2 FreeRTOS V7.4.2 - Copyright (C) 2013 Real Time Engineers Ltd.
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4 FEATURES AND PORTS ARE ADDED TO FREERTOS ALL THE TIME. PLEASE VISIT
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5 http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION.
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7 ***************************************************************************
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9 * FreeRTOS tutorial books are available in pdf and paperback. *
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10 * Complete, revised, and edited pdf reference manuals are also *
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13 * Purchasing FreeRTOS documentation will not only help you, by *
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14 * ensuring you get running as quickly as possible and with an *
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15 * in-depth knowledge of how to use FreeRTOS, it will also help *
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16 * the FreeRTOS project to continue with its mission of providing *
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17 * professional grade, cross platform, de facto standard solutions *
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18 * for microcontrollers - completely free of charge! *
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20 * >>> See http://www.FreeRTOS.org/Documentation for details. <<< *
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22 * Thank you for using FreeRTOS, and thank you for your support! *
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24 ***************************************************************************
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27 This file is part of the FreeRTOS distribution.
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29 FreeRTOS is free software; you can redistribute it and/or modify it under
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30 the terms of the GNU General Public License (version 2) as published by the
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31 Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
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33 >>>>>>NOTE<<<<<< The modification to the GPL is included to allow you to
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34 distribute a combined work that includes FreeRTOS without being obliged to
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35 provide the source code for proprietary components outside of the FreeRTOS
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38 FreeRTOS is distributed in the hope that it will be useful, but WITHOUT ANY
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39 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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40 FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
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41 details. You should have received a copy of the GNU General Public License
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42 and the FreeRTOS license exception along with FreeRTOS; if not it can be
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43 viewed here: http://www.freertos.org/a00114.html and also obtained by
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44 writing to Real Time Engineers Ltd., contact details for whom are available
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45 on the FreeRTOS WEB site.
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49 ***************************************************************************
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51 * Having a problem? Start by reading the FAQ "My application does *
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52 * not run, what could be wrong?" *
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54 * http://www.FreeRTOS.org/FAQHelp.html *
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56 ***************************************************************************
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59 http://www.FreeRTOS.org - Documentation, books, training, latest versions,
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60 license and Real Time Engineers Ltd. contact details.
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62 http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
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63 including FreeRTOS+Trace - an indispensable productivity tool, and our new
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64 fully thread aware and reentrant UDP/IP stack.
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66 http://www.OpenRTOS.com - Real Time Engineers ltd license FreeRTOS to High
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67 Integrity Systems, who sell the code with commercial support,
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68 indemnification and middleware, under the OpenRTOS brand.
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70 http://www.SafeRTOS.com - High Integrity Systems also provide a safety
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71 engineered and independently SIL3 certified version for use in safety and
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72 mission critical applications that require provable dependability.
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76 * Basic task to demonstrate the xQueueOverwrite() function. See the comments
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77 * in the function itself.
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80 /* Scheduler include files. */
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81 #include "FreeRTOS.h"
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85 /* Demo program include files. */
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86 #include "QueueOverwrite.h"
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88 /* A block time of 0 just means "don't block". */
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89 #define qoDONT_BLOCK 0
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91 /* Number of times to overwrite the value in the queue. */
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94 /* The task that uses the queue. */
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95 static void prvQueueOverwriteTask( void *pvParameters );
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97 /* Variable that is incremented on each loop of prvQueueOverwriteTask() provided
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98 prvQueueOverwriteTask() has not found any errors. */
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99 static unsigned long ulLoopCounter = 0;
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101 /* Set to pdFALSE if an error is discovered by the
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102 vQueueOverwritePeriodicISRDemo() function. */
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103 static portBASE_TYPE xISRTestStatus = pdPASS;
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105 /* The queue that is accessed from the ISR. The queue accessed by the task is
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106 created inside the task itself. */
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107 static xQueueHandle xISRQueue = NULL;
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109 /*-----------------------------------------------------------*/
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111 void vStartQueueOverwriteTask( unsigned portBASE_TYPE uxPriority )
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113 const unsigned portBASE_TYPE uxQueueLength = 1;
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115 /* Create the queue used by the ISR. xQueueOverwriteFromISR() should only
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116 be used on queues that have a length of 1. */
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117 xISRQueue = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( unsigned long ) );
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119 /* Create the test task. The queue used by the test task is created inside
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120 the task itself. */
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121 xTaskCreate( prvQueueOverwriteTask, ( signed char * ) "QOver", configMINIMAL_STACK_SIZE, NULL, uxPriority, ( xTaskHandle * ) NULL );
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123 /*-----------------------------------------------------------*/
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125 static void prvQueueOverwriteTask( void *pvParameters )
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127 xQueueHandle xTaskQueue;
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128 const unsigned portBASE_TYPE uxQueueLength = 1;
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129 unsigned long ulValue, ulStatus = pdPASS, x;
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131 /* The parameter is not used. */
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132 ( void ) pvParameters;
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134 /* Create the queue. xQueueOverwrite() should only be used on queues that
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135 have a length of 1. */
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136 xTaskQueue = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( unsigned long ) );
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137 configASSERT( xTaskQueue );
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141 /* The queue is empty. Writing to the queue then reading from the queue
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142 should return the item written. */
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144 xQueueOverwrite( xTaskQueue, &ulValue );
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147 xQueueReceive( xTaskQueue, &ulValue, qoDONT_BLOCK );
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149 if( ulValue != 10 )
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154 /* Now try writing to the queue several times. Each time the value
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155 in the queue should get overwritten. */
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156 for( x = 0; x < qoLOOPS; x++ )
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158 /* Write to the queue. */
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159 xQueueOverwrite( xTaskQueue, &x );
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161 /* Check the value in the queue is that written, even though the
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162 queue was not necessarily empty. */
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163 xQueuePeek( xTaskQueue, &ulValue, qoDONT_BLOCK );
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169 /* There should always be one item in the queue. */
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170 if( uxQueueMessagesWaiting( xTaskQueue ) != uxQueueLength )
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176 /* Empty the queue again. */
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177 xQueueReceive( xTaskQueue, &ulValue, qoDONT_BLOCK );
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179 if( uxQueueMessagesWaiting( xTaskQueue ) != 0 )
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184 if( ulStatus != pdFAIL )
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186 /* Increment a counter to show this task is still running without
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192 /*-----------------------------------------------------------*/
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194 portBASE_TYPE xIsQueueOverwriteTaskStillRunning( void )
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196 portBASE_TYPE xReturn;
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198 if( xISRTestStatus != pdPASS )
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202 else if( ulLoopCounter > 0 )
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208 /* The task has either stalled of discovered an error. */
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216 /*-----------------------------------------------------------*/
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218 void vQueueOverwritePeriodicISRDemo( void )
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220 static unsigned long ulCallCount = 0;
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221 const unsigned long ulTx1 = 10UL, ulTx2 = 20UL, ulNumberOfSwitchCases = 3UL;
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222 unsigned long ulRx;
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224 /* This function should be called from an interrupt, such as the tick hook
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225 function vApplicationTickHook(). */
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227 configASSERT( xISRQueue );
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229 switch( ulCallCount )
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232 /* The queue is empty. Write ulTx1 to the queue. In this demo the
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233 last parameter is not used because there are no tasks blocked on
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235 xQueueOverwriteFromISR( xISRQueue, &ulTx1, NULL );
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239 /* The queue already holds ulTx1. Overwrite the value in the queue
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241 xQueueOverwriteFromISR( xISRQueue, &ulTx2, NULL );
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245 /* Read from the queue to empty the queue again. The value read
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246 should be ulTx2. */
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247 xQueueReceiveFromISR( xISRQueue, &ulRx, NULL );
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249 if( ulRx != ulTx2 )
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251 xISRTestStatus = pdFAIL;
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256 /* Run the next case in the switch statement above next time this function
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260 if( ulCallCount >= ulNumberOfSwitchCases )
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262 /* Go back to the start. */
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