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jeremybenn |
/*
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FreeRTOS V6.1.1 - Copyright (C) 2011 Real Time Engineers Ltd.
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***************************************************************************
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* *
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* If you are: *
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* *
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* + New to FreeRTOS, *
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* + Wanting to learn FreeRTOS or multitasking in general quickly *
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* + Looking for basic training, *
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* + Wanting to improve your FreeRTOS skills and productivity *
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* *
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* then take a look at the FreeRTOS books - available as PDF or paperback *
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* *
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* "Using the FreeRTOS Real Time Kernel - a Practical Guide" *
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* http://www.FreeRTOS.org/Documentation *
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* *
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* A pdf reference manual is also available. Both are usually delivered *
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* to your inbox within 20 minutes to two hours when purchased between 8am *
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* and 8pm GMT (although please allow up to 24 hours in case of *
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* exceptional circumstances). Thank you for your support! *
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* *
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***************************************************************************
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This file is part of the FreeRTOS distribution.
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FreeRTOS is free software; you can redistribute it and/or modify it under
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the terms of the GNU General Public License (version 2) as published by the
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Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
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***NOTE*** The exception to the GPL is included to allow you to distribute
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a combined work that includes FreeRTOS without being obliged to provide the
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source code for proprietary components outside of the FreeRTOS kernel.
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FreeRTOS is distributed in the hope that it will be useful, but WITHOUT
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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more details. You should have received a copy of the GNU General Public
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License and the FreeRTOS license exception along with FreeRTOS; if not it
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can be viewed here: http://www.freertos.org/a00114.html and also obtained
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by writing to Richard Barry, contact details for whom are available on the
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FreeRTOS WEB site.
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1 tab == 4 spaces!
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http://www.FreeRTOS.org - Documentation, latest information, license and
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contact details.
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http://www.SafeRTOS.com - A version that is certified for use in safety
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critical systems.
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http://www.OpenRTOS.com - Commercial support, development, porting,
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licensing and training services.
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*/
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/*
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* This version of PollQ. c is for use on systems that have limited stack
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* space and no display facilities. The complete version can be found in
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* the Demo/Common/Full directory.
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*
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* Creates two tasks that communicate over a single queue. One task acts as a
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* producer, the other a consumer.
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*
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* The producer loops for three iteration, posting an incrementing number onto the
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* queue each cycle. It then delays for a fixed period before doing exactly the
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* same again.
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*
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* The consumer loops emptying the queue. Each item removed from the queue is
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* checked to ensure it contains the expected value. When the queue is empty it
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* blocks for a fixed period, then does the same again.
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*
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* All queue access is performed without blocking. The consumer completely empties
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* the queue each time it runs so the producer should never find the queue full.
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*
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* An error is flagged if the consumer obtains an unexpected value or the producer
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* find the queue is full.
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*/
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/*
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Changes from V2.0.0
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+ Delay periods are now specified using variables and constants of
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portTickType rather than unsigned long.
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*/
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#include <stdlib.h>
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/* Scheduler include files. */
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#include "FreeRTOS.h"
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#include "task.h"
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#include "queue.h"
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/* Demo program include files. */
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#include "PollQ.h"
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#define pollqSTACK_SIZE configMINIMAL_STACK_SIZE
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#define pollqQUEUE_SIZE ( 10 )
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#define pollqPRODUCER_DELAY ( ( portTickType ) 200 / portTICK_RATE_MS )
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#define pollqCONSUMER_DELAY ( pollqPRODUCER_DELAY - ( portTickType ) ( 20 / portTICK_RATE_MS ) )
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#define pollqNO_DELAY ( ( portTickType ) 0 )
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#define pollqVALUES_TO_PRODUCE ( ( signed portBASE_TYPE ) 3 )
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#define pollqINITIAL_VALUE ( ( signed portBASE_TYPE ) 0 )
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/* The task that posts the incrementing number onto the queue. */
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static portTASK_FUNCTION_PROTO( vPolledQueueProducer, pvParameters );
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/* The task that empties the queue. */
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static portTASK_FUNCTION_PROTO( vPolledQueueConsumer, pvParameters );
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/* Variables that are used to check that the tasks are still running with no
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errors. */
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static volatile signed portBASE_TYPE xPollingConsumerCount = pollqINITIAL_VALUE, xPollingProducerCount = pollqINITIAL_VALUE;
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/*-----------------------------------------------------------*/
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void vStartPolledQueueTasks( unsigned portBASE_TYPE uxPriority )
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{
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static xQueueHandle xPolledQueue;
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/* Create the queue used by the producer and consumer. */
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xPolledQueue = xQueueCreate( pollqQUEUE_SIZE, ( unsigned portBASE_TYPE ) sizeof( unsigned short ) );
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/* vQueueAddToRegistry() adds the queue to the queue registry, if one is
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in use. The queue registry is provided as a means for kernel aware
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debuggers to locate queues and has no purpose if a kernel aware debugger
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is not being used. The call to vQueueAddToRegistry() will be removed
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by the pre-processor if configQUEUE_REGISTRY_SIZE is not defined or is
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defined to be less than 1. */
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vQueueAddToRegistry( xPolledQueue, ( signed char * ) "Poll_Test_Queue" );
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/* Spawn the producer and consumer. */
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xTaskCreate( vPolledQueueConsumer, ( signed char * ) "QConsNB", pollqSTACK_SIZE, ( void * ) &xPolledQueue, uxPriority, ( xTaskHandle * ) NULL );
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xTaskCreate( vPolledQueueProducer, ( signed char * ) "QProdNB", pollqSTACK_SIZE, ( void * ) &xPolledQueue, uxPriority, ( xTaskHandle * ) NULL );
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}
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/*-----------------------------------------------------------*/
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static portTASK_FUNCTION( vPolledQueueProducer, pvParameters )
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{
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unsigned short usValue = ( unsigned short ) 0;
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signed portBASE_TYPE xError = pdFALSE, xLoop;
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for( ;; )
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{
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for( xLoop = 0; xLoop < pollqVALUES_TO_PRODUCE; xLoop++ )
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{
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/* Send an incrementing number on the queue without blocking. */
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if( xQueueSend( *( ( xQueueHandle * ) pvParameters ), ( void * ) &usValue, pollqNO_DELAY ) != pdPASS )
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{
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/* We should never find the queue full so if we get here there
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has been an error. */
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xError = pdTRUE;
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}
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else
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{
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if( xError == pdFALSE )
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{
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/* If an error has ever been recorded we stop incrementing the
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check variable. */
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portENTER_CRITICAL();
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xPollingProducerCount++;
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portEXIT_CRITICAL();
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}
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/* Update the value we are going to post next time around. */
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usValue++;
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}
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}
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/* Wait before we start posting again to ensure the consumer runs and
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empties the queue. */
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vTaskDelay( pollqPRODUCER_DELAY );
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}
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} /*lint !e818 Function prototype must conform to API. */
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/*-----------------------------------------------------------*/
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static portTASK_FUNCTION( vPolledQueueConsumer, pvParameters )
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{
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unsigned short usData, usExpectedValue = ( unsigned short ) 0;
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signed portBASE_TYPE xError = pdFALSE;
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for( ;; )
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{
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/* Loop until the queue is empty. */
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while( uxQueueMessagesWaiting( *( ( xQueueHandle * ) pvParameters ) ) )
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{
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if( xQueueReceive( *( ( xQueueHandle * ) pvParameters ), &usData, pollqNO_DELAY ) == pdPASS )
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{
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if( usData != usExpectedValue )
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{
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/* This is not what we expected to receive so an error has
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occurred. */
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xError = pdTRUE;
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/* Catch-up to the value we received so our next expected
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value should again be correct. */
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usExpectedValue = usData;
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}
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else
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{
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if( xError == pdFALSE )
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{
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/* Only increment the check variable if no errors have
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occurred. */
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portENTER_CRITICAL();
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xPollingConsumerCount++;
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portEXIT_CRITICAL();
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}
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}
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/* Next time round we would expect the number to be one higher. */
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usExpectedValue++;
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}
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}
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/* Now the queue is empty we block, allowing the producer to place more
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items in the queue. */
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vTaskDelay( pollqCONSUMER_DELAY );
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}
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} /*lint !e818 Function prototype must conform to API. */
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/*-----------------------------------------------------------*/
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/* This is called to check that all the created tasks are still running with no errors. */
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portBASE_TYPE xArePollingQueuesStillRunning( void )
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{
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portBASE_TYPE xReturn;
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/* Check both the consumer and producer poll count to check they have both
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been changed since out last trip round. We do not need a critical section
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around the check variables as this is called from a higher priority than
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the other tasks that access the same variables. */
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if( ( xPollingConsumerCount == pollqINITIAL_VALUE ) ||
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( xPollingProducerCount == pollqINITIAL_VALUE )
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)
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{
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xReturn = pdFALSE;
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}
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else
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{
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xReturn = pdTRUE;
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}
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/* Set the check variables back down so we know if they have been
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incremented the next time around. */
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xPollingConsumerCount = pollqINITIAL_VALUE;
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xPollingProducerCount = pollqINITIAL_VALUE;
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return xReturn;
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}
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