2 FreeRTOS.org V4.0.2 - Copyright (C) 2003-2006 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 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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30 ***************************************************************************
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34 * The first test creates three tasks - two counter tasks (one continuous count
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35 * and one limited count) and one controller. A "count" variable is shared
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36 * between all three tasks. The two counter tasks should never be in a "ready"
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37 * state at the same time. The controller task runs at the same priority as
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38 * the continuous count task, and at a lower priority than the limited count
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41 * One counter task loops indefinitely, incrementing the shared count variable
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42 * on each iteration. To ensure it has exclusive access to the variable it
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43 * raises it's priority above that of the controller task before each
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44 * increment, lowering it again to it's original priority before starting the
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47 * The other counter task increments the shared count variable on each
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48 * iteration of it's loop until the count has reached a limit of 0xff - at
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49 * which point it suspends itself. It will not start a new loop until the
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50 * controller task has made it "ready" again by calling vTaskResume ().
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51 * This second counter task operates at a higher priority than controller
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52 * task so does not need to worry about mutual exclusion of the counter
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55 * The controller task is in two sections. The first section controls and
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56 * monitors the continuous count task. When this section is operational the
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57 * limited count task is suspended. Likewise, the second section controls
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58 * and monitors the limited count task. When this section is operational the
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59 * continuous count task is suspended.
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61 * In the first section the controller task first takes a copy of the shared
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62 * count variable. To ensure mutual exclusion on the count variable it
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63 * suspends the continuous count task, resuming it again when the copy has been
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64 * taken. The controller task then sleeps for a fixed period - during which
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65 * the continuous count task will execute and increment the shared variable.
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66 * When the controller task wakes it checks that the continuous count task
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67 * has executed by comparing the copy of the shared variable with its current
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68 * value. This time, to ensure mutual exclusion, the scheduler itself is
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69 * suspended with a call to vTaskSuspendAll (). This is for demonstration
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70 * purposes only and is not a recommended technique due to its inefficiency.
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72 * After a fixed number of iterations the controller task suspends the
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73 * continuous count task, and moves on to its second section.
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75 * At the start of the second section the shared variable is cleared to zero.
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76 * The limited count task is then woken from it's suspension by a call to
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77 * vTaskResume (). As this counter task operates at a higher priority than
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78 * the controller task the controller task should not run again until the
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79 * shared variable has been counted up to the limited value causing the counter
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80 * task to suspend itself. The next line after vTaskResume () is therefore
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81 * a check on the shared variable to ensure everything is as expected.
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84 * The second test consists of a couple of very simple tasks that post onto a
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85 * queue while the scheduler is suspended. This test was added to test parts
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86 * of the scheduler not exercised by the first test.
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92 /* Scheduler include files. */
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93 #include "FreeRTOS.h"
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97 /* Demo app include files. */
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98 #include "dynamic.h"
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100 /* Function that implements the "limited count" task as described above. */
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101 static portTASK_FUNCTION_PROTO( vLimitedIncrementTask, pvParameters );
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103 /* Function that implements the "continuous count" task as described above. */
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104 static portTASK_FUNCTION_PROTO( vContinuousIncrementTask, pvParameters );
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106 /* Function that implements the controller task as described above. */
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107 static portTASK_FUNCTION_PROTO( vCounterControlTask, pvParameters );
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109 static portTASK_FUNCTION_PROTO( vQueueReceiveWhenSuspendedTask, pvParameters );
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110 static portTASK_FUNCTION_PROTO( vQueueSendWhenSuspendedTask, pvParameters );
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112 /* Demo task specific constants. */
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113 #define priSTACK_SIZE ( ( unsigned portSHORT ) 128 )
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114 #define priSLEEP_TIME ( ( portTickType ) 75 )
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115 #define priLOOPS ( 5 )
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116 #define priMAX_COUNT ( ( unsigned portLONG ) 0xff )
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117 #define priNO_BLOCK ( ( portTickType ) 0 )
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118 #define priSUSPENDED_QUEUE_LENGTH ( 1 )
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120 /*-----------------------------------------------------------*/
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122 /* Handles to the two counter tasks. These could be passed in as parameters
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123 to the controller task to prevent them having to be file scope. */
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124 static xTaskHandle xContinousIncrementHandle, xLimitedIncrementHandle;
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126 /* The shared counter variable. This is passed in as a parameter to the two
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127 counter variables for demonstration purposes. */
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128 static unsigned portLONG ulCounter;
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130 /* Variables used to check that the tasks are still operating without error.
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131 Each complete iteration of the controller task increments this variable
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132 provided no errors have been found. The variable maintaining the same value
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133 is therefore indication of an error. */
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134 static unsigned portSHORT usCheckVariable = ( unsigned portSHORT ) 0;
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135 static portBASE_TYPE xSuspendedQueueSendError = pdFALSE;
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136 static portBASE_TYPE xSuspendedQueueReceiveError = pdFALSE;
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138 /* Queue used by the second test. */
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139 xQueueHandle xSuspendedTestQueue;
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141 /*-----------------------------------------------------------*/
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143 * Start the three tasks as described at the top of the file.
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144 * Note that the limited count task is given a higher priority.
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146 void vStartDynamicPriorityTasks( void )
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148 xSuspendedTestQueue = xQueueCreate( priSUSPENDED_QUEUE_LENGTH, sizeof( unsigned portLONG ) );
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149 xTaskCreate( vContinuousIncrementTask, ( signed portCHAR * ) "CNT_INC", priSTACK_SIZE, ( void * ) &ulCounter, tskIDLE_PRIORITY, &xContinousIncrementHandle );
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150 xTaskCreate( vLimitedIncrementTask, ( signed portCHAR * ) "LIM_INC", priSTACK_SIZE, ( void * ) &ulCounter, tskIDLE_PRIORITY + 1, &xLimitedIncrementHandle );
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151 xTaskCreate( vCounterControlTask, ( signed portCHAR * ) "C_CTRL", priSTACK_SIZE, NULL, tskIDLE_PRIORITY, NULL );
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152 xTaskCreate( vQueueSendWhenSuspendedTask, ( signed portCHAR * ) "SUSP_TX", priSTACK_SIZE, NULL, tskIDLE_PRIORITY, NULL );
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153 xTaskCreate( vQueueReceiveWhenSuspendedTask, ( signed portCHAR * ) "SUSP_RX", priSTACK_SIZE, NULL, tskIDLE_PRIORITY, NULL );
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155 /*-----------------------------------------------------------*/
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158 * Just loops around incrementing the shared variable until the limit has been
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159 * reached. Once the limit has been reached it suspends itself.
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161 static portTASK_FUNCTION( vLimitedIncrementTask, pvParameters )
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163 unsigned portLONG *pulCounter;
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165 /* Take a pointer to the shared variable from the parameters passed into
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167 pulCounter = ( unsigned portLONG * ) pvParameters;
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169 /* This will run before the control task, so the first thing it does is
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170 suspend - the control task will resume it when ready. */
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171 vTaskSuspend( NULL );
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175 /* Just count up to a value then suspend. */
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176 ( *pulCounter )++;
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178 if( *pulCounter >= priMAX_COUNT )
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180 vTaskSuspend( NULL );
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184 /*-----------------------------------------------------------*/
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187 * Just keep counting the shared variable up. The control task will suspend
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188 * this task when it wants.
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190 static portTASK_FUNCTION( vContinuousIncrementTask, pvParameters )
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192 unsigned portLONG *pulCounter;
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193 unsigned portBASE_TYPE uxOurPriority;
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195 /* Take a pointer to the shared variable from the parameters passed into
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197 pulCounter = ( unsigned portLONG * ) pvParameters;
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199 /* Query our priority so we can raise it when exclusive access to the
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200 shared variable is required. */
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201 uxOurPriority = uxTaskPriorityGet( NULL );
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205 /* Raise our priority above the controller task to ensure a context
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206 switch does not occur while we are accessing this variable. */
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207 vTaskPrioritySet( NULL, uxOurPriority + 1 );
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208 ( *pulCounter )++;
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209 vTaskPrioritySet( NULL, uxOurPriority );
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212 /*-----------------------------------------------------------*/
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215 * Controller task as described above.
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217 static portTASK_FUNCTION( vCounterControlTask, pvParameters )
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219 unsigned portLONG ulLastCounter;
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221 portSHORT sError = pdFALSE;
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223 /* Just to stop warning messages. */
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224 ( void ) pvParameters;
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228 /* Start with the counter at zero. */
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229 ulCounter = ( unsigned portLONG ) 0;
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231 /* First section : */
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233 /* Check the continuous count task is running. */
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234 for( sLoops = 0; sLoops < priLOOPS; sLoops++ )
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236 /* Suspend the continuous count task so we can take a mirror of the
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237 shared variable without risk of corruption. */
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238 vTaskSuspend( xContinousIncrementHandle );
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239 ulLastCounter = ulCounter;
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240 vTaskResume( xContinousIncrementHandle );
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242 /* Now delay to ensure the other task has processor time. */
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243 vTaskDelay( priSLEEP_TIME );
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245 /* Check the shared variable again. This time to ensure mutual
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246 exclusion the whole scheduler will be locked. This is just for
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250 if( ulLastCounter == ulCounter )
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252 /* The shared variable has not changed. There is a problem
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253 with the continuous count task so flag an error. */
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261 /* Second section: */
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263 /* Suspend the continuous counter task so it stops accessing the shared variable. */
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264 vTaskSuspend( xContinousIncrementHandle );
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266 /* Reset the variable. */
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267 ulCounter = ( unsigned portLONG ) 0;
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269 /* Resume the limited count task which has a higher priority than us.
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270 We should therefore not return from this call until the limited count
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271 task has suspended itself with a known value in the counter variable. */
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272 vTaskResume( xLimitedIncrementHandle );
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274 /* Does the counter variable have the expected value? */
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275 if( ulCounter != priMAX_COUNT )
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280 if( sError == pdFALSE )
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282 /* If no errors have occurred then increment the check variable. */
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283 portENTER_CRITICAL();
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285 portEXIT_CRITICAL();
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288 /* Resume the continuous count task and do it all again. */
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289 vTaskResume( xContinousIncrementHandle );
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292 /*-----------------------------------------------------------*/
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294 static portTASK_FUNCTION( vQueueSendWhenSuspendedTask, pvParameters )
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296 static unsigned portLONG ulValueToSend = ( unsigned portLONG ) 0;
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298 /* Just to stop warning messages. */
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299 ( void ) pvParameters;
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305 /* We must not block while the scheduler is suspended! */
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306 if( xQueueSend( xSuspendedTestQueue, ( void * ) &ulValueToSend, priNO_BLOCK ) != pdTRUE )
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308 xSuspendedQueueSendError = pdTRUE;
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313 vTaskDelay( priSLEEP_TIME );
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318 /*-----------------------------------------------------------*/
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320 static portTASK_FUNCTION( vQueueReceiveWhenSuspendedTask, pvParameters )
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322 static unsigned portLONG ulExpectedValue = ( unsigned portLONG ) 0, ulReceivedValue;
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323 portBASE_TYPE xGotValue;
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325 /* Just to stop warning messages. */
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326 ( void ) pvParameters;
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332 /* Suspending the scheduler here is fairly pointless and
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333 undesirable for a normal application. It is done here purely
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334 to test the scheduler. The inner xTaskResumeAll() should
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335 never return pdTRUE as the scheduler is still locked by the
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341 xGotValue = xQueueReceive( xSuspendedTestQueue, ( void * ) &ulReceivedValue, priNO_BLOCK );
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343 if( xTaskResumeAll() )
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345 xSuspendedQueueReceiveError = pdTRUE;
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350 } while( xGotValue == pdFALSE );
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352 if( ulReceivedValue != ulExpectedValue )
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354 xSuspendedQueueReceiveError = pdTRUE;
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360 /*-----------------------------------------------------------*/
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362 /* Called to check that all the created tasks are still running without error. */
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363 portBASE_TYPE xAreDynamicPriorityTasksStillRunning( void )
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365 /* Keep a history of the check variables so we know if it has been incremented
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366 since the last call. */
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367 static unsigned portSHORT usLastTaskCheck = ( unsigned portSHORT ) 0;
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368 portBASE_TYPE xReturn = pdTRUE;
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370 /* Check the tasks are still running by ensuring the check variable
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371 is still incrementing. */
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373 if( usCheckVariable == usLastTaskCheck )
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375 /* The check has not incremented so an error exists. */
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379 if( xSuspendedQueueSendError == pdTRUE )
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384 if( xSuspendedQueueReceiveError == pdTRUE )
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389 usLastTaskCheck = usCheckVariable;
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