FreeRTOS/Demo/Common/Minimal/integer.c

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*/

/*
 * Creates one or more tasks that repeatedly perform a set of integer
 * calculations.  The result of each run-time calculation is compared to the 
 * known expected result - with a mismatch being indicative of an error in the
 * context switch mechanism.
 */

#include <stdlib.h>

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

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

/* The constants used in the calculation. */
#define intgCONST1				( ( long ) 123 )
#define intgCONST2				( ( long ) 234567 )
#define intgCONST3				( ( long ) -3 )
#define intgCONST4				( ( long ) 7 )
#define intgEXPECTED_ANSWER		( ( ( intgCONST1 + intgCONST2 ) * intgCONST3 ) / intgCONST4 )

#define intgSTACK_SIZE			configMINIMAL_STACK_SIZE

/* As this is the minimal version, we will only create one task. */
#define intgNUMBER_OF_TASKS		( 1 )

/* The task function.  Repeatedly performs a 32 bit calculation, checking the
result against the expected result.  If the result is incorrect then the
context switch must have caused some corruption. */
static portTASK_FUNCTION_PROTO( vCompeteingIntMathTask, pvParameters );

/* Variables that are set to true within the calculation task to indicate
that the task is still executing.  The check task sets the variable back to
false, flagging an error if the variable is still false the next time it
is called. */
static volatile BaseType_t xTaskCheck[ intgNUMBER_OF_TASKS ] = { ( BaseType_t ) pdFALSE };

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

void vStartIntegerMathTasks( UBaseType_t uxPriority )
{
short sTask;

	for( sTask = 0; sTask < intgNUMBER_OF_TASKS; sTask++ )
	{
		xTaskCreate( vCompeteingIntMathTask, "IntMath", intgSTACK_SIZE, ( void * ) &( xTaskCheck[ sTask ] ), uxPriority, ( TaskHandle_t * ) NULL );
	}
}
/*-----------------------------------------------------------*/

static portTASK_FUNCTION( vCompeteingIntMathTask, pvParameters )
{
/* These variables are all effectively set to constants so they are volatile to
ensure the compiler does not just get rid of them. */
volatile long lValue;
short sError = pdFALSE;
volatile BaseType_t *pxTaskHasExecuted;

	/* Set a pointer to the variable we are going to set to true each
	iteration.  This is also a good test of the parameter passing mechanism
	within each port. */
	pxTaskHasExecuted = ( volatile BaseType_t * ) pvParameters;

	/* Keep performing a calculation and checking the result against a constant. */
	for( ;; )
	{
		/* Perform the calculation.  This will store partial value in
		registers, resulting in a good test of the context switch mechanism. */
		lValue = intgCONST1;
		lValue += intgCONST2;

		/* Yield in case cooperative scheduling is being used. */
		#if configUSE_PREEMPTION == 0
		{
			taskYIELD();
		}
		#endif

		/* Finish off the calculation. */
		lValue *= intgCONST3;
		lValue /= intgCONST4;

		/* If the calculation is found to be incorrect we stop setting the 
		TaskHasExecuted variable so the check task can see an error has 
		occurred. */
		if( lValue != intgEXPECTED_ANSWER ) /*lint !e774 volatile used to prevent this being optimised out. */
		{
			sError = pdTRUE;
		}

		if( sError == pdFALSE )
		{
			/* We have not encountered any errors, so set the flag that show
			we are still executing.  This will be periodically cleared by
			the check task. */
			portENTER_CRITICAL();
				*pxTaskHasExecuted = pdTRUE;
			portEXIT_CRITICAL();
		}

		/* Yield in case cooperative scheduling is being used. */
		#if configUSE_PREEMPTION == 0
		{
			taskYIELD();
		}
		#endif
	}
}
/*-----------------------------------------------------------*/

/* This is called to check that all the created tasks are still running. */
BaseType_t xAreIntegerMathsTaskStillRunning( void )
{
BaseType_t xReturn = pdTRUE;
short sTask;

	/* Check the maths tasks are still running by ensuring their check variables 
	are still being set to true. */
	for( sTask = 0; sTask < intgNUMBER_OF_TASKS; sTask++ )
	{
		if( xTaskCheck[ sTask ] == pdFALSE )
		{
			/* The check has not incremented so an error exists. */
			xReturn = pdFALSE;
		}

		/* Reset the check variable so we can tell if it has been set by
		the next time around. */
		xTaskCheck[ sTask ] = pdFALSE;
	}

	return xReturn;
}