/**
 * @file
 *
 * @brief Thread Queue Dequeue
 *
 * @ingroup ScoreThreadQ
 */

/*
 *  COPYRIGHT (c) 1989-2008.
 *  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/threadqimpl.h>
#include <rtems/score/isrlevel.h>

Thread_Control *_Thread_queue_Dequeue(
  Thread_queue_Control *the_thread_queue
)
{
  Thread_Control *(*dequeue_p)( Thread_queue_Control * );
  Thread_Control *the_thread;
  ISR_Level       level;
  Thread_blocking_operation_States  sync_state;

  if ( the_thread_queue->discipline == THREAD_QUEUE_DISCIPLINE_PRIORITY )
    dequeue_p = _Thread_queue_Dequeue_priority;
  else /* must be THREAD_QUEUE_DISCIPLINE_FIFO */
    dequeue_p = _Thread_queue_Dequeue_fifo;

  the_thread = (*dequeue_p)( the_thread_queue );
  _ISR_Disable( level );
    if ( !the_thread ) {
      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;
      }
    }
  _ISR_Enable( level );
  return the_thread;
}