root/webserver/example/freeRTOS/Demo/Common/Full/PollQ.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
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        ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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        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.


        ***************************************************************************
        *                                                                         *
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        ***************************************************************************

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

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*/


/**
 * This is a very simple queue test.  See the BlockQ. c documentation for a more 
 * comprehensive version.
 *
 * 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.
 *
 * \page PollQC pollQ.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"
#include "queue.h"
#include "print.h"

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

#define pollqSTACK_SIZE         ( ( unsigned portSHORT ) configMINIMAL_STACK_SIZE )

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

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

/* Variables that are used to check that the tasks are still running with no errors. */
static volatile portSHORT sPollingConsumerCount = 0, sPollingProducerCount = 0;
/*-----------------------------------------------------------*/

void vStartPolledQueueTasks( unsigned portBASE_TYPE uxPriority )
{
static xQueueHandle xPolledQueue;
const unsigned portBASE_TYPE uxQueueSize = 10;

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

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

static void vPolledQueueProducer( void *pvParameters )
{
unsigned portSHORT usValue = 0, usLoop;
xQueueHandle *pxQueue;
const portTickType xDelay = ( portTickType ) 200 / portTICK_RATE_MS;
const unsigned portSHORT usNumToProduce = 3;
const portCHAR * const pcTaskStartMsg = "Polled queue producer started.\r\n";
const portCHAR * const pcTaskErrorMsg = "Could not post on polled queue.\r\n";
portSHORT sError = pdFALSE;

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

        /* The queue being used is passed in as the parameter. */
        pxQueue = ( xQueueHandle * ) pvParameters;

        for( ;; )
        {               
                for( usLoop = 0; usLoop < usNumToProduce; ++usLoop )
                {
                        /* Send an incrementing number on the queue without blocking. */
                        if( xQueueSendToBack( *pxQueue, ( void * ) &usValue, ( portTickType ) 0 ) != pdPASS )
                        {
                                /* We should never find the queue full - this is an error. */
                                vPrintDisplayMessage( &pcTaskErrorMsg );
                                sError = pdTRUE;
                        }
                        else
                        {
                                if( sError == pdFALSE )
                                {
                                        /* If an error has ever been recorded we stop incrementing the 
                                        check variable. */
                                        ++sPollingProducerCount;
                                }

                                /* 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( xDelay );
        }
}
/*-----------------------------------------------------------*/

static void vPolledQueueConsumer( void *pvParameters )
{
unsigned portSHORT usData, usExpectedValue = 0;
xQueueHandle *pxQueue;
const portTickType xDelay = ( portTickType ) 200 / portTICK_RATE_MS;
const portCHAR * const pcTaskStartMsg = "Polled queue consumer started.\r\n";
const portCHAR * const pcTaskErrorMsg = "Incorrect value received on polled queue.\r\n";
portSHORT sError = pdFALSE;

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

        /* The queue being used is passed in as the parameter. */
        pxQueue = ( xQueueHandle * ) pvParameters;

        for( ;; )
        {               
                /* Loop until the queue is empty. */
                while( uxQueueMessagesWaiting( *pxQueue ) )
                {
                        if( xQueueReceive( *pxQueue, &usData, ( portTickType ) 0 ) == pdPASS )
                        {
                                if( usData != usExpectedValue )
                                {
                                        /* This is not what we expected to receive so an error has 
                                        occurred. */
                                        vPrintDisplayMessage( &pcTaskErrorMsg );
                                        sError = pdTRUE;
                                        /* Catch-up to the value we received so our next expected value 
                                        should again be correct. */
                                        usExpectedValue = usData;
                                }
                                else
                                {
                                        if( sError == pdFALSE )
                                        {
                                                /* Only increment the check variable if no errors have 
                                                occurred. */
                                                ++sPollingConsumerCount;
                                        }
                                }
                                ++usExpectedValue;
                        }
                }

                /* Now the queue is empty we block, allowing the producer to place more 
                items in the queue. */
                vTaskDelay( xDelay );
        }
}
/*-----------------------------------------------------------*/

/* This is called to check that all the created tasks are still running with no errors. */
portBASE_TYPE xArePollingQueuesStillRunning( void )
{
static portSHORT sLastPollingConsumerCount = 0, sLastPollingProducerCount = 0;
portBASE_TYPE xReturn;

        if( ( sLastPollingConsumerCount == sPollingConsumerCount ) ||
                ( sLastPollingProducerCount == sPollingProducerCount ) 
          )
        {
                xReturn = pdFALSE;
        }
        else
        {
                xReturn = pdTRUE;
        }

        sLastPollingConsumerCount = sPollingConsumerCount;
        sLastPollingProducerCount = sPollingProducerCount;

        return xReturn;
}