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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.
*
* $Id$
*/
#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_Change_priority
*
* This kernel routine changes the priority of the thread. The
* thread chain is adjusted if necessary.
*
* Input parameters:
* the_thread - pointer to thread control block
* new_priority - ultimate priority
* prepend_it - TRUE if the thread should be prepended to the chain
*
* Output parameters: NONE
*
* INTERRUPT LATENCY:
* ready chain
* select heir
*/
void _Thread_Change_priority(
Thread_Control *the_thread,
Priority_Control new_priority,
boolean prepend_it
)
{
ISR_Level level;
/* boolean do_prepend = FALSE; */
/*
* If this is a case where prepending the task to its priority is
* potentially desired, then we need to consider whether to do it.
* This usually occurs when a task lowers its priority implcitly as
* the result of losing inherited priority. Normal explicit priority
* change calls (e.g. rtems_task_set_priority) should always do an
* append not a prepend.
*/
/*
* Techically, the prepend should conditional on the thread lowering
* its priority but that does allow cxd2004 of the acvc 2.0.1 to
* pass with rtems 4.0.0. This should change when gnat redoes its
* priority scheme.
*/
/*
if ( prepend_it &&
_Thread_Is_executing( the_thread ) &&
new_priority >= the_thread->current_priority )
prepend_it = TRUE;
*/
_Thread_Set_transient( the_thread );
if ( the_thread->current_priority != new_priority )
_Thread_Set_priority( the_thread, new_priority );
_ISR_Disable( level );
the_thread->current_state =
_States_Clear( STATES_TRANSIENT, the_thread->current_state );
if ( ! _States_Is_ready( the_thread->current_state ) ) {
/*
* XXX If a task is to be reordered while blocked on a priority
* XXX priority ordered thread queue, then this is where that
* XXX should occur.
*/
_ISR_Enable( level );
return;
}
_Priority_Add_to_bit_map( &the_thread->Priority_map );
if ( prepend_it )
_Chain_Prepend_unprotected( the_thread->ready, &the_thread->Object.Node );
else
_Chain_Append_unprotected( the_thread->ready, &the_thread->Object.Node );
_ISR_Flash( level );
_Thread_Calculate_heir();
if ( !_Thread_Is_executing_also_the_heir() &&
_Thread_Executing->is_preemptible )
_Context_Switch_necessary = TRUE;
_ISR_Enable( level );
}
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