FreeRTOS/Common/Full/death.c

   1 /*
   2     FreeRTOS V6.0.5 - Copyright (C) 2010 Real Time Engineers Ltd.
   3
   4     ***************************************************************************
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  24
  25     This file is part of the FreeRTOS distribution.
  26
  27     FreeRTOS is free software; you can redistribute it and/or modify it under
  28     the terms of the GNU General Public License (version 2) as published by the
  29     Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
  30     ***NOTE*** The exception to the GPL is included to allow you to distribute
  31     a combined work that includes FreeRTOS without being obliged to provide the
  32     source code for proprietary components outside of the FreeRTOS kernel.
  33     FreeRTOS is distributed in the hope that it will be useful, but WITHOUT
  34     ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  35     FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  36     more details. You should have received a copy of the GNU General Public
  37     License and the FreeRTOS license exception along with FreeRTOS; if not it
  38     can be viewed here: http://www.freertos.org/a00114.html and also obtained
  39     by writing to Richard Barry, contact details for whom are available on the
  40     FreeRTOS WEB site.
  41
  42     1 tab == 4 spaces!
  43
  44     http://www.FreeRTOS.org - Documentation, latest information, license and
  45     contact details.
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  48     critical systems.
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  51     licensing and training services.
  52 */
  53
  54 /**
  55  * Create a single persistent task which periodically dynamically creates another
  56  * four tasks.  The original task is called the creator task, the four tasks it
  57  * creates are called suicidal tasks.
  58  *
  59  * Two of the created suicidal tasks kill one other suicidal task before killing
  60  * themselves - leaving just the original task remaining.
  61  *
  62  * The creator task must be spawned after all of the other demo application tasks
  63  * as it keeps a check on the number of tasks under the scheduler control.  The
  64  * number of tasks it expects to see running should never be greater than the
  65  * number of tasks that were in existence when the creator task was spawned, plus
  66  * one set of four suicidal tasks.  If this number is exceeded an error is flagged.
  67  *
  68  * \page DeathC death.c
  69  * \ingroup DemoFiles
  70  * <HR>
  71  */
  72
  73 /*
  74 Changes from V2.0.0
  75
  76         + Delay periods are now specified using variables and constants of
  77           portTickType rather than unsigned long.
  78 */
  79
  80 #include <stdlib.h>
  81
  82 /* Scheduler include files. */
  83 #include "FreeRTOS.h"
  84 #include "task.h"
  85
  86 /* Demo program include files. */
  87 #include "death.h"
  88 #include "print.h"
  89
  90 #define deathSTACK_SIZE         ( ( unsigned short ) 512 )
  91
  92 /* The task originally created which is responsible for periodically dynamically
  93 creating another four tasks. */
  94 static void vCreateTasks( void *pvParameters );
  95
  96 /* The task function of the dynamically created tasks. */
  97 static void vSuicidalTask( void *pvParameters );
  98
  99 /* A variable which is incremented every time the dynamic tasks are created.  This
 100 is used to check that the task is still running. */
 101 static volatile short sCreationCount = 0;
 102
 103 /* Used to store the number of tasks that were originally running so the creator
 104 task can tell if any of the suicidal tasks have failed to die. */
 105 static volatile unsigned portBASE_TYPE uxTasksRunningAtStart = 0;
 106 static const unsigned portBASE_TYPE uxMaxNumberOfExtraTasksRunning = 5;
 107
 108 /* Used to store a handle to the tasks that should be killed by a suicidal task,
 109 before it kills itself. */
 110 xTaskHandle xCreatedTask1, xCreatedTask2;
 111
 112 /*-----------------------------------------------------------*/
 113
 114 void vCreateSuicidalTasks( unsigned portBASE_TYPE uxPriority )
 115 {
 116 unsigned portBASE_TYPE *puxPriority;
 117
 118         /* Create the Creator tasks - passing in as a parameter the priority at which
 119         the suicidal tasks should be created. */
 120         puxPriority = ( unsigned portBASE_TYPE * ) pvPortMalloc( sizeof( unsigned portBASE_TYPE ) );
 121         *puxPriority = uxPriority;
 122
 123         xTaskCreate( vCreateTasks, "CREATOR", deathSTACK_SIZE, ( void * ) puxPriority, uxPriority, NULL );
 124
 125         /* Record the number of tasks that are running now so we know if any of the
 126         suicidal tasks have failed to be killed. */
 127         uxTasksRunningAtStart = uxTaskGetNumberOfTasks();
 128 }
 129 /*-----------------------------------------------------------*/
 130
 131 static void vSuicidalTask( void *pvParameters )
 132 {
 133 portDOUBLE d1, d2;
 134 xTaskHandle xTaskToKill;
 135 const portTickType xDelay = ( portTickType ) 500 / portTICK_RATE_MS;
 136
 137         if( pvParameters != NULL )
 138         {
 139                 /* This task is periodically created four times.  Tow created tasks are
 140                 passed a handle to the other task so it can kill it before killing itself.
 141                 The other task is passed in null. */
 142                 xTaskToKill = *( xTaskHandle* )pvParameters;
 143         }
 144         else
 145         {
 146                 xTaskToKill = NULL;
 147         }
 148
 149         for( ;; )
 150         {
 151                 /* Do something random just to use some stack and registers. */
 152                 d1 = 2.4;
 153                 d2 = 89.2;
 154                 d2 *= d1;
 155                 vTaskDelay( xDelay );
 156
 157                 if( xTaskToKill != NULL )
 158                 {
 159                         /* Make sure the other task has a go before we delete it. */
 160                         vTaskDelay( ( portTickType ) 0 );
 161                         /* Kill the other task that was created by vCreateTasks(). */
 162                         vTaskDelete( xTaskToKill );
 163                         /* Kill ourselves. */
 164                         vTaskDelete( NULL );
 165                 }
 166         }
 167 }/*lint !e818 !e550 Function prototype must be as per standard for task functions. */
 168 /*-----------------------------------------------------------*/
 169
 170 static void vCreateTasks( void *pvParameters )
 171 {
 172 const portTickType xDelay = ( portTickType ) 1000 / portTICK_RATE_MS;
 173 unsigned portBASE_TYPE uxPriority;
 174 const char * const pcTaskStartMsg = "Create task started.\r\n";
 175
 176         /* Queue a message for printing to say the task has started. */
 177         vPrintDisplayMessage( &pcTaskStartMsg );
 178
 179         uxPriority = *( unsigned portBASE_TYPE * ) pvParameters;
 180         vPortFree( pvParameters );
 181
 182         for( ;; )
 183         {
 184                 /* Just loop round, delaying then creating the four suicidal tasks. */
 185                 vTaskDelay( xDelay );
 186
 187                 xTaskCreate( vSuicidalTask, "SUICIDE1", deathSTACK_SIZE, NULL, uxPriority, &xCreatedTask1 );
 188                 xTaskCreate( vSuicidalTask, "SUICIDE2", deathSTACK_SIZE, &xCreatedTask1, uxPriority, NULL );
 189
 190                 xTaskCreate( vSuicidalTask, "SUICIDE1", deathSTACK_SIZE, NULL, uxPriority, &xCreatedTask2 );
 191                 xTaskCreate( vSuicidalTask, "SUICIDE2", deathSTACK_SIZE, &xCreatedTask2, uxPriority, NULL );
 192
 193                 ++sCreationCount;
 194         }
 195 }
 196 /*-----------------------------------------------------------*/
 197
 198 /* This is called to check that the creator task is still running and that there
 199 are not any more than four extra tasks. */
 200 portBASE_TYPE xIsCreateTaskStillRunning( void )
 201 {
 202 static short sLastCreationCount = 0;
 203 short sReturn = pdTRUE;
 204 unsigned portBASE_TYPE uxTasksRunningNow;
 205
 206         if( sLastCreationCount == sCreationCount )
 207         {
 208                 sReturn = pdFALSE;
 209         }
 210
 211         uxTasksRunningNow = uxTaskGetNumberOfTasks();
 212
 213         if( uxTasksRunningNow < uxTasksRunningAtStart )
 214         {
 215                 sReturn = pdFALSE;
 216         }
 217         else if( ( uxTasksRunningNow - uxTasksRunningAtStart ) > uxMaxNumberOfExtraTasksRunning )
 218         {
 219                 sReturn = pdFALSE;
 220         }
 221         else
 222         {
 223                 /* Everything is okay. */
 224         }
 225
 226         return sReturn;
 227 }
 228
 229