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40 the FAQ page "My application does not run, what could be wrong?". Have you
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64 engineered and independently SIL3 certified version for use in safety and
65 mission critical applications that require provable dependability.
71 * This version of PollQ. c is for use on systems that have limited stack
72 * space and no display facilities. The complete version can be found in
73 * the Demo/Common/Full directory.
75 * Creates two tasks that communicate over a single queue. One task acts as a
76 * producer, the other a consumer.
78 * The producer loops for three iteration, posting an incrementing number onto the
79 * queue each cycle. It then delays for a fixed period before doing exactly the
82 * The consumer loops emptying the queue. Each item removed from the queue is
83 * checked to ensure it contains the expected value. When the queue is empty it
84 * blocks for a fixed period, then does the same again.
86 * All queue access is performed without blocking. The consumer completely empties
87 * the queue each time it runs so the producer should never find the queue full.
89 * An error is flagged if the consumer obtains an unexpected value or the producer
90 * find the queue is full.
96 + Delay periods are now specified using variables and constants of
97 TickType_t rather than uint32_t.
102 /* Scheduler include files. */
103 #include "FreeRTOS.h"
107 /* Demo program include files. */
110 #define pollqSTACK_SIZE configMINIMAL_STACK_SIZE
111 #define pollqQUEUE_SIZE ( 10 )
112 #define pollqPRODUCER_DELAY ( pdMS_TO_TICKS( ( TickType_t ) 200 ) )
113 #define pollqCONSUMER_DELAY ( pollqPRODUCER_DELAY - ( TickType_t ) ( 20 / portTICK_PERIOD_MS ) )
114 #define pollqNO_DELAY ( ( TickType_t ) 0 )
115 #define pollqVALUES_TO_PRODUCE ( ( BaseType_t ) 3 )
116 #define pollqINITIAL_VALUE ( ( BaseType_t ) 0 )
118 /* The task that posts the incrementing number onto the queue. */
119 static portTASK_FUNCTION_PROTO( vPolledQueueProducer, pvParameters );
121 /* The task that empties the queue. */
122 static portTASK_FUNCTION_PROTO( vPolledQueueConsumer, pvParameters );
124 /* Variables that are used to check that the tasks are still running with no
126 static volatile BaseType_t xPollingConsumerCount = pollqINITIAL_VALUE, xPollingProducerCount = pollqINITIAL_VALUE;
128 /*-----------------------------------------------------------*/
130 void vStartPolledQueueTasks( UBaseType_t uxPriority )
132 static QueueHandle_t xPolledQueue;
134 /* Create the queue used by the producer and consumer. */
135 xPolledQueue = xQueueCreate( pollqQUEUE_SIZE, ( UBaseType_t ) sizeof( uint16_t ) );
137 if( xPolledQueue != NULL )
139 /* vQueueAddToRegistry() adds the queue to the queue registry, if one is
140 in use. The queue registry is provided as a means for kernel aware
141 debuggers to locate queues and has no purpose if a kernel aware debugger
142 is not being used. The call to vQueueAddToRegistry() will be removed
143 by the pre-processor if configQUEUE_REGISTRY_SIZE is not defined or is
144 defined to be less than 1. */
145 vQueueAddToRegistry( xPolledQueue, "Poll_Test_Queue" );
147 /* Spawn the producer and consumer. */
148 xTaskCreate( vPolledQueueConsumer, "QConsNB", pollqSTACK_SIZE, ( void * ) &xPolledQueue, uxPriority, ( TaskHandle_t * ) NULL );
149 xTaskCreate( vPolledQueueProducer, "QProdNB", pollqSTACK_SIZE, ( void * ) &xPolledQueue, uxPriority, ( TaskHandle_t * ) NULL );
152 /*-----------------------------------------------------------*/
154 static portTASK_FUNCTION( vPolledQueueProducer, pvParameters )
156 uint16_t usValue = ( uint16_t ) 0;
157 BaseType_t xError = pdFALSE, xLoop;
161 for( xLoop = 0; xLoop < pollqVALUES_TO_PRODUCE; xLoop++ )
163 /* Send an incrementing number on the queue without blocking. */
164 if( xQueueSend( *( ( QueueHandle_t * ) pvParameters ), ( void * ) &usValue, pollqNO_DELAY ) != pdPASS )
166 /* We should never find the queue full so if we get here there
167 has been an error. */
172 if( xError == pdFALSE )
174 /* If an error has ever been recorded we stop incrementing the
176 portENTER_CRITICAL();
177 xPollingProducerCount++;
181 /* Update the value we are going to post next time around. */
186 /* Wait before we start posting again to ensure the consumer runs and
187 empties the queue. */
188 vTaskDelay( pollqPRODUCER_DELAY );
190 } /*lint !e818 Function prototype must conform to API. */
191 /*-----------------------------------------------------------*/
193 static portTASK_FUNCTION( vPolledQueueConsumer, pvParameters )
195 uint16_t usData, usExpectedValue = ( uint16_t ) 0;
196 BaseType_t xError = pdFALSE;
200 /* Loop until the queue is empty. */
201 while( uxQueueMessagesWaiting( *( ( QueueHandle_t * ) pvParameters ) ) )
203 if( xQueueReceive( *( ( QueueHandle_t * ) pvParameters ), &usData, pollqNO_DELAY ) == pdPASS )
205 if( usData != usExpectedValue )
207 /* This is not what we expected to receive so an error has
211 /* Catch-up to the value we received so our next expected
212 value should again be correct. */
213 usExpectedValue = usData;
217 if( xError == pdFALSE )
219 /* Only increment the check variable if no errors have
221 portENTER_CRITICAL();
222 xPollingConsumerCount++;
227 /* Next time round we would expect the number to be one higher. */
232 /* Now the queue is empty we block, allowing the producer to place more
233 items in the queue. */
234 vTaskDelay( pollqCONSUMER_DELAY );
236 } /*lint !e818 Function prototype must conform to API. */
237 /*-----------------------------------------------------------*/
239 /* This is called to check that all the created tasks are still running with no errors. */
240 BaseType_t xArePollingQueuesStillRunning( void )
244 /* Check both the consumer and producer poll count to check they have both
245 been changed since out last trip round. We do not need a critical section
246 around the check variables as this is called from a higher priority than
247 the other tasks that access the same variables. */
248 if( ( xPollingConsumerCount == pollqINITIAL_VALUE ) ||
249 ( xPollingProducerCount == pollqINITIAL_VALUE )
259 /* Set the check variables back down so we know if they have been
260 incremented the next time around. */
261 xPollingConsumerCount = pollqINITIAL_VALUE;
262 xPollingProducerCount = pollqINITIAL_VALUE;