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/*
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* Thread Handler
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*
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*
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* COPYRIGHT (c) 1989-1999.
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* On-Line Applications Research Corporation (OAR).
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*
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* The license and distribution terms for this file may be
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* found in found in the file LICENSE in this distribution or at
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* http://www.OARcorp.com/rtems/license.html.
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*
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* $Id: threadchangepriority.c,v 1.2 2001-09-27 11:59:34 chris Exp $
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*/
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#include <rtems/system.h>
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#include <rtems/score/apiext.h>
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#include <rtems/score/context.h>
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#include <rtems/score/interr.h>
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#include <rtems/score/isr.h>
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#include <rtems/score/object.h>
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#include <rtems/score/priority.h>
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#include <rtems/score/states.h>
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#include <rtems/score/sysstate.h>
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#include <rtems/score/thread.h>
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#include <rtems/score/threadq.h>
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#include <rtems/score/userext.h>
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#include <rtems/score/wkspace.h>
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/*PAGE
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*
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* _Thread_Change_priority
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*
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* This kernel routine changes the priority of the thread. The
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* thread chain is adjusted if necessary.
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*
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* Input parameters:
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* the_thread - pointer to thread control block
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* new_priority - ultimate priority
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* prepend_it - TRUE if the thread should be prepended to the chain
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*
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* Output parameters: NONE
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*
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* INTERRUPT LATENCY:
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* ready chain
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* select heir
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*/
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void _Thread_Change_priority(
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Thread_Control *the_thread,
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Priority_Control new_priority,
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boolean prepend_it
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)
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{
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ISR_Level level;
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/* boolean do_prepend = FALSE; */
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/*
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* If this is a case where prepending the task to its priority is
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* potentially desired, then we need to consider whether to do it.
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* This usually occurs when a task lowers its priority implcitly as
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* the result of losing inherited priority. Normal explicit priority
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* change calls (e.g. rtems_task_set_priority) should always do an
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* append not a prepend.
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*/
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/*
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* Techically, the prepend should conditional on the thread lowering
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* its priority but that does allow cxd2004 of the acvc 2.0.1 to
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* pass with rtems 4.0.0. This should change when gnat redoes its
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* priority scheme.
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*/
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/*
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if ( prepend_it &&
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_Thread_Is_executing( the_thread ) &&
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new_priority >= the_thread->current_priority )
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prepend_it = TRUE;
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*/
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_Thread_Set_transient( the_thread );
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if ( the_thread->current_priority != new_priority )
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_Thread_Set_priority( the_thread, new_priority );
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_ISR_Disable( level );
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the_thread->current_state =
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_States_Clear( STATES_TRANSIENT, the_thread->current_state );
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if ( ! _States_Is_ready( the_thread->current_state ) ) {
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/*
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* XXX If a task is to be reordered while blocked on a priority
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* XXX priority ordered thread queue, then this is where that
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* XXX should occur.
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*/
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_ISR_Enable( level );
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return;
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}
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_Priority_Add_to_bit_map( &the_thread->Priority_map );
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if ( prepend_it )
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_Chain_Prepend_unprotected( the_thread->ready, &the_thread->Object.Node );
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else
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_Chain_Append_unprotected( the_thread->ready, &the_thread->Object.Node );
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_ISR_Flash( level );
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_Thread_Calculate_heir();
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if ( !_Thread_Is_executing_also_the_heir() &&
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_Thread_Executing->is_preemptible )
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_Context_Switch_necessary = TRUE;
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_ISR_Enable( level );
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}
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