2 * FreeRTOS Kernel V10.3.0
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3 * Copyright (C) 2020 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 * This file exercises the event mechanism whereby more than one task is
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30 * blocked waiting for the same event.
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32 * The demo creates five tasks - four 'event' tasks, and a controlling task.
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33 * The event tasks have various different priorities and all block on reading
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34 * the same queue. The controlling task writes data to the queue, then checks
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35 * to see which of the event tasks read the data from the queue. The
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36 * controlling task has the lowest priority of all the tasks so is guaranteed
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37 * to always get preempted immediately upon writing to the queue.
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39 * By selectively suspending and resuming the event tasks the controlling task
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40 * can check that the highest priority task that is blocked on the queue is the
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41 * task that reads the posted data from the queue.
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43 * Two of the event tasks share the same priority. When neither of these tasks
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44 * are suspended they should alternate - one reading one message from the queue,
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45 * the other the next message, etc.
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48 /* Standard includes. */
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53 /* Scheduler include files. */
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54 #include "FreeRTOS.h"
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58 /* Demo program include files. */
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59 #include "mevents.h"
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62 /* Demo specific constants. */
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63 #define evtSTACK_SIZE ( ( unsigned portBASE_TYPE ) configMINIMAL_STACK_SIZE )
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64 #define evtNUM_TASKS ( 4 )
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65 #define evtQUEUE_LENGTH ( ( unsigned portBASE_TYPE ) 3 )
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66 #define evtNO_DELAY 0
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68 /* Just indexes used to uniquely identify the tasks. Note that two tasks are
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69 'highest' priority. */
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70 #define evtHIGHEST_PRIORITY_INDEX_2 3
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71 #define evtHIGHEST_PRIORITY_INDEX_1 2
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72 #define evtMEDIUM_PRIORITY_INDEX 1
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73 #define evtLOWEST_PRIORITY_INDEX 0
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75 /* Each event task increments one of these counters each time it reads data
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77 static volatile portBASE_TYPE xTaskCounters[ evtNUM_TASKS ] = { 0, 0, 0, 0 };
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79 /* Each time the controlling task posts onto the queue it increments the
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80 expected count of the task that it expected to read the data from the queue
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81 (i.e. the task with the highest priority that should be blocked on the queue).
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83 xExpectedTaskCounters are incremented from the controlling task, and
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84 xTaskCounters are incremented from the individual event tasks - therefore
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85 comparing xTaskCounters to xExpectedTaskCounters shows whether or not the
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86 correct task was unblocked by the post. */
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87 static portBASE_TYPE xExpectedTaskCounters[ evtNUM_TASKS ] = { 0, 0, 0, 0 };
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89 /* Handles to the four event tasks. These are required to suspend and resume
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91 static TaskHandle_t xCreatedTasks[ evtNUM_TASKS ];
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93 /* The single queue onto which the controlling task posts, and the four event
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95 static QueueHandle_t xQueue;
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97 /* Flag used to indicate whether or not an error has occurred at any time.
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98 An error is either the queue being full when not expected, or an unexpected
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99 task reading data from the queue. */
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100 static portBASE_TYPE xHealthStatus = pdPASS;
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102 /*-----------------------------------------------------------*/
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104 /* Function that implements the event task. This is created four times. */
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105 static void prvMultiEventTask( void *pvParameters );
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107 /* Function that implements the controlling task. */
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108 static void prvEventControllerTask( void *pvParameters );
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110 /* This is a utility function that posts data to the queue, then compares
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111 xExpectedTaskCounters with xTaskCounters to ensure everything worked as
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114 The event tasks all have higher priorities the controlling task. Therefore
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115 the controlling task will always get preempted between writhing to the queue
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116 and checking the task counters.
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118 @param xExpectedTask The index to the task that the controlling task thinks
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119 should be the highest priority task waiting for data, and
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120 therefore the task that will unblock.
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122 @param xIncrement The number of items that should be written to the queue.
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124 static void prvCheckTaskCounters( portBASE_TYPE xExpectedTask, portBASE_TYPE xIncrement );
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126 /* This is just incremented each cycle of the controlling tasks function so
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127 the main application can ensure the test is still running. */
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128 static portBASE_TYPE xCheckVariable = 0;
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130 /*-----------------------------------------------------------*/
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132 void vStartMultiEventTasks( void )
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134 /* Create the queue to be used for all the communications. */
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135 xQueue = xQueueCreate( evtQUEUE_LENGTH, ( unsigned portBASE_TYPE ) sizeof( unsigned portBASE_TYPE ) );
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137 /* Start the controlling task. This has the idle priority to ensure it is
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138 always preempted by the event tasks. */
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139 xTaskCreate( prvEventControllerTask, "EvntCTRL", evtSTACK_SIZE, NULL, tskIDLE_PRIORITY, NULL );
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141 /* Start the four event tasks. Note that two have priority 3, one
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142 priority 2 and the other priority 1. */
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143 xTaskCreate( prvMultiEventTask, "Event0", evtSTACK_SIZE, ( void * ) &( xTaskCounters[ 0 ] ), 1, &( xCreatedTasks[ evtLOWEST_PRIORITY_INDEX ] ) );
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144 xTaskCreate( prvMultiEventTask, "Event1", evtSTACK_SIZE, ( void * ) &( xTaskCounters[ 1 ] ), 2, &( xCreatedTasks[ evtMEDIUM_PRIORITY_INDEX ] ) );
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145 xTaskCreate( prvMultiEventTask, "Event2", evtSTACK_SIZE, ( void * ) &( xTaskCounters[ 2 ] ), 3, &( xCreatedTasks[ evtHIGHEST_PRIORITY_INDEX_1 ] ) );
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146 xTaskCreate( prvMultiEventTask, "Event3", evtSTACK_SIZE, ( void * ) &( xTaskCounters[ 3 ] ), 3, &( xCreatedTasks[ evtHIGHEST_PRIORITY_INDEX_2 ] ) );
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148 /*-----------------------------------------------------------*/
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150 static void prvMultiEventTask( void *pvParameters )
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152 portBASE_TYPE *pxCounter;
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153 unsigned portBASE_TYPE uxDummy;
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154 const char * const pcTaskStartMsg = "Multi event task started.\r\n";
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156 /* The variable this task will increment is passed in as a parameter. */
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157 pxCounter = ( portBASE_TYPE * ) pvParameters;
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159 vPrintDisplayMessage( &pcTaskStartMsg );
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163 /* Block on the queue. */
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164 if( xQueueReceive( xQueue, &uxDummy, portMAX_DELAY ) )
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166 /* We unblocked by reading the queue - so simply increment
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167 the counter specific to this task instance. */
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172 xHealthStatus = pdFAIL;
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176 /*-----------------------------------------------------------*/
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178 static void prvEventControllerTask( void *pvParameters )
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180 const char * const pcTaskStartMsg = "Multi event controller task started.\r\n";
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181 portBASE_TYPE xDummy = 0;
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183 /* Just to stop warnings. */
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184 ( void ) pvParameters;
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186 vPrintDisplayMessage( &pcTaskStartMsg );
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190 /* All tasks are blocked on the queue. When a message is posted one of
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191 the two tasks that share the highest priority should unblock to read
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192 the queue. The next message written should unblock the other task with
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193 the same high priority, and so on in order. No other task should
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194 unblock to read data as they have lower priorities. */
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196 prvCheckTaskCounters( evtHIGHEST_PRIORITY_INDEX_1, 1 );
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197 prvCheckTaskCounters( evtHIGHEST_PRIORITY_INDEX_2, 1 );
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198 prvCheckTaskCounters( evtHIGHEST_PRIORITY_INDEX_1, 1 );
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199 prvCheckTaskCounters( evtHIGHEST_PRIORITY_INDEX_2, 1 );
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200 prvCheckTaskCounters( evtHIGHEST_PRIORITY_INDEX_1, 1 );
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202 /* For the rest of these tests we don't need the second 'highest'
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203 priority task - so it is suspended. */
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204 vTaskSuspend( xCreatedTasks[ evtHIGHEST_PRIORITY_INDEX_2 ] );
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208 /* Now suspend the other highest priority task. The medium priority
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209 task will then be the task with the highest priority that remains
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210 blocked on the queue. */
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211 vTaskSuspend( xCreatedTasks[ evtHIGHEST_PRIORITY_INDEX_1 ] );
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213 /* This time, when we post onto the queue we will expect the medium
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214 priority task to unblock and preempt us. */
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215 prvCheckTaskCounters( evtMEDIUM_PRIORITY_INDEX, 1 );
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217 /* Now try resuming the highest priority task while the scheduler is
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218 suspended. The task should start executing as soon as the scheduler
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219 is resumed - therefore when we post to the queue again, the highest
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220 priority task should again preempt us. */
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222 vTaskResume( xCreatedTasks[ evtHIGHEST_PRIORITY_INDEX_1 ] );
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224 prvCheckTaskCounters( evtHIGHEST_PRIORITY_INDEX_1, 1 );
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226 /* Now we are going to suspend the high and medium priority tasks. The
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227 low priority task should then preempt us. Again the task suspension is
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228 done with the whole scheduler suspended just for test purposes. */
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230 vTaskSuspend( xCreatedTasks[ evtHIGHEST_PRIORITY_INDEX_1 ] );
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231 vTaskSuspend( xCreatedTasks[ evtMEDIUM_PRIORITY_INDEX ] );
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233 prvCheckTaskCounters( evtLOWEST_PRIORITY_INDEX, 1 );
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235 /* Do the same basic test another few times - selectively suspending
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236 and resuming tasks and each time calling prvCheckTaskCounters() passing
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237 to the function the number of the task we expected to be unblocked by
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240 vTaskResume( xCreatedTasks[ evtHIGHEST_PRIORITY_INDEX_1 ] );
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241 prvCheckTaskCounters( evtHIGHEST_PRIORITY_INDEX_1, 1 );
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243 vTaskSuspendAll(); /* Just for test. */
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244 vTaskSuspendAll(); /* Just for test. */
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245 vTaskSuspendAll(); /* Just for even more test. */
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246 vTaskSuspend( xCreatedTasks[ evtHIGHEST_PRIORITY_INDEX_1 ] );
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250 prvCheckTaskCounters( evtLOWEST_PRIORITY_INDEX, 1 );
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252 vTaskResume( xCreatedTasks[ evtMEDIUM_PRIORITY_INDEX ] );
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253 prvCheckTaskCounters( evtMEDIUM_PRIORITY_INDEX, 1 );
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255 vTaskResume( xCreatedTasks[ evtHIGHEST_PRIORITY_INDEX_1 ] );
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256 prvCheckTaskCounters( evtHIGHEST_PRIORITY_INDEX_1, 1 );
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258 /* Now a slight change, first suspend all tasks. */
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259 vTaskSuspend( xCreatedTasks[ evtHIGHEST_PRIORITY_INDEX_1 ] );
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260 vTaskSuspend( xCreatedTasks[ evtMEDIUM_PRIORITY_INDEX ] );
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261 vTaskSuspend( xCreatedTasks[ evtLOWEST_PRIORITY_INDEX ] );
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263 /* Now when we resume the low priority task and write to the queue 3
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264 times. We expect the low priority task to service the queue three
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266 vTaskResume( xCreatedTasks[ evtLOWEST_PRIORITY_INDEX ] );
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267 prvCheckTaskCounters( evtLOWEST_PRIORITY_INDEX, evtQUEUE_LENGTH );
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269 /* Again suspend all tasks (only the low priority task is not suspended
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271 vTaskSuspend( xCreatedTasks[ evtLOWEST_PRIORITY_INDEX ] );
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273 /* This time we are going to suspend the scheduler, resume the low
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274 priority task, then resume the high priority task. In this state we
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275 will write to the queue three times. When the scheduler is resumed
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276 we expect the high priority task to service all three messages. */
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279 vTaskResume( xCreatedTasks[ evtLOWEST_PRIORITY_INDEX ] );
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280 vTaskResume( xCreatedTasks[ evtHIGHEST_PRIORITY_INDEX_1 ] );
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282 for( xDummy = 0; xDummy < evtQUEUE_LENGTH; xDummy++ )
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284 if( xQueueSend( xQueue, &xDummy, evtNO_DELAY ) != pdTRUE )
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286 xHealthStatus = pdFAIL;
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290 /* The queue should not have been serviced yet!. The scheduler
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291 is still suspended. */
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292 if( memcmp( ( void * ) xExpectedTaskCounters, ( void * ) xTaskCounters, sizeof( xExpectedTaskCounters ) ) )
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294 xHealthStatus = pdFAIL;
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299 /* We should have been preempted by resuming the scheduler - so by the
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300 time we are running again we expect the high priority task to have
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301 removed three items from the queue. */
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302 xExpectedTaskCounters[ evtHIGHEST_PRIORITY_INDEX_1 ] += evtQUEUE_LENGTH;
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303 if( memcmp( ( void * ) xExpectedTaskCounters, ( void * ) xTaskCounters, sizeof( xExpectedTaskCounters ) ) )
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305 xHealthStatus = pdFAIL;
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308 /* The medium priority and second high priority tasks are still
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309 suspended. Make sure to resume them before starting again. */
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310 vTaskResume( xCreatedTasks[ evtMEDIUM_PRIORITY_INDEX ] );
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311 vTaskResume( xCreatedTasks[ evtHIGHEST_PRIORITY_INDEX_2 ] );
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313 /* Just keep incrementing to show the task is still executing. */
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317 /*-----------------------------------------------------------*/
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319 static void prvCheckTaskCounters( portBASE_TYPE xExpectedTask, portBASE_TYPE xIncrement )
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321 portBASE_TYPE xDummy = 0;
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323 /* Write to the queue the requested number of times. The data written is
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325 for( xDummy = 0; xDummy < xIncrement; xDummy++ )
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327 if( xQueueSend( xQueue, &xDummy, evtNO_DELAY ) != pdTRUE )
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329 /* Did not expect to ever find the queue full. */
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330 xHealthStatus = pdFAIL;
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334 /* All the tasks blocked on the queue have a priority higher than the
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335 controlling task. Writing to the queue will therefore have caused this
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336 task to be preempted. By the time this line executes the event task will
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337 have executed and incremented its counter. Increment the expected counter
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338 to the same value. */
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339 ( xExpectedTaskCounters[ xExpectedTask ] ) += xIncrement;
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341 /* Check the actual counts and expected counts really are the same. */
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342 if( memcmp( ( void * ) xExpectedTaskCounters, ( void * ) xTaskCounters, sizeof( xExpectedTaskCounters ) ) )
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344 /* The counters were not the same. This means a task we did not expect
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345 to unblock actually did unblock. */
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346 xHealthStatus = pdFAIL;
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349 /*-----------------------------------------------------------*/
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351 portBASE_TYPE xAreMultiEventTasksStillRunning( void )
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353 static portBASE_TYPE xPreviousCheckVariable = 0;
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355 /* Called externally to periodically check that this test is still
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358 if( xPreviousCheckVariable == xCheckVariable )
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360 xHealthStatus = pdFAIL;
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363 xPreviousCheckVariable = xCheckVariable;
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365 return xHealthStatus;
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