2 * FreeRTOS Kernel V10.0.0
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3 * Copyright (C) 2017 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. If you wish to use our Amazon
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14 * FreeRTOS name, please do so in a fair use way that does not cause confusion.
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16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
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18 * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
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19 * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
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20 * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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21 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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23 * http://www.FreeRTOS.org
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24 * http://aws.amazon.com/freertos
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26 * 1 tab == 4 spaces!
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30 * Create a single persistent task which periodically dynamically creates another
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31 * four tasks. The original task is called the creator task, the four tasks it
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32 * creates are called suicidal tasks.
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34 * Two of the created suicidal tasks kill one other suicidal task before killing
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35 * themselves - leaving just the original task remaining.
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37 * The creator task must be spawned after all of the other demo application tasks
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38 * as it keeps a check on the number of tasks under the scheduler control. The
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39 * number of tasks it expects to see running should never be greater than the
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40 * number of tasks that were in existence when the creator task was spawned, plus
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41 * one set of four suicidal tasks. If this number is exceeded an error is flagged.
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43 * \page DeathC death.c
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44 * \ingroup DemoFiles
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51 + Delay periods are now specified using variables and constants of
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52 TickType_t rather than unsigned long.
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57 /* Scheduler include files. */
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58 #include "FreeRTOS.h"
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61 /* Demo program include files. */
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65 #define deathSTACK_SIZE ( ( unsigned short ) 512 )
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67 /* The task originally created which is responsible for periodically dynamically
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68 creating another four tasks. */
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69 static void vCreateTasks( void *pvParameters );
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71 /* The task function of the dynamically created tasks. */
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72 static void vSuicidalTask( void *pvParameters );
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74 /* A variable which is incremented every time the dynamic tasks are created. This
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75 is used to check that the task is still running. */
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76 static volatile short sCreationCount = 0;
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78 /* Used to store the number of tasks that were originally running so the creator
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79 task can tell if any of the suicidal tasks have failed to die. */
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80 static volatile unsigned portBASE_TYPE uxTasksRunningAtStart = 0;
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81 static const unsigned portBASE_TYPE uxMaxNumberOfExtraTasksRunning = 5;
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83 /* Used to store a handle to the tasks that should be killed by a suicidal task,
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84 before it kills itself. */
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85 TaskHandle_t xCreatedTask1, xCreatedTask2;
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87 /*-----------------------------------------------------------*/
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89 void vCreateSuicidalTasks( unsigned portBASE_TYPE uxPriority )
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91 unsigned portBASE_TYPE *puxPriority;
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93 /* Create the Creator tasks - passing in as a parameter the priority at which
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94 the suicidal tasks should be created. */
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95 puxPriority = ( unsigned portBASE_TYPE * ) pvPortMalloc( sizeof( unsigned portBASE_TYPE ) );
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96 *puxPriority = uxPriority;
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98 xTaskCreate( vCreateTasks, "CREATOR", deathSTACK_SIZE, ( void * ) puxPriority, uxPriority, NULL );
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100 /* Record the number of tasks that are running now so we know if any of the
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101 suicidal tasks have failed to be killed. */
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102 uxTasksRunningAtStart = uxTaskGetNumberOfTasks();
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104 /*-----------------------------------------------------------*/
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106 static void vSuicidalTask( void *pvParameters )
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109 TaskHandle_t xTaskToKill;
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110 const TickType_t xDelay = ( TickType_t ) 500 / portTICK_PERIOD_MS;
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112 if( pvParameters != NULL )
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114 /* This task is periodically created four times. Tow created tasks are
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115 passed a handle to the other task so it can kill it before killing itself.
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116 The other task is passed in null. */
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117 xTaskToKill = *( TaskHandle_t* )pvParameters;
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121 xTaskToKill = NULL;
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126 /* Do something random just to use some stack and registers. */
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130 vTaskDelay( xDelay );
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132 if( xTaskToKill != NULL )
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134 /* Make sure the other task has a go before we delete it. */
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135 vTaskDelay( ( TickType_t ) 0 );
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136 /* Kill the other task that was created by vCreateTasks(). */
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137 vTaskDelete( xTaskToKill );
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138 /* Kill ourselves. */
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139 vTaskDelete( NULL );
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142 }/*lint !e818 !e550 Function prototype must be as per standard for task functions. */
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143 /*-----------------------------------------------------------*/
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145 static void vCreateTasks( void *pvParameters )
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147 const TickType_t xDelay = ( TickType_t ) 1000 / portTICK_PERIOD_MS;
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148 unsigned portBASE_TYPE uxPriority;
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149 const char * const pcTaskStartMsg = "Create task started.\r\n";
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151 /* Queue a message for printing to say the task has started. */
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152 vPrintDisplayMessage( &pcTaskStartMsg );
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154 uxPriority = *( unsigned portBASE_TYPE * ) pvParameters;
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155 vPortFree( pvParameters );
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159 /* Just loop round, delaying then creating the four suicidal tasks. */
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160 vTaskDelay( xDelay );
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162 xTaskCreate( vSuicidalTask, "SUICIDE1", deathSTACK_SIZE, NULL, uxPriority, &xCreatedTask1 );
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163 xTaskCreate( vSuicidalTask, "SUICIDE2", deathSTACK_SIZE, &xCreatedTask1, uxPriority, NULL );
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165 xTaskCreate( vSuicidalTask, "SUICIDE1", deathSTACK_SIZE, NULL, uxPriority, &xCreatedTask2 );
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166 xTaskCreate( vSuicidalTask, "SUICIDE2", deathSTACK_SIZE, &xCreatedTask2, uxPriority, NULL );
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171 /*-----------------------------------------------------------*/
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173 /* This is called to check that the creator task is still running and that there
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174 are not any more than four extra tasks. */
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175 portBASE_TYPE xIsCreateTaskStillRunning( void )
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177 static short sLastCreationCount = 0;
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178 short sReturn = pdTRUE;
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179 unsigned portBASE_TYPE uxTasksRunningNow;
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181 if( sLastCreationCount == sCreationCount )
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186 uxTasksRunningNow = uxTaskGetNumberOfTasks();
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188 if( uxTasksRunningNow < uxTasksRunningAtStart )
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192 else if( ( uxTasksRunningNow - uxTasksRunningAtStart ) > uxMaxNumberOfExtraTasksRunning )
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198 /* Everything is okay. */
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