FreeRTOS/Common/Minimal/AltPollQ.c

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  25     This file is part of the FreeRTOS distribution.
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  52 */
  53
  54 /*
  55  * This is a version of PollQ.c that uses the alternative (Alt) API.
  56  *
  57  * Creates two tasks that communicate over a single queue.  One task acts as a
  58  * producer, the other a consumer.
  59  *
  60  * The producer loops for three iteration, posting an incrementing number onto the
  61  * queue each cycle.  It then delays for a fixed period before doing exactly the
  62  * same again.
  63  *
  64  * The consumer loops emptying the queue.  Each item removed from the queue is
  65  * checked to ensure it contains the expected value.  When the queue is empty it
  66  * blocks for a fixed period, then does the same again.
  67  *
  68  * All queue access is performed without blocking.  The consumer completely empties
  69  * the queue each time it runs so the producer should never find the queue full.
  70  *
  71  * An error is flagged if the consumer obtains an unexpected value or the producer
  72  * find the queue is full.
  73  */
  74
  75 /*
  76 Changes from V2.0.0
  77
  78         + Delay periods are now specified using variables and constants of
  79           portTickType rather than unsigned portLONG.
  80 */
  81
  82 #include <stdlib.h>
  83
  84 /* Scheduler include files. */
  85 #include "FreeRTOS.h"
  86 #include "task.h"
  87 #include "queue.h"
  88
  89 /* Demo program include files. */
  90 #include "AltPollQ.h"
  91
  92 #define pollqSTACK_SIZE                 configMINIMAL_STACK_SIZE
  93 #define pollqQUEUE_SIZE                 ( 10 )
  94 #define pollqPRODUCER_DELAY             ( ( portTickType ) 200 / portTICK_RATE_MS )
  95 #define pollqCONSUMER_DELAY             ( pollqPRODUCER_DELAY - ( portTickType ) ( 20 / portTICK_RATE_MS ) )
  96 #define pollqNO_DELAY                   ( ( portTickType ) 0 )
  97 #define pollqVALUES_TO_PRODUCE  ( ( signed portBASE_TYPE ) 3 )
  98 #define pollqINITIAL_VALUE              ( ( signed portBASE_TYPE ) 0 )
  99
 100 /* The task that posts the incrementing number onto the queue. */
 101 static portTASK_FUNCTION_PROTO( vPolledQueueProducer, pvParameters );
 102
 103 /* The task that empties the queue. */
 104 static portTASK_FUNCTION_PROTO( vPolledQueueConsumer, pvParameters );
 105
 106 /* Variables that are used to check that the tasks are still running with no
 107 errors. */
 108 static volatile signed portBASE_TYPE xPollingConsumerCount = pollqINITIAL_VALUE, xPollingProducerCount = pollqINITIAL_VALUE;
 109
 110 /*-----------------------------------------------------------*/
 111
 112 void vStartAltPolledQueueTasks( unsigned portBASE_TYPE uxPriority )
 113 {
 114 static xQueueHandle xPolledQueue;
 115
 116         /* Create the queue used by the producer and consumer. */
 117         xPolledQueue = xQueueCreate( pollqQUEUE_SIZE, ( unsigned portBASE_TYPE ) sizeof( unsigned portSHORT ) );
 118
 119         /* vQueueAddToRegistry() adds the queue to the queue registry, if one is
 120         in use.  The queue registry is provided as a means for kernel aware
 121         debuggers to locate queues and has no purpose if a kernel aware debugger
 122         is not being used.  The call to vQueueAddToRegistry() will be removed
 123         by the pre-processor if configQUEUE_REGISTRY_SIZE is not defined or is
 124         defined to be less than 1. */
 125         vQueueAddToRegistry( xPolledQueue, ( signed portCHAR * ) "AltPollQueue" );
 126
 127
 128         /* Spawn the producer and consumer. */
 129         xTaskCreate( vPolledQueueConsumer, ( signed portCHAR * ) "QConsNB", pollqSTACK_SIZE, ( void * ) &xPolledQueue, uxPriority, ( xTaskHandle * ) NULL );
 130         xTaskCreate( vPolledQueueProducer, ( signed portCHAR * ) "QProdNB", pollqSTACK_SIZE, ( void * ) &xPolledQueue, uxPriority, ( xTaskHandle * ) NULL );
 131 }
 132 /*-----------------------------------------------------------*/
 133
 134 static portTASK_FUNCTION( vPolledQueueProducer, pvParameters )
 135 {
 136 unsigned portSHORT usValue = ( unsigned portSHORT ) 0;
 137 signed portBASE_TYPE xError = pdFALSE, xLoop;
 138
 139         #ifdef USE_STDIO
 140         void vPrintDisplayMessage( const portCHAR * const * ppcMessageToSend );
 141
 142                 const portCHAR * const pcTaskStartMsg = "Alt polling queue producer task started.\r\n";
 143
 144                 /* Queue a message for printing to say the task has started. */
 145                 vPrintDisplayMessage( &pcTaskStartMsg );
 146         #endif
 147
 148         for( ;; )
 149         {
 150                 for( xLoop = 0; xLoop < pollqVALUES_TO_PRODUCE; xLoop++ )
 151                 {
 152                         /* Send an incrementing number on the queue without blocking. */
 153                         if( xQueueAltSendToBack( *( ( xQueueHandle * ) pvParameters ), ( void * ) &usValue, pollqNO_DELAY ) != pdPASS )
 154                         {
 155                                 /* We should never find the queue full so if we get here there
 156                                 has been an error. */
 157                                 xError = pdTRUE;
 158                         }
 159                         else
 160                         {
 161                                 if( xError == pdFALSE )
 162                                 {
 163                                         /* If an error has ever been recorded we stop incrementing the
 164                                         check variable. */
 165                                         portENTER_CRITICAL();
 166                                                 xPollingProducerCount++;
 167                                         portEXIT_CRITICAL();
 168                                 }
 169
 170                                 /* Update the value we are going to post next time around. */
 171                                 usValue++;
 172                         }
 173                 }
 174
 175                 /* Wait before we start posting again to ensure the consumer runs and
 176                 empties the queue. */
 177                 vTaskDelay( pollqPRODUCER_DELAY );
 178         }
 179 }  /*lint !e818 Function prototype must conform to API. */
 180 /*-----------------------------------------------------------*/
 181
 182 static portTASK_FUNCTION( vPolledQueueConsumer, pvParameters )
 183 {
 184 unsigned portSHORT usData, usExpectedValue = ( unsigned portSHORT ) 0;
 185 signed portBASE_TYPE xError = pdFALSE;
 186
 187         #ifdef USE_STDIO
 188         void vPrintDisplayMessage( const portCHAR * const * ppcMessageToSend );
 189
 190                 const portCHAR * const pcTaskStartMsg = "Alt blocking queue consumer task started.\r\n";
 191
 192                 /* Queue a message for printing to say the task has started. */
 193                 vPrintDisplayMessage( &pcTaskStartMsg );
 194         #endif
 195
 196         for( ;; )
 197         {
 198                 /* Loop until the queue is empty. */
 199                 while( uxQueueMessagesWaiting( *( ( xQueueHandle * ) pvParameters ) ) )
 200                 {
 201                         if( xQueueAltReceive( *( ( xQueueHandle * ) pvParameters ), &usData, pollqNO_DELAY ) == pdPASS )
 202                         {
 203                                 if( usData != usExpectedValue )
 204                                 {
 205                                         /* This is not what we expected to receive so an error has
 206                                         occurred. */
 207                                         xError = pdTRUE;
 208
 209                                         /* Catch-up to the value we received so our next expected
 210                                         value should again be correct. */
 211                                         usExpectedValue = usData;
 212                                 }
 213                                 else
 214                                 {
 215                                         if( xError == pdFALSE )
 216                                         {
 217                                                 /* Only increment the check variable if no errors have
 218                                                 occurred. */
 219                                                 portENTER_CRITICAL();
 220                                                         xPollingConsumerCount++;
 221                                                 portEXIT_CRITICAL();
 222                                         }
 223                                 }
 224
 225                                 /* Next time round we would expect the number to be one higher. */
 226                                 usExpectedValue++;
 227                         }
 228                 }
 229
 230                 /* Now the queue is empty we block, allowing the producer to place more
 231                 items in the queue. */
 232                 vTaskDelay( pollqCONSUMER_DELAY );
 233         }
 234 } /*lint !e818 Function prototype must conform to API. */
 235 /*-----------------------------------------------------------*/
 236
 237 /* This is called to check that all the created tasks are still running with no errors. */
 238 portBASE_TYPE xAreAltPollingQueuesStillRunning( void )
 239 {
 240 portBASE_TYPE xReturn;
 241
 242         /* Check both the consumer and producer poll count to check they have both
 243         been changed since out last trip round.  We do not need a critical section
 244         around the check variables as this is called from a higher priority than
 245         the other tasks that access the same variables. */
 246         if( ( xPollingConsumerCount == pollqINITIAL_VALUE ) ||
 247                 ( xPollingProducerCount == pollqINITIAL_VALUE )
 248           )
 249         {
 250                 xReturn = pdFALSE;
 251         }
 252         else
 253         {
 254                 xReturn = pdTRUE;
 255         }
 256
 257         /* Set the check variables back down so we know if they have been
 258         incremented the next time around. */
 259         xPollingConsumerCount = pollqINITIAL_VALUE;
 260         xPollingProducerCount = pollqINITIAL_VALUE;
 261
 262         return xReturn;
 263 }