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/**
* @file
*
* @brief Changes the Priority of a Thread
*
* @ingroup ScoreThread
*/
/*
* COPYRIGHT (c) 1989-2011.
* 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.org/license/LICENSE.
*/
#if HAVE_CONFIG_H
#include "config.h"
#endif
#include <rtems/score/threadimpl.h>
#include <rtems/score/schedulerimpl.h>
#include <rtems/score/threadqimpl.h>
void _Thread_Change_priority(
Thread_Control *the_thread,
Priority_Control new_priority,
bool prepend_it
)
{
Scheduler_Control *scheduler = _Scheduler_Get( the_thread );
ISR_Level level;
States_Control state, original_state;
/*
* Save original state
*/
original_state = the_thread->current_state;
/*
* Set a transient state for the thread so it is pulled off the Ready chains.
* This will prevent it from being scheduled no matter what happens in an
* ISR.
*/
_Thread_Set_transient( the_thread );
/*
* Do not bother recomputing all the priority related information if
* we are not REALLY changing priority.
*/
if ( the_thread->current_priority != new_priority )
_Thread_Set_priority( the_thread, new_priority );
_ISR_Disable( level );
/*
* If the thread has more than STATES_TRANSIENT set, then it is blocked,
* If it is blocked on a thread queue, then we need to requeue it.
*/
state = the_thread->current_state;
if ( state != STATES_TRANSIENT ) {
/* Only clear the transient state if it wasn't set already */
if ( ! _States_Is_transient( original_state ) )
the_thread->current_state = _States_Clear( STATES_TRANSIENT, state );
/*
* The thread may have new blocking states added by interrupt service
* routines after the change into the transient state. This will not
* result in a _Scheduler_Block() operation. Make sure we select an heir
* now.
*/
_Scheduler_Schedule( scheduler, the_thread );
_ISR_Enable( level );
if ( _States_Is_waiting_on_thread_queue( state ) ) {
_Thread_queue_Requeue( the_thread->Wait.queue, the_thread );
}
return;
}
/* Only clear the transient state if it wasn't set already */
if ( ! _States_Is_transient( original_state ) ) {
/*
* Interrupts are STILL disabled.
* We now know the thread will be in the READY state when we remove
* the TRANSIENT state. So we have to place it on the appropriate
* Ready Queue with interrupts off.
*/
the_thread->current_state = _States_Clear( STATES_TRANSIENT, state );
if ( prepend_it )
_Scheduler_Enqueue_first( scheduler, the_thread );
else
_Scheduler_Enqueue( scheduler, the_thread );
}
_ISR_Flash( level );
/*
* We altered the set of thread priorities. So let's figure out
* who is the heir and if we need to switch to them.
*/
_Scheduler_Schedule( scheduler, the_thread );
_ISR_Enable( level );
}
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