2 FreeRTOS.org V5.4.0 - Copyright (C) 2003-2009 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 it
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7 under the terms of the GNU General Public License (version 2) as published
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8 by the Free Software Foundation and modified by the FreeRTOS exception.
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9 **NOTE** The exception to the GPL is included to allow you to distribute a
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10 combined work that includes FreeRTOS.org without being obliged to provide
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11 the source code for any proprietary components. Alternative commercial
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12 license and support terms are also available upon request. See the
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13 licensing section of http://www.FreeRTOS.org for full details.
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15 FreeRTOS.org is distributed in the hope that it will be useful, but WITHOUT
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16 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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17 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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20 You should have received a copy of the GNU General Public License along
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21 with FreeRTOS.org; if not, write to the Free Software Foundation, Inc., 59
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22 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
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25 ***************************************************************************
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27 * Get the FreeRTOS eBook! See http://www.FreeRTOS.org/Documentation *
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29 * This is a concise, step by step, 'hands on' guide that describes both *
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30 * general multitasking concepts and FreeRTOS specifics. It presents and *
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31 * explains numerous examples that are written using the FreeRTOS API. *
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32 * Full source code for all the examples is provided in an accompanying *
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35 ***************************************************************************
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39 Please ensure to read the configuration and relevant port sections of the
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40 online documentation.
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42 http://www.FreeRTOS.org - Documentation, latest information, license and
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45 http://www.SafeRTOS.com - A version that is certified for use in safety
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48 http://www.OpenRTOS.com - Commercial support, development, porting,
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49 licensing and training services.
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53 * Creates six tasks that operate on three queues as follows:
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55 * The first two tasks send and receive an incrementing number to/from a queue.
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56 * One task acts as a producer and the other as the consumer. The consumer is a
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57 * higher priority than the producer and is set to block on queue reads. The queue
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58 * only has space for one item - as soon as the producer posts a message on the
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59 * queue the consumer will unblock, pre-empt the producer, and remove the item.
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61 * The second two tasks work the other way around. Again the queue used only has
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62 * enough space for one item. This time the consumer has a lower priority than the
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63 * producer. The producer will try to post on the queue blocking when the queue is
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64 * full. When the consumer wakes it will remove the item from the queue, causing
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65 * the producer to unblock, pre-empt the consumer, and immediately re-fill the
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68 * The last two tasks use the same queue producer and consumer functions. This time the queue has
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69 * enough space for lots of items and the tasks operate at the same priority. The
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70 * producer will execute, placing items into the queue. The consumer will start
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71 * executing when either the queue becomes full (causing the producer to block) or
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72 * a context switch occurs (tasks of the same priority will time slice).
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80 + The second set of tasks were created the wrong way around. This has been
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87 /* Scheduler include files. */
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88 #include "FreeRTOS.h"
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92 /* Demo program include files. */
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95 #define blckqSTACK_SIZE configMINIMAL_STACK_SIZE
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96 #define blckqNUM_TASK_SETS ( 3 )
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98 /* Structure used to pass parameters to the blocking queue tasks. */
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99 typedef struct BLOCKING_QUEUE_PARAMETERS
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101 xQueueHandle xQueue; /*< The queue to be used by the task. */
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102 portTickType xBlockTime; /*< The block time to use on queue reads/writes. */
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103 volatile portSHORT *psCheckVariable; /*< Incremented on each successful cycle to check the task is still running. */
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104 } xBlockingQueueParameters;
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106 /* Task function that creates an incrementing number and posts it on a queue. */
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107 static portTASK_FUNCTION_PROTO( vBlockingQueueProducer, pvParameters );
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109 /* Task function that removes the incrementing number from a queue and checks that
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110 it is the expected number. */
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111 static portTASK_FUNCTION_PROTO( vBlockingQueueConsumer, pvParameters );
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113 /* Variables which are incremented each time an item is removed from a queue, and
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114 found to be the expected value.
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115 These are used to check that the tasks are still running. */
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116 static volatile portSHORT sBlockingConsumerCount[ blckqNUM_TASK_SETS ] = { ( unsigned portSHORT ) 0, ( unsigned portSHORT ) 0, ( unsigned portSHORT ) 0 };
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118 /* Variable which are incremented each time an item is posted on a queue. These
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119 are used to check that the tasks are still running. */
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120 static volatile portSHORT sBlockingProducerCount[ blckqNUM_TASK_SETS ] = { ( unsigned portSHORT ) 0, ( unsigned portSHORT ) 0, ( unsigned portSHORT ) 0 };
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122 /*-----------------------------------------------------------*/
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124 void vStartBlockingQueueTasks( unsigned portBASE_TYPE uxPriority )
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126 xBlockingQueueParameters *pxQueueParameters1, *pxQueueParameters2;
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127 xBlockingQueueParameters *pxQueueParameters3, *pxQueueParameters4;
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128 xBlockingQueueParameters *pxQueueParameters5, *pxQueueParameters6;
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129 const unsigned portBASE_TYPE uxQueueSize1 = 1, uxQueueSize5 = 5;
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130 const portTickType xBlockTime = ( portTickType ) 1000 / portTICK_RATE_MS;
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131 const portTickType xDontBlock = ( portTickType ) 0;
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133 /* Create the first two tasks as described at the top of the file. */
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135 /* First create the structure used to pass parameters to the consumer tasks. */
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136 pxQueueParameters1 = ( xBlockingQueueParameters * ) pvPortMalloc( sizeof( xBlockingQueueParameters ) );
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138 /* Create the queue used by the first two tasks to pass the incrementing number.
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139 Pass a pointer to the queue in the parameter structure. */
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140 pxQueueParameters1->xQueue = xQueueCreate( uxQueueSize1, ( unsigned portBASE_TYPE ) sizeof( unsigned portSHORT ) );
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142 /* The consumer is created first so gets a block time as described above. */
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143 pxQueueParameters1->xBlockTime = xBlockTime;
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145 /* Pass in the variable that this task is going to increment so we can check it
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146 is still running. */
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147 pxQueueParameters1->psCheckVariable = &( sBlockingConsumerCount[ 0 ] );
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149 /* Create the structure used to pass parameters to the producer task. */
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150 pxQueueParameters2 = ( xBlockingQueueParameters * ) pvPortMalloc( sizeof( xBlockingQueueParameters ) );
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152 /* Pass the queue to this task also, using the parameter structure. */
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153 pxQueueParameters2->xQueue = pxQueueParameters1->xQueue;
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155 /* The producer is not going to block - as soon as it posts the consumer will
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156 wake and remove the item so the producer should always have room to post. */
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157 pxQueueParameters2->xBlockTime = xDontBlock;
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159 /* Pass in the variable that this task is going to increment so we can check
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160 it is still running. */
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161 pxQueueParameters2->psCheckVariable = &( sBlockingProducerCount[ 0 ] );
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164 /* Note the producer has a lower priority than the consumer when the tasks are
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166 xTaskCreate( vBlockingQueueConsumer, ( signed portCHAR * ) "QConsB1", blckqSTACK_SIZE, ( void * ) pxQueueParameters1, uxPriority, NULL );
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167 xTaskCreate( vBlockingQueueProducer, ( signed portCHAR * ) "QProdB2", blckqSTACK_SIZE, ( void * ) pxQueueParameters2, tskIDLE_PRIORITY, NULL );
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171 /* Create the second two tasks as described at the top of the file. This uses
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172 the same mechanism but reverses the task priorities. */
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174 pxQueueParameters3 = ( xBlockingQueueParameters * ) pvPortMalloc( sizeof( xBlockingQueueParameters ) );
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175 pxQueueParameters3->xQueue = xQueueCreate( uxQueueSize1, ( unsigned portBASE_TYPE ) sizeof( unsigned portSHORT ) );
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176 pxQueueParameters3->xBlockTime = xDontBlock;
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177 pxQueueParameters3->psCheckVariable = &( sBlockingProducerCount[ 1 ] );
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179 pxQueueParameters4 = ( xBlockingQueueParameters * ) pvPortMalloc( sizeof( xBlockingQueueParameters ) );
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180 pxQueueParameters4->xQueue = pxQueueParameters3->xQueue;
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181 pxQueueParameters4->xBlockTime = xBlockTime;
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182 pxQueueParameters4->psCheckVariable = &( sBlockingConsumerCount[ 1 ] );
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184 xTaskCreate( vBlockingQueueConsumer, ( signed portCHAR * ) "QProdB3", blckqSTACK_SIZE, ( void * ) pxQueueParameters3, tskIDLE_PRIORITY, NULL );
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185 xTaskCreate( vBlockingQueueProducer, ( signed portCHAR * ) "QConsB4", blckqSTACK_SIZE, ( void * ) pxQueueParameters4, uxPriority, NULL );
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189 /* Create the last two tasks as described above. The mechanism is again just
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190 the same. This time both parameter structures are given a block time. */
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191 pxQueueParameters5 = ( xBlockingQueueParameters * ) pvPortMalloc( sizeof( xBlockingQueueParameters ) );
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192 pxQueueParameters5->xQueue = xQueueCreate( uxQueueSize5, ( unsigned portBASE_TYPE ) sizeof( unsigned portSHORT ) );
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193 pxQueueParameters5->xBlockTime = xBlockTime;
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194 pxQueueParameters5->psCheckVariable = &( sBlockingProducerCount[ 2 ] );
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196 pxQueueParameters6 = ( xBlockingQueueParameters * ) pvPortMalloc( sizeof( xBlockingQueueParameters ) );
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197 pxQueueParameters6->xQueue = pxQueueParameters5->xQueue;
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198 pxQueueParameters6->xBlockTime = xBlockTime;
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199 pxQueueParameters6->psCheckVariable = &( sBlockingConsumerCount[ 2 ] );
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201 xTaskCreate( vBlockingQueueProducer, ( signed portCHAR * ) "QProdB5", blckqSTACK_SIZE, ( void * ) pxQueueParameters5, tskIDLE_PRIORITY, NULL );
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202 xTaskCreate( vBlockingQueueConsumer, ( signed portCHAR * ) "QConsB6", blckqSTACK_SIZE, ( void * ) pxQueueParameters6, tskIDLE_PRIORITY, NULL );
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204 /*-----------------------------------------------------------*/
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206 static portTASK_FUNCTION( vBlockingQueueProducer, pvParameters )
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208 unsigned portSHORT usValue = 0;
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209 xBlockingQueueParameters *pxQueueParameters;
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210 portSHORT sErrorEverOccurred = pdFALSE;
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212 pxQueueParameters = ( xBlockingQueueParameters * ) pvParameters;
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216 if( xQueueSend( pxQueueParameters->xQueue, ( void * ) &usValue, pxQueueParameters->xBlockTime ) != pdPASS )
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218 sErrorEverOccurred = pdTRUE;
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222 /* We have successfully posted a message, so increment the variable
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223 used to check we are still running. */
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224 if( sErrorEverOccurred == pdFALSE )
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226 ( *pxQueueParameters->psCheckVariable )++;
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229 /* Increment the variable we are going to post next time round. The
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230 consumer will expect the numbers to follow in numerical order. */
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235 /*-----------------------------------------------------------*/
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237 static portTASK_FUNCTION( vBlockingQueueConsumer, pvParameters )
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239 unsigned portSHORT usData, usExpectedValue = 0;
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240 xBlockingQueueParameters *pxQueueParameters;
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241 portSHORT sErrorEverOccurred = pdFALSE;
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243 pxQueueParameters = ( xBlockingQueueParameters * ) pvParameters;
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247 if( xQueueReceive( pxQueueParameters->xQueue, &usData, pxQueueParameters->xBlockTime ) == pdPASS )
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249 if( usData != usExpectedValue )
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252 usExpectedValue = usData;
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254 sErrorEverOccurred = pdTRUE;
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258 /* We have successfully received a message, so increment the
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259 variable used to check we are still running. */
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260 if( sErrorEverOccurred == pdFALSE )
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262 ( *pxQueueParameters->psCheckVariable )++;
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265 /* Increment the value we expect to remove from the queue next time
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272 /*-----------------------------------------------------------*/
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274 /* This is called to check that all the created tasks are still running. */
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275 portBASE_TYPE xAreBlockingQueuesStillRunning( void )
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277 static portSHORT sLastBlockingConsumerCount[ blckqNUM_TASK_SETS ] = { ( unsigned portSHORT ) 0, ( unsigned portSHORT ) 0, ( unsigned portSHORT ) 0 };
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278 static portSHORT sLastBlockingProducerCount[ blckqNUM_TASK_SETS ] = { ( unsigned portSHORT ) 0, ( unsigned portSHORT ) 0, ( unsigned portSHORT ) 0 };
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279 portBASE_TYPE xReturn = pdPASS, xTasks;
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281 /* Not too worried about mutual exclusion on these variables as they are 16
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282 bits and we are only reading them. We also only care to see if they have
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285 Loop through each check variable to and return pdFALSE if any are found not
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286 to have changed since the last call. */
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288 for( xTasks = 0; xTasks < blckqNUM_TASK_SETS; xTasks++ )
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290 if( sBlockingConsumerCount[ xTasks ] == sLastBlockingConsumerCount[ xTasks ] )
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294 sLastBlockingConsumerCount[ xTasks ] = sBlockingConsumerCount[ xTasks ];
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297 if( sBlockingProducerCount[ xTasks ] == sLastBlockingProducerCount[ xTasks ] )
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301 sLastBlockingProducerCount[ xTasks ] = sBlockingProducerCount[ xTasks ];
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