2 FreeRTOS V6.0.4 - Copyright (C) 2010 Real Time Engineers Ltd.
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4 ***************************************************************************
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8 * + New to FreeRTOS, *
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9 * + Wanting to learn FreeRTOS or multitasking in general quickly *
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10 * + Looking for basic training, *
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11 * + Wanting to improve your FreeRTOS skills and productivity *
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13 * then take a look at the FreeRTOS eBook *
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15 * "Using the FreeRTOS Real Time Kernel - a Practical Guide" *
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16 * http://www.FreeRTOS.org/Documentation *
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18 * A pdf reference manual is also available. Both are usually delivered *
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19 * to your inbox within 20 minutes to two hours when purchased between 8am *
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20 * and 8pm GMT (although please allow up to 24 hours in case of *
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21 * exceptional circumstances). Thank you for your support! *
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23 ***************************************************************************
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25 This file is part of the FreeRTOS distribution.
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27 FreeRTOS is free software; you can redistribute it and/or modify it under
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28 the terms of the GNU General Public License (version 2) as published by the
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29 Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
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30 ***NOTE*** The exception to the GPL is included to allow you to distribute
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31 a combined work that includes FreeRTOS without being obliged to provide the
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32 source code for proprietary components outside of the FreeRTOS kernel.
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33 FreeRTOS is distributed in the hope that it will be useful, but WITHOUT
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34 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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35 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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36 more details. You should have received a copy of the GNU General Public
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37 License and the FreeRTOS license exception along with FreeRTOS; if not it
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38 can be viewed here: http://www.freertos.org/a00114.html and also obtained
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39 by writing to Richard Barry, contact details for whom are available on the
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44 http://www.FreeRTOS.org - Documentation, latest information, license and
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47 http://www.SafeRTOS.com - A version that is certified for use in safety
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50 http://www.OpenRTOS.com - Commercial support, development, porting,
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51 licensing and training services.
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55 * Creates six tasks that operate on three queues as follows:
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57 * The first two tasks send and receive an incrementing number to/from a queue.
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58 * One task acts as a producer and the other as the consumer. The consumer is a
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59 * higher priority than the producer and is set to block on queue reads. The queue
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60 * only has space for one item - as soon as the producer posts a message on the
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61 * queue the consumer will unblock, pre-empt the producer, and remove the item.
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63 * The second two tasks work the other way around. Again the queue used only has
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64 * enough space for one item. This time the consumer has a lower priority than the
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65 * producer. The producer will try to post on the queue blocking when the queue is
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66 * full. When the consumer wakes it will remove the item from the queue, causing
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67 * the producer to unblock, pre-empt the consumer, and immediately re-fill the
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70 * The last two tasks use the same queue producer and consumer functions. This time the queue has
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71 * enough space for lots of items and the tasks operate at the same priority. The
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72 * producer will execute, placing items into the queue. The consumer will start
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73 * executing when either the queue becomes full (causing the producer to block) or
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74 * a context switch occurs (tasks of the same priority will time slice).
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82 + The second set of tasks were created the wrong way around. This has been
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89 /* Scheduler include files. */
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90 #include "FreeRTOS.h"
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94 /* Demo program include files. */
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97 #define blckqSTACK_SIZE configMINIMAL_STACK_SIZE
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98 #define blckqNUM_TASK_SETS ( 3 )
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100 /* Structure used to pass parameters to the blocking queue tasks. */
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101 typedef struct BLOCKING_QUEUE_PARAMETERS
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103 xQueueHandle xQueue; /*< The queue to be used by the task. */
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104 portTickType xBlockTime; /*< The block time to use on queue reads/writes. */
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105 volatile short *psCheckVariable; /*< Incremented on each successful cycle to check the task is still running. */
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106 } xBlockingQueueParameters;
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108 /* Task function that creates an incrementing number and posts it on a queue. */
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109 static portTASK_FUNCTION_PROTO( vBlockingQueueProducer, pvParameters );
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111 /* Task function that removes the incrementing number from a queue and checks that
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112 it is the expected number. */
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113 static portTASK_FUNCTION_PROTO( vBlockingQueueConsumer, pvParameters );
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115 /* Variables which are incremented each time an item is removed from a queue, and
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116 found to be the expected value.
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117 These are used to check that the tasks are still running. */
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118 static volatile short sBlockingConsumerCount[ blckqNUM_TASK_SETS ] = { ( unsigned short ) 0, ( unsigned short ) 0, ( unsigned short ) 0 };
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120 /* Variable which are incremented each time an item is posted on a queue. These
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121 are used to check that the tasks are still running. */
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122 static volatile short sBlockingProducerCount[ blckqNUM_TASK_SETS ] = { ( unsigned short ) 0, ( unsigned short ) 0, ( unsigned short ) 0 };
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124 /*-----------------------------------------------------------*/
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126 void vStartBlockingQueueTasks( unsigned portBASE_TYPE uxPriority )
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128 xBlockingQueueParameters *pxQueueParameters1, *pxQueueParameters2;
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129 xBlockingQueueParameters *pxQueueParameters3, *pxQueueParameters4;
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130 xBlockingQueueParameters *pxQueueParameters5, *pxQueueParameters6;
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131 const unsigned portBASE_TYPE uxQueueSize1 = 1, uxQueueSize5 = 5;
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132 const portTickType xBlockTime = ( portTickType ) 1000 / portTICK_RATE_MS;
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133 const portTickType xDontBlock = ( portTickType ) 0;
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135 /* Create the first two tasks as described at the top of the file. */
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137 /* First create the structure used to pass parameters to the consumer tasks. */
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138 pxQueueParameters1 = ( xBlockingQueueParameters * ) pvPortMalloc( sizeof( xBlockingQueueParameters ) );
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140 /* Create the queue used by the first two tasks to pass the incrementing number.
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141 Pass a pointer to the queue in the parameter structure. */
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142 pxQueueParameters1->xQueue = xQueueCreate( uxQueueSize1, ( unsigned portBASE_TYPE ) sizeof( unsigned short ) );
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144 /* The consumer is created first so gets a block time as described above. */
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145 pxQueueParameters1->xBlockTime = xBlockTime;
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147 /* Pass in the variable that this task is going to increment so we can check it
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148 is still running. */
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149 pxQueueParameters1->psCheckVariable = &( sBlockingConsumerCount[ 0 ] );
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151 /* Create the structure used to pass parameters to the producer task. */
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152 pxQueueParameters2 = ( xBlockingQueueParameters * ) pvPortMalloc( sizeof( xBlockingQueueParameters ) );
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154 /* Pass the queue to this task also, using the parameter structure. */
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155 pxQueueParameters2->xQueue = pxQueueParameters1->xQueue;
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157 /* The producer is not going to block - as soon as it posts the consumer will
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158 wake and remove the item so the producer should always have room to post. */
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159 pxQueueParameters2->xBlockTime = xDontBlock;
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161 /* Pass in the variable that this task is going to increment so we can check
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162 it is still running. */
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163 pxQueueParameters2->psCheckVariable = &( sBlockingProducerCount[ 0 ] );
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166 /* Note the producer has a lower priority than the consumer when the tasks are
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168 xTaskCreate( vBlockingQueueConsumer, ( signed char * ) "QConsB1", blckqSTACK_SIZE, ( void * ) pxQueueParameters1, uxPriority, NULL );
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169 xTaskCreate( vBlockingQueueProducer, ( signed char * ) "QProdB2", blckqSTACK_SIZE, ( void * ) pxQueueParameters2, tskIDLE_PRIORITY, NULL );
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173 /* Create the second two tasks as described at the top of the file. This uses
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174 the same mechanism but reverses the task priorities. */
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176 pxQueueParameters3 = ( xBlockingQueueParameters * ) pvPortMalloc( sizeof( xBlockingQueueParameters ) );
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177 pxQueueParameters3->xQueue = xQueueCreate( uxQueueSize1, ( unsigned portBASE_TYPE ) sizeof( unsigned short ) );
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178 pxQueueParameters3->xBlockTime = xDontBlock;
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179 pxQueueParameters3->psCheckVariable = &( sBlockingProducerCount[ 1 ] );
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181 pxQueueParameters4 = ( xBlockingQueueParameters * ) pvPortMalloc( sizeof( xBlockingQueueParameters ) );
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182 pxQueueParameters4->xQueue = pxQueueParameters3->xQueue;
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183 pxQueueParameters4->xBlockTime = xBlockTime;
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184 pxQueueParameters4->psCheckVariable = &( sBlockingConsumerCount[ 1 ] );
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186 xTaskCreate( vBlockingQueueConsumer, ( signed char * ) "QProdB3", blckqSTACK_SIZE, ( void * ) pxQueueParameters3, tskIDLE_PRIORITY, NULL );
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187 xTaskCreate( vBlockingQueueProducer, ( signed char * ) "QConsB4", blckqSTACK_SIZE, ( void * ) pxQueueParameters4, uxPriority, NULL );
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191 /* Create the last two tasks as described above. The mechanism is again just
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192 the same. This time both parameter structures are given a block time. */
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193 pxQueueParameters5 = ( xBlockingQueueParameters * ) pvPortMalloc( sizeof( xBlockingQueueParameters ) );
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194 pxQueueParameters5->xQueue = xQueueCreate( uxQueueSize5, ( unsigned portBASE_TYPE ) sizeof( unsigned short ) );
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195 pxQueueParameters5->xBlockTime = xBlockTime;
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196 pxQueueParameters5->psCheckVariable = &( sBlockingProducerCount[ 2 ] );
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198 pxQueueParameters6 = ( xBlockingQueueParameters * ) pvPortMalloc( sizeof( xBlockingQueueParameters ) );
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199 pxQueueParameters6->xQueue = pxQueueParameters5->xQueue;
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200 pxQueueParameters6->xBlockTime = xBlockTime;
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201 pxQueueParameters6->psCheckVariable = &( sBlockingConsumerCount[ 2 ] );
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203 xTaskCreate( vBlockingQueueProducer, ( signed char * ) "QProdB5", blckqSTACK_SIZE, ( void * ) pxQueueParameters5, tskIDLE_PRIORITY, NULL );
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204 xTaskCreate( vBlockingQueueConsumer, ( signed char * ) "QConsB6", blckqSTACK_SIZE, ( void * ) pxQueueParameters6, tskIDLE_PRIORITY, NULL );
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206 /*-----------------------------------------------------------*/
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208 static portTASK_FUNCTION( vBlockingQueueProducer, pvParameters )
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210 unsigned short usValue = 0;
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211 xBlockingQueueParameters *pxQueueParameters;
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212 short sErrorEverOccurred = pdFALSE;
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214 pxQueueParameters = ( xBlockingQueueParameters * ) pvParameters;
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218 if( xQueueSend( pxQueueParameters->xQueue, ( void * ) &usValue, pxQueueParameters->xBlockTime ) != pdPASS )
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220 sErrorEverOccurred = pdTRUE;
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224 /* We have successfully posted a message, so increment the variable
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225 used to check we are still running. */
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226 if( sErrorEverOccurred == pdFALSE )
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228 ( *pxQueueParameters->psCheckVariable )++;
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231 /* Increment the variable we are going to post next time round. The
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232 consumer will expect the numbers to follow in numerical order. */
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237 /*-----------------------------------------------------------*/
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239 static portTASK_FUNCTION( vBlockingQueueConsumer, pvParameters )
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241 unsigned short usData, usExpectedValue = 0;
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242 xBlockingQueueParameters *pxQueueParameters;
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243 short sErrorEverOccurred = pdFALSE;
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245 pxQueueParameters = ( xBlockingQueueParameters * ) pvParameters;
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249 if( xQueueReceive( pxQueueParameters->xQueue, &usData, pxQueueParameters->xBlockTime ) == pdPASS )
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251 if( usData != usExpectedValue )
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254 usExpectedValue = usData;
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256 sErrorEverOccurred = pdTRUE;
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260 /* We have successfully received a message, so increment the
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261 variable used to check we are still running. */
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262 if( sErrorEverOccurred == pdFALSE )
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264 ( *pxQueueParameters->psCheckVariable )++;
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267 /* Increment the value we expect to remove from the queue next time
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274 /*-----------------------------------------------------------*/
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276 /* This is called to check that all the created tasks are still running. */
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277 portBASE_TYPE xAreBlockingQueuesStillRunning( void )
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279 static short sLastBlockingConsumerCount[ blckqNUM_TASK_SETS ] = { ( unsigned short ) 0, ( unsigned short ) 0, ( unsigned short ) 0 };
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280 static short sLastBlockingProducerCount[ blckqNUM_TASK_SETS ] = { ( unsigned short ) 0, ( unsigned short ) 0, ( unsigned short ) 0 };
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281 portBASE_TYPE xReturn = pdPASS, xTasks;
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283 /* Not too worried about mutual exclusion on these variables as they are 16
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284 bits and we are only reading them. We also only care to see if they have
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287 Loop through each check variable to and return pdFALSE if any are found not
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288 to have changed since the last call. */
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290 for( xTasks = 0; xTasks < blckqNUM_TASK_SETS; xTasks++ )
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292 if( sBlockingConsumerCount[ xTasks ] == sLastBlockingConsumerCount[ xTasks ] )
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296 sLastBlockingConsumerCount[ xTasks ] = sBlockingConsumerCount[ xTasks ];
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299 if( sBlockingProducerCount[ xTasks ] == sLastBlockingProducerCount[ xTasks ] )
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303 sLastBlockingProducerCount[ xTasks ] = sBlockingProducerCount[ xTasks ];
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