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楼主 |
发表于 2013-6-18 19:19:00
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从ISR中向消息队列里面发送数据
/**
* queue. h
* <pre>
portBASE_TYPE xQueueGenericSendFromISR(
xQueueHandle xQueue,
const void *pvItemToQueue,
portBASE_TYPE *pxHigherPriorityTaskWoken,
portBASE_TYPE xCopyPosition
);
</pre>
*
* It is preferred that the macros xQueueSendFromISR(),
* xQueueSendToFrontFromISR() and xQueueSendToBackFromISR() be used in place
* of calling this function directly.
*
* Post an item on a queue. It is safe to use this function from within an
* interrupt service routine.
*
* Items are queued by copy not reference so it is preferable to only
* queue small items, especially when called from an ISR. In most cases
* it would be preferable to store a pointer to the item being queued.
*
* @param xQueue The handle to the queue on which the item is to be posted.
*
* @param pvItemToQueue A pointer to the item that is to be placed on the
* queue. The size of the items the queue will hold was defined when the
* queue was created, so this many bytes will be copied from pvItemToQueue
* into the queue storage area.
*
* @param pxHigherPriorityTaskWoken xQueueGenericSendFromISR() will set
* *pxHigherPriorityTaskWoken to pdTRUE if sending to the queue caused a task
* to unblock, and the unblocked task has a priority higher than the currently
* running task. If xQueueGenericSendFromISR() sets this value to pdTRUE then
* a context switch should be requested before the interrupt is exited.
*
* @param xCopyPosition Can take the value queueSEND_TO_BACK to place the
* item at the back of the queue, or queueSEND_TO_FRONT to place the item
* at the front of the queue (for high priority messages).
*
* @return pdTRUE if the data was successfully sent to the queue, otherwise
* errQUEUE_FULL.
*
* Example usage for buffered IO (where the ISR can obtain more than one value
* per call):
<pre>
程序里面带的例子
void vBufferISR( void )
{
char cIn;
portBASE_TYPE xHigherPriorityTaskWokenByPost;
// We have not woken a task at the start of the ISR.
xHigherPriorityTaskWokenByPost = pdFALSE;
// Loop until the buffer is empty.
do
{
// Obtain a byte from the buffer.
cIn = portINPUT_BYTE( RX_REGISTER_ADDRESS );
// Post each byte.
xQueueGenericSendFromISR( xRxQueue, &cIn, &xHigherPriorityTaskWokenByPost, queueSEND_TO_BACK );
} while( portINPUT_BYTE( BUFFER_COUNT ) );
// Now the buffer is empty we can switch context if necessary. Note that the
// name of the yield function required is port specific.
if( xHigherPriorityTaskWokenByPost )
{
taskYIELD_YIELD_FROM_ISR();
}
}
signed portBASE_TYPE xQueueGenericSendFromISR( xQueueHandle xQueue,
const void * const pvItemToQueue,
signed portBASE_TYPE *pxHigherPriorityTaskWoken,
portBASE_TYPE xCopyPosition )
{
signed portBASE_TYPE xReturn;
unsigned portBASE_TYPE uxSavedInterruptStatus;
xQUEUE *pxQueue;
pxQueue = ( xQUEUE * ) xQueue;
configASSERT( pxQueue );
configASSERT( !( ( pvItemToQueue == NULL ) && ( pxQueue->uxItemSize != ( unsigned portBASE_TYPE ) 0U ) ) );
/* 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). */
//和xQueueGenericSend类似，只是没有可用的队列空间的时候，不会阻塞
uxSavedInterruptStatus = portSET_INTERRUPT_MASK_FROM_ISR();
{
if( pxQueue->uxMessagesWaiting < pxQueue->uxLength )
{
traceQUEUE_SEND_FROM_ISR( pxQueue );
//将数据复制到相应的队列里面
prvCopyDataToQueue( pxQueue, pvItemToQueue, xCopyPosition );
//如果xTxLock被锁了，那么队列解锁以后再执行
/* 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 ( configUSE_QUEUE_SETS == 1 )
{
if( pxQueue->pxQueueSetContainer != NULL )
{
if( prvNotifyQueueSetContainer( pxQueue, xCopyPosition ) == pdTRUE )
{
/* The queue is a member of a queue set, and posting
to the queue set caused a higher priority task to
unblock. A context switch is required. */
if( pxHigherPriorityTaskWoken != NULL )
{
*pxHigherPriorityTaskWoken = pdTRUE;
}
}
}
else
{
if( listLIST_IS_EMPTY( &( pxQueue->xTasksWaitingToReceive ) ) == pdFALSE )
{
if( xTaskRemoveFromEventList( &( pxQueue->xTasksWaitingToReceive ) ) != pdFALSE )
{
/* The task waiting has a higher priority so record that a
context switch is required. */
if( pxHigherPriorityTaskWoken != NULL )
{
*pxHigherPriorityTaskWoken = pdTRUE;
}
}
}
}
}
#else /* configUSE_QUEUE_SETS */
{
if( listLIST_IS_EMPTY( &( pxQueue->xTasksWaitingToReceive ) ) == pdFALSE )
{
if( xTaskRemoveFromEventList( &( pxQueue->xTasksWaitingToReceive ) ) != pdFALSE )
{
/* The task waiting has a higher priority so record that a
context switch is required. */
if( pxHigherPriorityTaskWoken != NULL )
{
*pxHigherPriorityTaskWoken = pdTRUE;
}
}
}
}
#endif /* configUSE_QUEUE_SETS */
}
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;
}
//队列已经满了
else
{
traceQUEUE_SEND_FROM_ISR_FAILED( pxQueue );
xReturn = errQUEUE_FULL;
}
}
portCLEAR_INTERRUPT_MASK_FROM_ISR( uxSavedInterruptStatus );
return xReturn;
} |
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发表于 2013-6-18 14:43:31
发表于 2014-4-5 08:25:52
