tasksetpriority.c

RTEMS (Real-Time Executive for Multiprocessor Systems) is a free open source real-time operating sys

/*
 *  RTEMS Task Manager
 *
 *
 *  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.rtems.com/license/LICENSE.
 *
 *  $Id: tasksetpriority.c,v 1.4.6.1 2003/09/04 18:47:18 joel Exp $
 */

#include <rtems/system.h>
#include <rtems/rtems/status.h>
#include <rtems/rtems/support.h>
#include <rtems/rtems/modes.h>
#include <rtems/score/object.h>
#include <rtems/score/stack.h>
#include <rtems/score/states.h>
#include <rtems/rtems/tasks.h>
#include <rtems/score/thread.h>
#include <rtems/score/threadq.h>
#include <rtems/score/tod.h>
#include <rtems/score/userext.h>
#include <rtems/score/wkspace.h>
#include <rtems/score/apiext.h>
#include <rtems/score/sysstate.h>

/*PAGE
 *
 *  rtems_task_set_priority
 *
 *  This directive changes the priority of the specified thread.
 *  The specified thread can be any thread in the system including
 *  the requesting thread.
 *
 *  Input parameters:
 *    id           - thread id (0 indicates requesting thread)
 *    new_priority - thread priority (0 indicates current priority)
 *    old_priority - pointer to previous priority
 *
 *  Output parameters:
 *    old_priority      - previous priority
 *    RTEMS_SUCCESSFUL - if successful
 *    error code        - if unsuccessful
 */

rtems_status_code rtems_task_set_priority(
  Objects_Id           id,
  rtems_task_priority  new_priority,
  rtems_task_priority *old_priority
)
{
  register Thread_Control *the_thread;
  Objects_Locations               location;

  if ( new_priority != RTEMS_CURRENT_PRIORITY &&
       !_RTEMS_tasks_Priority_is_valid( new_priority ) )
    return RTEMS_INVALID_PRIORITY;

  if ( !old_priority )
    return RTEMS_INVALID_ADDRESS;

  the_thread = _Thread_Get( id, &location );
  switch ( location ) {

    case OBJECTS_REMOTE:
#if defined(RTEMS_MULTIPROCESSING)
      _Thread_Executing->Wait.return_argument = old_priority;
      return _RTEMS_tasks_MP_Send_request_packet(
          RTEMS_TASKS_MP_SET_PRIORITY_REQUEST,
          id,
          new_priority,
          0,          /* Not used */
          0           /* Not used */
      );
#endif

    case OBJECTS_ERROR:
      return RTEMS_INVALID_ID;

    case OBJECTS_LOCAL:
      /* XXX convert from core priority */
      *old_priority = the_thread->current_priority;
      if ( new_priority != RTEMS_CURRENT_PRIORITY ) {
        the_thread->real_priority = new_priority;
        if ( the_thread->resource_count == 0 ||
             the_thread->current_priority > new_priority )
          _Thread_Change_priority( the_thread, new_priority, FALSE );
      }
      _Thread_Enable_dispatch();
      return RTEMS_SUCCESSFUL;
  }

  return RTEMS_INTERNAL_ERROR;   /* unreached - only to remove warnings */
}