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/*

 *  Thread Queue Handler

 *

 *

 *  COPYRIGHT (c) 1989-1999.

 *  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.OARcorp.com/rtems/license.html.

 *

 *  $Id: threadqdequeuepriority.c,v 1.2 2001-09-27 11:59:34 chris Exp $

 */

#include <rtems/system.h>

#include <rtems/score/chain.h>

#include <rtems/score/isr.h>

#include <rtems/score/object.h>

#include <rtems/score/states.h>

#include <rtems/score/thread.h>

#include <rtems/score/threadq.h>

#include <rtems/score/tqdata.h>

/*PAGE

 *

 *  _Thread_queue_Dequeue_priority

 *

 *  This routine removes a thread from the specified PRIORITY based

 *  threadq, unblocks it, and cancels its timeout timer.

 *

 *  Input parameters:

 *    the_thread_queue - pointer to thread queue

 *

 *  Output parameters:

 *    returns - thread dequeued or NULL

 *

 *  INTERRUPT LATENCY:

 *    only case

 */

Thread_Control *_Thread_queue_Dequeue_priority(

  Thread_queue_Control *the_thread_queue

)

{

  unsigned32      index;

  ISR_Level       level;

  Thread_Control *the_thread = NULL;  /* just to remove warnings */

  Thread_Control *new_first_thread;

  Chain_Node     *new_first_node;

  Chain_Node     *new_second_node;

  Chain_Node     *last_node;

  Chain_Node     *next_node;

  Chain_Node     *previous_node;

  _ISR_Disable( level );

  for( index=0 ;

       index < TASK_QUEUE_DATA_NUMBER_OF_PRIORITY_HEADERS ;

       index++ ) {

    if ( !_Chain_Is_empty( &the_thread_queue->Queues.Priority[ index ] ) ) {

      the_thread = (Thread_Control *)

                    the_thread_queue->Queues.Priority[ index ].first;

      goto dequeue;

    }

  }

  switch ( the_thread_queue->sync_state ) {

    case THREAD_QUEUE_SYNCHRONIZED:

    case THREAD_QUEUE_SATISFIED:

      _ISR_Enable( level );

      return NULL;

    case THREAD_QUEUE_NOTHING_HAPPENED:

    case THREAD_QUEUE_TIMEOUT:

      the_thread_queue->sync_state = THREAD_QUEUE_SATISFIED;

      _ISR_Enable( level );

      return _Thread_Executing;

  }

dequeue:

  new_first_node   = the_thread->Wait.Block2n.first;

  new_first_thread = (Thread_Control *) new_first_node;

  next_node        = the_thread->Object.Node.next;

  previous_node    = the_thread->Object.Node.previous;

  if ( !_Chain_Is_empty( &the_thread->Wait.Block2n ) ) {

    last_node       = the_thread->Wait.Block2n.last;

    new_second_node = new_first_node->next;

    previous_node->next      = new_first_node;

    next_node->previous      = new_first_node;

    new_first_node->next     = next_node;

    new_first_node->previous = previous_node;

    if ( !_Chain_Has_only_one_node( &the_thread->Wait.Block2n ) ) {

                                                /* > two threads on 2-n */

      new_second_node->previous =

                _Chain_Head( &new_first_thread->Wait.Block2n );

      new_first_thread->Wait.Block2n.first = new_second_node;

      new_first_thread->Wait.Block2n.last  = last_node;

      last_node->next = _Chain_Tail( &new_first_thread->Wait.Block2n );

    }

  } else {

    previous_node->next = next_node;

    next_node->previous = previous_node;

  }

  if ( !_Watchdog_Is_active( &the_thread->Timer ) ) {

    _ISR_Enable( level );

    _Thread_Unblock( the_thread );

  } else {

    _Watchdog_Deactivate( &the_thread->Timer );

    _ISR_Enable( level );

    (void) _Watchdog_Remove( &the_thread->Timer );

    _Thread_Unblock( the_thread );

  }

#if defined(RTEMS_MULTIPROCESSING)

  if ( !_Objects_Is_local_id( the_thread->Object.id ) )

    _Thread_MP_Free_proxy( the_thread );

#endif

  return( the_thread );

}