FreeRTOS-Kernel/FreeRTOS/Demo/Common/Minimal/TaskNotify.c

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*/


/*
 * Tests the behaviour of direct task notifications.
 */

/* Standard includes. */
#include <limits.h>

/* Scheduler include files. */
#include "FreeRTOS.h"
#include "task.h"
#include "timers.h"

/* Demo program include files. */
#include "TaskNotify.h"

#define notifyTASK_PRIORITY		( tskIDLE_PRIORITY )

/*-----------------------------------------------------------*/

/*
 * Implementation of the task that gets notified.
 */
static void prvNotifiedTask( void *pvParameters );

/*
 * Performs a few initial tests that can be done prior to creating the second
 * task.
 */
static void prvSingleTaskTests( void );

/*
 * Software timer callback function from which xTaskNotify() is called.
 */
static void prvNotifyingTimer( TimerHandle_t xTimer );

/*
 * Utility function to create pseudo random numbers.
 */
static UBaseType_t prvRand( void );

/*-----------------------------------------------------------*/

/* Used to latch errors during the test's execution. */
static BaseType_t xErrorStatus = pdPASS;

/* Used to ensure the task has not stalled. */
static volatile uint32_t ulNotifyCycleCount = 0;

/* The handle of the task that receives the notifications. */
static TaskHandle_t xTaskToNotify = NULL;

/* Used to count the notifications sent to the task from a software timer and
the number of notifications received by the task from the software timer.  The
two should stay synchronised. */
static uint32_t ulTimerNotificationsReceived = 0UL, ulTimerNotificationsSent = 0UL;

/* The timer used to notify the task. */
static TimerHandle_t xTimer = NULL;

/* Used by the pseudo random number generating function. */
static uint32_t ulNextRand = 0;

/*-----------------------------------------------------------*/

void vStartTaskNotifyTask( void  )
{
	/* Create the task that performs some tests by itself, then loops around
	being notified by both a software timer and an interrupt. */
	xTaskCreate( prvNotifiedTask, "Notified", configMINIMAL_STACK_SIZE, NULL, notifyTASK_PRIORITY, &xTaskToNotify );

	/* Pseudo seed the random number generator. */
	ulNextRand = ( uint32_t ) prvRand;
}
/*-----------------------------------------------------------*/

static void prvSingleTaskTests( void )
{
const TickType_t xTicksToWait = pdMS_TO_TICKS( 100UL );
BaseType_t xReturned;
uint32_t ulNotifiedValue, ulLoop, ulNotifyingValue, ulPreviousValue, ulExpectedValue;
TickType_t xTimeOnEntering;
const uint32_t ulFirstNotifiedConst = 100001UL, ulSecondNotifiedValueConst = 5555UL, ulMaxLoops = 5UL;
const uint32_t ulBit0 = 0x01UL, ulBit1 = 0x02UL;

	/* -------------------------------------------------------------------------
	Check blocking when there are no notifications. */
	xTimeOnEntering = xTaskGetTickCount();
	xReturned = xTaskNotifyWait( ULONG_MAX, 0, &ulNotifiedValue, xTicksToWait );

	/* Should have blocked for the entire block time. */
	if( ( xTaskGetTickCount() - xTimeOnEntering ) < xTicksToWait )
	{
		xErrorStatus = pdFAIL;
	}
	configASSERT( xReturned == pdFAIL );
	configASSERT( ulNotifiedValue == 0UL );




	/* -------------------------------------------------------------------------
	Check no blocking when notifications are pending.  First notify itself -
	this would not be a normal thing to do and is done here for test purposes
	only. */
	xReturned = xTaskNotifyAndQuery( xTaskToNotify, ulFirstNotifiedConst, eSetValueWithoutOverwrite, &ulPreviousValue );

	/* Even through the 'without overwrite' action was used the update should
	have been successful. */
	configASSERT( xReturned == pdPASS );

	/* No bits should have been pending previously. */
	configASSERT( ulPreviousValue == 0 );

	/* The task should now have a notification pending, and so not time out. */
	xTimeOnEntering = xTaskGetTickCount();
	xReturned = xTaskNotifyWait( ULONG_MAX, 0, &ulNotifiedValue, xTicksToWait );

	if( ( xTaskGetTickCount() - xTimeOnEntering ) >= xTicksToWait )
	{
		xErrorStatus = pdFAIL;
	}

	/* The task should have been notified, and the notified value should
	be equal to ulFirstNotifiedConst. */
	configASSERT( xReturned == pdPASS );
	configASSERT( ulNotifiedValue == ulFirstNotifiedConst );

	/* Incremented to show the task is still running. */
	ulNotifyCycleCount++;





	/*--------------------------------------------------------------------------
	Check the non-overwriting functionality.  The notification is done twice
	using two different notification values.  The action says don't overwrite so
	only the first notification should pass and the value read back should also
	be that used with the first notification. */
	xReturned = xTaskNotify( xTaskToNotify, ulFirstNotifiedConst, eSetValueWithoutOverwrite );
	configASSERT( xReturned == pdPASS );

	xReturned = xTaskNotify( xTaskToNotify, ulSecondNotifiedValueConst, eSetValueWithoutOverwrite );
	configASSERT( xReturned == pdFAIL );

	/* Waiting for the notification should now return immediately so a block
	time of zero is used. */
	xReturned = xTaskNotifyWait( ULONG_MAX, 0, &ulNotifiedValue, 0 );

	configASSERT( xReturned == pdPASS );
	configASSERT( ulNotifiedValue == ulFirstNotifiedConst );





	/*--------------------------------------------------------------------------
	Do the same again, only this time use the overwriting version.  This time
	both notifications should pass, and the value written the second time should
	overwrite the value written the first time, and so be the value that is read
	back. */
	xReturned = xTaskNotify( xTaskToNotify, ulFirstNotifiedConst, eSetValueWithOverwrite );
	configASSERT( xReturned == pdPASS );
	xReturned = xTaskNotify( xTaskToNotify, ulSecondNotifiedValueConst, eSetValueWithOverwrite );
	configASSERT( xReturned == pdPASS );
	xReturned = xTaskNotifyWait( ULONG_MAX, 0, &ulNotifiedValue, 0 );
	configASSERT( xReturned == pdPASS );
	configASSERT( ulNotifiedValue == ulSecondNotifiedValueConst );




	/*--------------------------------------------------------------------------
	Check notifications with no action pass without updating the value.  Even
	though ulFirstNotifiedConst is used as the value the value read back should
	remain at ulSecondNotifiedConst. */
	xReturned = xTaskNotify( xTaskToNotify, ulFirstNotifiedConst, eNoAction );
	configASSERT( xReturned == pdPASS );
	xReturned = xTaskNotifyWait( ULONG_MAX, 0, &ulNotifiedValue, 0 );
	configASSERT( ulNotifiedValue == ulSecondNotifiedValueConst );




	/*--------------------------------------------------------------------------
	Check incrementing values.  Send ulMaxLoop increment notifications, then
	ensure the received value is as expected - which should be
	ulSecondNotificationValueConst plus how ever many times to loop iterated. */
	for( ulLoop = 0; ulLoop < ulMaxLoops; ulLoop++ )
	{
		xReturned = xTaskNotify( xTaskToNotify, 0, eIncrement );
		configASSERT( xReturned == pdPASS );
	}

	xReturned = xTaskNotifyWait( ULONG_MAX, 0, &ulNotifiedValue, 0 );
	configASSERT( xReturned == pdPASS );
	configASSERT( ulNotifiedValue == ( ulSecondNotifiedValueConst + ulMaxLoops ) );

	/* Should not be any notifications pending now. */
	xReturned = xTaskNotifyWait( 0, 0, &ulNotifiedValue, 0 );
	configASSERT( xReturned == pdFAIL );




	/*--------------------------------------------------------------------------
	Check all bits can be set by notifying the task with one additional bit	set
	on each notification, and exiting the loop when all the bits are found to be
	set.  As there are 32-bits the loop should execute 32 times before all the
	bits are found to be set. */
	ulNotifyingValue = 0x01;
	ulLoop = 0;

	/* Start with all bits clear. */
	xTaskNotifyWait( ULONG_MAX, 0, &ulNotifiedValue, 0 );

	do
	{
		/* Set the next bit in the task's notified value. */
		xTaskNotify( xTaskToNotify, ulNotifyingValue, eSetBits );

		/* Wait for the notified value - which of course will already be
		available.  Don't clear the bits on entry or exit as this loop is exited
		when all the bits are set. */
		xReturned = xTaskNotifyWait( 0, 0, &ulNotifiedValue, 0 );
		configASSERT( xReturned == pdPASS );

		ulLoop++;

		/* Use the next bit on the next iteration around this loop. */
		ulNotifyingValue <<= 1UL;

	} while ( ulNotifiedValue != ULONG_MAX );

	/* As a 32-bit value was used the loop should have executed 32 times before
	all the bits were set. */
	configASSERT( ulLoop == 32 );




	/*--------------------------------------------------------------------------
	Check bits are cleared on entry but not on exit when a notification fails
	to arrive before timing out - both with and without a timeout value.  Wait
	for the notification again - but this time it is not given by anything and
	should return pdFAIL.  The parameters are set to clear bit zero on entry and
	bit one on exit.  As no notification was received only the bit cleared on
	entry should actually get cleared. */
	xReturned = xTaskNotifyWait( ulBit0, ulBit1, &ulNotifiedValue, xTicksToWait );
	configASSERT( xReturned == pdFAIL );

	/* Notify the task with no action so as not to update the bits even though
	ULONG_MAX is used as the notification value. */
	xTaskNotify( xTaskToNotify, ULONG_MAX, eNoAction );

	/* Reading back the value should should find bit 0 is clear, as this was
	cleared on entry, but bit 1 is not clear as it will not have been cleared on
	exit as no notification was received. */
	xReturned = xTaskNotifyWait( 0x00UL, 0x00UL, &ulNotifiedValue, 0 );
	configASSERT( xReturned == pdPASS );
	configASSERT( ulNotifiedValue == ( ULONG_MAX & ~ulBit0 ) );





	/*--------------------------------------------------------------------------
	Now try clearing the bit on exit.  For that to happen a notification must be
	received, so the task is notified first. */
	xTaskNotify( xTaskToNotify, 0, eNoAction );
	xTaskNotifyWait( 0x00, ulBit1, &ulNotifiedValue, 0 );

	/* However as the bit is cleared on exit, after the returned notification
	value is set, the returned notification value should not have the bit
	cleared... */
	configASSERT( ulNotifiedValue == ( ULONG_MAX & ~ulBit0 ) );

	/* ...but reading the value back again should find that the bit was indeed
	cleared internally.  The returned value should be pdFAIL however as nothing
	has notified the task in the mean time. */
	xReturned = xTaskNotifyWait( 0x00, 0x00, &ulNotifiedValue, 0 );
	configASSERT( xReturned == pdFAIL );
	configASSERT( ulNotifiedValue == ( ULONG_MAX & ~( ulBit0 | ulBit1 ) ) );




	/*--------------------------------------------------------------------------
	Now try querying the previous value while notifying a task. */
	xTaskNotifyAndQuery( xTaskToNotify, 0x00, eSetBits, &ulPreviousValue );
	configASSERT( ulNotifiedValue == ( ULONG_MAX & ~( ulBit0 | ulBit1 ) ) );

	/* Clear all bits. */
	xTaskNotifyWait( 0x00, ULONG_MAX, &ulNotifiedValue, 0 );
	xTaskNotifyAndQuery( xTaskToNotify, 0x00, eSetBits, &ulPreviousValue );
	configASSERT( ulPreviousValue == 0 );

	ulExpectedValue = 0;
	for( ulLoop = 0x01; ulLoop < 0x80UL; ulLoop <<= 1UL )
	{
		/* Set the next bit up, and expect to receive the last bits set (so
		the previous value will not yet have the bit being set this time
		around). */
		xTaskNotifyAndQuery( xTaskToNotify, ulLoop, eSetBits, &ulPreviousValue );
		configASSERT( ulExpectedValue == ulPreviousValue );
		ulExpectedValue |= ulLoop;
	}



	/* -------------------------------------------------------------------------
	Clear the previous notifications. */
	xTaskNotifyWait( ULONG_MAX, 0, &ulNotifiedValue, 0 );

	/* The task should not have any notifications pending, so an attempt to clear
	the notification state should fail. */
	configASSERT( xTaskNotifyStateClear( NULL ) == pdFALSE );

	/* Get the task to notify itself.  This is not a normal thing to do, and is
	only done here for test purposes. */
	xTaskNotifyAndQuery( xTaskToNotify, ulFirstNotifiedConst, eSetValueWithoutOverwrite, &ulPreviousValue );

	/* Now the notification state should be eNotified, so it should now be
	possible to clear the notification state. */
	configASSERT( xTaskNotifyStateClear( NULL ) == pdTRUE );
	configASSERT( xTaskNotifyStateClear( NULL ) == pdFALSE );




	/* Incremented to show the task is still running. */
	ulNotifyCycleCount++;

	/* Leave all bits cleared. */
	xTaskNotifyWait( ULONG_MAX, 0, NULL, 0 );
}
/*-----------------------------------------------------------*/

static void prvNotifyingTimer( TimerHandle_t xNotUsed )
{
	( void ) xNotUsed;

	xTaskNotifyGive( xTaskToNotify );

	/* This value is also incremented from an interrupt. */
	taskENTER_CRITICAL();
	{
		ulTimerNotificationsSent++;
	}
	taskEXIT_CRITICAL();
}
/*-----------------------------------------------------------*/

static void prvNotifiedTask( void *pvParameters )
{
const TickType_t xMaxPeriod = pdMS_TO_TICKS( 90 ), xMinPeriod = pdMS_TO_TICKS( 10 ), xDontBlock = 0;
TickType_t xPeriod;
const uint32_t ulCyclesToRaisePriority = 50UL;

	/* Remove compiler warnings about unused parameters. */
	( void ) pvParameters;

	/* Run a few tests that can be done from a single task before entering the
	main loop. */
	prvSingleTaskTests();

	/* Create the software timer that is used to send notifications to this
	task.  Notifications are also received from an interrupt. */
	xTimer = xTimerCreate( "Notifier", xMaxPeriod, pdFALSE, NULL, prvNotifyingTimer );

	for( ;; )
	{
		/* Start the timer again with a different period.  Sometimes the period
		will be higher than the tasks block time, sometimes it will be lower
		than the tasks block time. */
		xPeriod = prvRand() % xMaxPeriod;
		if( xPeriod < xMinPeriod )
		{
			xPeriod = xMinPeriod;
		}

		/* Change the timer period and start the timer. */
		xTimerChangePeriod( xTimer, xPeriod, portMAX_DELAY );

		/* Block waiting for the notification again with a different period.
		Sometimes the period will be higher than the tasks block time, sometimes
		it will be lower than the tasks block time. */
		xPeriod = prvRand() % xMaxPeriod;
		if( xPeriod < xMinPeriod )
		{
			xPeriod = xMinPeriod;
		}

		/* Block to wait for a notification but without clearing the
		notification count, so only add one to the count of received
		notifications as any other notifications will remain pending. */
		if( ulTaskNotifyTake( pdFALSE, xPeriod ) != 0 )
		{
			ulTimerNotificationsReceived++;
		}


		/* Take a notification without clearing again, but this time without a
		block time specified. */
		if( ulTaskNotifyTake( pdFALSE, xDontBlock ) != 0 )
		{
			ulTimerNotificationsReceived++;
		}

		/* Wait for the next notification from the timer, clearing all
		notifications if one is received, so this time adding the total number
		of notifications that were pending as none will be left pending after
		the function call. */
		ulTimerNotificationsReceived += ulTaskNotifyTake( pdTRUE, xPeriod );

		/* Occasionally raise the priority of the task being notified to test
		the path where the task is notified from an ISR and becomes the highest
		priority ready state task, but the pxHigherPriorityTaskWoken parameter
		is NULL (which it is in the tick hook that sends notifications to this
		task. */
		if( ( ulNotifyCycleCount % ulCyclesToRaisePriority ) == 0 )
		{
			vTaskPrioritySet( xTaskToNotify, configMAX_PRIORITIES - 1 );

			/* Wait for the next notification again, clearing all notifications if
			one is received, but this time blocking indefinitely. */
			ulTimerNotificationsReceived += ulTaskNotifyTake( pdTRUE, portMAX_DELAY );

			/* Reset the priority. */
			vTaskPrioritySet( xTaskToNotify, notifyTASK_PRIORITY );
		}
		else
		{
			/* Wait for the next notification again, clearing all notifications if
			one is received, but this time blocking indefinitely. */
			ulTimerNotificationsReceived += ulTaskNotifyTake( pdTRUE, portMAX_DELAY );
		}

		/* Incremented to show the task is still running. */
		ulNotifyCycleCount++;
	}
}
/*-----------------------------------------------------------*/

void xNotifyTaskFromISR( void )
{
static BaseType_t xCallCount = 0, xAPIToUse = 0;
const BaseType_t xCallInterval = pdMS_TO_TICKS( 50 );
uint32_t ulPreviousValue;
const uint32_t ulUnexpectedValue = 0xff;

	/* The task performs some tests before starting the timer that gives the
	notification from this interrupt.  If the timer has not been created yet
	then the initial tests have not yet completed and the notification should
	not be sent. */
	if( xTimer != NULL )
	{
		xCallCount++;

		if( xCallCount >= xCallInterval )
		{
			/* It is time to 'give' the notification again. */
			xCallCount = 0;

			/* Test using both vTaskNotifyGiveFromISR(), xTaskNotifyFromISR()
			and xTaskNotifyAndQueryFromISR(). */
			switch( xAPIToUse )
			{
				case 0:	vTaskNotifyGiveFromISR( xTaskToNotify, NULL );
						xAPIToUse++;
						break;

				case 1:	xTaskNotifyFromISR( xTaskToNotify, 0, eIncrement, NULL );
						xAPIToUse++;
						break;

				case 2: ulPreviousValue = ulUnexpectedValue;
						xTaskNotifyAndQueryFromISR( xTaskToNotify, 0, eIncrement, &ulPreviousValue, NULL );
						configASSERT( ulPreviousValue != ulUnexpectedValue );
						xAPIToUse = 0;
						break;

				default:/* Should never get here!. */
						break;
			}

			ulTimerNotificationsSent++;
		}
	}
}
/*-----------------------------------------------------------*/

/* This is called to check the created tasks are still running and have not
detected any errors. */
BaseType_t xAreTaskNotificationTasksStillRunning( void )
{
static uint32_t ulLastNotifyCycleCount = 0;
const uint32_t ulMaxSendReceiveDeviation = 5UL;

	/* Check the cycle count is still incrementing to ensure the task is still
	actually running. */
	if( ulLastNotifyCycleCount == ulNotifyCycleCount )
	{
		xErrorStatus = pdFAIL;
	}
	else
	{
		ulLastNotifyCycleCount = ulNotifyCycleCount;
	}

	/* Check the count of 'takes' from the software timer is keeping track with
	the amount of 'gives'. */
	if( ulTimerNotificationsSent > ulTimerNotificationsReceived )
	{
		if( ( ulTimerNotificationsSent - ulTimerNotificationsReceived ) > ulMaxSendReceiveDeviation )
		{
			xErrorStatus = pdFAIL;
		}
	}

	return xErrorStatus;
}
/*-----------------------------------------------------------*/

static UBaseType_t prvRand( void )
{
const uint32_t ulMultiplier = 0x015a4e35UL, ulIncrement = 1UL;

	/* Utility function to generate a pseudo random number. */
	ulNextRand = ( ulMultiplier * ulNextRand ) + ulIncrement;
	return( ( ulNextRand >> 16UL ) & 0x7fffUL );
}
/*-----------------------------------------------------------*/