FreeRTOS/Common/Full/PollQ.c

   1 /*
   2     FreeRTOS V6.0.5 - Copyright (C) 2010 Real Time Engineers Ltd.
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  24
  25     This file is part of the FreeRTOS distribution.
  26
  27     FreeRTOS is free software; you can redistribute it and/or modify it under
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  29     Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
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  52 */
  53
  54
  55 /**
  56  * This is a very simple queue test.  See the BlockQ. c documentation for a more
  57  * comprehensive version.
  58  *
  59  * Creates two tasks that communicate over a single queue.  One task acts as a
  60  * producer, the other a consumer.
  61  *
  62  * The producer loops for three iteration, posting an incrementing number onto the
  63  * queue each cycle.  It then delays for a fixed period before doing exactly the
  64  * same again.
  65  *
  66  * The consumer loops emptying the queue.  Each item removed from the queue is
  67  * checked to ensure it contains the expected value.  When the queue is empty it
  68  * blocks for a fixed period, then does the same again.
  69  *
  70  * All queue access is performed without blocking.  The consumer completely empties
  71  * the queue each time it runs so the producer should never find the queue full.
  72  *
  73  * An error is flagged if the consumer obtains an unexpected value or the producer
  74  * find the queue is full.
  75  *
  76  * \page PollQC pollQ.c
  77  * \ingroup DemoFiles
  78  * <HR>
  79  */
  80
  81 /*
  82 Changes from V2.0.0
  83
  84         + Delay periods are now specified using variables and constants of
  85           portTickType rather than unsigned long.
  86 */
  87
  88 #include <stdlib.h>
  89
  90 /* Scheduler include files. */
  91 #include "FreeRTOS.h"
  92 #include "task.h"
  93 #include "queue.h"
  94 #include "print.h"
  95
  96 /* Demo program include files. */
  97 #include "PollQ.h"
  98
  99 #define pollqSTACK_SIZE         ( ( unsigned short ) configMINIMAL_STACK_SIZE )
 100
 101 /* The task that posts the incrementing number onto the queue. */
 102 static void vPolledQueueProducer( void *pvParameters );
 103
 104 /* The task that empties the queue. */
 105 static void vPolledQueueConsumer( void *pvParameters );
 106
 107 /* Variables that are used to check that the tasks are still running with no errors. */
 108 static volatile short sPollingConsumerCount = 0, sPollingProducerCount = 0;
 109 /*-----------------------------------------------------------*/
 110
 111 void vStartPolledQueueTasks( unsigned portBASE_TYPE uxPriority )
 112 {
 113 static xQueueHandle xPolledQueue;
 114 const unsigned portBASE_TYPE uxQueueSize = 10;
 115
 116         /* Create the queue used by the producer and consumer. */
 117         xPolledQueue = xQueueCreate( uxQueueSize, ( unsigned portBASE_TYPE ) sizeof( unsigned short ) );
 118
 119         /* Spawn the producer and consumer. */
 120         xTaskCreate( vPolledQueueConsumer, "QConsNB", pollqSTACK_SIZE, ( void * ) &xPolledQueue, uxPriority, NULL );
 121         xTaskCreate( vPolledQueueProducer, "QProdNB", pollqSTACK_SIZE, ( void * ) &xPolledQueue, uxPriority, NULL );
 122 }
 123 /*-----------------------------------------------------------*/
 124
 125 static void vPolledQueueProducer( void *pvParameters )
 126 {
 127 unsigned short usValue = 0, usLoop;
 128 xQueueHandle *pxQueue;
 129 const portTickType xDelay = ( portTickType ) 200 / portTICK_RATE_MS;
 130 const unsigned short usNumToProduce = 3;
 131 const char * const pcTaskStartMsg = "Polled queue producer started.\r\n";
 132 const char * const pcTaskErrorMsg = "Could not post on polled queue.\r\n";
 133 short sError = pdFALSE;
 134
 135         /* Queue a message for printing to say the task has started. */
 136         vPrintDisplayMessage( &pcTaskStartMsg );
 137
 138         /* The queue being used is passed in as the parameter. */
 139         pxQueue = ( xQueueHandle * ) pvParameters;
 140
 141         for( ;; )
 142         {
 143                 for( usLoop = 0; usLoop < usNumToProduce; ++usLoop )
 144                 {
 145                         /* Send an incrementing number on the queue without blocking. */
 146                         if( xQueueSendToBack( *pxQueue, ( void * ) &usValue, ( portTickType ) 0 ) != pdPASS )
 147                         {
 148                                 /* We should never find the queue full - this is an error. */
 149                                 vPrintDisplayMessage( &pcTaskErrorMsg );
 150                                 sError = pdTRUE;
 151                         }
 152                         else
 153                         {
 154                                 if( sError == pdFALSE )
 155                                 {
 156                                         /* If an error has ever been recorded we stop incrementing the
 157                                         check variable. */
 158                                         ++sPollingProducerCount;
 159                                 }
 160
 161                                 /* Update the value we are going to post next time around. */
 162                                 ++usValue;
 163                         }
 164                 }
 165
 166                 /* Wait before we start posting again to ensure the consumer runs and
 167                 empties the queue. */
 168                 vTaskDelay( xDelay );
 169         }
 170 }
 171 /*-----------------------------------------------------------*/
 172
 173 static void vPolledQueueConsumer( void *pvParameters )
 174 {
 175 unsigned short usData, usExpectedValue = 0;
 176 xQueueHandle *pxQueue;
 177 const portTickType xDelay = ( portTickType ) 200 / portTICK_RATE_MS;
 178 const char * const pcTaskStartMsg = "Polled queue consumer started.\r\n";
 179 const char * const pcTaskErrorMsg = "Incorrect value received on polled queue.\r\n";
 180 short sError = pdFALSE;
 181
 182         /* Queue a message for printing to say the task has started. */
 183         vPrintDisplayMessage( &pcTaskStartMsg );
 184
 185         /* The queue being used is passed in as the parameter. */
 186         pxQueue = ( xQueueHandle * ) pvParameters;
 187
 188         for( ;; )
 189         {
 190                 /* Loop until the queue is empty. */
 191                 while( uxQueueMessagesWaiting( *pxQueue ) )
 192                 {
 193                         if( xQueueReceive( *pxQueue, &usData, ( portTickType ) 0 ) == pdPASS )
 194                         {
 195                                 if( usData != usExpectedValue )
 196                                 {
 197                                         /* This is not what we expected to receive so an error has
 198                                         occurred. */
 199                                         vPrintDisplayMessage( &pcTaskErrorMsg );
 200                                         sError = pdTRUE;
 201                                         /* Catch-up to the value we received so our next expected value
 202                                         should again be correct. */
 203                                         usExpectedValue = usData;
 204                                 }
 205                                 else
 206                                 {
 207                                         if( sError == pdFALSE )
 208                                         {
 209                                                 /* Only increment the check variable if no errors have
 210                                                 occurred. */
 211                                                 ++sPollingConsumerCount;
 212                                         }
 213                                 }
 214                                 ++usExpectedValue;
 215                         }
 216                 }
 217
 218                 /* Now the queue is empty we block, allowing the producer to place more
 219                 items in the queue. */
 220                 vTaskDelay( xDelay );
 221         }
 222 }
 223 /*-----------------------------------------------------------*/
 224
 225 /* This is called to check that all the created tasks are still running with no errors. */
 226 portBASE_TYPE xArePollingQueuesStillRunning( void )
 227 {
 228 static short sLastPollingConsumerCount = 0, sLastPollingProducerCount = 0;
 229 portBASE_TYPE xReturn;
 230
 231         if( ( sLastPollingConsumerCount == sPollingConsumerCount ) ||
 232                 ( sLastPollingProducerCount == sPollingProducerCount )
 233           )
 234         {
 235                 xReturn = pdFALSE;
 236         }
 237         else
 238         {
 239                 xReturn = pdTRUE;
 240         }
 241
 242         sLastPollingConsumerCount = sPollingConsumerCount;
 243         sLastPollingProducerCount = sPollingProducerCount;
 244
 245         return xReturn;
 246 }