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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: threadqenqueuepriority.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_Enqueue_priority

 *

 *  This routine blocks a thread, places it on a thread, and optionally

 *  starts a timeout timer.

 *

 *  Input parameters:

 *    the_thread_queue - pointer to threadq

 *    thread           - thread to insert

 *    timeout          - timeout interval in ticks

 *

 *  Output parameters: NONE

 *

 *  INTERRUPT LATENCY:

 *    forward less than

 *    forward equal

 */

void _Thread_queue_Enqueue_priority(

  Thread_queue_Control *the_thread_queue,

  Thread_Control       *the_thread,

  Watchdog_Interval     timeout

)

{

  Priority_Control     search_priority;

  Thread_Control      *search_thread;

  ISR_Level            level;

  Chain_Control       *header;

  unsigned32           header_index;

  Chain_Node          *the_node;

  Chain_Node          *next_node;

  Chain_Node          *previous_node;

  Chain_Node          *search_node;

  Priority_Control     priority;

  States_Control       block_state;

  Thread_queue_States  sync_state;

  _Chain_Initialize_empty( &the_thread->Wait.Block2n );

  priority     = the_thread->current_priority;

  header_index = _Thread_queue_Header_number( priority );

  header       = &the_thread_queue->Queues.Priority[ header_index ];

  block_state  = the_thread_queue->state;

  if ( _Thread_queue_Is_reverse_search( priority ) )

    goto restart_reverse_search;

restart_forward_search:

  search_priority = PRIORITY_MINIMUM - 1;

  _ISR_Disable( level );

  search_thread = (Thread_Control *) header->first;

  while ( !_Chain_Is_tail( header, (Chain_Node *)search_thread ) ) {

    search_priority = search_thread->current_priority;

    if ( priority <= search_priority )

      break;

#if ( CPU_UNROLL_ENQUEUE_PRIORITY == TRUE )

    search_thread = (Thread_Control *) search_thread->Object.Node.next;

    if ( _Chain_Is_tail( header, (Chain_Node *)search_thread ) )

      break;

    search_priority = search_thread->current_priority;

    if ( priority <= search_priority )

      break;

#endif

    _ISR_Flash( level );

    if ( !_States_Are_set( search_thread->current_state, block_state) ) {

      _ISR_Enable( level );

      goto restart_forward_search;

    }

    search_thread =

       (Thread_Control *)search_thread->Object.Node.next;

  }

  if ( the_thread_queue->sync_state != THREAD_QUEUE_NOTHING_HAPPENED )

    goto synchronize;

  the_thread_queue->sync_state = THREAD_QUEUE_SYNCHRONIZED;

  if ( priority == search_priority )

    goto equal_priority;

  search_node   = (Chain_Node *) search_thread;

  previous_node = search_node->previous;

  the_node      = (Chain_Node *) the_thread;

  the_node->next        = search_node;

  the_node->previous    = previous_node;

  previous_node->next   = the_node;

  search_node->previous = the_node;

  _ISR_Enable( level );

  return;

restart_reverse_search:

  search_priority     = PRIORITY_MAXIMUM + 1;

  _ISR_Disable( level );

  search_thread = (Thread_Control *) header->last;

  while ( !_Chain_Is_head( header, (Chain_Node *)search_thread ) ) {

    search_priority = search_thread->current_priority;

    if ( priority >= search_priority )

      break;

#if ( CPU_UNROLL_ENQUEUE_PRIORITY == TRUE )

    search_thread = (Thread_Control *) search_thread->Object.Node.previous;

    if ( _Chain_Is_head( header, (Chain_Node *)search_thread ) )

      break;

    search_priority = search_thread->current_priority;

    if ( priority >= search_priority )

      break;

#endif

    _ISR_Flash( level );

    if ( !_States_Are_set( search_thread->current_state, block_state) ) {

      _ISR_Enable( level );

      goto restart_reverse_search;

    }

    search_thread = (Thread_Control *)

                         search_thread->Object.Node.previous;

  }

  if ( the_thread_queue->sync_state != THREAD_QUEUE_NOTHING_HAPPENED )

    goto synchronize;

  the_thread_queue->sync_state = THREAD_QUEUE_SYNCHRONIZED;

  if ( priority == search_priority )

    goto equal_priority;

  search_node = (Chain_Node *) search_thread;

  next_node   = search_node->next;

  the_node    = (Chain_Node *) the_thread;

  the_node->next      = next_node;

  the_node->previous  = search_node;

  search_node->next   = the_node;

  next_node->previous = the_node;

  _ISR_Enable( level );

  return;

equal_priority:               /* add at end of priority group */

  search_node   = _Chain_Tail( &search_thread->Wait.Block2n );

  previous_node = search_node->previous;

  the_node      = (Chain_Node *) the_thread;

  the_node->next        = search_node;

  the_node->previous    = previous_node;

  previous_node->next   = the_node;

  search_node->previous = the_node;

  _ISR_Enable( level );

  return;

synchronize:

  sync_state = the_thread_queue->sync_state;

  the_thread_queue->sync_state = THREAD_QUEUE_SYNCHRONIZED;

  switch ( sync_state ) {

    case THREAD_QUEUE_SYNCHRONIZED:

      /*

       *  This should never happen.  It indicates that someone did not

       *  enter a thread queue critical section.

       */

      break;

    case THREAD_QUEUE_NOTHING_HAPPENED:

      /*

       *  This should never happen.  All of this was dealt with above.

       */

      break;

    case THREAD_QUEUE_TIMEOUT:

      the_thread->Wait.return_code = the_thread->Wait.queue->timeout_status;

      _ISR_Enable( level );

      break;

    case THREAD_QUEUE_SATISFIED:

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

        _Watchdog_Deactivate( &the_thread->Timer );

        _ISR_Enable( level );

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

      } else

        _ISR_Enable( level );

      break;

  }

  /*

   *  Global objects with thread queue's should not be operated on from an

   *  ISR.  But the sync code still must allow short timeouts to be processed

   *  correctly.

   */

  _Thread_Unblock( the_thread );

#if defined(RTEMS_MULTIPROCESSING)

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

    _Thread_MP_Free_proxy( the_thread );

#endif

}