2 FreeRTOS.org V4.7.0 - 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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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 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 a version that has been certified for use
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32 in safety critical systems, plus commercial licensing, development and
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34 ***************************************************************************
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38 * The first test creates three tasks - two counter tasks (one continuous count
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39 * and one limited count) and one controller. A "count" variable is shared
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40 * between all three tasks. The two counter tasks should never be in a "ready"
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41 * state at the same time. The controller task runs at the same priority as
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42 * the continuous count task, and at a lower priority than the limited count
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45 * One counter task loops indefinitely, incrementing the shared count variable
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46 * on each iteration. To ensure it has exclusive access to the variable it
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47 * raises it's priority above that of the controller task before each
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48 * increment, lowering it again to it's original priority before starting the
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51 * The other counter task increments the shared count variable on each
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52 * iteration of it's loop until the count has reached a limit of 0xff - at
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53 * which point it suspends itself. It will not start a new loop until the
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54 * controller task has made it "ready" again by calling vTaskResume ().
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55 * This second counter task operates at a higher priority than controller
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56 * task so does not need to worry about mutual exclusion of the counter
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59 * The controller task is in two sections. The first section controls and
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60 * monitors the continuous count task. When this section is operational the
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61 * limited count task is suspended. Likewise, the second section controls
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62 * and monitors the limited count task. When this section is operational the
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63 * continuous count task is suspended.
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65 * In the first section the controller task first takes a copy of the shared
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66 * count variable. To ensure mutual exclusion on the count variable it
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67 * suspends the continuous count task, resuming it again when the copy has been
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68 * taken. The controller task then sleeps for a fixed period - during which
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69 * the continuous count task will execute and increment the shared variable.
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70 * When the controller task wakes it checks that the continuous count task
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71 * has executed by comparing the copy of the shared variable with its current
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72 * value. This time, to ensure mutual exclusion, the scheduler itself is
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73 * suspended with a call to vTaskSuspendAll (). This is for demonstration
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74 * purposes only and is not a recommended technique due to its inefficiency.
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76 * After a fixed number of iterations the controller task suspends the
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77 * continuous count task, and moves on to its second section.
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79 * At the start of the second section the shared variable is cleared to zero.
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80 * The limited count task is then woken from it's suspension by a call to
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81 * vTaskResume (). As this counter task operates at a higher priority than
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82 * the controller task the controller task should not run again until the
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83 * shared variable has been counted up to the limited value causing the counter
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84 * task to suspend itself. The next line after vTaskResume () is therefore
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85 * a check on the shared variable to ensure everything is as expected.
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88 * The second test consists of a couple of very simple tasks that post onto a
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89 * queue while the scheduler is suspended. This test was added to test parts
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90 * of the scheduler not exercised by the first test.
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96 /* Scheduler include files. */
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97 #include "FreeRTOS.h"
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101 /* Demo app include files. */
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102 #include "dynamic.h"
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104 /* Function that implements the "limited count" task as described above. */
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105 static portTASK_FUNCTION_PROTO( vLimitedIncrementTask, pvParameters );
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107 /* Function that implements the "continuous count" task as described above. */
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108 static portTASK_FUNCTION_PROTO( vContinuousIncrementTask, pvParameters );
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110 /* Function that implements the controller task as described above. */
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111 static portTASK_FUNCTION_PROTO( vCounterControlTask, pvParameters );
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113 static portTASK_FUNCTION_PROTO( vQueueReceiveWhenSuspendedTask, pvParameters );
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114 static portTASK_FUNCTION_PROTO( vQueueSendWhenSuspendedTask, pvParameters );
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116 /* Demo task specific constants. */
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117 #define priSTACK_SIZE ( configMINIMAL_STACK_SIZE )
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118 #define priSLEEP_TIME ( ( portTickType ) 128 / portTICK_RATE_MS )
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119 #define priLOOPS ( 5 )
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120 #define priMAX_COUNT ( ( unsigned portLONG ) 0xff )
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121 #define priNO_BLOCK ( ( portTickType ) 0 )
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122 #define priSUSPENDED_QUEUE_LENGTH ( 1 )
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124 /*-----------------------------------------------------------*/
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126 /* Handles to the two counter tasks. These could be passed in as parameters
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127 to the controller task to prevent them having to be file scope. */
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128 static xTaskHandle xContinousIncrementHandle, xLimitedIncrementHandle;
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130 /* The shared counter variable. This is passed in as a parameter to the two
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131 counter variables for demonstration purposes. */
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132 static unsigned portLONG ulCounter;
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134 /* Variables used to check that the tasks are still operating without error.
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135 Each complete iteration of the controller task increments this variable
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136 provided no errors have been found. The variable maintaining the same value
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137 is therefore indication of an error. */
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138 static unsigned portSHORT usCheckVariable = ( unsigned portSHORT ) 0;
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139 static portBASE_TYPE xSuspendedQueueSendError = pdFALSE;
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140 static portBASE_TYPE xSuspendedQueueReceiveError = pdFALSE;
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142 /* Queue used by the second test. */
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143 xQueueHandle xSuspendedTestQueue;
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145 /*-----------------------------------------------------------*/
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147 * Start the three tasks as described at the top of the file.
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148 * Note that the limited count task is given a higher priority.
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150 void vStartDynamicPriorityTasks( void )
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152 xSuspendedTestQueue = xQueueCreate( priSUSPENDED_QUEUE_LENGTH, sizeof( unsigned portLONG ) );
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153 xTaskCreate( vContinuousIncrementTask, ( signed portCHAR * ) "CNT_INC", priSTACK_SIZE, ( void * ) &ulCounter, tskIDLE_PRIORITY, &xContinousIncrementHandle );
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154 xTaskCreate( vLimitedIncrementTask, ( signed portCHAR * ) "LIM_INC", priSTACK_SIZE, ( void * ) &ulCounter, tskIDLE_PRIORITY + 1, &xLimitedIncrementHandle );
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155 xTaskCreate( vCounterControlTask, ( signed portCHAR * ) "C_CTRL", priSTACK_SIZE, NULL, tskIDLE_PRIORITY, NULL );
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156 xTaskCreate( vQueueSendWhenSuspendedTask, ( signed portCHAR * ) "SUSP_TX", priSTACK_SIZE, NULL, tskIDLE_PRIORITY, NULL );
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157 xTaskCreate( vQueueReceiveWhenSuspendedTask, ( signed portCHAR * ) "SUSP_RX", priSTACK_SIZE, NULL, tskIDLE_PRIORITY, NULL );
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159 /*-----------------------------------------------------------*/
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162 * Just loops around incrementing the shared variable until the limit has been
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163 * reached. Once the limit has been reached it suspends itself.
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165 static portTASK_FUNCTION( vLimitedIncrementTask, pvParameters )
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167 unsigned portLONG *pulCounter;
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169 /* Take a pointer to the shared variable from the parameters passed into
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171 pulCounter = ( unsigned portLONG * ) pvParameters;
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173 /* This will run before the control task, so the first thing it does is
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174 suspend - the control task will resume it when ready. */
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175 vTaskSuspend( NULL );
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179 /* Just count up to a value then suspend. */
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180 ( *pulCounter )++;
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182 if( *pulCounter >= priMAX_COUNT )
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184 vTaskSuspend( NULL );
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188 /*-----------------------------------------------------------*/
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191 * Just keep counting the shared variable up. The control task will suspend
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192 * this task when it wants.
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194 static portTASK_FUNCTION( vContinuousIncrementTask, pvParameters )
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196 unsigned portLONG *pulCounter;
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197 unsigned portBASE_TYPE uxOurPriority;
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199 /* Take a pointer to the shared variable from the parameters passed into
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201 pulCounter = ( unsigned portLONG * ) pvParameters;
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203 /* Query our priority so we can raise it when exclusive access to the
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204 shared variable is required. */
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205 uxOurPriority = uxTaskPriorityGet( NULL );
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209 /* Raise our priority above the controller task to ensure a context
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210 switch does not occur while we are accessing this variable. */
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211 vTaskPrioritySet( NULL, uxOurPriority + 1 );
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212 ( *pulCounter )++;
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213 vTaskPrioritySet( NULL, uxOurPriority );
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216 /*-----------------------------------------------------------*/
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219 * Controller task as described above.
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221 static portTASK_FUNCTION( vCounterControlTask, pvParameters )
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223 unsigned portLONG ulLastCounter;
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225 portSHORT sError = pdFALSE;
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227 /* Just to stop warning messages. */
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228 ( void ) pvParameters;
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232 /* Start with the counter at zero. */
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233 ulCounter = ( unsigned portLONG ) 0;
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235 /* First section : */
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237 /* Check the continuous count task is running. */
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238 for( sLoops = 0; sLoops < priLOOPS; sLoops++ )
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240 /* Suspend the continuous count task so we can take a mirror of the
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241 shared variable without risk of corruption. */
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242 vTaskSuspend( xContinousIncrementHandle );
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243 ulLastCounter = ulCounter;
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244 vTaskResume( xContinousIncrementHandle );
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246 /* Now delay to ensure the other task has processor time. */
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247 vTaskDelay( priSLEEP_TIME );
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249 /* Check the shared variable again. This time to ensure mutual
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250 exclusion the whole scheduler will be locked. This is just for
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254 if( ulLastCounter == ulCounter )
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256 /* The shared variable has not changed. There is a problem
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257 with the continuous count task so flag an error. */
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265 /* Second section: */
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267 /* Suspend the continuous counter task so it stops accessing the shared variable. */
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268 vTaskSuspend( xContinousIncrementHandle );
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270 /* Reset the variable. */
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271 ulCounter = ( unsigned portLONG ) 0;
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273 /* Resume the limited count task which has a higher priority than us.
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274 We should therefore not return from this call until the limited count
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275 task has suspended itself with a known value in the counter variable. */
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276 vTaskResume( xLimitedIncrementHandle );
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278 /* Does the counter variable have the expected value? */
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279 if( ulCounter != priMAX_COUNT )
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284 if( sError == pdFALSE )
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286 /* If no errors have occurred then increment the check variable. */
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287 portENTER_CRITICAL();
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289 portEXIT_CRITICAL();
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292 /* Resume the continuous count task and do it all again. */
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293 vTaskResume( xContinousIncrementHandle );
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296 /*-----------------------------------------------------------*/
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298 static portTASK_FUNCTION( vQueueSendWhenSuspendedTask, pvParameters )
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300 static unsigned portLONG ulValueToSend = ( unsigned portLONG ) 0;
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302 /* Just to stop warning messages. */
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303 ( void ) pvParameters;
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309 /* We must not block while the scheduler is suspended! */
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310 if( xQueueSend( xSuspendedTestQueue, ( void * ) &ulValueToSend, priNO_BLOCK ) != pdTRUE )
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312 xSuspendedQueueSendError = pdTRUE;
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317 vTaskDelay( priSLEEP_TIME );
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322 /*-----------------------------------------------------------*/
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324 static portTASK_FUNCTION( vQueueReceiveWhenSuspendedTask, pvParameters )
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326 static unsigned portLONG ulExpectedValue = ( unsigned portLONG ) 0, ulReceivedValue;
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327 portBASE_TYPE xGotValue;
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329 /* Just to stop warning messages. */
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330 ( void ) pvParameters;
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336 /* Suspending the scheduler here is fairly pointless and
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337 undesirable for a normal application. It is done here purely
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338 to test the scheduler. The inner xTaskResumeAll() should
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339 never return pdTRUE as the scheduler is still locked by the
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345 xGotValue = xQueueReceive( xSuspendedTestQueue, ( void * ) &ulReceivedValue, priNO_BLOCK );
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347 if( xTaskResumeAll() )
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349 xSuspendedQueueReceiveError = pdTRUE;
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354 #if configUSE_PREEMPTION == 0
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360 } while( xGotValue == pdFALSE );
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362 if( ulReceivedValue != ulExpectedValue )
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364 xSuspendedQueueReceiveError = pdTRUE;
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370 /*-----------------------------------------------------------*/
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372 /* Called to check that all the created tasks are still running without error. */
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373 portBASE_TYPE xAreDynamicPriorityTasksStillRunning( void )
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375 /* Keep a history of the check variables so we know if it has been incremented
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376 since the last call. */
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377 static unsigned portSHORT usLastTaskCheck = ( unsigned portSHORT ) 0;
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378 portBASE_TYPE xReturn = pdTRUE;
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380 /* Check the tasks are still running by ensuring the check variable
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381 is still incrementing. */
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383 if( usCheckVariable == usLastTaskCheck )
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385 /* The check has not incremented so an error exists. */
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389 if( xSuspendedQueueSendError == pdTRUE )
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394 if( xSuspendedQueueReceiveError == pdTRUE )
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399 usLastTaskCheck = usCheckVariable;
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