in queue.c [1212:1375]
BaseType_t xQueueGiveFromISR( QueueHandle_t xQueue,
BaseType_t * const pxHigherPriorityTaskWoken )
{
BaseType_t xReturn;
UBaseType_t uxSavedInterruptStatus;
Queue_t * const pxQueue = xQueue;
/* Similar to xQueueGenericSendFromISR() but used with semaphores where the
* item size is 0. Don't directly wake a task that was blocked on a queue
* read, instead 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). */
configASSERT( pxQueue );
/* xQueueGenericSendFromISR() should be used instead of xQueueGiveFromISR()
* if the item size is not 0. */
configASSERT( pxQueue->uxItemSize == 0 );
/* Normally a mutex would not be given from an interrupt, especially if
* there is a mutex holder, as priority inheritance makes no sense for an
* interrupts, only tasks. */
configASSERT( !( ( pxQueue->uxQueueType == queueQUEUE_IS_MUTEX ) && ( pxQueue->u.xSemaphore.xMutexHolder != NULL ) ) );
/* RTOS ports that support interrupt nesting have the concept of a maximum
* system call (or maximum API call) interrupt priority. Interrupts that are
* above the maximum system call priority are kept permanently enabled, even
* when the RTOS kernel is in a critical section, but cannot make any calls to
* FreeRTOS API functions. If configASSERT() is defined in FreeRTOSConfig.h
* then portASSERT_IF_INTERRUPT_PRIORITY_INVALID() will result in an assertion
* failure if a FreeRTOS API function is called from an interrupt that has been
* assigned a priority above the configured maximum system call priority.
* Only FreeRTOS functions that end in FromISR can be called from interrupts
* that have been assigned a priority at or (logically) below the maximum
* system call interrupt priority. FreeRTOS maintains a separate interrupt
* safe API to ensure interrupt entry is as fast and as simple as possible.
* More information (albeit Cortex-M specific) is provided on the following
* link: https://www.FreeRTOS.org/RTOS-Cortex-M3-M4.html */
portASSERT_IF_INTERRUPT_PRIORITY_INVALID();
uxSavedInterruptStatus = portSET_INTERRUPT_MASK_FROM_ISR();
{
const UBaseType_t uxMessagesWaiting = pxQueue->uxMessagesWaiting;
/* When the queue is used to implement a semaphore no data is ever
* moved through the queue but it is still valid to see if the queue 'has
* space'. */
if( uxMessagesWaiting < pxQueue->uxLength )
{
const int8_t cTxLock = pxQueue->cTxLock;
traceQUEUE_SEND_FROM_ISR( pxQueue );
/* A task can only have an inherited priority if it is a mutex
* holder - and if there is a mutex holder then the mutex cannot be
* given from an ISR. As this is the ISR version of the function it
* can be assumed there is no mutex holder and no need to determine if
* priority disinheritance is needed. Simply increase the count of
* messages (semaphores) available. */
pxQueue->uxMessagesWaiting = uxMessagesWaiting + ( UBaseType_t ) 1;
/* The event list is not altered if the queue is locked. This will
* be done when the queue is unlocked later. */
if( cTxLock == queueUNLOCKED )
{
#if ( configUSE_QUEUE_SETS == 1 )
{
if( pxQueue->pxQueueSetContainer != NULL )
{
if( prvNotifyQueueSetContainer( pxQueue ) != pdFALSE )
{
/* The semaphore 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
{
mtCOVERAGE_TEST_MARKER();
}
}
else
{
mtCOVERAGE_TEST_MARKER();
}
}
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
{
mtCOVERAGE_TEST_MARKER();
}
}
else
{
mtCOVERAGE_TEST_MARKER();
}
}
else
{
mtCOVERAGE_TEST_MARKER();
}
}
}
#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;
}
else
{
mtCOVERAGE_TEST_MARKER();
}
}
else
{
mtCOVERAGE_TEST_MARKER();
}
}
else
{
mtCOVERAGE_TEST_MARKER();
}
}
#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. */
prvIncrementQueueTxLock( pxQueue, cTxLock );
}
xReturn = pdPASS;
}
else
{
traceQUEUE_SEND_FROM_ISR_FAILED( pxQueue );
xReturn = errQUEUE_FULL;
}
}
portCLEAR_INTERRUPT_MASK_FROM_ISR( uxSavedInterruptStatus );
return xReturn;
}