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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.rtems.com/license/LICENSE.
*
* $Id$
*/
#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;
}
}
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