freertos kernel.c

这是一个FreeRTOS(V511)的移植程序,MCU为FREESCALE公司的MC9S08AW60

						if( xTaskCheckForTimeOut( &xTimeOut, &xTicksToWait ) == pdFALSE )
						{
							traceBLOCKING_ON_QUEUE_SEND( pxQueue );
							vTaskPlaceOnEventList( &( pxQueue->xTasksWaitingToSend ), xTicksToWait );

							/* This will exit the critical section, then re-enter when
							the task next runs. */
							taskYIELD();
						}
					}
				}
				portEXIT_CRITICAL();
			}

   			/* Higher priority tasks and interrupts can execute during
   			this time and could possible refill the queue - even if we
   			unblocked because space became available. */

			taskENTER_CRITICAL();
			{
   				/* Is there room on the queue now?  To be running we must be
   				the highest priority task wanting to access the queue. */
				if( pxQueue->uxMessagesWaiting < pxQueue->uxLength )
				{
					traceQUEUE_SEND( pxQueue );
					prvCopyDataToQueue( pxQueue, pvItemToQueue, xCopyPosition );
					xReturn = pdPASS;

					/* If there was a task waiting for data to arrive on the
					queue then unblock it now. */
					if( listLIST_IS_EMPTY( &( pxQueue->xTasksWaitingToReceive ) ) == pdFALSE )
					{
						if( xTaskRemoveFromEventList( &( pxQueue->xTasksWaitingToReceive ) ) == pdTRUE )
						{
							/* The unblocked task has a priority higher than
							our own so yield immediately. */
							taskYIELD();
						}
					}
				}
				else
				{
   					/* Setting xReturn to errQUEUE_FULL will force its timeout
   					to be re-evaluated.  This is necessary in case interrupts
   					and higher priority tasks accessed the queue between this
   					task being unblocked and subsequently attempting to write
   					to the queue. */
					xReturn = errQUEUE_FULL;
				}
			}
			taskEXIT_CRITICAL();

			if( xReturn == errQUEUE_FULL )
			{
				if( xTicksToWait > ( portTickType ) 0 )
				{
					if( xTaskCheckForTimeOut( &xTimeOut, &xTicksToWait ) == pdFALSE )
					{
						xReturn = queueERRONEOUS_UNBLOCK;
					}
					else
					{
						traceQUEUE_SEND_FAILED( pxQueue );
					}
				}
				else
				{
					traceQUEUE_SEND_FAILED( pxQueue );
				}
			}
		}
		while( xReturn == queueERRONEOUS_UNBLOCK );

		return xReturn;
	}

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

#if configUSE_ALTERNATIVE_API == 1

	signed portBASE_TYPE xQueueAltGenericReceive( xQueueHandle pxQueue, void * const pvBuffer, portTickType xTicksToWait, portBASE_TYPE xJustPeeking )
	{
	signed portBASE_TYPE xReturn = pdTRUE;
	xTimeOutType xTimeOut;
	signed portCHAR *pcOriginalReadPosition;

		/* The source code that implements the alternative (Alt) API is
		simpler	because it makes more use of critical sections.  This is
		the approach taken by many other RTOSes, but FreeRTOS.org has the
		preferred fully featured API too.  The fully featured API has more
		complex	code that takes longer to execute, but makes less use of
		critical sections.  */

		do
		{
			/* If there are no messages in the queue we may have to block. */
			if( xTicksToWait > ( portTickType ) 0 )
			{
				portENTER_CRITICAL();
				{
					if( xReturn == pdPASS )
					{
						/* This is the first time through - capture the time
						inside the critical section to ensure we attempt to
						block at least once. */
						vTaskSetTimeOutState( &xTimeOut );
					}

					if( prvIsQueueEmpty( pxQueue ) )
					{
	    				/* Need to call xTaskCheckForTimeout again as time could
	    				have passed since it was last called if this is not the
	    				first time around this loop. */
						if( xTaskCheckForTimeOut( &xTimeOut, &xTicksToWait ) == pdFALSE )
						{
							traceBLOCKING_ON_QUEUE_RECEIVE( pxQueue );

							#if ( configUSE_MUTEXES == 1 )
							{
								if( pxQueue->uxQueueType == queueQUEUE_IS_MUTEX )
								{
									vTaskPriorityInherit( ( void * ) pxQueue->pxMutexHolder );
								}
							}
							#endif

							vTaskPlaceOnEventList( &( pxQueue->xTasksWaitingToReceive ), xTicksToWait );
							taskYIELD();
						}
					}
				}
				portEXIT_CRITICAL();
			}

			taskENTER_CRITICAL();
			{
				if( pxQueue->uxMessagesWaiting > ( unsigned portBASE_TYPE ) 0 )
				{
					/* Remember our read position in case we are just peeking. */
					pcOriginalReadPosition = pxQueue->pcReadFrom;

					prvCopyDataFromQueue( pxQueue, pvBuffer );

					if( xJustPeeking == pdFALSE )
					{
						traceQUEUE_RECEIVE( pxQueue );

						/* We are actually removing data. */
						--( pxQueue->uxMessagesWaiting );

						#if ( configUSE_MUTEXES == 1 )
						{
							if( pxQueue->uxQueueType == queueQUEUE_IS_MUTEX )
							{
								/* Record the information required to implement
								priority inheritance should it become necessary. */
								pxQueue->pxMutexHolder = xTaskGetCurrentTaskHandle();
							}
						}
						#endif

						if( listLIST_IS_EMPTY( &( pxQueue->xTasksWaitingToSend ) ) == pdFALSE )
						{
							if( xTaskRemoveFromEventList( &( pxQueue->xTasksWaitingToSend ) ) == pdTRUE )
							{
								taskYIELD();
							}
						}
					}
					else
					{
						traceQUEUE_PEEK( pxQueue );

						/* We are not removing the data, so reset our read
						pointer. */
						pxQueue->pcReadFrom = pcOriginalReadPosition;

						/* The data is being left in the queue, so see if there are
						any other tasks waiting for the data. */
						if( !listLIST_IS_EMPTY( &( pxQueue->xTasksWaitingToReceive ) ) )
						{
							/* Tasks that are removed from the event list will get added to
							the pending ready list as the scheduler is still suspended. */
							if( xTaskRemoveFromEventList( &( pxQueue->xTasksWaitingToReceive ) ) != pdFALSE )
							{
								/* The task waiting has a higher priority that this task. */
								taskYIELD();
							}
						}

					}

					xReturn = pdPASS;
				}
				else
				{
					xReturn = errQUEUE_EMPTY;
				}
			}
			taskEXIT_CRITICAL();

			if( xReturn == errQUEUE_EMPTY )
			{
				if( xTicksToWait > ( portTickType ) 0 )
				{
					if( xTaskCheckForTimeOut( &xTimeOut, &xTicksToWait ) == pdFALSE )
					{
						xReturn = queueERRONEOUS_UNBLOCK;
					}
					else
					{
						traceQUEUE_RECEIVE_FAILED( pxQueue );
					}
				}
				else
				{
					traceQUEUE_RECEIVE_FAILED( pxQueue );
				}
			}
		} while( xReturn == queueERRONEOUS_UNBLOCK );

		return xReturn;
	}


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

signed portBASE_TYPE xQueueGenericSendFromISR( xQueueHandle pxQueue, const void * const pvItemToQueue, signed portBASE_TYPE *pxHigherPriorityTaskWoken, portBASE_TYPE xCopyPosition )
{
signed portBASE_TYPE xReturn;
unsigned portBASE_TYPE uxSavedInterruptStatus;

	/* Similar to xQueueGenericSend, except we don't block if there is no room
	in the queue.  Also we don't directly wake a task that was blocked on a
	queue read, instead we return a flag to say whether a context switch is
	required or not (i.e. has a task with a higher priority than us been woken
	by this	post). */
	uxSavedInterruptStatus = portSET_INTERRUPT_MASK_FROM_ISR();
	{
		if( pxQueue->uxMessagesWaiting < pxQueue->uxLength )
		{
			traceQUEUE_SEND_FROM_ISR( pxQueue );

			prvCopyDataToQueue( pxQueue, pvItemToQueue, xCopyPosition );

			/* If the queue is locked we do not alter the event list.  This will
			be done when the queue is unlocked later. */
			if( pxQueue->xTxLock == queueUNLOCKED )
			{
				if( !listLIST_IS_EMPTY( &( pxQueue->xTasksWaitingToReceive ) ) )
				{
					if( xTaskRemoveFromEventList( &( pxQueue->xTasksWaitingToReceive ) ) != pdFALSE )
					{
						/* The task waiting has a higher priority so record that a
						context	switch is required. */
						*pxHigherPriorityTaskWoken = pdTRUE;
					}
				}
			}
			else
			{
				/* Increment the lock count so the task that unlocks the queue
				knows that data was posted while it was locked. */
				++( pxQueue->xTxLock );
			}

			xReturn = pdPASS;
		}
		else
		{
			traceQUEUE_SEND_FROM_ISR_FAILED( pxQueue );
			xReturn = errQUEUE_FULL;
		}
	}
	portCLEAR_INTERRUPT_MASK_FROM_ISR( uxSavedInterruptStatus );

	return xReturn;
}
/*-----------------------------------------------------------*/

signed portBASE_TYPE xQueueGenericReceive( xQueueHandle pxQueue, void * const pvBuffer, portTickType xTicksToWait, portBASE_TYPE xJustPeeking )
{
signed portBASE_TYPE xReturn = pdTRUE;
xTimeOutType xTimeOut;
signed portCHAR *pcOriginalReadPosition;

	do
	{
		/* If there are no messages in the queue we may have to block. */
		if( xTicksToWait > ( portTickType ) 0 )
		{
			vTaskSuspendAll();
			prvLockQueue( pxQueue );

			if( xReturn == pdTRUE )
			{
				/* This is the first time through - we need to capture the
				time while the scheduler is locked to ensure we attempt to
				block at least once. */
				vTaskSetTimeOutState( &xTimeOut );
			}

			if( prvIsQueueEmpty( pxQueue ) )
			{
	    		/* Need to call xTaskCheckForTimeout again as time could
	    		have passed since it was last called if this is not the
	    		first time around this loop. */
				if( xTaskCheckForTimeOut( &xTimeOut, &xTicksToWait ) == pdFALSE )
				{
					traceBLOCKING_ON_QUEUE_RECEIVE( pxQueue );

					#if ( configUSE_MUTEXES == 1 )
					{
						if( pxQueue->uxQueueType == queueQUEUE_IS_MUTEX )
						{
							portENTER_CRITICAL();
								vTaskPriorityInherit( ( void * ) pxQueue->pxMutexHolder );
							portEXIT_CRITICAL();
						}
					}
					#endif

					vTaskPlaceOnEventList( &( pxQueue->xTasksWaitingToReceive ), xTicksToWait );
					prvUnlockQueue( pxQueue );
					if( !xTaskResumeAll() )
					{
						taskYIELD();
					}
				}
				else
				{
					prvUnlockQueue( pxQueue );
					( void ) xTaskResumeAll();
				}
			}
			else
			{
				prvUnlockQueue( pxQueue );
				( void ) xTaskResumeAll();
			}
		}

/* The two tasks are blocked on the queue, the low priority task is polling/running. */

/* An interrupt occurs here - which unblocks the HP tasks, but they do not run. */
		taskENTER_CRITICAL();
		{
/* Because the interrupt occurred the LP task manages to grab the data as the other two tasks are not yet running. */
			if( pxQueue->uxMessagesWaiting > ( unsigned portBASE_TYPE ) 0 )
			{
				/* Remember our read position in case we are just peeking. */
				pcOriginalReadPosition = pxQueue->pcReadFrom;

				prvCopyDataFromQueue( pxQueue, pvBuffer );

				if( xJustPeeking == pdFALSE )
				{
					traceQUEUE_RECEIVE( pxQueue );

					/* We are actually removing data. */
					--( pxQueue->uxMessagesWaiting );

					#if ( configUSE_MUTEXES == 1 )
					{
						if( pxQueue->uxQueueType == queueQUEUE_IS_MUTEX )
						{
							/* Record the information required to implement
							priority inheritance should it become necessary. */
							pxQueue->pxMutexHolder = xTaskGetCurrentTaskHandle();
						}
					}
					#endif

					if( listLIST_IS_EMPTY( &( pxQueue->xTasksWaitingToSend ) ) == pdFALSE )
					{
						if( xTaskRemoveFromEventList( &( pxQueue->xTasksWaitingToSend ) ) == pdTRUE )
						{