2 FreeRTOS.org V5.1.0 - Copyright (C) 2003-2008 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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23 of http://www.FreeRTOS.org for full details of how and when the exception
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26 ***************************************************************************
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27 ***************************************************************************
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29 * SAVE TIME AND MONEY! We can port FreeRTOS.org to your own hardware, *
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30 * and even write all or part of your application on your behalf. *
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31 * See http://www.OpenRTOS.com for details of the services we provide to *
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32 * expedite your project. *
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34 ***************************************************************************
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35 ***************************************************************************
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37 Please ensure to read the configuration and relevant port sections of the
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38 online documentation.
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40 http://www.FreeRTOS.org - Documentation, latest information, license and
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43 http://www.SafeRTOS.com - A version that is certified for use in safety
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46 http://www.OpenRTOS.com - Commercial support, development, porting,
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47 licensing and training services.
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52 * Simple demonstration of the usage of counting semaphore.
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55 /* Scheduler include files. */
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56 #include "FreeRTOS.h"
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60 /* Demo program include files. */
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61 #include "countsem.h"
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63 /* The maximum count value that the semaphore used for the demo can hold. */
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64 #define countMAX_COUNT_VALUE ( 200 )
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66 /* Constants used to indicate whether or not the semaphore should have been
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67 created with its maximum count value, or its minimum count value. These
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68 numbers are used to ensure that the pointers passed in as the task parameters
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70 #define countSTART_AT_MAX_COUNT ( 0xaa )
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71 #define countSTART_AT_ZERO ( 0x55 )
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73 /* Two tasks are created for the test. One uses a semaphore created with its
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74 count value set to the maximum, and one with the count value set to zero. */
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75 #define countNUM_TEST_TASKS ( 2 )
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76 #define countDONT_BLOCK ( 0 )
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78 /*-----------------------------------------------------------*/
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80 /* Flag that will be latched to pdTRUE should any unexpected behaviour be
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81 detected in any of the tasks. */
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82 static volatile portBASE_TYPE xErrorDetected = pdFALSE;
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84 /*-----------------------------------------------------------*/
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87 * The demo task. This simply counts the semaphore up to its maximum value,
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88 * the counts it back down again. The result of each semaphore 'give' and
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89 * 'take' is inspected, with an error being flagged if it is found not to be
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90 * the expected result.
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92 static void prvCountingSemaphoreTask( void *pvParameters );
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95 * Utility function to increment the semaphore count value up from zero to
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96 * countMAX_COUNT_VALUE.
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98 static void prvIncrementSemaphoreCount( xSemaphoreHandle xSemaphore, unsigned portBASE_TYPE *puxLoopCounter );
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101 * Utility function to decrement the semaphore count value up from
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102 * countMAX_COUNT_VALUE to zero.
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104 static void prvDecrementSemaphoreCount( xSemaphoreHandle xSemaphore, unsigned portBASE_TYPE *puxLoopCounter );
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106 /*-----------------------------------------------------------*/
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108 /* The structure that is passed into the task as the task parameter. */
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109 typedef struct COUNT_SEM_STRUCT
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111 /* The semaphore to be used for the demo. */
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112 xSemaphoreHandle xSemaphore;
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114 /* Set to countSTART_AT_MAX_COUNT if the semaphore should be created with
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115 its count value set to its max count value, or countSTART_AT_ZERO if it
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116 should have been created with its count value set to 0. */
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117 unsigned portBASE_TYPE uxExpectedStartCount;
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119 /* Incremented on each cycle of the demo task. Used to detect a stalled
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121 unsigned portBASE_TYPE uxLoopCounter;
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124 /* Two structures are defined, one is passed to each test task. */
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125 static volatile xCountSemStruct xParameters[ countNUM_TEST_TASKS ];
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127 /*-----------------------------------------------------------*/
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129 void vStartCountingSemaphoreTasks( void )
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131 /* Create the semaphores that we are going to use for the test/demo. The
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132 first should be created such that it starts at its maximum count value,
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133 the second should be created such that it starts with a count value of zero. */
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134 xParameters[ 0 ].xSemaphore = xSemaphoreCreateCounting( countMAX_COUNT_VALUE, countMAX_COUNT_VALUE );
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135 xParameters[ 0 ].uxExpectedStartCount = countSTART_AT_MAX_COUNT;
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136 xParameters[ 0 ].uxLoopCounter = 0;
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138 xParameters[ 1 ].xSemaphore = xSemaphoreCreateCounting( countMAX_COUNT_VALUE, 0 );
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139 xParameters[ 1 ].uxExpectedStartCount = 0;
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140 xParameters[ 1 ].uxLoopCounter = 0;
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142 /* vQueueAddToRegistry() adds the semaphore to the registry, if one is
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143 in use. The registry is provided as a means for kernel aware
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144 debuggers to locate semaphores and has no purpose if a kernel aware debugger
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145 is not being used. The call to vQueueAddToRegistry() will be removed
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146 by the pre-processor if configQUEUE_REGISTRY_SIZE is not defined or is
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147 defined to be less than 1. */
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148 vQueueAddToRegistry( ( xQueueHandle ) xParameters[ 0 ].xSemaphore, ( signed portCHAR * ) "Counting_Sem_1" );
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149 vQueueAddToRegistry( ( xQueueHandle ) xParameters[ 1 ].xSemaphore, ( signed portCHAR * ) "Counting_Sem_2" );
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152 /* Were the semaphores created? */
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153 if( ( xParameters[ 0 ].xSemaphore != NULL ) || ( xParameters[ 1 ].xSemaphore != NULL ) )
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155 /* Create the demo tasks, passing in the semaphore to use as the parameter. */
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156 xTaskCreate( prvCountingSemaphoreTask, ( signed portCHAR * ) "CNT1", configMINIMAL_STACK_SIZE, ( void * ) &( xParameters[ 0 ] ), tskIDLE_PRIORITY, NULL );
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157 xTaskCreate( prvCountingSemaphoreTask, ( signed portCHAR * ) "CNT2", configMINIMAL_STACK_SIZE, ( void * ) &( xParameters[ 1 ] ), tskIDLE_PRIORITY, NULL );
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160 /*-----------------------------------------------------------*/
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162 static void prvDecrementSemaphoreCount( xSemaphoreHandle xSemaphore, unsigned portBASE_TYPE *puxLoopCounter )
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164 unsigned portBASE_TYPE ux;
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166 /* If the semaphore count is at its maximum then we should not be able to
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167 'give' the semaphore. */
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168 if( xSemaphoreGive( xSemaphore ) == pdPASS )
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170 xErrorDetected = pdTRUE;
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173 /* We should be able to 'take' the semaphore countMAX_COUNT_VALUE times. */
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174 for( ux = 0; ux < countMAX_COUNT_VALUE; ux++ )
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176 if( xSemaphoreTake( xSemaphore, countDONT_BLOCK ) != pdPASS )
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178 /* We expected to be able to take the semaphore. */
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179 xErrorDetected = pdTRUE;
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182 ( *puxLoopCounter )++;
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185 #if configUSE_PREEMPTION == 0
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189 /* If the semaphore count is zero then we should not be able to 'take'
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191 if( xSemaphoreTake( xSemaphore, countDONT_BLOCK ) == pdPASS )
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193 xErrorDetected = pdTRUE;
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196 /*-----------------------------------------------------------*/
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198 static void prvIncrementSemaphoreCount( xSemaphoreHandle xSemaphore, unsigned portBASE_TYPE *puxLoopCounter )
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200 unsigned portBASE_TYPE ux;
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202 /* If the semaphore count is zero then we should not be able to 'take'
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204 if( xSemaphoreTake( xSemaphore, countDONT_BLOCK ) == pdPASS )
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206 xErrorDetected = pdTRUE;
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209 /* We should be able to 'give' the semaphore countMAX_COUNT_VALUE times. */
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210 for( ux = 0; ux < countMAX_COUNT_VALUE; ux++ )
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212 if( xSemaphoreGive( xSemaphore ) != pdPASS )
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214 /* We expected to be able to take the semaphore. */
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215 xErrorDetected = pdTRUE;
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218 ( *puxLoopCounter )++;
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221 #if configUSE_PREEMPTION == 0
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225 /* If the semaphore count is at its maximum then we should not be able to
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226 'give' the semaphore. */
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227 if( xSemaphoreGive( xSemaphore ) == pdPASS )
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229 xErrorDetected = pdTRUE;
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232 /*-----------------------------------------------------------*/
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234 static void prvCountingSemaphoreTask( void *pvParameters )
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236 xCountSemStruct *pxParameter;
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239 void vPrintDisplayMessage( const portCHAR * const * ppcMessageToSend );
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241 const portCHAR * const pcTaskStartMsg = "Counting semaphore demo started.\r\n";
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243 /* Queue a message for printing to say the task has started. */
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244 vPrintDisplayMessage( &pcTaskStartMsg );
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247 /* The semaphore to be used was passed as the parameter. */
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248 pxParameter = ( xCountSemStruct * ) pvParameters;
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250 /* Did we expect to find the semaphore already at its max count value, or
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252 if( pxParameter->uxExpectedStartCount == countSTART_AT_MAX_COUNT )
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254 prvDecrementSemaphoreCount( pxParameter->xSemaphore, &( pxParameter->uxLoopCounter ) );
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257 /* Now we expect the semaphore count to be 0, so this time there is an
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258 error if we can take the semaphore. */
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259 if( xSemaphoreTake( pxParameter->xSemaphore, 0 ) == pdPASS )
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261 xErrorDetected = pdTRUE;
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266 prvIncrementSemaphoreCount( pxParameter->xSemaphore, &( pxParameter->uxLoopCounter ) );
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267 prvDecrementSemaphoreCount( pxParameter->xSemaphore, &( pxParameter->uxLoopCounter ) );
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270 /*-----------------------------------------------------------*/
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272 portBASE_TYPE xAreCountingSemaphoreTasksStillRunning( void )
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274 static unsigned portBASE_TYPE uxLastCount0 = 0, uxLastCount1 = 0;
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275 portBASE_TYPE xReturn = pdPASS;
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277 /* Return fail if any 'give' or 'take' did not result in the expected
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279 if( xErrorDetected != pdFALSE )
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284 /* Return fail if either task is not still incrementing its loop counter. */
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285 if( uxLastCount0 == xParameters[ 0 ].uxLoopCounter )
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291 uxLastCount0 = xParameters[ 0 ].uxLoopCounter;
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294 if( uxLastCount1 == xParameters[ 1 ].uxLoopCounter )
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300 uxLastCount1 = xParameters[ 1 ].uxLoopCounter;
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