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FreeRTOS V5.4.2 - 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 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.
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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 for details *
* *
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Please ensure to read the configuration and relevant port sections of the
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* This version of integer. c is for use on systems that have limited stack
* space and no display facilities. The complete version can be found in
* the Demo/Common/Full directory.
* As with the full version, the tasks created in this file are a good test
* of the scheduler context switch mechanism. The processor has to access
* 32bit variables in two or four chunks (depending on the processor). The low
* priority of these tasks means there is a high probability that a context
* switch will occur mid calculation. See flop. c documentation for
* more information.
Changes from V1.2.1
+ The constants used in the calculations are larger to ensure the
optimiser does not truncate them to 16 bits.
Changes from V1.2.3
+ uxTaskCheck is now just used as a boolean. Instead of incrementing
the variable each cycle of the task, the variable is simply set to
true. sAreIntegerMathsTaskStillRunning() sets it back to false and
expects it to have been set back to true by the time it is called
+ A division has been included in the calculation.
#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 ( ( portLONG ) 123 )
#define intgCONST2 ( ( portLONG ) 234567 )
#define intgCONST3 ( ( portLONG ) -3 )
#define intgCONST4 ( ( portLONG ) 7 )
#define intgEXPECTED_ANSWER ( ( ( intgCONST1 + intgCONST2 ) * intgCONST3 ) / intgCONST4 )
/* 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 signed portBASE_TYPE xTaskCheck[ intgNUMBER_OF_TASKS ] = { ( signed portBASE_TYPE ) pdFALSE };
void vStartIntegerMathTasks( unsigned portBASE_TYPE uxPriority )
portSHORT sTask;
for( sTask = 0; sTask < intgNUMBER_OF_TASKS; sTask++ )
xTaskCreate( vCompeteingIntMathTask, ( signed portCHAR * ) "IntMath", intgSTACK_SIZE, ( void * ) &( xTaskCheck[ sTask ] ), uxPriority, ( xTaskHandle * ) 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 portLONG lValue;
portSHORT sError = pdFALSE;
volatile signed portBASE_TYPE *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 signed portBASE_TYPE * ) 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
/* 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. */
*pxTaskHasExecuted = pdTRUE;
/* Yield in case cooperative scheduling is being used. */
#if configUSE_PREEMPTION == 0
/* This is called to check that all the created tasks are still running. */
portBASE_TYPE xAreIntegerMathsTaskStillRunning( void )
portBASE_TYPE xReturn = pdTRUE;
portSHORT 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;