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/*
 *  Multiprocessing Support for the Thread 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: threadmp.c,v 1.2 2001-09-27 11:59:34 chris Exp $
 */
 
#include <rtems/system.h>
#include <rtems/score/priority.h>
#include <rtems/score/thread.h>
#include <rtems/score/wkspace.h>
#include <rtems/score/isr.h>
 
/*PAGE
 *
 *  _Thread_MP_Handler_initialization
 *
 */
 
void _Thread_MP_Handler_initialization (
  unsigned32  maximum_proxies
)
{
 
  _Chain_Initialize_empty( &_Thread_MP_Active_proxies );
 
  if ( maximum_proxies == 0 ) {
    _Chain_Initialize_empty( &_Thread_MP_Inactive_proxies );
    return;
  }
 
 
  _Chain_Initialize(
    &_Thread_MP_Inactive_proxies,
    _Workspace_Allocate_or_fatal_error(
      maximum_proxies * sizeof( Thread_Proxy_control )
    ),
    maximum_proxies,
    sizeof( Thread_Proxy_control )
  );
 
}
 
/*PAGE
 *
 *  _Thread_MP_Allocate_proxy
 *
 */
 
Thread_Control *_Thread_MP_Allocate_proxy (
  States_Control  the_state
)
{
  Thread_Control       *the_thread;
  Thread_Proxy_control *the_proxy;
 
  the_thread = (Thread_Control *)_Chain_Get( &_Thread_MP_Inactive_proxies );
 
  if ( !_Thread_Is_null( the_thread ) ) {
 
    the_proxy = (Thread_Proxy_control *) the_thread;
 
    _Thread_Executing->Wait.return_code = THREAD_STATUS_PROXY_BLOCKING;
 
    the_proxy->receive_packet = _Thread_MP_Receive->receive_packet;
 
    the_proxy->Object.id = _Thread_MP_Receive->receive_packet->source_tid;
 
    the_proxy->current_priority =
      _Thread_MP_Receive->receive_packet->source_priority;
 
    the_proxy->current_state = _States_Set( STATES_DORMANT, the_state );
 
    the_proxy->Wait = _Thread_Executing->Wait;
 
    _Chain_Append( &_Thread_MP_Active_proxies, &the_proxy->Active );
 
    return the_thread;
  }
 
  _Internal_error_Occurred(
    INTERNAL_ERROR_CORE,
    TRUE,
    INTERNAL_ERROR_OUT_OF_PROXIES
  );
 
  /*
   *  NOTE: The following return insures that the compiler will
   *        think that all paths return a value.
   */
 
  return NULL;
}
 
/*PAGE
 *
 *  _Thread_MP_Find_proxy
 *
 */
 
/*
 *  The following macro provides the offset of the Active element
 *  in the Thread_Proxy_control structure.  This is the logical
 *  equivalent of the POSITION attribute in Ada.
 */
 
#define _Thread_MP_Proxy_Active_offset \
     ((unsigned32)&(((Thread_Proxy_control *)0))->Active)
 
Thread_Control *_Thread_MP_Find_proxy (
  Objects_Id  the_id
)
{
 
  Chain_Node           *proxy_node;
  Thread_Control       *the_thread;
  ISR_Level             level;
 
restart:
 
  _ISR_Disable( level );
 
    for (  proxy_node = _Thread_MP_Active_proxies.first;
           !_Chain_Is_tail( &_Thread_MP_Active_proxies, proxy_node ) ;
        ) {
 
      the_thread = (Thread_Control *) _Addresses_Subtract_offset(
                     proxy_node,
                     _Thread_MP_Proxy_Active_offset
                   );
 
      if ( _Objects_Are_ids_equal( the_thread->Object.id, the_id ) ) {
        _ISR_Enable( level );
        return the_thread;
      }
 
      _ISR_Flash( level );
 
      proxy_node = proxy_node->next;
 
      /*
       *  A proxy which is only dormant is not in a blocking state.
       *  Therefore, we are looking at proxy which has been moved from
       *  active to inactive chain (by an ISR) and need to restart
       *  the search.
       */
 
      if ( _States_Is_only_dormant( the_thread->current_state ) ) {
        _ISR_Enable( level );
        goto restart;
      }
    }
 
  _ISR_Enable( level );
  return NULL;
}