2 FreeRTOS.org V4.2.1 - Copyright (C) 2003-2007 Richard Barry.
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4 This file is part of the FreeRTOS.org distribution.
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6 FreeRTOS.org is free software; you can redistribute it and/or modify
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7 it under the terms of the GNU General Public License as published by
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8 the Free Software Foundation; either version 2 of the License, or
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9 (at your option) any later version.
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11 FreeRTOS.org is distributed in the hope that it will be useful,
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12 but WITHOUT ANY WARRANTY; without even the implied warranty of
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13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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14 GNU General Public License for more details.
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16 You should have received a copy of the GNU General Public License
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17 along with FreeRTOS.org; if not, write to the Free Software
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18 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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20 A special exception to the GPL can be applied should you wish to distribute
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21 a combined work that includes FreeRTOS.org, without being obliged to provide
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22 the source code for any proprietary components. See the licensing section
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26 ***************************************************************************
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27 See http://www.FreeRTOS.org for documentation, latest information, license
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28 and contact details. Please ensure to read the configuration and relevant
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29 port sections of the online documentation.
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31 Also see http://www.SafeRTOS.com for an IEC 61508 compliant version along
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32 with commercial development and support options.
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33 ***************************************************************************
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37 * This version of PollQ. c is for use on systems that have limited stack
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38 * space and no display facilities. The complete version can be found in
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39 * the Demo/Common/Full directory.
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41 * Creates two tasks that communicate over a single queue. One task acts as a
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42 * producer, the other a consumer.
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44 * The producer loops for three iteration, posting an incrementing number onto the
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45 * queue each cycle. It then delays for a fixed period before doing exactly the
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48 * The consumer loops emptying the queue. Each item removed from the queue is
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49 * checked to ensure it contains the expected value. When the queue is empty it
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50 * blocks for a fixed period, then does the same again.
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52 * All queue access is performed without blocking. The consumer completely empties
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53 * the queue each time it runs so the producer should never find the queue full.
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55 * An error is flagged if the consumer obtains an unexpected value or the producer
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56 * find the queue is full.
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62 + Delay periods are now specified using variables and constants of
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63 portTickType rather than unsigned portLONG.
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68 /* Scheduler include files. */
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69 #include "FreeRTOS.h"
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73 /* Demo program include files. */
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76 #define pollqSTACK_SIZE configMINIMAL_STACK_SIZE
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77 #define pollqQUEUE_SIZE ( 10 )
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78 #define pollqPRODUCER_DELAY ( ( portTickType ) 200 / portTICK_RATE_MS )
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79 #define pollqCONSUMER_DELAY ( pollqPRODUCER_DELAY - ( portTickType ) ( 20 / portTICK_RATE_MS ) )
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80 #define pollqNO_DELAY ( ( portTickType ) 0 )
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81 #define pollqVALUES_TO_PRODUCE ( ( signed portBASE_TYPE ) 3 )
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82 #define pollqINITIAL_VALUE ( ( signed portBASE_TYPE ) 0 )
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84 /* The task that posts the incrementing number onto the queue. */
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85 static portTASK_FUNCTION_PROTO( vPolledQueueProducer, pvParameters );
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87 /* The task that empties the queue. */
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88 static portTASK_FUNCTION_PROTO( vPolledQueueConsumer, pvParameters );
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90 /* Variables that are used to check that the tasks are still running with no
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92 static volatile signed portBASE_TYPE xPollingConsumerCount = pollqINITIAL_VALUE, xPollingProducerCount = pollqINITIAL_VALUE;
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94 /*-----------------------------------------------------------*/
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96 void vStartPolledQueueTasks( unsigned portBASE_TYPE uxPriority )
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98 static xQueueHandle xPolledQueue;
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100 /* Create the queue used by the producer and consumer. */
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101 xPolledQueue = xQueueCreate( pollqQUEUE_SIZE, ( unsigned portBASE_TYPE ) sizeof( unsigned portSHORT ) );
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103 /* Spawn the producer and consumer. */
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104 xTaskCreate( vPolledQueueConsumer, ( signed portCHAR * ) "QConsNB", pollqSTACK_SIZE, ( void * ) &xPolledQueue, uxPriority, ( xTaskHandle * ) NULL );
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105 xTaskCreate( vPolledQueueProducer, ( signed portCHAR * ) "QProdNB", pollqSTACK_SIZE, ( void * ) &xPolledQueue, uxPriority, ( xTaskHandle * ) NULL );
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107 /*-----------------------------------------------------------*/
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109 static portTASK_FUNCTION( vPolledQueueProducer, pvParameters )
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111 unsigned portSHORT usValue = ( unsigned portSHORT ) 0;
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112 signed portBASE_TYPE xError = pdFALSE, xLoop;
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116 for( xLoop = 0; xLoop < pollqVALUES_TO_PRODUCE; xLoop++ )
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118 /* Send an incrementing number on the queue without blocking. */
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119 if( xQueueSend( *( ( xQueueHandle * ) pvParameters ), ( void * ) &usValue, pollqNO_DELAY ) != pdPASS )
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121 /* We should never find the queue full so if we get here there
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122 has been an error. */
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127 if( xError == pdFALSE )
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129 /* If an error has ever been recorded we stop incrementing the
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131 portENTER_CRITICAL();
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132 xPollingProducerCount++;
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133 portEXIT_CRITICAL();
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136 /* Update the value we are going to post next time around. */
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141 /* Wait before we start posting again to ensure the consumer runs and
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142 empties the queue. */
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143 vTaskDelay( pollqPRODUCER_DELAY );
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145 } /*lint !e818 Function prototype must conform to API. */
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146 /*-----------------------------------------------------------*/
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148 static portTASK_FUNCTION( vPolledQueueConsumer, pvParameters )
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150 unsigned portSHORT usData, usExpectedValue = ( unsigned portSHORT ) 0;
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151 signed portBASE_TYPE xError = pdFALSE;
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155 /* Loop until the queue is empty. */
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156 while( uxQueueMessagesWaiting( *( ( xQueueHandle * ) pvParameters ) ) )
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158 if( xQueueReceive( *( ( xQueueHandle * ) pvParameters ), &usData, pollqNO_DELAY ) == pdPASS )
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160 if( usData != usExpectedValue )
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162 /* This is not what we expected to receive so an error has
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166 /* Catch-up to the value we received so our next expected
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167 value should again be correct. */
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168 usExpectedValue = usData;
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172 if( xError == pdFALSE )
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174 /* Only increment the check variable if no errors have
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176 portENTER_CRITICAL();
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177 xPollingConsumerCount++;
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178 portEXIT_CRITICAL();
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182 /* Next time round we would expect the number to be one higher. */
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187 /* Now the queue is empty we block, allowing the producer to place more
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188 items in the queue. */
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189 vTaskDelay( pollqCONSUMER_DELAY );
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191 } /*lint !e818 Function prototype must conform to API. */
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192 /*-----------------------------------------------------------*/
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194 /* This is called to check that all the created tasks are still running with no errors. */
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195 portBASE_TYPE xArePollingQueuesStillRunning( void )
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197 portBASE_TYPE xReturn;
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199 /* Check both the consumer and producer poll count to check they have both
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200 been changed since out last trip round. We do not need a critical section
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201 around the check variables as this is called from a higher priority than
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202 the other tasks that access the same variables. */
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203 if( ( xPollingConsumerCount == pollqINITIAL_VALUE ) ||
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204 ( xPollingProducerCount == pollqINITIAL_VALUE )
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214 /* Set the check variables back down so we know if they have been
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215 incremented the next time around. */
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216 xPollingConsumerCount = pollqINITIAL_VALUE;
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217 xPollingProducerCount = pollqINITIAL_VALUE;
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