432 | ); |
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433 | @end example |
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434 | @end ifset |
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435 | |
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436 | @subheading DIRECTIVE STATUS CODES: |
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437 | @code{SUCCESSFUL} - timer initiated successfully@* |
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438 | @code{INVALID_ID} - invalid timer id@* |
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439 | @code{INVALID_NUMBER} - invalid interval |
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440 | |
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441 | @subheading DESCRIPTION: |
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442 | |
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443 | This directive initiates the timer specified by id. |
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444 | If the timer is running, it is automatically canceled before |
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445 | being initiated. The timer is scheduled to fire after an |
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446 | interval ticks clock ticks has passed. When the timer fires, |
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447 | the timer service routine routine will be invoked with the |
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448 | argument user_data. |
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449 | |
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450 | @subheading NOTES: |
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451 | |
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452 | This directive will not cause the running task to be |
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453 | preempted. |
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454 | |
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455 | @page |
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456 | @ifinfo |
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457 | @node TIMER_FIRE_WHEN - Fire timer when specified, TIMER_RESET - Reset an interval timer, TIMER_FIRE_AFTER - Fire timer after interval, Timer Manager Directives |
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458 | @end ifinfo |
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459 | @subsection TIMER_FIRE_WHEN - Fire timer when specified |
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460 | |
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461 | @subheading CALLING SEQUENCE: |
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462 | |
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463 | @ifset is-C |
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464 | @example |
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465 | rtems_status_code rtems_timer_fire_when( |
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466 | rtems_id id, |
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467 | rtems_time_of_day *wall_time, |
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468 | rtems_timer_service_routine_entry routine, |
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469 | void *user_data |
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470 | ); |
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471 | @end example |
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472 | @end ifset |
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473 | |
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474 | @ifset is-Ada |
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475 | @example |
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476 | procedure Timer_Fire_When ( |
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477 | ID : in RTEMS.ID; |
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478 | Wall_Time : in RTEMS.Time_Of_Day; |
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479 | Routine : in RTEMS.Timer_Service_Routine; |
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480 | User_Data : in RTEMS.Address; |
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481 | Result : out RTEMS.Status_Codes |
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482 | ); |
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483 | @end example |
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484 | @end ifset |
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485 | |
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486 | @subheading DIRECTIVE STATUS CODES: |
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487 | @code{SUCCESSFUL} - timer initiated successfully@* |
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488 | @code{INVALID_ID} - invalid timer id@* |
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489 | @code{NOT_DEFINED} - system date and time is not set@* |
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490 | @code{INVALID_CLOCK} - invalid time of day |
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491 | |
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492 | @subheading DESCRIPTION: |
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493 | |
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494 | This directive initiates the timer specified by id. |
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495 | If the timer is running, it is automatically canceled before |
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496 | being initiated. The timer is scheduled to fire at the time of |
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497 | day specified by wall_time. When the timer fires, the timer |
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498 | service routine routine will be invoked with the argument |
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499 | user_data. |
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500 | |
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501 | @subheading NOTES: |
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502 | |
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503 | This directive will not cause the running task to be |
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504 | preempted. |
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505 | |
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506 | @page |
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507 | @ifinfo |
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508 | @node TIMER_RESET - Reset an interval timer, Semaphore Manager, TIMER_FIRE_WHEN - Fire timer when specified, Timer Manager Directives |
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509 | @end ifinfo |
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510 | @subsection TIMER_RESET - Reset an interval timer |
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511 | |
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512 | @subheading CALLING SEQUENCE: |
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513 | |
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514 | @ifset is-C |
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515 | @example |
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516 | rtems_status_code rtems_timer_reset( |
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517 | rtems_id id |
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518 | ); |
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519 | @end example |
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520 | @end ifset |
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521 | |
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522 | @ifset is-Ada |
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523 | @example |
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524 | procedure Timer_Reset ( |
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525 | ID : in RTEMS.ID; |
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526 | Result : out RTEMS.Status_Codes |
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527 | ); |
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528 | @end example |
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529 | @end ifset |
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530 | |
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531 | @subheading DIRECTIVE STATUS CODES: |
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532 | @code{SUCCESSFUL} - timer reset successfully@* |
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533 | @code{INVALID_ID} - invalid timer id@* |
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534 | @code{NOT_DEFINED} - attempted to reset a when or newly created timer |
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535 | |
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536 | @subheading DESCRIPTION: |
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537 | |
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538 | This directive resets the timer associated with id. |
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539 | This timer must have been previously initiated with a |
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540 | timer_fire_after directive. If active the timer is canceled, |
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541 | after which the timer is reinitiated using the same interval and |
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542 | timer service routine which the original timer_fire_after |
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543 | directive used. |
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544 | |
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545 | @subheading NOTES: |
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546 | |
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547 | If the timer has not been used or the last usage of this timer |
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548 | was by a timer_fire_when directive, then the NOT_DEFINED error is |
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549 | returned. |
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550 | |
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551 | Restarting a cancelled after timer results in the timer being |
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552 | reinitiated with its previous timer service routine and interval. |
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553 | |
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554 | This directive will not cause the running task to be preempted. |
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555 | |
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