root/webserver/example/freeRTOSexample/Demo/Common/Full/death.c

/*
        FreeRTOS V5.4.1 - Copyright (C) 2009 Real Time Engineers Ltd.

        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 exception 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 kernel.  
        Alternative commercial license and support terms are also available upon 
        request.  See the licensing section of http://www.FreeRTOS.org for full 
        license details.

        FreeRTOS is distributed in the hope that it will be useful,     but WITHOUT
        ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
        FITNESS 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 along
        with FreeRTOS; if not, write to the Free Software Foundation, Inc., 59
        Temple Place, Suite 330, Boston, MA  02111-1307  USA.


        ***************************************************************************
        *                                                                         *
        * Looking for a quick start?  Then check out the FreeRTOS eBook!          *
        * See http://www.FreeRTOS.org/Documentation for details                   *
        *                                                                         *
        ***************************************************************************

        1 tab == 4 spaces!

        Please ensure to read the configuration and relevant port sections of the
        online documentation.

        http://www.FreeRTOS.org - Documentation, latest information, license and
        contact details.

        http://www.SafeRTOS.com - A version that is certified for use in safety
        critical systems.

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*/

/**
 * 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 portLONG.
*/

#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 portSHORT ) 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 portSHORT 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;
        }
        else
        {
                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 portCHAR * 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 );

                ++sCreationCount;
        }
}
/*-----------------------------------------------------------*/

/* 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 portSHORT sLastCreationCount = 0;
portSHORT 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;
        }
        else
        {
                /* Everything is okay. */
        }

        return sReturn;
}