369 lines
16 KiB
C
369 lines
16 KiB
C
/*
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* FreeRTOS V202212.00
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* Copyright (C) 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy of
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* this software and associated documentation files (the "Software"), to deal in
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* the Software without restriction, including without limitation the rights to
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* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
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* the Software, and to permit persons to whom the Software is furnished to do so,
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* subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
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* FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
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* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
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* IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*
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* https://www.FreeRTOS.org
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* https://github.com/FreeRTOS
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*
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*/
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/**
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* This file exercises the event mechanism whereby more than one task is
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* blocked waiting for the same event.
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*
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* The demo creates five tasks - four 'event' tasks, and a controlling task.
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* The event tasks have various different priorities and all block on reading
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* the same queue. The controlling task writes data to the queue, then checks
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* to see which of the event tasks read the data from the queue. The
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* controlling task has the lowest priority of all the tasks so is guaranteed
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* to always get preempted immediately upon writing to the queue.
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*
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* By selectively suspending and resuming the event tasks the controlling task
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* can check that the highest priority task that is blocked on the queue is the
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* task that reads the posted data from the queue.
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*
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* Two of the event tasks share the same priority. When neither of these tasks
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* are suspended they should alternate - one reading one message from the queue,
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* the other the next message, etc.
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*/
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/* Standard includes. */
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#include <stdlib.h>
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#include <stdio.h>
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#include <string.h>
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/* Scheduler include files. */
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#include "FreeRTOS.h"
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#include "task.h"
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#include "queue.h"
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/* Demo program include files. */
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#include "mevents.h"
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#include "print.h"
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/* Demo specific constants. */
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#define evtSTACK_SIZE ( ( unsigned portBASE_TYPE ) configMINIMAL_STACK_SIZE )
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#define evtNUM_TASKS ( 4 )
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#define evtQUEUE_LENGTH ( ( unsigned portBASE_TYPE ) 3 )
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#define evtNO_DELAY 0
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/* Just indexes used to uniquely identify the tasks. Note that two tasks are
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* 'highest' priority. */
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#define evtHIGHEST_PRIORITY_INDEX_2 3
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#define evtHIGHEST_PRIORITY_INDEX_1 2
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#define evtMEDIUM_PRIORITY_INDEX 1
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#define evtLOWEST_PRIORITY_INDEX 0
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/* Each event task increments one of these counters each time it reads data
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* from the queue. */
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static volatile portBASE_TYPE xTaskCounters[ evtNUM_TASKS ] = { 0, 0, 0, 0 };
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/* Each time the controlling task posts onto the queue it increments the
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* expected count of the task that it expected to read the data from the queue
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* (i.e. the task with the highest priority that should be blocked on the queue).
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*
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* xExpectedTaskCounters are incremented from the controlling task, and
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* xTaskCounters are incremented from the individual event tasks - therefore
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* comparing xTaskCounters to xExpectedTaskCounters shows whether or not the
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* correct task was unblocked by the post. */
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static portBASE_TYPE xExpectedTaskCounters[ evtNUM_TASKS ] = { 0, 0, 0, 0 };
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/* Handles to the four event tasks. These are required to suspend and resume
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* the tasks. */
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static TaskHandle_t xCreatedTasks[ evtNUM_TASKS ];
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/* The single queue onto which the controlling task posts, and the four event
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* tasks block. */
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static QueueHandle_t xQueue;
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/* Flag used to indicate whether or not an error has occurred at any time.
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* An error is either the queue being full when not expected, or an unexpected
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* task reading data from the queue. */
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static portBASE_TYPE xHealthStatus = pdPASS;
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/*-----------------------------------------------------------*/
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/* Function that implements the event task. This is created four times. */
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static void prvMultiEventTask( void * pvParameters );
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/* Function that implements the controlling task. */
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static void prvEventControllerTask( void * pvParameters );
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/* This is a utility function that posts data to the queue, then compares
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* xExpectedTaskCounters with xTaskCounters to ensure everything worked as
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* expected.
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*
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* The event tasks all have higher priorities the controlling task. Therefore
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* the controlling task will always get preempted between writhing to the queue
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* and checking the task counters.
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*
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* @param xExpectedTask The index to the task that the controlling task thinks
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* should be the highest priority task waiting for data, and
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* therefore the task that will unblock.
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*
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* @param xIncrement The number of items that should be written to the queue.
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*/
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static void prvCheckTaskCounters( portBASE_TYPE xExpectedTask,
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portBASE_TYPE xIncrement );
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/* This is just incremented each cycle of the controlling tasks function so
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* the main application can ensure the test is still running. */
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static portBASE_TYPE xCheckVariable = 0;
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/*-----------------------------------------------------------*/
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void vStartMultiEventTasks( void )
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{
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/* Create the queue to be used for all the communications. */
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xQueue = xQueueCreate( evtQUEUE_LENGTH, ( unsigned portBASE_TYPE ) sizeof( unsigned portBASE_TYPE ) );
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/* Start the controlling task. This has the idle priority to ensure it is
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* always preempted by the event tasks. */
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xTaskCreate( prvEventControllerTask, "EvntCTRL", evtSTACK_SIZE, NULL, tskIDLE_PRIORITY, NULL );
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/* Start the four event tasks. Note that two have priority 3, one
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* priority 2 and the other priority 1. */
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xTaskCreate( prvMultiEventTask, "Event0", evtSTACK_SIZE, ( void * ) &( xTaskCounters[ 0 ] ), 1, &( xCreatedTasks[ evtLOWEST_PRIORITY_INDEX ] ) );
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xTaskCreate( prvMultiEventTask, "Event1", evtSTACK_SIZE, ( void * ) &( xTaskCounters[ 1 ] ), 2, &( xCreatedTasks[ evtMEDIUM_PRIORITY_INDEX ] ) );
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xTaskCreate( prvMultiEventTask, "Event2", evtSTACK_SIZE, ( void * ) &( xTaskCounters[ 2 ] ), 3, &( xCreatedTasks[ evtHIGHEST_PRIORITY_INDEX_1 ] ) );
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xTaskCreate( prvMultiEventTask, "Event3", evtSTACK_SIZE, ( void * ) &( xTaskCounters[ 3 ] ), 3, &( xCreatedTasks[ evtHIGHEST_PRIORITY_INDEX_2 ] ) );
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}
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/*-----------------------------------------------------------*/
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static void prvMultiEventTask( void * pvParameters )
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{
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portBASE_TYPE * pxCounter;
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unsigned portBASE_TYPE uxDummy;
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const char * const pcTaskStartMsg = "Multi event task started.\r\n";
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/* The variable this task will increment is passed in as a parameter. */
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pxCounter = ( portBASE_TYPE * ) pvParameters;
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vPrintDisplayMessage( &pcTaskStartMsg );
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for( ; ; )
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{
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/* Block on the queue. */
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if( xQueueReceive( xQueue, &uxDummy, portMAX_DELAY ) )
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{
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/* We unblocked by reading the queue - so simply increment
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* the counter specific to this task instance. */
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( *pxCounter )++;
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}
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else
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{
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xHealthStatus = pdFAIL;
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}
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}
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}
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/*-----------------------------------------------------------*/
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static void prvEventControllerTask( void * pvParameters )
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{
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const char * const pcTaskStartMsg = "Multi event controller task started.\r\n";
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portBASE_TYPE xDummy = 0;
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/* Just to stop warnings. */
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( void ) pvParameters;
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vPrintDisplayMessage( &pcTaskStartMsg );
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for( ; ; )
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{
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/* All tasks are blocked on the queue. When a message is posted one of
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* the two tasks that share the highest priority should unblock to read
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* the queue. The next message written should unblock the other task with
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* the same high priority, and so on in order. No other task should
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* unblock to read data as they have lower priorities. */
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prvCheckTaskCounters( evtHIGHEST_PRIORITY_INDEX_1, 1 );
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prvCheckTaskCounters( evtHIGHEST_PRIORITY_INDEX_2, 1 );
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prvCheckTaskCounters( evtHIGHEST_PRIORITY_INDEX_1, 1 );
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prvCheckTaskCounters( evtHIGHEST_PRIORITY_INDEX_2, 1 );
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prvCheckTaskCounters( evtHIGHEST_PRIORITY_INDEX_1, 1 );
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/* For the rest of these tests we don't need the second 'highest'
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* priority task - so it is suspended. */
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vTaskSuspend( xCreatedTasks[ evtHIGHEST_PRIORITY_INDEX_2 ] );
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/* Now suspend the other highest priority task. The medium priority
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* task will then be the task with the highest priority that remains
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* blocked on the queue. */
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vTaskSuspend( xCreatedTasks[ evtHIGHEST_PRIORITY_INDEX_1 ] );
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/* This time, when we post onto the queue we will expect the medium
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* priority task to unblock and preempt us. */
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prvCheckTaskCounters( evtMEDIUM_PRIORITY_INDEX, 1 );
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/* Now try resuming the highest priority task while the scheduler is
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* suspended. The task should start executing as soon as the scheduler
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* is resumed - therefore when we post to the queue again, the highest
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* priority task should again preempt us. */
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vTaskSuspendAll();
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vTaskResume( xCreatedTasks[ evtHIGHEST_PRIORITY_INDEX_1 ] );
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xTaskResumeAll();
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prvCheckTaskCounters( evtHIGHEST_PRIORITY_INDEX_1, 1 );
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/* Now we are going to suspend the high and medium priority tasks. The
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* low priority task should then preempt us. Again the task suspension is
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* done with the whole scheduler suspended just for test purposes. */
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vTaskSuspendAll();
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vTaskSuspend( xCreatedTasks[ evtHIGHEST_PRIORITY_INDEX_1 ] );
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vTaskSuspend( xCreatedTasks[ evtMEDIUM_PRIORITY_INDEX ] );
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xTaskResumeAll();
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prvCheckTaskCounters( evtLOWEST_PRIORITY_INDEX, 1 );
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/* Do the same basic test another few times - selectively suspending
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* and resuming tasks and each time calling prvCheckTaskCounters() passing
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* to the function the number of the task we expected to be unblocked by
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* the post. */
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vTaskResume( xCreatedTasks[ evtHIGHEST_PRIORITY_INDEX_1 ] );
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prvCheckTaskCounters( evtHIGHEST_PRIORITY_INDEX_1, 1 );
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vTaskSuspendAll(); /* Just for test. */
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vTaskSuspendAll(); /* Just for test. */
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vTaskSuspendAll(); /* Just for even more test. */
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vTaskSuspend( xCreatedTasks[ evtHIGHEST_PRIORITY_INDEX_1 ] );
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xTaskResumeAll();
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xTaskResumeAll();
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xTaskResumeAll();
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prvCheckTaskCounters( evtLOWEST_PRIORITY_INDEX, 1 );
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vTaskResume( xCreatedTasks[ evtMEDIUM_PRIORITY_INDEX ] );
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prvCheckTaskCounters( evtMEDIUM_PRIORITY_INDEX, 1 );
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vTaskResume( xCreatedTasks[ evtHIGHEST_PRIORITY_INDEX_1 ] );
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prvCheckTaskCounters( evtHIGHEST_PRIORITY_INDEX_1, 1 );
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/* Now a slight change, first suspend all tasks. */
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vTaskSuspend( xCreatedTasks[ evtHIGHEST_PRIORITY_INDEX_1 ] );
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vTaskSuspend( xCreatedTasks[ evtMEDIUM_PRIORITY_INDEX ] );
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vTaskSuspend( xCreatedTasks[ evtLOWEST_PRIORITY_INDEX ] );
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/* Now when we resume the low priority task and write to the queue 3
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* times. We expect the low priority task to service the queue three
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* times. */
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vTaskResume( xCreatedTasks[ evtLOWEST_PRIORITY_INDEX ] );
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prvCheckTaskCounters( evtLOWEST_PRIORITY_INDEX, evtQUEUE_LENGTH );
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/* Again suspend all tasks (only the low priority task is not suspended
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* already). */
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vTaskSuspend( xCreatedTasks[ evtLOWEST_PRIORITY_INDEX ] );
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/* This time we are going to suspend the scheduler, resume the low
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* priority task, then resume the high priority task. In this state we
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* will write to the queue three times. When the scheduler is resumed
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* we expect the high priority task to service all three messages. */
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vTaskSuspendAll();
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{
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vTaskResume( xCreatedTasks[ evtLOWEST_PRIORITY_INDEX ] );
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vTaskResume( xCreatedTasks[ evtHIGHEST_PRIORITY_INDEX_1 ] );
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for( xDummy = 0; xDummy < evtQUEUE_LENGTH; xDummy++ )
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{
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if( xQueueSend( xQueue, &xDummy, evtNO_DELAY ) != pdTRUE )
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{
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xHealthStatus = pdFAIL;
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}
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}
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/* The queue should not have been serviced yet!. The scheduler
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* is still suspended. */
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if( memcmp( ( void * ) xExpectedTaskCounters, ( void * ) xTaskCounters, sizeof( xExpectedTaskCounters ) ) )
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{
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xHealthStatus = pdFAIL;
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}
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}
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xTaskResumeAll();
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/* We should have been preempted by resuming the scheduler - so by the
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* time we are running again we expect the high priority task to have
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* removed three items from the queue. */
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xExpectedTaskCounters[ evtHIGHEST_PRIORITY_INDEX_1 ] += evtQUEUE_LENGTH;
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if( memcmp( ( void * ) xExpectedTaskCounters, ( void * ) xTaskCounters, sizeof( xExpectedTaskCounters ) ) )
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{
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xHealthStatus = pdFAIL;
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}
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/* The medium priority and second high priority tasks are still
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* suspended. Make sure to resume them before starting again. */
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vTaskResume( xCreatedTasks[ evtMEDIUM_PRIORITY_INDEX ] );
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vTaskResume( xCreatedTasks[ evtHIGHEST_PRIORITY_INDEX_2 ] );
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/* Just keep incrementing to show the task is still executing. */
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xCheckVariable++;
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}
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}
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/*-----------------------------------------------------------*/
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static void prvCheckTaskCounters( portBASE_TYPE xExpectedTask,
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portBASE_TYPE xIncrement )
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{
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portBASE_TYPE xDummy = 0;
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/* Write to the queue the requested number of times. The data written is
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* not important. */
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for( xDummy = 0; xDummy < xIncrement; xDummy++ )
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{
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if( xQueueSend( xQueue, &xDummy, evtNO_DELAY ) != pdTRUE )
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{
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/* Did not expect to ever find the queue full. */
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xHealthStatus = pdFAIL;
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}
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}
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/* All the tasks blocked on the queue have a priority higher than the
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* controlling task. Writing to the queue will therefore have caused this
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* task to be preempted. By the time this line executes the event task will
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* have executed and incremented its counter. Increment the expected counter
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* to the same value. */
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( xExpectedTaskCounters[ xExpectedTask ] ) += xIncrement;
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/* Check the actual counts and expected counts really are the same. */
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if( memcmp( ( void * ) xExpectedTaskCounters, ( void * ) xTaskCounters, sizeof( xExpectedTaskCounters ) ) )
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{
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/* The counters were not the same. This means a task we did not expect
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* to unblock actually did unblock. */
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xHealthStatus = pdFAIL;
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}
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}
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/*-----------------------------------------------------------*/
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portBASE_TYPE xAreMultiEventTasksStillRunning( void )
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{
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static portBASE_TYPE xPreviousCheckVariable = 0;
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/* Called externally to periodically check that this test is still
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* operational. */
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if( xPreviousCheckVariable == xCheckVariable )
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{
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xHealthStatus = pdFAIL;
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}
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xPreviousCheckVariable = xCheckVariable;
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return xHealthStatus;
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}
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