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FreeRTOS V7.4.1 - Copyright (C) 2013 Real Time Engineers Ltd.
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This file is part of the FreeRTOS distribution.
FreeRTOS is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License (version 2) as published by the
Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
>>>>>>NOTE<<<<<< The modification to the GPL is included to allow you to
distribute a combined work that includes FreeRTOS without being obliged to
provide the source code for proprietary components outside of the FreeRTOS
FreeRTOS is distributed in the hope that it will be useful, but WITHOUT ANY
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FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
details. You should have received a copy of the GNU General Public License
and the FreeRTOS license exception along with FreeRTOS; if not it can be
viewed here: and also obtained by
writing to Real Time Engineers Ltd., contact details for whom are available
on the FreeRTOS WEB site.
1 tab == 4 spaces!
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* Having a problem? Start by reading the FAQ "My application does *
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*************************************************************************** - Documentation, books, training, latest versions,
license and Real Time Engineers Ltd. contact details. - A selection of FreeRTOS ecosystem products,
including FreeRTOS+Trace - an indispensable productivity tool, and our new
fully thread aware and reentrant UDP/IP stack. - Real Time Engineers ltd license FreeRTOS to High
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indemnification and middleware, under the OpenRTOS brand. - High Integrity Systems also provide a safety
engineered and independently SIL3 certified version for use in safety and
mission critical applications that require provable dependability.
* Create a single persistent task which periodically dynamically creates another
* four tasks. The original task is called the creator task, the four tasks it
* creates are called suicidal tasks.
* Two of the created suicidal tasks kill one other suicidal task before killing
* themselves - leaving just the original task remaining.
* The creator task must be spawned after all of the other demo application tasks
* as it keeps a check on the number of tasks under the scheduler control. The
* number of tasks it expects to see running should never be greater than the
* number of tasks that were in existence when the creator task was spawned, plus
* one set of four suicidal tasks. If this number is exceeded an error is flagged.
* \page DeathC death.c
* \ingroup DemoFiles
* <HR>
Changes from V2.0.0
+ Delay periods are now specified using variables and constants of
portTickType rather than unsigned long.
#include <stdlib.h>
/* Scheduler include files. */
#include "FreeRTOS.h"
#include "task.h"
/* Demo program include files. */
#include "death.h"
#include "print.h"
#define deathSTACK_SIZE ( ( unsigned short ) 512 )
/* The task originally created which is responsible for periodically dynamically
creating another four tasks. */
static void vCreateTasks( void *pvParameters );
/* The task function of the dynamically created tasks. */
static void vSuicidalTask( void *pvParameters );
/* A variable which is incremented every time the dynamic tasks are created. This
is used to check that the task is still running. */
static volatile short sCreationCount = 0;
/* Used to store the number of tasks that were originally running so the creator
task can tell if any of the suicidal tasks have failed to die. */
static volatile unsigned portBASE_TYPE uxTasksRunningAtStart = 0;
static const unsigned portBASE_TYPE uxMaxNumberOfExtraTasksRunning = 5;
/* Used to store a handle to the tasks that should be killed by a suicidal task,
before it kills itself. */
xTaskHandle xCreatedTask1, xCreatedTask2;
void vCreateSuicidalTasks( unsigned portBASE_TYPE uxPriority )
unsigned portBASE_TYPE *puxPriority;
/* Create the Creator tasks - passing in as a parameter the priority at which
the suicidal tasks should be created. */
puxPriority = ( unsigned portBASE_TYPE * ) pvPortMalloc( sizeof( unsigned portBASE_TYPE ) );
*puxPriority = uxPriority;
xTaskCreate( vCreateTasks, "CREATOR", deathSTACK_SIZE, ( void * ) puxPriority, uxPriority, NULL );
/* Record the number of tasks that are running now so we know if any of the
suicidal tasks have failed to be killed. */
uxTasksRunningAtStart = uxTaskGetNumberOfTasks();
static void vSuicidalTask( void *pvParameters )
portDOUBLE d1, d2;
xTaskHandle xTaskToKill;
const portTickType xDelay = ( portTickType ) 500 / portTICK_RATE_MS;
if( pvParameters != NULL )
/* This task is periodically created four times. Tow created tasks are
passed a handle to the other task so it can kill it before killing itself.
The other task is passed in null. */
xTaskToKill = *( xTaskHandle* )pvParameters;
xTaskToKill = NULL;
for( ;; )
/* Do something random just to use some stack and registers. */
d1 = 2.4;
d2 = 89.2;
d2 *= d1;
vTaskDelay( xDelay );
if( xTaskToKill != NULL )
/* Make sure the other task has a go before we delete it. */
vTaskDelay( ( portTickType ) 0 );
/* Kill the other task that was created by vCreateTasks(). */
vTaskDelete( xTaskToKill );
/* Kill ourselves. */
vTaskDelete( NULL );
}/*lint !e818 !e550 Function prototype must be as per standard for task functions. */
static void vCreateTasks( void *pvParameters )
const portTickType xDelay = ( portTickType ) 1000 / portTICK_RATE_MS;
unsigned portBASE_TYPE uxPriority;
const char * const pcTaskStartMsg = "Create task started.\r\n";
/* Queue a message for printing to say the task has started. */
vPrintDisplayMessage( &pcTaskStartMsg );
uxPriority = *( unsigned portBASE_TYPE * ) pvParameters;
vPortFree( pvParameters );
for( ;; )
/* Just loop round, delaying then creating the four suicidal tasks. */
vTaskDelay( xDelay );
xTaskCreate( vSuicidalTask, "SUICIDE1", deathSTACK_SIZE, NULL, uxPriority, &xCreatedTask1 );
xTaskCreate( vSuicidalTask, "SUICIDE2", deathSTACK_SIZE, &xCreatedTask1, uxPriority, NULL );
xTaskCreate( vSuicidalTask, "SUICIDE1", deathSTACK_SIZE, NULL, uxPriority, &xCreatedTask2 );
xTaskCreate( vSuicidalTask, "SUICIDE2", deathSTACK_SIZE, &xCreatedTask2, uxPriority, NULL );
/* This is called to check that the creator task is still running and that there
are not any more than four extra tasks. */
portBASE_TYPE xIsCreateTaskStillRunning( void )
static short sLastCreationCount = 0;
short sReturn = pdTRUE;
unsigned portBASE_TYPE uxTasksRunningNow;
if( sLastCreationCount == sCreationCount )
sReturn = pdFALSE;
uxTasksRunningNow = uxTaskGetNumberOfTasks();
if( uxTasksRunningNow < uxTasksRunningAtStart )
sReturn = pdFALSE;
else if( ( uxTasksRunningNow - uxTasksRunningAtStart ) > uxMaxNumberOfExtraTasksRunning )
sReturn = pdFALSE;
/* Everything is okay. */
return sReturn;