FreeRTOS/Demo/Common/Full/flop.c - nest-detect/1.0.2/freertos - Git at Google

 /*
     FreeRTOS V8.0.1 - Copyright (C) 2014 Real Time Engineers Ltd.
     All rights reserved

     VISIT http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION.

     ***************************************************************************
      *                                                                       *
      *    FreeRTOS provides completely free yet professionally developed,    *
      *    robust, strictly quality controlled, supported, and cross          *
      *    platform software that has become a de facto standard.             *
      *                                                                       *
      *    Help yourself get started quickly and support the FreeRTOS         *
      *    project by purchasing a FreeRTOS tutorial book, reference          *
      *    manual, or both from: http://www.FreeRTOS.org/Documentation        *
      *                                                                       *
      *    Thank you!                                                         *
      *                                                                       *
     ***************************************************************************

     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 kernel.                                   !<<

     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.  Full license text is available from the following
     link: http://www.freertos.org/a00114.html

     1 tab == 4 spaces!

     ***************************************************************************
      *                                                                       *
      *    Having a problem?  Start by reading the FAQ "My application does   *
      *    not run, what could be wrong?"                                     *
      *                                                                       *
      *    http://www.FreeRTOS.org/FAQHelp.html                               *
      *                                                                       *
     ***************************************************************************

     http://www.FreeRTOS.org - Documentation, books, training, latest versions,
     license and Real Time Engineers Ltd. contact details.

     http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
     including FreeRTOS+Trace - an indispensable productivity tool, a DOS
     compatible FAT file system, and our tiny thread aware UDP/IP stack.

     http://www.OpenRTOS.com - Real Time Engineers ltd license FreeRTOS to High
     Integrity Systems to sell under the OpenRTOS brand.  Low cost OpenRTOS
     licenses offer ticketed support, indemnification and middleware.

     http://www.SafeRTOS.com - 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.

     1 tab == 4 spaces!
 */

 /*
 Changes from V1.2.3

 	+ The created tasks now include calls to tskYIELD(), allowing them to be used
 	  with the cooperative scheduler.
 */

 /**
  * Creates eight tasks, each of which loops continuously performing an (emulated)
  * floating point calculation.
  *
  * All the tasks run at the idle priority and never block or yield.  This causes
  * all eight tasks to time slice with the idle task.  Running at the idle priority
  * means that these tasks will get pre-empted any time another task is ready to run
  * or a time slice occurs.  More often than not the pre-emption will occur mid
  * calculation, creating a good test of the schedulers context switch mechanism - a
  * calculation producing an unexpected result could be a symptom of a corruption in
  * the context of a task.
  *
  * \page FlopC flop.c
  * \ingroup DemoFiles
  * <HR>
  */

 #include <stdlib.h>
 #include <math.h>

 /* Scheduler include files. */
 #include "FreeRTOS.h"
 #include "task.h"
 #include "print.h"

 /* Demo program include files. */
 #include "flop.h"

 #define mathSTACK_SIZE		( ( unsigned short ) 512 )
 #define mathNUMBER_OF_TASKS  ( 8 )

 /* Four tasks, each of which performs a different floating point calculation.
 Each of the four is created twice. */
 static void vCompetingMathTask1( void *pvParameters );
 static void vCompetingMathTask2( void *pvParameters );
 static void vCompetingMathTask3( void *pvParameters );
 static void vCompetingMathTask4( void *pvParameters );

 /* These variables are used to check that all the tasks are still running.  If a
 task gets a calculation wrong it will
 stop incrementing its check variable. */
 static volatile unsigned short usTaskCheck[ mathNUMBER_OF_TASKS ] = { ( unsigned short ) 0 };

 /*-----------------------------------------------------------*/

 void vStartMathTasks( unsigned portBASE_TYPE uxPriority )
 {
 	xTaskCreate( vCompetingMathTask1, "Math1", mathSTACK_SIZE, ( void * ) &( usTaskCheck[ 0 ] ), uxPriority, NULL );
 	xTaskCreate( vCompetingMathTask2, "Math2", mathSTACK_SIZE, ( void * ) &( usTaskCheck[ 1 ] ), uxPriority, NULL );
 	xTaskCreate( vCompetingMathTask3, "Math3", mathSTACK_SIZE, ( void * ) &( usTaskCheck[ 2 ] ), uxPriority, NULL );
 	xTaskCreate( vCompetingMathTask4, "Math4", mathSTACK_SIZE, ( void * ) &( usTaskCheck[ 3 ] ), uxPriority, NULL );
 	xTaskCreate( vCompetingMathTask1, "Math5", mathSTACK_SIZE, ( void * ) &( usTaskCheck[ 4 ] ), uxPriority, NULL );
 	xTaskCreate( vCompetingMathTask2, "Math6", mathSTACK_SIZE, ( void * ) &( usTaskCheck[ 5 ] ), uxPriority, NULL );
 	xTaskCreate( vCompetingMathTask3, "Math7", mathSTACK_SIZE, ( void * ) &( usTaskCheck[ 6 ] ), uxPriority, NULL );
 	xTaskCreate( vCompetingMathTask4, "Math8", mathSTACK_SIZE, ( void * ) &( usTaskCheck[ 7 ] ), uxPriority, NULL );
 }
 /*-----------------------------------------------------------*/

 static void vCompetingMathTask1( void *pvParameters )
 {
 portDOUBLE d1, d2, d3, d4;
 volatile unsigned short *pusTaskCheckVariable;
 const portDOUBLE dAnswer = ( 123.4567 + 2345.6789 ) * -918.222;
 const char * const pcTaskStartMsg = "Math task 1 started.\r\n";
 const char * const pcTaskFailMsg = "Math task 1 failed.\r\n";
 short sError = pdFALSE;

 	/* Queue a message for printing to say the task has started. */
 	vPrintDisplayMessage( &pcTaskStartMsg );

 	/* The variable this task increments to show it is still running is passed in
 	as the parameter. */
 	pusTaskCheckVariable = ( unsigned short * ) pvParameters;

 	/* Keep performing a calculation and checking the result against a constant. */
 	for(;;)
 	{
 		d1 = 123.4567;
 		d2 = 2345.6789;
 		d3 = -918.222;

 		d4 = ( d1 + d2 ) * d3;

 		taskYIELD();

 		/* If the calculation does not match the expected constant, stop the
 		increment of the check variable. */
 		if( fabs( d4 - dAnswer ) > 0.001 )
 		{
 			vPrintDisplayMessage( &pcTaskFailMsg );
 			sError = pdTRUE;
 		}

 		if( sError == pdFALSE )
 		{
 			/* If the calculation has always been correct, increment the check
 			variable so we know this task is still running okay. */
 			( *pusTaskCheckVariable )++;
 		}

 		taskYIELD();
 	}
 }
 /*-----------------------------------------------------------*/

 static void vCompetingMathTask2( void *pvParameters )
 {
 portDOUBLE d1, d2, d3, d4;
 volatile unsigned short *pusTaskCheckVariable;
 const portDOUBLE dAnswer = ( -389.38 / 32498.2 ) * -2.0001;
 const char * const pcTaskStartMsg = "Math task 2 started.\r\n";
 const char * const pcTaskFailMsg = "Math task 2 failed.\r\n";
 short sError = pdFALSE;

 	/* Queue a message for printing to say the task has started. */
 	vPrintDisplayMessage( &pcTaskStartMsg );

 	/* The variable this task increments to show it is still running is passed in
 	as the parameter. */
 	pusTaskCheckVariable = ( unsigned short * ) pvParameters;

 	/* Keep performing a calculation and checking the result against a constant. */
 	for( ;; )
 	{
 		d1 = -389.38;
 		d2 = 32498.2;
 		d3 = -2.0001;

 		d4 = ( d1 / d2 ) * d3;

 		taskYIELD();

 		/* If the calculation does not match the expected constant, stop the
 		increment of the check variable. */
 		if( fabs( d4 - dAnswer ) > 0.001 )
 		{
 			vPrintDisplayMessage( &pcTaskFailMsg );
 			sError = pdTRUE;
 		}

 		if( sError == pdFALSE )
 		{
 			/* If the calculation has always been correct, increment the check
 			variable so we know
 			this task is still running okay. */
 			( *pusTaskCheckVariable )++;
 		}

 		taskYIELD();
 	}
 }
 /*-----------------------------------------------------------*/

 static void vCompetingMathTask3( void *pvParameters )
 {
 portDOUBLE *pdArray, dTotal1, dTotal2, dDifference;
 volatile unsigned short *pusTaskCheckVariable;
 const unsigned short usArraySize = 250;
 unsigned short usPosition;
 const char * const pcTaskStartMsg = "Math task 3 started.\r\n";
 const char * const pcTaskFailMsg = "Math task 3 failed.\r\n";
 short sError = pdFALSE;

 	/* Queue a message for printing to say the task has started. */
 	vPrintDisplayMessage( &pcTaskStartMsg );

 	/* The variable this task increments to show it is still running is passed in
 	as the parameter. */
 	pusTaskCheckVariable = ( unsigned short * ) pvParameters;

 	pdArray = ( portDOUBLE * ) pvPortMalloc( ( size_t ) 250 * sizeof( portDOUBLE ) );

 	/* Keep filling an array, keeping a running total of the values placed in the
 	array.  Then run through the array adding up all the values.  If the two totals
 	do not match, stop the check variable from incrementing. */
 	for( ;; )
 	{
 		dTotal1 = 0.0;
 		dTotal2 = 0.0;

 		for( usPosition = 0; usPosition < usArraySize; usPosition++ )
 		{
 			pdArray[ usPosition ] = ( portDOUBLE ) usPosition + 5.5;
 			dTotal1 += ( portDOUBLE ) usPosition + 5.5;
 		}

 		taskYIELD();

 		for( usPosition = 0; usPosition < usArraySize; usPosition++ )
 		{
 			dTotal2 += pdArray[ usPosition ];
 		}

 		dDifference = dTotal1 - dTotal2;
 		if( fabs( dDifference ) > 0.001 )
 		{
 			vPrintDisplayMessage( &pcTaskFailMsg );
 			sError = pdTRUE;
 		}

 		taskYIELD();

 		if( sError == pdFALSE )
 		{
 			/* If the calculation has always been correct, increment the check
 			variable so we know	this task is still running okay. */
 			( *pusTaskCheckVariable )++;
 		}
 	}
 }
 /*-----------------------------------------------------------*/

 static void vCompetingMathTask4( void *pvParameters )
 {
 portDOUBLE *pdArray, dTotal1, dTotal2, dDifference;
 volatile unsigned short *pusTaskCheckVariable;
 const unsigned short usArraySize = 250;
 unsigned short usPosition;
 const char * const pcTaskStartMsg = "Math task 4 started.\r\n";
 const char * const pcTaskFailMsg = "Math task 4 failed.\r\n";
 short sError = pdFALSE;

 	/* Queue a message for printing to say the task has started. */
 	vPrintDisplayMessage( &pcTaskStartMsg );

 	/* The variable this task increments to show it is still running is passed in
 	as the parameter. */
 	pusTaskCheckVariable = ( unsigned short * ) pvParameters;

 	pdArray = ( portDOUBLE * ) pvPortMalloc( ( size_t ) 250 * sizeof( portDOUBLE ) );

 	/* Keep filling an array, keeping a running total of the values placed in the
 	array.  Then run through the array adding up all the values.  If the two totals
 	do not match, stop the check variable from incrementing. */
 	for( ;; )
 	{
 		dTotal1 = 0.0;
 		dTotal2 = 0.0;

 		for( usPosition = 0; usPosition < usArraySize; usPosition++ )
 		{
 			pdArray[ usPosition ] = ( portDOUBLE ) usPosition * 12.123;
 			dTotal1 += ( portDOUBLE ) usPosition * 12.123;
 		}

 		taskYIELD();

 		for( usPosition = 0; usPosition < usArraySize; usPosition++ )
 		{
 			dTotal2 += pdArray[ usPosition ];
 		}

 		dDifference = dTotal1 - dTotal2;
 		if( fabs( dDifference ) > 0.001 )
 		{
 			vPrintDisplayMessage( &pcTaskFailMsg );
 			sError = pdTRUE;
 		}

 		taskYIELD();

 		if( sError == pdFALSE )
 		{
 			/* If the calculation has always been correct, increment the check
 			variable so we know	this task is still running okay. */
 			( *pusTaskCheckVariable )++;
 		}
 	}
 }
 /*-----------------------------------------------------------*/

 /* This is called to check that all the created tasks are still running. */
 portBASE_TYPE xAreMathsTaskStillRunning( void )
 {
 /* Keep a history of the check variables so we know if they have been incremented
 since the last call. */
 static unsigned short usLastTaskCheck[ mathNUMBER_OF_TASKS ] = { ( unsigned short ) 0 };
 portBASE_TYPE xReturn = pdTRUE, xTask;

 	/* Check the maths tasks are still running by ensuring their check variables
 	are still incrementing. */
 	for( xTask = 0; xTask < mathNUMBER_OF_TASKS; xTask++ )
 	{
 		if( usTaskCheck[ xTask ] == usLastTaskCheck[ xTask ] )
 		{
 			/* The check has not incremented so an error exists. */
 			xReturn = pdFALSE;
 		}

 		usLastTaskCheck[ xTask ] = usTaskCheck[ xTask ];
 	}

 	return xReturn;
 }
	/*
	FreeRTOS V8.0.1 - Copyright (C) 2014 Real Time Engineers Ltd.
	All rights reserved

	VISIT http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION.

	***************************************************************************
	* *
	* FreeRTOS provides completely free yet professionally developed, *
	* robust, strictly quality controlled, supported, and cross *
	* platform software that has become a de facto standard. *
	* *
	* Help yourself get started quickly and support the FreeRTOS *
	* project by purchasing a FreeRTOS tutorial book, reference *
	* manual, or both from: http://www.FreeRTOS.org/Documentation *
	* *
	* Thank you! *
	* *
	***************************************************************************

	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 kernel. !<<

	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. Full license text is available from the following
	link: http://www.freertos.org/a00114.html

	1 tab == 4 spaces!

	***************************************************************************
	* *
	* Having a problem? Start by reading the FAQ "My application does *
	* not run, what could be wrong?" *
	* *
	* http://www.FreeRTOS.org/FAQHelp.html *
	* *
	***************************************************************************

	http://www.FreeRTOS.org - Documentation, books, training, latest versions,
	license and Real Time Engineers Ltd. contact details.

	http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
	including FreeRTOS+Trace - an indispensable productivity tool, a DOS
	compatible FAT file system, and our tiny thread aware UDP/IP stack.

	http://www.OpenRTOS.com - Real Time Engineers ltd license FreeRTOS to High
	Integrity Systems to sell under the OpenRTOS brand. Low cost OpenRTOS
	licenses offer ticketed support, indemnification and middleware.

	http://www.SafeRTOS.com - 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.

	1 tab == 4 spaces!
	*/

	/*
	Changes from V1.2.3

	+ The created tasks now include calls to tskYIELD(), allowing them to be used
	with the cooperative scheduler.
	*/

	/**
	* Creates eight tasks, each of which loops continuously performing an (emulated)
	* floating point calculation.
	*
	* All the tasks run at the idle priority and never block or yield. This causes
	* all eight tasks to time slice with the idle task. Running at the idle priority
	* means that these tasks will get pre-empted any time another task is ready to run
	* or a time slice occurs. More often than not the pre-emption will occur mid
	* calculation, creating a good test of the schedulers context switch mechanism - a
	* calculation producing an unexpected result could be a symptom of a corruption in
	* the context of a task.
	*
	* \page FlopC flop.c
	* \ingroup DemoFiles
	* <HR>
	*/

	#include <stdlib.h>
	#include <math.h>

	/* Scheduler include files. */
	#include "FreeRTOS.h"
	#include "task.h"
	#include "print.h"

	/* Demo program include files. */
	#include "flop.h"

	#define mathSTACK_SIZE ( ( unsigned short ) 512 )
	#define mathNUMBER_OF_TASKS ( 8 )

	/* Four tasks, each of which performs a different floating point calculation.
	Each of the four is created twice. */
	static void vCompetingMathTask1( void *pvParameters );
	static void vCompetingMathTask2( void *pvParameters );
	static void vCompetingMathTask3( void *pvParameters );
	static void vCompetingMathTask4( void *pvParameters );

	/* These variables are used to check that all the tasks are still running. If a
	task gets a calculation wrong it will
	stop incrementing its check variable. */
	static volatile unsigned short usTaskCheck[ mathNUMBER_OF_TASKS ] = { ( unsigned short ) 0 };

	/-----------------------------------------------------------/

	void vStartMathTasks( unsigned portBASE_TYPE uxPriority )
	{
	xTaskCreate( vCompetingMathTask1, "Math1", mathSTACK_SIZE, ( void * ) &( usTaskCheck[ 0 ] ), uxPriority, NULL );
	xTaskCreate( vCompetingMathTask2, "Math2", mathSTACK_SIZE, ( void * ) &( usTaskCheck[ 1 ] ), uxPriority, NULL );
	xTaskCreate( vCompetingMathTask3, "Math3", mathSTACK_SIZE, ( void * ) &( usTaskCheck[ 2 ] ), uxPriority, NULL );
	xTaskCreate( vCompetingMathTask4, "Math4", mathSTACK_SIZE, ( void * ) &( usTaskCheck[ 3 ] ), uxPriority, NULL );
	xTaskCreate( vCompetingMathTask1, "Math5", mathSTACK_SIZE, ( void * ) &( usTaskCheck[ 4 ] ), uxPriority, NULL );
	xTaskCreate( vCompetingMathTask2, "Math6", mathSTACK_SIZE, ( void * ) &( usTaskCheck[ 5 ] ), uxPriority, NULL );
	xTaskCreate( vCompetingMathTask3, "Math7", mathSTACK_SIZE, ( void * ) &( usTaskCheck[ 6 ] ), uxPriority, NULL );
	xTaskCreate( vCompetingMathTask4, "Math8", mathSTACK_SIZE, ( void * ) &( usTaskCheck[ 7 ] ), uxPriority, NULL );
	}
	/-----------------------------------------------------------/

	static void vCompetingMathTask1( void *pvParameters )
	{
	portDOUBLE d1, d2, d3, d4;
	volatile unsigned short *pusTaskCheckVariable;
	const portDOUBLE dAnswer = ( 123.4567 + 2345.6789 ) * -918.222;
	const char * const pcTaskStartMsg = "Math task 1 started.\r\n";
	const char * const pcTaskFailMsg = "Math task 1 failed.\r\n";
	short sError = pdFALSE;

	/* Queue a message for printing to say the task has started. */
	vPrintDisplayMessage( &pcTaskStartMsg );

	/* The variable this task increments to show it is still running is passed in
	as the parameter. */
	pusTaskCheckVariable = ( unsigned short * ) pvParameters;

	/* Keep performing a calculation and checking the result against a constant. */
	for(;;)
	{
	d1 = 123.4567;
	d2 = 2345.6789;
	d3 = -918.222;

	d4 = ( d1 + d2 ) * d3;

	taskYIELD();

	/* If the calculation does not match the expected constant, stop the
	increment of the check variable. */
	if( fabs( d4 - dAnswer ) > 0.001 )
	{
	vPrintDisplayMessage( &pcTaskFailMsg );
	sError = pdTRUE;
	}

	if( sError == pdFALSE )
	{
	/* If the calculation has always been correct, increment the check
	variable so we know this task is still running okay. */
	( *pusTaskCheckVariable )++;
	}

	taskYIELD();
	}
	}
	/-----------------------------------------------------------/

	static void vCompetingMathTask2( void *pvParameters )
	{
	portDOUBLE d1, d2, d3, d4;
	volatile unsigned short *pusTaskCheckVariable;
	const portDOUBLE dAnswer = ( -389.38 / 32498.2 ) * -2.0001;
	const char * const pcTaskStartMsg = "Math task 2 started.\r\n";
	const char * const pcTaskFailMsg = "Math task 2 failed.\r\n";
	short sError = pdFALSE;

	/* Queue a message for printing to say the task has started. */
	vPrintDisplayMessage( &pcTaskStartMsg );

	/* The variable this task increments to show it is still running is passed in
	as the parameter. */
	pusTaskCheckVariable = ( unsigned short * ) pvParameters;

	/* Keep performing a calculation and checking the result against a constant. */
	for( ;; )
	{
	d1 = -389.38;
	d2 = 32498.2;
	d3 = -2.0001;

	d4 = ( d1 / d2 ) * d3;

	taskYIELD();

	/* If the calculation does not match the expected constant, stop the
	increment of the check variable. */
	if( fabs( d4 - dAnswer ) > 0.001 )
	{
	vPrintDisplayMessage( &pcTaskFailMsg );
	sError = pdTRUE;
	}

	if( sError == pdFALSE )
	{
	/* If the calculation has always been correct, increment the check
	variable so we know
	this task is still running okay. */
	( *pusTaskCheckVariable )++;
	}

	taskYIELD();
	}
	}
	/-----------------------------------------------------------/

	static void vCompetingMathTask3( void *pvParameters )
	{
	portDOUBLE *pdArray, dTotal1, dTotal2, dDifference;
	volatile unsigned short *pusTaskCheckVariable;
	const unsigned short usArraySize = 250;
	unsigned short usPosition;
	const char * const pcTaskStartMsg = "Math task 3 started.\r\n";
	const char * const pcTaskFailMsg = "Math task 3 failed.\r\n";
	short sError = pdFALSE;

	/* Queue a message for printing to say the task has started. */
	vPrintDisplayMessage( &pcTaskStartMsg );

	/* The variable this task increments to show it is still running is passed in
	as the parameter. */
	pusTaskCheckVariable = ( unsigned short * ) pvParameters;

	pdArray = ( portDOUBLE * ) pvPortMalloc( ( size_t ) 250 * sizeof( portDOUBLE ) );

	/* Keep filling an array, keeping a running total of the values placed in the
	array. Then run through the array adding up all the values. If the two totals
	do not match, stop the check variable from incrementing. */
	for( ;; )
	{
	dTotal1 = 0.0;
	dTotal2 = 0.0;

	for( usPosition = 0; usPosition < usArraySize; usPosition++ )
	{
	pdArray[ usPosition ] = ( portDOUBLE ) usPosition + 5.5;
	dTotal1 += ( portDOUBLE ) usPosition + 5.5;
	}

	taskYIELD();

	for( usPosition = 0; usPosition < usArraySize; usPosition++ )
	{
	dTotal2 += pdArray[ usPosition ];
	}

	dDifference = dTotal1 - dTotal2;
	if( fabs( dDifference ) > 0.001 )
	{
	vPrintDisplayMessage( &pcTaskFailMsg );
	sError = pdTRUE;
	}

	taskYIELD();

	if( sError == pdFALSE )
	{
	/* If the calculation has always been correct, increment the check
	variable so we know this task is still running okay. */
	( *pusTaskCheckVariable )++;
	}
	}
	}
	/-----------------------------------------------------------/

	static void vCompetingMathTask4( void *pvParameters )
	{
	portDOUBLE *pdArray, dTotal1, dTotal2, dDifference;
	volatile unsigned short *pusTaskCheckVariable;
	const unsigned short usArraySize = 250;
	unsigned short usPosition;
	const char * const pcTaskStartMsg = "Math task 4 started.\r\n";
	const char * const pcTaskFailMsg = "Math task 4 failed.\r\n";
	short sError = pdFALSE;

	/* Queue a message for printing to say the task has started. */
	vPrintDisplayMessage( &pcTaskStartMsg );

	/* The variable this task increments to show it is still running is passed in
	as the parameter. */
	pusTaskCheckVariable = ( unsigned short * ) pvParameters;

	pdArray = ( portDOUBLE * ) pvPortMalloc( ( size_t ) 250 * sizeof( portDOUBLE ) );

	/* Keep filling an array, keeping a running total of the values placed in the
	array. Then run through the array adding up all the values. If the two totals
	do not match, stop the check variable from incrementing. */
	for( ;; )
	{
	dTotal1 = 0.0;
	dTotal2 = 0.0;

	for( usPosition = 0; usPosition < usArraySize; usPosition++ )
	{
	pdArray[ usPosition ] = ( portDOUBLE ) usPosition * 12.123;
	dTotal1 += ( portDOUBLE ) usPosition * 12.123;
	}

	taskYIELD();

	for( usPosition = 0; usPosition < usArraySize; usPosition++ )
	{
	dTotal2 += pdArray[ usPosition ];
	}

	dDifference = dTotal1 - dTotal2;
	if( fabs( dDifference ) > 0.001 )
	{
	vPrintDisplayMessage( &pcTaskFailMsg );
	sError = pdTRUE;
	}

	taskYIELD();

	if( sError == pdFALSE )
	{
	/* If the calculation has always been correct, increment the check
	variable so we know this task is still running okay. */
	( *pusTaskCheckVariable )++;
	}
	}
	}
	/-----------------------------------------------------------/

	/* This is called to check that all the created tasks are still running. */
	portBASE_TYPE xAreMathsTaskStillRunning( void )
	{
	/* Keep a history of the check variables so we know if they have been incremented
	since the last call. */
	static unsigned short usLastTaskCheck[ mathNUMBER_OF_TASKS ] = { ( unsigned short ) 0 };
	portBASE_TYPE xReturn = pdTRUE, xTask;

	/* Check the maths tasks are still running by ensuring their check variables
	are still incrementing. */
	for( xTask = 0; xTask < mathNUMBER_OF_TASKS; xTask++ )
	{
	if( usTaskCheck[ xTask ] == usLastTaskCheck[ xTask ] )
	{
	/* The check has not incremented so an error exists. */
	xReturn = pdFALSE;
	}

	usLastTaskCheck[ xTask ] = usTaskCheck[ xTask ];
	}

	return xReturn;
	}