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/*

 *  Thread Handler

 *

 *

 *  COPYRIGHT (c) 1989-1999.

 *  On-Line Applications Research Corporation (OAR).

 *

 *  The license and distribution terms for this file may be

 *  found in found in the file LICENSE in this distribution or at

 *  http://www.OARcorp.com/rtems/license.html.

 *

 *  threadtickletimeslice.c,v 1.2 1999/11/17 17:50:42 joel Exp

 */

#include <rtems/system.h>

#include <rtems/score/apiext.h>

#include <rtems/score/context.h>

#include <rtems/score/interr.h>

#include <rtems/score/isr.h>

#include <rtems/score/object.h>

#include <rtems/score/priority.h>

#include <rtems/score/states.h>

#include <rtems/score/sysstate.h>

#include <rtems/score/thread.h>

#include <rtems/score/threadq.h>

#include <rtems/score/userext.h>

#include <rtems/score/wkspace.h>

/*PAGE

 *

 *  _Thread_Tickle_timeslice

 *

 *  This scheduler routine determines if timeslicing is enabled

 *  for the currently executing thread and, if so, updates the

 *  timeslice count and checks for timeslice expiration.

 *

 *  Input parameters:   NONE

 *

 *  Output parameters:  NONE

 */

void _Thread_Tickle_timeslice( void )

{

  Thread_Control *executing;

  executing = _Thread_Executing;

  /*

   *  Increment the number of ticks this thread has been executing

   */

  executing->ticks_executed++;

  /*

   *  If the thread is not preemptible or is not ready, then

   *  just return.

   */

  if ( !executing->is_preemptible )

    return;

  if ( !_States_Is_ready( executing->current_state ) )

    return;

  /*

   *  The cpu budget algorithm determines what happens next.

   */

  switch ( executing->budget_algorithm ) {

    case THREAD_CPU_BUDGET_ALGORITHM_NONE:

      break;

    case THREAD_CPU_BUDGET_ALGORITHM_RESET_TIMESLICE:

    case THREAD_CPU_BUDGET_ALGORITHM_EXHAUST_TIMESLICE:

      if ( --executing->cpu_time_budget == 0 ) {

        _Thread_Reset_timeslice();

        executing->cpu_time_budget = _Thread_Ticks_per_timeslice;

      }

      break;

    case THREAD_CPU_BUDGET_ALGORITHM_CALLOUT:

      if ( --executing->cpu_time_budget == 0 )

        (*executing->budget_callout)( executing );

      break;

  }

}