Demo/Common/Minimal/PollQ.c

/*
    FreeRTOS V7.0.2 - Copyright (C) 2011 Real Time Engineers Ltd.
	

    ***************************************************************************
     *                                                                       *
     *    FreeRTOS tutorial books are available in pdf and paperback.        *
     *    Complete, revised, and edited pdf reference manuals are also       *
     *    available.                                                         *
     *                                                                       *
     *    Purchasing FreeRTOS documentation will not only help you, by       *
     *    ensuring you get running as quickly as possible and with an        *
     *    in-depth knowledge of how to use FreeRTOS, it will also help       *
     *    the FreeRTOS project to continue with its mission of providing     *
     *    professional grade, cross platform, de facto standard solutions    *
     *    for microcontrollers - completely free of charge!                  *
     *                                                                       *
     *    >>> See http://www.FreeRTOS.org/Documentation for details. <<<     *
     *                                                                       *
     *    Thank you for using FreeRTOS, and thank you for your support!      *
     *                                                                       *
    ***************************************************************************


    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.  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: http://www.freertos.org/a00114.html and also obtained
    by writing to Richard Barry, contact details for whom are available on the
    FreeRTOS WEB site.

    1 tab == 4 spaces!

    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.

    http://www.OpenRTOS.com - Commercial support, development, porting,
    licensing and training services.
*/

/*
 * This version of PollQ. 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.
 *
 * Creates two tasks that communicate over a single queue.  One task acts as a
 * producer, the other a consumer.
 *
 * The producer loops for three iteration, posting an incrementing number onto the
 * queue each cycle.  It then delays for a fixed period before doing exactly the
 * same again.
 *
 * The consumer loops emptying the queue.  Each item removed from the queue is
 * checked to ensure it contains the expected value.  When the queue is empty it
 * blocks for a fixed period, then does the same again.
 *
 * All queue access is performed without blocking.  The consumer completely empties
 * the queue each time it runs so the producer should never find the queue full.
 *
 * An error is flagged if the consumer obtains an unexpected value or the producer
 * find the queue is full.
 */

/*
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"
#include "queue.h"

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

#define pollqSTACK_SIZE			configMINIMAL_STACK_SIZE
#define pollqQUEUE_SIZE			( 10 )
#define pollqPRODUCER_DELAY		( ( portTickType ) 200 / portTICK_RATE_MS )
#define pollqCONSUMER_DELAY		( pollqPRODUCER_DELAY - ( portTickType ) ( 20 / portTICK_RATE_MS ) )
#define pollqNO_DELAY			( ( portTickType ) 0 )
#define pollqVALUES_TO_PRODUCE	( ( signed portBASE_TYPE ) 3 )
#define pollqINITIAL_VALUE		( ( signed portBASE_TYPE ) 0 )

/* The task that posts the incrementing number onto the queue. */
static portTASK_FUNCTION_PROTO( vPolledQueueProducer, pvParameters );

/* The task that empties the queue. */
static portTASK_FUNCTION_PROTO( vPolledQueueConsumer, pvParameters );

/* Variables that are used to check that the tasks are still running with no
errors. */
static volatile signed portBASE_TYPE xPollingConsumerCount = pollqINITIAL_VALUE, xPollingProducerCount = pollqINITIAL_VALUE;

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

void vStartPolledQueueTasks( unsigned portBASE_TYPE uxPriority )
{
static xQueueHandle xPolledQueue;

	/* Create the queue used by the producer and consumer. */
	xPolledQueue = xQueueCreate( pollqQUEUE_SIZE, ( unsigned portBASE_TYPE ) sizeof( unsigned short ) );

	/* vQueueAddToRegistry() adds the queue to the queue registry, if one is
	in use.  The queue registry is provided as a means for kernel aware 
	debuggers to locate queues and has no purpose if a kernel aware debugger
	is not being used.  The call to vQueueAddToRegistry() will be removed
	by the pre-processor if configQUEUE_REGISTRY_SIZE is not defined or is 
	defined to be less than 1. */
	vQueueAddToRegistry( xPolledQueue, ( signed char * ) "Poll_Test_Queue" );

	/* Spawn the producer and consumer. */
	xTaskCreate( vPolledQueueConsumer, ( signed char * ) "QConsNB", pollqSTACK_SIZE, ( void * ) &xPolledQueue, uxPriority, ( xTaskHandle * ) NULL );
	xTaskCreate( vPolledQueueProducer, ( signed char * ) "QProdNB", pollqSTACK_SIZE, ( void * ) &xPolledQueue, uxPriority, ( xTaskHandle * ) NULL );
}
/*-----------------------------------------------------------*/

static portTASK_FUNCTION( vPolledQueueProducer, pvParameters )
{
unsigned short usValue = ( unsigned short ) 0;
signed portBASE_TYPE xError = pdFALSE, xLoop;

	for( ;; )
	{		
		for( xLoop = 0; xLoop < pollqVALUES_TO_PRODUCE; xLoop++ )
		{
			/* Send an incrementing number on the queue without blocking. */
			if( xQueueSend( *( ( xQueueHandle * ) pvParameters ), ( void * ) &usValue, pollqNO_DELAY ) != pdPASS )
			{
				/* We should never find the queue full so if we get here there
				has been an error. */
				xError = pdTRUE;
			}
			else
			{
				if( xError == pdFALSE )
				{
					/* If an error has ever been recorded we stop incrementing the
					check variable. */
					portENTER_CRITICAL();
						xPollingProducerCount++;
					portEXIT_CRITICAL();
				}

				/* Update the value we are going to post next time around. */
				usValue++;
			}
		}

		/* Wait before we start posting again to ensure the consumer runs and
		empties the queue. */
		vTaskDelay( pollqPRODUCER_DELAY );
	}
}  /*lint !e818 Function prototype must conform to API. */
/*-----------------------------------------------------------*/

static portTASK_FUNCTION( vPolledQueueConsumer, pvParameters )
{
unsigned short usData, usExpectedValue = ( unsigned short ) 0;
signed portBASE_TYPE xError = pdFALSE;

	for( ;; )
	{		
		/* Loop until the queue is empty. */
		while( uxQueueMessagesWaiting( *( ( xQueueHandle * ) pvParameters ) ) )
		{
			if( xQueueReceive( *( ( xQueueHandle * ) pvParameters ), &usData, pollqNO_DELAY ) == pdPASS )
			{
				if( usData != usExpectedValue )
				{
					/* This is not what we expected to receive so an error has
					occurred. */
					xError = pdTRUE;

					/* Catch-up to the value we received so our next expected
					value should again be correct. */
					usExpectedValue = usData;
				}
				else
				{
					if( xError == pdFALSE )
					{
						/* Only increment the check variable if no errors have
						occurred. */
						portENTER_CRITICAL();
							xPollingConsumerCount++;
						portEXIT_CRITICAL();
					}
				}

				/* Next time round we would expect the number to be one higher. */
				usExpectedValue++;
			}
		}

		/* Now the queue is empty we block, allowing the producer to place more
		items in the queue. */
		vTaskDelay( pollqCONSUMER_DELAY );
	}
} /*lint !e818 Function prototype must conform to API. */
/*-----------------------------------------------------------*/

/* This is called to check that all the created tasks are still running with no errors. */
portBASE_TYPE xArePollingQueuesStillRunning( void )
{
portBASE_TYPE xReturn;

	/* Check both the consumer and producer poll count to check they have both
	been changed since out last trip round.  We do not need a critical section
	around the check variables as this is called from a higher priority than
	the other tasks that access the same variables. */
	if( ( xPollingConsumerCount == pollqINITIAL_VALUE ) ||
		( xPollingProducerCount == pollqINITIAL_VALUE )
	  )
	{
		xReturn = pdFALSE;
	}
	else
	{
		xReturn = pdTRUE;
	}

	/* Set the check variables back down so we know if they have been
	incremented the next time around. */
	xPollingConsumerCount = pollqINITIAL_VALUE;
	xPollingProducerCount = pollqINITIAL_VALUE;

	return xReturn;
}