tasks.c

freescale k40/k60 freertos-lwip例程

				else if( pxTask == NULL )
				{
					/* Setting our own priority down means there may now be another
					task of higher priority that is ready to execute. */
					xYieldRequired = pdTRUE;
				}



				#if ( configUSE_MUTEXES == 1 )
				{
					/* Only change the priority being used if the task is not
					currently using an inherited priority. */
					if( pxTCB->uxBasePriority == pxTCB->uxPriority )
					{
						pxTCB->uxPriority = uxNewPriority;
					}

					/* The base priority gets set whatever. */
					pxTCB->uxBasePriority = uxNewPriority;
				}
				#else
				{
					pxTCB->uxPriority = uxNewPriority;
				}
				#endif

				listSET_LIST_ITEM_VALUE( &( pxTCB->xEventListItem ), ( configMAX_PRIORITIES - ( portTickType ) uxNewPriority ) );

				/* If the task is in the blocked or suspended list we need do
				nothing more than change it's priority variable. However, if
				the task is in a ready list it needs to be removed and placed
				in the queue appropriate to its new priority. */
				if( listIS_CONTAINED_WITHIN( &( pxReadyTasksLists[ uxCurrentPriority ] ), &( pxTCB->xGenericListItem ) ) )
				{
					/* The task is currently in its ready list - remove before adding
					it to it's new ready list.  As we are in a critical section we
					can do this even if the scheduler is suspended. */
					vListRemove( &( pxTCB->xGenericListItem ) );
					prvAddTaskToReadyQueue( pxTCB );
				}

				if( xYieldRequired == pdTRUE )
				{
					portYIELD_WITHIN_API();
				}
			}
		}
		portEXIT_CRITICAL();
	}

#endif
/*-----------------------------------------------------------*/

#if ( INCLUDE_vTaskSuspend == 1 )

	void vTaskSuspend( xTaskHandle pxTaskToSuspend )
	{
	tskTCB *pxTCB;

		portENTER_CRITICAL();
		{
			/* Ensure a yield is performed if the current task is being
			suspended. */
			if( pxTaskToSuspend == pxCurrentTCB )
			{
				pxTaskToSuspend = NULL;
			}

			/* If null is passed in here then we are suspending ourselves. */
			pxTCB = prvGetTCBFromHandle( pxTaskToSuspend );

			traceTASK_SUSPEND( pxTCB );

			/* Remove task from the ready/delayed list and place in the	suspended list. */
			vListRemove( &( pxTCB->xGenericListItem ) );

			/* Is the task waiting on an event also? */
			if( pxTCB->xEventListItem.pvContainer )
			{
				vListRemove( &( pxTCB->xEventListItem ) );
			}

			vListInsertEnd( ( xList * ) &xSuspendedTaskList, &( pxTCB->xGenericListItem ) );
		}
		portEXIT_CRITICAL();

		/* We may have just suspended the current task. */
		if( ( void * ) pxTaskToSuspend == NULL )
		{
			portYIELD_WITHIN_API();
		}
	}

#endif
/*-----------------------------------------------------------*/

#if ( INCLUDE_vTaskSuspend == 1 )

	signed portBASE_TYPE xTaskIsTaskSuspended( xTaskHandle xTask )
	{
	portBASE_TYPE xReturn = pdFALSE;
	const tskTCB * const pxTCB = ( tskTCB * ) xTask;

		/* Is the task we are attempting to resume actually in the
		suspended list? */
		if( listIS_CONTAINED_WITHIN( &xSuspendedTaskList, &( pxTCB->xGenericListItem ) ) != pdFALSE )
		{
			/* Has the task already been resumed from within an ISR? */
			if( listIS_CONTAINED_WITHIN( &xPendingReadyList, &( pxTCB->xEventListItem ) ) != pdTRUE )
			{
				/* Is it in the suspended list because it is in the
				Suspended state?  It is possible to be in the suspended
				list because it is blocked on a task with no timeout
				specified. */
				if( listIS_CONTAINED_WITHIN( NULL, &( pxTCB->xEventListItem ) ) == pdTRUE )
				{
					xReturn = pdTRUE;
				}
			}
		}

		return xReturn;
	}

#endif
/*-----------------------------------------------------------*/

#if ( INCLUDE_vTaskSuspend == 1 )

	void vTaskResume( xTaskHandle pxTaskToResume )
	{
	tskTCB *pxTCB;

		/* Remove the task from whichever list it is currently in, and place
		it in the ready list. */
		pxTCB = ( tskTCB * ) pxTaskToResume;

		/* The parameter cannot be NULL as it is impossible to resume the
		currently executing task. */
		if( ( pxTCB != NULL ) && ( pxTCB != pxCurrentTCB ) )
		{
			portENTER_CRITICAL();
			{
				if( xTaskIsTaskSuspended( pxTCB ) == pdTRUE )
				{
					traceTASK_RESUME( pxTCB );

					/* As we are in a critical section we can access the ready
					lists even if the scheduler is suspended. */
					vListRemove(  &( pxTCB->xGenericListItem ) );
					prvAddTaskToReadyQueue( pxTCB );

					/* We may have just resumed a higher priority task. */
					if( pxTCB->uxPriority >= pxCurrentTCB->uxPriority )
					{
						/* This yield may not cause the task just resumed to run, but
						will leave the lists in the correct state for the next yield. */
						portYIELD_WITHIN_API();
					}
				}
			}
			portEXIT_CRITICAL();
		}
	}

#endif

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

#if ( ( INCLUDE_xTaskResumeFromISR == 1 ) && ( INCLUDE_vTaskSuspend == 1 ) )

	portBASE_TYPE xTaskResumeFromISR( xTaskHandle pxTaskToResume )
	{
	portBASE_TYPE xYieldRequired = pdFALSE;
	tskTCB *pxTCB;

		pxTCB = ( tskTCB * ) pxTaskToResume;

		if( xTaskIsTaskSuspended( pxTCB ) == pdTRUE )
		{
			traceTASK_RESUME_FROM_ISR( pxTCB );

			if( uxSchedulerSuspended == ( unsigned portBASE_TYPE ) pdFALSE )
			{
				xYieldRequired = ( pxTCB->uxPriority >= pxCurrentTCB->uxPriority );
				vListRemove(  &( pxTCB->xGenericListItem ) );
				prvAddTaskToReadyQueue( pxTCB );
			}
			else
			{
				/* We cannot access the delayed or ready lists, so will hold this
				task pending until the scheduler is resumed, at which point a
				yield will be performed if necessary. */
				vListInsertEnd( ( xList * ) &( xPendingReadyList ), &( pxTCB->xEventListItem ) );
			}
		}

		return xYieldRequired;
	}

#endif




/*-----------------------------------------------------------
 * PUBLIC SCHEDULER CONTROL documented in task.h
 *----------------------------------------------------------*/


void vTaskStartScheduler( void )
{
portBASE_TYPE xReturn;

	/* Add the idle task at the lowest priority. */
	xReturn = xTaskCreate( prvIdleTask, ( signed char * ) "IDLE", tskIDLE_STACK_SIZE, ( void * ) NULL, ( tskIDLE_PRIORITY | portPRIVILEGE_BIT ), ( xTaskHandle * ) NULL );

	if( xReturn == pdPASS )
	{
		/* Interrupts are turned off here, to ensure a tick does not occur
		before or during the call to xPortStartScheduler().  The stacks of
		the created tasks contain a status word with interrupts switched on
		so interrupts will automatically get re-enabled when the first task
		starts to run.

		STEPPING THROUGH HERE USING A DEBUGGER CAN CAUSE BIG PROBLEMS IF THE
		DEBUGGER ALLOWS INTERRUPTS TO BE PROCESSED. */
		portDISABLE_INTERRUPTS();

		xSchedulerRunning = pdTRUE;
		xTickCount = ( portTickType ) 0;

		/* If configGENERATE_RUN_TIME_STATS is defined then the following
		macro must be defined to configure the timer/counter used to generate
		the run time counter time base. */
		portCONFIGURE_TIMER_FOR_RUN_TIME_STATS();

		/* Setting up the timer tick is hardware specific and thus in the
		portable interface. */
		if( xPortStartScheduler() )
		{
			/* Should not reach here as if the scheduler is running the
			function will not return. */
		}
		else
		{
			/* Should only reach here if a task calls xTaskEndScheduler(). */
		}
	}
}
/*-----------------------------------------------------------*/

void vTaskEndScheduler( void )
{
	/* Stop the scheduler interrupts and call the portable scheduler end
	routine so the original ISRs can be restored if necessary.  The port
	layer must ensure interrupts enable	bit is left in the correct state. */
	portDISABLE_INTERRUPTS();
	xSchedulerRunning = pdFALSE;
	vPortEndScheduler();
}
/*----------------------------------------------------------*/

void vTaskSuspendAll( void )
{
	/* A critical section is not required as the variable is of type
	portBASE_TYPE. */
	++uxSchedulerSuspended;
}
/*----------------------------------------------------------*/

signed portBASE_TYPE xTaskResumeAll( void )
{
register tskTCB *pxTCB;
signed portBASE_TYPE xAlreadyYielded = pdFALSE;

	/* It is possible that an ISR caused a task to be removed from an event
	list while the scheduler was suspended.  If this was the case then the
	removed task will have been added to the xPendingReadyList.  Once the
	scheduler has been resumed it is safe to move all the pending ready
	tasks from this list into their appropriate ready list. */
	portENTER_CRITICAL();
	{
		--uxSchedulerSuspended;

		if( uxSchedulerSuspended == ( unsigned portBASE_TYPE ) pdFALSE )
		{
			if( uxCurrentNumberOfTasks > ( unsigned portBASE_TYPE ) 0 )
			{
				portBASE_TYPE xYieldRequired = pdFALSE;

				/* Move any readied tasks from the pending list into the
				appropriate ready list. */
				while( ( pxTCB = ( tskTCB * ) listGET_OWNER_OF_HEAD_ENTRY(  ( ( xList * ) &xPendingReadyList ) ) ) != NULL )
				{
					vListRemove( &( pxTCB->xEventListItem ) );
					vListRemove( &( pxTCB->xGenericListItem ) );
					prvAddTaskToReadyQueue( pxTCB );

					/* If we have moved a task that has a priority higher than
					the current task then we should yield. */
					if( pxTCB->uxPriority >= pxCurrentTCB->uxPriority )
					{
						xYieldRequired = pdTRUE;
					}
				}

				/* If any ticks occurred while the scheduler was suspended then
				they should be processed now.  This ensures the tick count does not
				slip, and that any delayed tasks are resumed at the correct time. */
				if( uxMissedTicks > ( unsigned portBASE_TYPE ) 0 )
				{
					while( uxMissedTicks > ( unsigned portBASE_TYPE ) 0 )
					{
						vTaskIncrementTick();
						--uxMissedTicks;
					}

					/* As we have processed some ticks it is appropriate to yield
					to ensure the highest priority task that is ready to run is
					the task actually running. */
					#if configUSE_PREEMPTION == 1
					{
						xYieldRequired = pdTRUE;
					}
					#endif
				}

				if( ( xYieldRequired == pdTRUE ) || ( xMissedYield == pdTRUE ) )
				{
					xAlreadyYielded = pdTRUE;
					xMissedYield = pdFALSE;
					portYIELD_WITHIN_API();
				}
			}
		}
	}
	portEXIT_CRITICAL();

	return xAlreadyYielded;
}






/*-----------------------------------------------------------
 * PUBLIC TASK UTILITIES documented in task.h
 *----------------------------------------------------------*/



portTickType xTaskGetTickCount( void )
{
portTickType xTicks;

	/* Critical section required if running on a 16 bit processor. */
	portENTER_CRITICAL();
	{
		xTicks = xTickCount;
	}
	portEXIT_CRITICAL();

	return xTicks;
}
/*-----------------------------------------------------------*/

unsigned portBASE_TYPE uxTaskGetNumberOfTasks( void )
{
	/* A critical section is not required because the variables are of type
	portBASE_TYPE. */
	return uxCurrentNumberOfTasks;
}
/*-----------------------------------------------------------*/

#if ( configUSE_TRACE_FACILITY == 1 )

	void vTaskList( signed char *pcWriteBuffer )
	{
	unsigned portBASE_TYPE uxQueue;

		/* This is a VERY costly function that should be used for debug only.
		It leaves interrupts disabled for a LONG time. */

		vTaskSuspendAll();
		{
			/* Run through all the lists that could potentially contain a TCB and
			report the task name, state and stack high water mark. */

			pcWriteBuffer[ 0 ] = ( signed char ) 0x00;
			strcat( ( char * ) pcWriteBuffer, ( const char * ) "\r\n" );

			uxQueue = uxTopUsedPriority + 1;

			do
			{
				uxQueue--;

				if( !listLIST_IS_EMPTY( &( pxReadyTasksLists[ uxQueue ] ) ) )
				{
					prvListTaskWithinSingleList( pcWriteBuffer, ( xList * ) &( pxReadyTasksLists[ uxQueue ] ), tskREADY_CHAR );
				}