2 * FreeRTOS Kernel V10.2.1
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3 * Copyright (C) 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
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5 * Permission is hereby granted, free of charge, to any person obtaining a copy of
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6 * this software and associated documentation files (the "Software"), to deal in
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7 * the Software without restriction, including without limitation the rights to
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8 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
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9 * the Software, and to permit persons to whom the Software is furnished to do so,
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10 * subject to the following conditions:
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12 * The above copyright notice and this permission notice shall be included in all
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13 * copies or substantial portions of the Software.
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15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
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17 * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
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18 * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
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19 * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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20 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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22 * http://www.FreeRTOS.org
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23 * http://aws.amazon.com/freertos
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25 * 1 tab == 4 spaces!
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29 * Create a single persistent task which periodically dynamically creates another
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30 * four tasks. The original task is called the creator task, the four tasks it
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31 * creates are called suicidal tasks.
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33 * Two of the created suicidal tasks kill one other suicidal task before killing
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34 * themselves - leaving just the original task remaining.
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36 * The creator task must be spawned after all of the other demo application tasks
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37 * as it keeps a check on the number of tasks under the scheduler control. The
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38 * number of tasks it expects to see running should never be greater than the
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39 * number of tasks that were in existence when the creator task was spawned, plus
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40 * one set of four suicidal tasks. If this number is exceeded an error is flagged.
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42 * \page DeathC death.c
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43 * \ingroup DemoFiles
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50 + Delay periods are now specified using variables and constants of
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51 TickType_t rather than unsigned long.
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56 /* Scheduler include files. */
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57 #include "FreeRTOS.h"
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60 /* Demo program include files. */
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64 #define deathSTACK_SIZE ( ( unsigned short ) 512 )
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66 /* The task originally created which is responsible for periodically dynamically
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67 creating another four tasks. */
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68 static void vCreateTasks( void *pvParameters );
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70 /* The task function of the dynamically created tasks. */
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71 static void vSuicidalTask( void *pvParameters );
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73 /* A variable which is incremented every time the dynamic tasks are created. This
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74 is used to check that the task is still running. */
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75 static volatile short sCreationCount = 0;
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77 /* Used to store the number of tasks that were originally running so the creator
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78 task can tell if any of the suicidal tasks have failed to die. */
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79 static volatile unsigned portBASE_TYPE uxTasksRunningAtStart = 0;
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80 static const unsigned portBASE_TYPE uxMaxNumberOfExtraTasksRunning = 5;
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82 /* Used to store a handle to the tasks that should be killed by a suicidal task,
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83 before it kills itself. */
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84 TaskHandle_t xCreatedTask1, xCreatedTask2;
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86 /*-----------------------------------------------------------*/
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88 void vCreateSuicidalTasks( unsigned portBASE_TYPE uxPriority )
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90 unsigned portBASE_TYPE *puxPriority;
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92 /* Create the Creator tasks - passing in as a parameter the priority at which
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93 the suicidal tasks should be created. */
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94 puxPriority = ( unsigned portBASE_TYPE * ) pvPortMalloc( sizeof( unsigned portBASE_TYPE ) );
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95 *puxPriority = uxPriority;
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97 xTaskCreate( vCreateTasks, "CREATOR", deathSTACK_SIZE, ( void * ) puxPriority, uxPriority, NULL );
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99 /* Record the number of tasks that are running now so we know if any of the
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100 suicidal tasks have failed to be killed. */
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101 uxTasksRunningAtStart = uxTaskGetNumberOfTasks();
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103 /*-----------------------------------------------------------*/
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105 static void vSuicidalTask( void *pvParameters )
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108 TaskHandle_t xTaskToKill;
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109 const TickType_t xDelay = ( TickType_t ) 500 / portTICK_PERIOD_MS;
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111 if( pvParameters != NULL )
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113 /* This task is periodically created four times. Tow created tasks are
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114 passed a handle to the other task so it can kill it before killing itself.
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115 The other task is passed in null. */
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116 xTaskToKill = *( TaskHandle_t* )pvParameters;
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120 xTaskToKill = NULL;
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125 /* Do something random just to use some stack and registers. */
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129 vTaskDelay( xDelay );
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131 if( xTaskToKill != NULL )
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133 /* Make sure the other task has a go before we delete it. */
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134 vTaskDelay( ( TickType_t ) 0 );
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135 /* Kill the other task that was created by vCreateTasks(). */
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136 vTaskDelete( xTaskToKill );
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137 /* Kill ourselves. */
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138 vTaskDelete( NULL );
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141 }/*lint !e818 !e550 Function prototype must be as per standard for task functions. */
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142 /*-----------------------------------------------------------*/
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144 static void vCreateTasks( void *pvParameters )
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146 const TickType_t xDelay = ( TickType_t ) 1000 / portTICK_PERIOD_MS;
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147 unsigned portBASE_TYPE uxPriority;
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148 const char * const pcTaskStartMsg = "Create task started.\r\n";
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150 /* Queue a message for printing to say the task has started. */
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151 vPrintDisplayMessage( &pcTaskStartMsg );
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153 uxPriority = *( unsigned portBASE_TYPE * ) pvParameters;
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154 vPortFree( pvParameters );
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158 /* Just loop round, delaying then creating the four suicidal tasks. */
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159 vTaskDelay( xDelay );
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161 xTaskCreate( vSuicidalTask, "SUICIDE1", deathSTACK_SIZE, NULL, uxPriority, &xCreatedTask1 );
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162 xTaskCreate( vSuicidalTask, "SUICIDE2", deathSTACK_SIZE, &xCreatedTask1, uxPriority, NULL );
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164 xTaskCreate( vSuicidalTask, "SUICIDE1", deathSTACK_SIZE, NULL, uxPriority, &xCreatedTask2 );
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165 xTaskCreate( vSuicidalTask, "SUICIDE2", deathSTACK_SIZE, &xCreatedTask2, uxPriority, NULL );
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170 /*-----------------------------------------------------------*/
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172 /* This is called to check that the creator task is still running and that there
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173 are not any more than four extra tasks. */
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174 portBASE_TYPE xIsCreateTaskStillRunning( void )
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176 static short sLastCreationCount = 0;
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177 short sReturn = pdTRUE;
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178 unsigned portBASE_TYPE uxTasksRunningNow;
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180 if( sLastCreationCount == sCreationCount )
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185 uxTasksRunningNow = uxTaskGetNumberOfTasks();
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187 if( uxTasksRunningNow < uxTasksRunningAtStart )
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191 else if( ( uxTasksRunningNow - uxTasksRunningAtStart ) > uxMaxNumberOfExtraTasksRunning )
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197 /* Everything is okay. */
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