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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_Yield_processor
*
* This kernel routine will remove the running THREAD from the ready chain
* and place it immediatly at the rear of this chain. Reset timeslice
* and yield the processor functions both use this routine, therefore if
* reset is TRUE and this is the only thread on the chain then the
* timeslice counter is reset. The heir THREAD will be updated if the
* running is also the currently the heir.
*
* Input parameters: NONE
*
* Output parameters: NONE
*
* INTERRUPT LATENCY:
* ready chain
* select heir
*/
void _Thread_Yield_processor( void )
{
ISR_Level level;
Thread_Control *executing;
Chain_Control *ready;
executing = _Thread_Executing;
ready = executing->ready;
_ISR_Disable( level );
if ( !_Chain_Has_only_one_node( ready ) ) {
_Chain_Extract_unprotected( &executing->Object.Node );
_Chain_Append_unprotected( ready, &executing->Object.Node );
_ISR_Flash( level );
if ( _Thread_Is_heir( executing ) )
_Thread_Heir = (Thread_Control *) ready->first;
_Context_Switch_necessary = TRUE;
}
else if ( !_Thread_Is_heir( executing ) )
_Context_Switch_necessary = TRUE;
_ISR_Enable( level );
}
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