20100923-V6.1.0-RC2/Demo/Common/Full/PollQ.c

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+/*
+    FreeRTOS V6.1.0 - Copyright (C) 2010 Real Time Engineers Ltd.
+
+    ***************************************************************************
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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
+    the terms of the GNU General Public License (version 2) as published by the
+    Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
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+    License and the FreeRTOS license exception along with FreeRTOS; if not it 
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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 long.
+*/
+
+#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 short ) 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 short 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 short ) );
+
+	/* 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 short usValue = 0, usLoop;
+xQueueHandle *pxQueue;
+const portTickType xDelay = ( portTickType ) 200 / portTICK_RATE_MS;
+const unsigned short usNumToProduce = 3;
+const char * const pcTaskStartMsg = "Polled queue producer started.\r\n";
+const char * const pcTaskErrorMsg = "Could not post on polled queue.\r\n";
+short 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 short usData, usExpectedValue = 0;
+xQueueHandle *pxQueue;
+const portTickType xDelay = ( portTickType ) 200 / portTICK_RATE_MS;
+const char * const pcTaskStartMsg = "Polled queue consumer started.\r\n";
+const char * const pcTaskErrorMsg = "Incorrect value received on polled queue.\r\n";
+short 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 short sLastPollingConsumerCount = 0, sLastPollingProducerCount = 0;
+portBASE_TYPE xReturn;
+
+	if( ( sLastPollingConsumerCount == sPollingConsumerCount ) ||
+		( sLastPollingProducerCount == sPollingProducerCount ) 
+	  )
+	{
+		xReturn = pdFALSE;
+	}
+	else
+	{
+		xReturn = pdTRUE;
+	}
+
+	sLastPollingConsumerCount = sPollingConsumerCount;
+	sLastPollingProducerCount = sPollingProducerCount;
+
+	return xReturn;
+}