2 * FreeRTOS Kernel V10.1.0
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3 * Copyright (C) 2017 Amazon.com, Inc. or its affiliates. All Rights Reserved.
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5 * Permission is hereby granted, free of charge, to any person obtaining a copy of
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6 * this software and associated documentation files (the "Software"), to deal in
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7 * the Software without restriction, including without limitation the rights to
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8 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
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9 * the Software, and to permit persons to whom the Software is furnished to do so,
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10 * subject to the following conditions:
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12 * The above copyright notice and this permission notice shall be included in all
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13 * copies or substantial portions of the Software.
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15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
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17 * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
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18 * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
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19 * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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20 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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22 * http://www.FreeRTOS.org
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23 * http://aws.amazon.com/freertos
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25 * 1 tab == 4 spaces!
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29 * The first test creates three tasks - two counter tasks (one continuous count
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30 * and one limited count) and one controller. A "count" variable is shared
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31 * between all three tasks. The two counter tasks should never be in a "ready"
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32 * state at the same time. The controller task runs at the same priority as
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33 * the continuous count task, and at a lower priority than the limited count
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36 * One counter task loops indefinitely, incrementing the shared count variable
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37 * on each iteration. To ensure it has exclusive access to the variable it
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38 * raises its priority above that of the controller task before each
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39 * increment, lowering it again to its original priority before starting the
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42 * The other counter task increments the shared count variable on each
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43 * iteration of its loop until the count has reached a limit of 0xff - at
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44 * which point it suspends itself. It will not start a new loop until the
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45 * controller task has made it "ready" again by calling vTaskResume().
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46 * This second counter task operates at a higher priority than controller
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47 * task so does not need to worry about mutual exclusion of the counter
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50 * The controller task is in two sections. The first section controls and
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51 * monitors the continuous count task. When this section is operational the
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52 * limited count task is suspended. Likewise, the second section controls
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53 * and monitors the limited count task. When this section is operational the
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54 * continuous count task is suspended.
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56 * In the first section the controller task first takes a copy of the shared
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57 * count variable. To ensure mutual exclusion on the count variable it
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58 * suspends the continuous count task, resuming it again when the copy has been
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59 * taken. The controller task then sleeps for a fixed period - during which
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60 * the continuous count task will execute and increment the shared variable.
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61 * When the controller task wakes it checks that the continuous count task
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62 * has executed by comparing the copy of the shared variable with its current
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63 * value. This time, to ensure mutual exclusion, the scheduler itself is
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64 * suspended with a call to vTaskSuspendAll (). This is for demonstration
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65 * purposes only and is not a recommended technique due to its inefficiency.
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67 * After a fixed number of iterations the controller task suspends the
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68 * continuous count task, and moves on to its second section.
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70 * At the start of the second section the shared variable is cleared to zero.
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71 * The limited count task is then woken from its suspension by a call to
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72 * vTaskResume (). As this counter task operates at a higher priority than
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73 * the controller task the controller task should not run again until the
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74 * shared variable has been counted up to the limited value causing the counter
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75 * task to suspend itself. The next line after vTaskResume () is therefore
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76 * a check on the shared variable to ensure everything is as expected.
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79 * The second test consists of a couple of very simple tasks that post onto a
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80 * queue while the scheduler is suspended. This test was added to test parts
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81 * of the scheduler not exercised by the first test.
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87 /* Scheduler include files. */
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88 #include "FreeRTOS.h"
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92 /* Demo app include files. */
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93 #include "dynamic.h"
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95 /* Function that implements the "limited count" task as described above. */
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96 static portTASK_FUNCTION_PROTO( vLimitedIncrementTask, pvParameters );
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98 /* Function that implements the "continuous count" task as described above. */
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99 static portTASK_FUNCTION_PROTO( vContinuousIncrementTask, pvParameters );
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101 /* Function that implements the controller task as described above. */
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102 static portTASK_FUNCTION_PROTO( vCounterControlTask, pvParameters );
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104 static portTASK_FUNCTION_PROTO( vQueueReceiveWhenSuspendedTask, pvParameters );
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105 static portTASK_FUNCTION_PROTO( vQueueSendWhenSuspendedTask, pvParameters );
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107 /* Demo task specific constants. */
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108 #define priSTACK_SIZE ( configMINIMAL_STACK_SIZE )
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109 #define priSLEEP_TIME pdMS_TO_TICKS( 128 )
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110 #define priLOOPS ( 5 )
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111 #define priMAX_COUNT ( ( uint32_t ) 0xff )
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112 #define priNO_BLOCK ( ( TickType_t ) 0 )
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113 #define priSUSPENDED_QUEUE_LENGTH ( 1 )
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115 /*-----------------------------------------------------------*/
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117 /* Handles to the two counter tasks. These could be passed in as parameters
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118 to the controller task to prevent them having to be file scope. */
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119 static TaskHandle_t xContinuousIncrementHandle, xLimitedIncrementHandle;
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121 /* The shared counter variable. This is passed in as a parameter to the two
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122 counter variables for demonstration purposes. */
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123 static uint32_t ulCounter;
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125 /* Variables used to check that the tasks are still operating without error.
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126 Each complete iteration of the controller task increments this variable
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127 provided no errors have been found. The variable maintaining the same value
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128 is therefore indication of an error. */
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129 static volatile uint16_t usCheckVariable = ( uint16_t ) 0;
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130 static volatile BaseType_t xSuspendedQueueSendError = pdFALSE;
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131 static volatile BaseType_t xSuspendedQueueReceiveError = pdFALSE;
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133 /* Queue used by the second test. */
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134 QueueHandle_t xSuspendedTestQueue;
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136 /* The value the queue receive task expects to receive next. This is file
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137 scope so xAreDynamicPriorityTasksStillRunning() can ensure it is still
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139 static uint32_t ulExpectedValue = ( uint32_t ) 0;
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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( uint32_t ) );
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150 if( xSuspendedTestQueue != NULL )
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152 /* vQueueAddToRegistry() adds the queue to the queue registry, if one is
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153 in use. The queue registry is provided as a means for kernel aware
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154 debuggers to locate queues and has no purpose if a kernel aware debugger
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155 is not being used. The call to vQueueAddToRegistry() will be removed
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156 by the pre-processor if configQUEUE_REGISTRY_SIZE is not defined or is
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157 defined to be less than 1. */
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158 vQueueAddToRegistry( xSuspendedTestQueue, "Suspended_Test_Queue" );
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160 xTaskCreate( vContinuousIncrementTask, "CNT_INC", priSTACK_SIZE, ( void * ) &ulCounter, tskIDLE_PRIORITY, &xContinuousIncrementHandle );
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161 xTaskCreate( vLimitedIncrementTask, "LIM_INC", priSTACK_SIZE, ( void * ) &ulCounter, tskIDLE_PRIORITY + 1, &xLimitedIncrementHandle );
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162 xTaskCreate( vCounterControlTask, "C_CTRL", priSTACK_SIZE, NULL, tskIDLE_PRIORITY, NULL );
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163 xTaskCreate( vQueueSendWhenSuspendedTask, "SUSP_TX", priSTACK_SIZE, NULL, tskIDLE_PRIORITY, NULL );
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164 xTaskCreate( vQueueReceiveWhenSuspendedTask, "SUSP_RX", priSTACK_SIZE, NULL, tskIDLE_PRIORITY, NULL );
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167 /*-----------------------------------------------------------*/
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170 * Just loops around incrementing the shared variable until the limit has been
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171 * reached. Once the limit has been reached it suspends itself.
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173 static portTASK_FUNCTION( vLimitedIncrementTask, pvParameters )
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175 volatile uint32_t *pulCounter;
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177 /* Take a pointer to the shared variable from the parameters passed into
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179 pulCounter = ( volatile uint32_t * ) pvParameters;
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181 /* This will run before the control task, so the first thing it does is
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182 suspend - the control task will resume it when ready. */
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183 vTaskSuspend( NULL );
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187 /* Just count up to a value then suspend. */
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190 if( *pulCounter >= priMAX_COUNT )
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192 vTaskSuspend( NULL );
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196 /*-----------------------------------------------------------*/
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199 * Just keep counting the shared variable up. The control task will suspend
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200 * this task when it wants.
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202 static portTASK_FUNCTION( vContinuousIncrementTask, pvParameters )
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204 volatile uint32_t *pulCounter;
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205 UBaseType_t uxOurPriority;
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207 /* Take a pointer to the shared variable from the parameters passed into
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209 pulCounter = ( volatile uint32_t * ) pvParameters;
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211 /* Query our priority so we can raise it when exclusive access to the
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212 shared variable is required. */
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213 uxOurPriority = uxTaskPriorityGet( NULL );
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217 /* Raise the priority above the controller task to ensure a context
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218 switch does not occur while the variable is being accessed. */
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219 vTaskPrioritySet( NULL, uxOurPriority + 1 );
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221 configASSERT( ( uxTaskPriorityGet( NULL ) == ( uxOurPriority + 1 ) ) );
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224 vTaskPrioritySet( NULL, uxOurPriority );
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226 #if( configUSE_PREEMPTION == 0 )
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230 configASSERT( ( uxTaskPriorityGet( NULL ) == uxOurPriority ) );
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233 /*-----------------------------------------------------------*/
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236 * Controller task as described above.
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238 static portTASK_FUNCTION( vCounterControlTask, pvParameters )
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240 uint32_t ulLastCounter;
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242 short sError = pdFALSE;
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244 /* Just to stop warning messages. */
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245 ( void ) pvParameters;
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249 /* Start with the counter at zero. */
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250 ulCounter = ( uint32_t ) 0;
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252 /* First section : */
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254 /* Check the continuous count task is running. */
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255 for( sLoops = 0; sLoops < priLOOPS; sLoops++ )
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257 /* Suspend the continuous count task so we can take a mirror of the
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258 shared variable without risk of corruption. This is not really
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259 needed as the other task raises its priority above this task's
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261 vTaskSuspend( xContinuousIncrementHandle );
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263 #if( INCLUDE_eTaskGetState == 1 )
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265 configASSERT( eTaskGetState( xContinuousIncrementHandle ) == eSuspended );
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267 #endif /* INCLUDE_eTaskGetState */
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269 ulLastCounter = ulCounter;
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271 vTaskResume( xContinuousIncrementHandle );
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273 #if( configUSE_PREEMPTION == 0 )
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277 #if( INCLUDE_eTaskGetState == 1 )
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279 configASSERT( eTaskGetState( xContinuousIncrementHandle ) == eReady );
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281 #endif /* INCLUDE_eTaskGetState */
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283 /* Now delay to ensure the other task has processor time. */
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284 vTaskDelay( priSLEEP_TIME );
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286 /* Check the shared variable again. This time to ensure mutual
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287 exclusion the whole scheduler will be locked. This is just for
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291 if( ulLastCounter == ulCounter )
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293 /* The shared variable has not changed. There is a problem
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294 with the continuous count task so flag an error. */
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301 /* Second section: */
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303 /* Suspend the continuous counter task so it stops accessing the shared
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305 vTaskSuspend( xContinuousIncrementHandle );
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307 /* Reset the variable. */
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308 ulCounter = ( uint32_t ) 0;
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310 #if( INCLUDE_eTaskGetState == 1 )
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312 configASSERT( eTaskGetState( xLimitedIncrementHandle ) == eSuspended );
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314 #endif /* INCLUDE_eTaskGetState */
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316 /* Resume the limited count task which has a higher priority than us.
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317 We should therefore not return from this call until the limited count
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318 task has suspended itself with a known value in the counter variable. */
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319 vTaskResume( xLimitedIncrementHandle );
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321 #if( configUSE_PREEMPTION == 0 )
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325 /* This task should not run again until xLimitedIncrementHandle has
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326 suspended itself. */
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327 #if( INCLUDE_eTaskGetState == 1 )
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329 configASSERT( eTaskGetState( xLimitedIncrementHandle ) == eSuspended );
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331 #endif /* INCLUDE_eTaskGetState */
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333 /* Does the counter variable have the expected value? */
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334 if( ulCounter != priMAX_COUNT )
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339 if( sError == pdFALSE )
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341 /* If no errors have occurred then increment the check variable. */
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342 portENTER_CRITICAL();
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344 portEXIT_CRITICAL();
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347 /* Resume the continuous count task and do it all again. */
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348 vTaskResume( xContinuousIncrementHandle );
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350 #if( configUSE_PREEMPTION == 0 )
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355 /*-----------------------------------------------------------*/
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357 static portTASK_FUNCTION( vQueueSendWhenSuspendedTask, pvParameters )
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359 static uint32_t ulValueToSend = ( uint32_t ) 0;
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361 /* Just to stop warning messages. */
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362 ( void ) pvParameters;
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368 /* We must not block while the scheduler is suspended! */
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369 if( xQueueSend( xSuspendedTestQueue, ( void * ) &ulValueToSend, priNO_BLOCK ) != pdTRUE )
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371 xSuspendedQueueSendError = pdTRUE;
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376 vTaskDelay( priSLEEP_TIME );
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381 /*-----------------------------------------------------------*/
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383 static portTASK_FUNCTION( vQueueReceiveWhenSuspendedTask, pvParameters )
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385 uint32_t ulReceivedValue;
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386 BaseType_t xGotValue;
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388 /* Just to stop warning messages. */
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389 ( void ) pvParameters;
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395 /* Suspending the scheduler here is fairly pointless and
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396 undesirable for a normal application. It is done here purely
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397 to test the scheduler. The inner xTaskResumeAll() should
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398 never return pdTRUE as the scheduler is still locked by the
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404 xGotValue = xQueueReceive( xSuspendedTestQueue, ( void * ) &ulReceivedValue, priNO_BLOCK );
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406 if( xTaskResumeAll() != pdFALSE )
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408 xSuspendedQueueReceiveError = pdTRUE;
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413 #if configUSE_PREEMPTION == 0
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419 } while( xGotValue == pdFALSE );
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421 if( ulReceivedValue != ulExpectedValue )
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423 xSuspendedQueueReceiveError = pdTRUE;
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426 if( xSuspendedQueueReceiveError != pdTRUE )
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428 /* Only increment the variable if an error has not occurred. This
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429 allows xAreDynamicPriorityTasksStillRunning() to check for stalled
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430 tasks as well as explicit errors. */
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435 /*-----------------------------------------------------------*/
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437 /* Called to check that all the created tasks are still running without error. */
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438 BaseType_t xAreDynamicPriorityTasksStillRunning( void )
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440 /* Keep a history of the check variables so we know if it has been incremented
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441 since the last call. */
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442 static uint16_t usLastTaskCheck = ( uint16_t ) 0;
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443 static uint32_t ulLastExpectedValue = ( uint32_t ) 0U;
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444 BaseType_t xReturn = pdTRUE;
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446 /* Check the tasks are still running by ensuring the check variable
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447 is still incrementing. */
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449 if( usCheckVariable == usLastTaskCheck )
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451 /* The check has not incremented so an error exists. */
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455 if( ulExpectedValue == ulLastExpectedValue )
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457 /* The value being received by the queue receive task has not
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458 incremented so an error exists. */
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462 if( xSuspendedQueueSendError == pdTRUE )
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467 if( xSuspendedQueueReceiveError == pdTRUE )
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472 usLastTaskCheck = usCheckVariable;
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473 ulLastExpectedValue = ulExpectedValue;
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