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/**
* @file
*
* @brief Thread Queue Dequeue
*
* @ingroup ScoreThreadQ
*/
/*
* COPYRIGHT (c) 1989-2014.
* On-Line Applications Research Corporation (OAR).
*
* The license and distribution terms for this file may be
* found in the file LICENSE in this distribution or at
* http://www.rtems.org/license/LICENSE.
*/
#if HAVE_CONFIG_H
#include "config.h"
#endif
#include <rtems/score/chainimpl.h>
#include <rtems/score/threadimpl.h>
#include <rtems/score/threadqimpl.h>
#include <rtems/score/isrlevel.h>
#include <rtems/score/rbtreeimpl.h>
#include <rtems/score/watchdogimpl.h>
Thread_Control *_Thread_queue_Dequeue(
Thread_queue_Control *the_thread_queue
)
{
Thread_Control *the_thread;
ISR_Level level;
Thread_blocking_operation_States sync_state;
the_thread = NULL;
_ISR_Disable( level );
/*
* Invoke the discipline specific dequeue method.
*/
if ( the_thread_queue->discipline == THREAD_QUEUE_DISCIPLINE_FIFO ) {
if ( !_Chain_Is_empty( &the_thread_queue->Queues.Fifo ) ) {
the_thread = (Thread_Control *)
_Chain_Get_first_unprotected( &the_thread_queue->Queues.Fifo );
}
} else { /* must be THREAD_QUEUE_DISCIPLINE_PRIORITY */
RBTree_Node *first;
first = _RBTree_Get( &the_thread_queue->Queues.Priority, RBT_LEFT );
if ( first ) {
the_thread = THREAD_RBTREE_NODE_TO_THREAD( first );
}
}
if ( the_thread == NULL ) {
/*
* We did not find a thread to unblock in the queue. Maybe the executing
* thread is about to block on this thread queue.
*/
sync_state = the_thread_queue->sync_state;
if ( (sync_state == THREAD_BLOCKING_OPERATION_TIMEOUT) ||
(sync_state == THREAD_BLOCKING_OPERATION_NOTHING_HAPPENED) ) {
the_thread_queue->sync_state = THREAD_BLOCKING_OPERATION_SATISFIED;
the_thread = _Thread_Executing;
} else {
_ISR_Enable( level );
return NULL;
}
}
/*
* We found a thread to unblock.
*
* NOTE: This is invoked with interrupts still disabled.
*/
_Thread_blocking_operation_Finalize( the_thread, level );
return the_thread;
}
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