FreeRTOS/Source/event_groups.c

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    This file is part of the FreeRTOS distribution.

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*/

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

/* Defining MPU_WRAPPERS_INCLUDED_FROM_API_FILE prevents task.h from redefining
all the API functions to use the MPU wrappers.  That should only be done when
task.h is included from an application file. */
#define MPU_WRAPPERS_INCLUDED_FROM_API_FILE

/* FreeRTOS includes. */
#include "FreeRTOS.h"
#include "task.h"
#include "timers.h"
#include "event_groups.h"

/* Lint e961 and e750 are suppressed as a MISRA exception justified because the
MPU ports require MPU_WRAPPERS_INCLUDED_FROM_API_FILE to be defined for the
header files above, but not in this file, in order to generate the correct
privileged Vs unprivileged linkage and placement. */
#undef MPU_WRAPPERS_INCLUDED_FROM_API_FILE /*lint !e961 !e750. */

#if ( INCLUDE_xEventGroupSetBitFromISR == 1 ) && ( configUSE_TIMERS == 0 )
	#error configUSE_TIMERS must be set to 1 to make the xEventGroupSetBitFromISR() function available.
#endif

#if ( INCLUDE_xEventGroupSetBitFromISR == 1 ) && ( INCLUDE_xTimerPendCallbackFromISR == 0 )
	#error INCLUDE_xTimerPendCallbackFromISR must also be set to one to make the xEventGroupSetBitFromISR() function available.
#endif

/* The following bit fields convey control information in a task's event list
item value.  It is important they don't clash with the
taskEVENT_LIST_ITEM_VALUE_IN_USE definition. */
#if configUSE_16_BIT_TICKS == 1
	#define eventCLEAR_EVENTS_ON_EXIT_BIT	0x0100U
	#define eventUNBLOCKED_DUE_TO_BIT_SET	0x0200U
	#define eventWAIT_FOR_ALL_BITS			0x0400U
	#define eventEVENT_BITS_CONTROL_BYTES	0xff00U
#else
	#define eventCLEAR_EVENTS_ON_EXIT_BIT	0x01000000UL
	#define eventUNBLOCKED_DUE_TO_BIT_SET	0x02000000UL
	#define eventWAIT_FOR_ALL_BITS			0x04000000UL
	#define eventEVENT_BITS_CONTROL_BYTES	0xff000000UL
#endif

typedef struct EVENT_GROUP_DEFINITION
{
	EventBits_t uxEventBits;
	List_t xTasksWaitingForBits;		/*< List of tasks waiting for a bit to be set. */
} EventGroup_t;

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

/*
 * Test the bits set in uxCurrentEventBits to see if the wait condition is met.
 * The wait condition is defined by xWaitForAllBits.  If xWaitForAllBits is
 * pdTRUE then the wait condition is met if all the bits set in uxBitsToWaitFor
 * are also set in uxCurrentEventBits.  If xWaitForAllBits is pdFALSE then the
 * wait condition is met if any of the bits set in uxBitsToWait for are also set
 * in uxCurrentEventBits.
 */
static BaseType_t prvTestWaitCondition( const EventBits_t uxCurrentEventBits, const EventBits_t uxBitsToWaitFor, const BaseType_t xWaitForAllBits );

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

EventGroupHandle_t xEventGroupCreate( void )
{
EventGroup_t *pxEventBits;

	pxEventBits = pvPortMalloc( sizeof( EventGroup_t ) );
	if( pxEventBits != NULL )
	{
		pxEventBits->uxEventBits = 0;
		vListInitialise( &( pxEventBits->xTasksWaitingForBits ) );
		traceEVENT_GROUP_CREATE( pxEventBits );
	}
	else
	{
		traceEVENT_GROUP_CREATE_FAILED();
	}

	return ( EventGroupHandle_t ) pxEventBits;
}
/*-----------------------------------------------------------*/

EventBits_t xEventGroupSync( EventGroupHandle_t xEventGroup, const EventBits_t uxBitsToSet, const EventBits_t uxBitsToWaitFor, TickType_t xTicksToWait )
{
EventBits_t uxOriginalBitValue, uxReturn;
EventGroup_t *pxEventBits = ( EventGroup_t * ) xEventGroup;
BaseType_t xAlreadyYielded;

	configASSERT( ( uxBitsToWaitFor & eventEVENT_BITS_CONTROL_BYTES ) == 0 );
	configASSERT( uxBitsToWaitFor != 0 );
	#if ( ( INCLUDE_xTaskGetSchedulerState == 1 ) || ( configUSE_TIMERS == 1 ) )
	{
		configASSERT( !( ( xTaskGetSchedulerState() == taskSCHEDULER_SUSPENDED ) && ( xTicksToWait != 0 ) ) );
	}
	#endif

	vTaskSuspendAll();
	{
		traceEVENT_GROUP_SYNC_START( xEventGroup, uxBitsToSet );

		uxOriginalBitValue = pxEventBits->uxEventBits;

		( void ) xEventGroupSetBits( xEventGroup, uxBitsToSet );

		if( ( ( uxOriginalBitValue | uxBitsToSet ) & uxBitsToWaitFor ) == uxBitsToWaitFor )
		{
			/* All the rendezvous bits are now set - no need to block. */
			uxReturn = ( uxOriginalBitValue | uxBitsToSet );

			/* Rendezvous always clear the bits.  They will have been cleared
			already unless this is the only task in the rendezvous. */
			pxEventBits->uxEventBits &= uxBitsToWaitFor;

			xTicksToWait = 0;
		}
		else
		{
			if( xTicksToWait != ( TickType_t ) 0 )
			{
				/* Store the bits that the calling task is waiting for in the
				task's event list item so the kernel knows when a match is
				found.  Then enter the blocked state. */
				vTaskPlaceOnUnorderedEventList( &( pxEventBits->xTasksWaitingForBits ), ( uxBitsToWaitFor | eventCLEAR_EVENTS_ON_EXIT_BIT | eventWAIT_FOR_ALL_BITS ), xTicksToWait );

				/* This assignment is obsolete as uxReturn will get set after
				the task unblocks, but some compilers mistakenly generate a
				warning about uxReturn being returned without being set if the
				assignment is omitted. */
				uxReturn = 0;
			}
			else
			{
				/* The rendezvous bits were not set, but no block time was
				specified - just return the current event bit value. */
				uxReturn = pxEventBits->uxEventBits;
			}
		}
	}
	xAlreadyYielded = xTaskResumeAll();

	if( xTicksToWait != ( TickType_t ) 0 )
	{
		if( xAlreadyYielded == pdFALSE )
		{
			portYIELD_WITHIN_API();
		}
		else
		{
			mtCOVERAGE_TEST_MARKER();
		}

		/* The task blocked to wait for its required bits to be set - at this
		point either the required bits were set or the block time expired.  If
		the required bits were set they will have been stored in the task's
		event list item, and they should now be retrieved then cleared. */
		uxReturn = uxTaskResetEventItemValue();

		if( ( uxReturn & eventUNBLOCKED_DUE_TO_BIT_SET ) == ( EventBits_t ) 0 )
		{
			/* The task timed out, just return the current event bit value. */
			taskENTER_CRITICAL();
			{
				uxReturn = pxEventBits->uxEventBits;

				/* Although the task got here because it timed out before the
				bits it was waiting for were set, it is possible that since it
				unblocked another task has set the bits.  If this is the case
				then it may be required to clear the bits before exiting. */
				if( ( uxReturn & uxBitsToWaitFor ) == uxBitsToWaitFor )
				{
					pxEventBits->uxEventBits &= ~uxBitsToWaitFor;
				}
				else
				{
					mtCOVERAGE_TEST_MARKER();
				}
			}
			taskEXIT_CRITICAL();
		}
		else
		{
			/* The task unblocked because the bits were set.  Clear the control
			bits before returning the value. */
			uxReturn &= ~eventEVENT_BITS_CONTROL_BYTES;
		}
	}

	traceEVENT_GROUP_SYNC_END( xEventGroup, uxReturn );
	return uxReturn;
}
/*-----------------------------------------------------------*/

EventBits_t xEventGroupWaitBits( EventGroupHandle_t xEventGroup, const EventBits_t uxBitsToWaitFor, const BaseType_t xClearOnExit, const BaseType_t xWaitForAllBits, TickType_t xTicksToWait )
{
EventGroup_t *pxEventBits = ( EventGroup_t * ) xEventGroup;
EventBits_t uxReturn, uxControlBits = 0;
BaseType_t xWaitConditionMet, xAlreadyYielded;

	/* Check the user is not attempting to wait on the bits used by the kernel
	itself, and that at least one bit is being requested. */
	configASSERT( ( uxBitsToWaitFor & eventEVENT_BITS_CONTROL_BYTES ) == 0 );
	configASSERT( uxBitsToWaitFor != 0 );
	#if ( ( INCLUDE_xTaskGetSchedulerState == 1 ) || ( configUSE_TIMERS == 1 ) )
	{
		configASSERT( !( ( xTaskGetSchedulerState() == taskSCHEDULER_SUSPENDED ) && ( xTicksToWait != 0 ) ) );
	}
	#endif

	vTaskSuspendAll();
	{
		const EventBits_t uxCurrentEventBits = pxEventBits->uxEventBits;

		traceEVENT_GROUP_WAIT_BITS_START( xEventGroup, uxBitsToWaitFor );

		/* Check to see if the wait condition is already met or not. */
		xWaitConditionMet = prvTestWaitCondition( uxCurrentEventBits, uxBitsToWaitFor, xWaitForAllBits );

		if( xWaitConditionMet != pdFALSE )
		{
			/* The wait condition has already been met so there is no need to
			block. */
			uxReturn = uxCurrentEventBits;
			xTicksToWait = ( TickType_t ) 0;

			/* Clear the wait bits if requested to do so. */
			if( xClearOnExit != pdFALSE )
			{
				pxEventBits->uxEventBits &= ~uxBitsToWaitFor;
			}
			else
			{
				mtCOVERAGE_TEST_MARKER();
			}
		}
		else if( xTicksToWait == ( TickType_t ) 0 )
		{
			/* The wait condition has not been met, but no block time was
			specified, so just return the current value. */
			uxReturn = uxCurrentEventBits;
		}
		else
		{
			/* The task is going to block to wait for its required bits to be
			set.  uxControlBits are used to remember the specified behaviour of
			this call to xEventGroupWaitBits() - for use when the event bits
			unblock the task. */
			if( xClearOnExit != pdFALSE )
			{
				uxControlBits |= eventCLEAR_EVENTS_ON_EXIT_BIT;
			}
			else
			{
				mtCOVERAGE_TEST_MARKER();
			}

			if( xWaitForAllBits != pdFALSE )
			{
				uxControlBits |= eventWAIT_FOR_ALL_BITS;
			}
			else
			{
				mtCOVERAGE_TEST_MARKER();
			}

			/* Store the bits that the calling task is waiting for in the
			task's event list item so the kernel knows when a match is
			found.  Then enter the blocked state. */
			vTaskPlaceOnUnorderedEventList( &( pxEventBits->xTasksWaitingForBits ), ( uxBitsToWaitFor | uxControlBits ), xTicksToWait );

			/* This is obsolete as it will get set after the task unblocks, but
			some compilers mistakenly generate a warning about the variable
			being returned without being set if it is not done. */
			uxReturn = 0;
		}
	}
	xAlreadyYielded = xTaskResumeAll();

	if( xTicksToWait != ( TickType_t ) 0 )
	{
		if( xAlreadyYielded == pdFALSE )
		{
			portYIELD_WITHIN_API();
		}
		else
		{
			mtCOVERAGE_TEST_MARKER();
		}

		/* The task blocked to wait for its required bits to be set - at this
		point either the required bits were set or the block time expired.  If
		the required bits were set they will have been stored in the task's
		event list item, and they should now be retrieved then cleared. */
		uxReturn = uxTaskResetEventItemValue();

		if( ( uxReturn & eventUNBLOCKED_DUE_TO_BIT_SET ) == ( EventBits_t ) 0 )
		{
			taskENTER_CRITICAL();
			{
				/* The task timed out, just return the current event bit value. */
				uxReturn = pxEventBits->uxEventBits;

				/* It is possible that the event bits were updated between this
				task leaving the Blocked state and running again. */
				if( prvTestWaitCondition( uxReturn, uxBitsToWaitFor, xWaitForAllBits ) != pdFALSE )
				{
					if( xClearOnExit != pdFALSE )
					{
						pxEventBits->uxEventBits &= ~uxBitsToWaitFor;
					}
					else
					{
						mtCOVERAGE_TEST_MARKER();
					}
				}
				else
				{
					mtCOVERAGE_TEST_MARKER();
				}
			}
			taskEXIT_CRITICAL();
		}
		else
		{
			/* The task unblocked because the bits were set.  Clear the control
			bits before returning the value. */
			uxReturn &= ~eventEVENT_BITS_CONTROL_BYTES;
		}
	}

	traceEVENT_GROUP_WAIT_BITS_END( xEventGroup, uxReturn );
	return uxReturn;
}
/*-----------------------------------------------------------*/

EventBits_t xEventGroupClearBits( EventGroupHandle_t xEventGroup, const EventBits_t uxBitsToClear )
{
EventGroup_t *pxEventBits = ( EventGroup_t * ) xEventGroup;
EventBits_t uxReturn;

	/* Check the user is not attempting to clear the bits used by the kernel
	itself. */
	configASSERT( ( uxBitsToClear & eventEVENT_BITS_CONTROL_BYTES ) == 0 );

	taskENTER_CRITICAL();
	{
		traceEVENT_GROUP_CLEAR_BITS( xEventGroup, uxBitsToClear );

		/* The value returned is the event group value prior to the bits being
		cleared. */
		uxReturn = pxEventBits->uxEventBits;

		/* Clear the bits. */
		pxEventBits->uxEventBits &= ~uxBitsToClear;
	}
	taskEXIT_CRITICAL();

	return uxReturn;
}
/*-----------------------------------------------------------*/

EventBits_t xEventGroupSetBits( EventGroupHandle_t xEventGroup, const EventBits_t uxBitsToSet )
{
ListItem_t *pxListItem, *pxNext;
ListItem_t const *pxListEnd;
List_t *pxList;
EventBits_t uxBitsToClear = 0, uxBitsWaitedFor, uxControlBits;
EventGroup_t *pxEventBits = ( EventGroup_t * ) xEventGroup;
BaseType_t xMatchFound = pdFALSE;

	/* Check the user is not attempting to set the bits used by the kernel
	itself. */
	configASSERT( ( uxBitsToSet & eventEVENT_BITS_CONTROL_BYTES ) == 0 );

	pxList = &( pxEventBits->xTasksWaitingForBits );
	pxListEnd = listGET_END_MARKER( pxList ); /*lint !e826 !e740 The mini list structure is used as the list end to save RAM.  This is checked and valid. */
	vTaskSuspendAll();
	{
		traceEVENT_GROUP_SET_BITS( xEventGroup, uxBitsToSet );

		pxListItem = listGET_HEAD_ENTRY( pxList );

		/* Set the bits. */
		pxEventBits->uxEventBits |= uxBitsToSet;

		/* See if the new bit value should unblock any tasks. */
		while( pxListItem != pxListEnd )
		{
			pxNext = listGET_NEXT( pxListItem );
			uxBitsWaitedFor = listGET_LIST_ITEM_VALUE( pxListItem );
			xMatchFound = pdFALSE;

			/* Split the bits waited for from the control bits. */
			uxControlBits = uxBitsWaitedFor & eventEVENT_BITS_CONTROL_BYTES;
			uxBitsWaitedFor &= ~eventEVENT_BITS_CONTROL_BYTES;

			if( ( uxControlBits & eventWAIT_FOR_ALL_BITS ) == ( EventBits_t ) 0 )
			{
				/* Just looking for single bit being set. */
				if( ( uxBitsWaitedFor & pxEventBits->uxEventBits ) != ( EventBits_t ) 0 )
				{
					xMatchFound = pdTRUE;
				}
				else
				{
					mtCOVERAGE_TEST_MARKER();
				}
			}
			else if( ( uxBitsWaitedFor & pxEventBits->uxEventBits ) == uxBitsWaitedFor )
			{
				/* All bits are set. */
				xMatchFound = pdTRUE;
			}
			else
			{
				/* Need all bits to be set, but not all the bits were set. */
			}

			if( xMatchFound != pdFALSE )
			{
				/* The bits match.  Should the bits be cleared on exit? */
				if( ( uxControlBits & eventCLEAR_EVENTS_ON_EXIT_BIT ) != ( EventBits_t ) 0 )
				{
					uxBitsToClear |= uxBitsWaitedFor;
				}
				else
				{
					mtCOVERAGE_TEST_MARKER();
				}

				/* Store the actual event flag value in the task's event list
				item before removing the task from the event list.  The
				eventUNBLOCKED_DUE_TO_BIT_SET bit is set so the task knows
				that is was unblocked due to its required bits matching, rather
				than because it timed out. */
				( void ) xTaskRemoveFromUnorderedEventList( pxListItem, pxEventBits->uxEventBits | eventUNBLOCKED_DUE_TO_BIT_SET );
			}

			/* Move onto the next list item.  Note pxListItem->pxNext is not
			used here as the list item may have been removed from the event list
			and inserted into the ready/pending reading list. */
			pxListItem = pxNext;
		}

		/* Clear any bits that matched when the eventCLEAR_EVENTS_ON_EXIT_BIT
		bit was set in the control word. */
		pxEventBits->uxEventBits &= ~uxBitsToClear;
	}
	( void ) xTaskResumeAll();

	return pxEventBits->uxEventBits;
}
/*-----------------------------------------------------------*/

void vEventGroupDelete( EventGroupHandle_t xEventGroup )
{
EventGroup_t *pxEventBits = ( EventGroup_t * ) xEventGroup;
const List_t *pxTasksWaitingForBits = &( pxEventBits->xTasksWaitingForBits );

	vTaskSuspendAll();
	{
		traceEVENT_GROUP_DELETE( xEventGroup );

		while( listCURRENT_LIST_LENGTH( pxTasksWaitingForBits ) > ( UBaseType_t ) 0 )
		{
			/* Unblock the task, returning 0 as the event list is being deleted
			and	cannot therefore have any bits set. */
			configASSERT( pxTasksWaitingForBits->xListEnd.pxNext != ( ListItem_t * ) &( pxTasksWaitingForBits->xListEnd ) );
			( void ) xTaskRemoveFromUnorderedEventList( pxTasksWaitingForBits->xListEnd.pxNext, ( TickType_t ) eventUNBLOCKED_DUE_TO_BIT_SET );
		}

		vPortFree( pxEventBits );
	}
	( void ) xTaskResumeAll();
}
/*-----------------------------------------------------------*/

/* For internal use only - execute a 'set bits' command that was pended from
an interrupt. */
void vEventGroupSetBitsCallback( void *pvEventGroup, const uint32_t ulBitsToSet )
{
	( void ) xEventGroupSetBits( pvEventGroup, ( EventBits_t ) ulBitsToSet );
}
/*-----------------------------------------------------------*/

static BaseType_t prvTestWaitCondition( const EventBits_t uxCurrentEventBits, const EventBits_t uxBitsToWaitFor, const BaseType_t xWaitForAllBits )
{
BaseType_t xWaitConditionMet = pdFALSE;

	if( xWaitForAllBits == pdFALSE )
	{
		/* Task only has to wait for one bit within uxBitsToWaitFor to be
		set.  Is one already set? */
		if( ( uxCurrentEventBits & uxBitsToWaitFor ) != ( EventBits_t ) 0 )
		{
			xWaitConditionMet = pdTRUE;
		}
		else
		{
			mtCOVERAGE_TEST_MARKER();
		}
	}
	else
	{
		/* Task has to wait for all the bits in uxBitsToWaitFor to be set.
		Are they set already? */
		if( ( uxCurrentEventBits & uxBitsToWaitFor ) == uxBitsToWaitFor )
		{
			xWaitConditionMet = pdTRUE;
		}
		else
		{
			mtCOVERAGE_TEST_MARKER();
		}
	}

	return xWaitConditionMet;
}