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[/] [or1k/] [trunk/] [rtems/] [c/] [src/] [exec/] [score/] [src/] [threadyieldprocessor.c] - Rev 1765
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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: threadyieldprocessor.c,v 1.2 2001-09-27 11:59:34 chris Exp $ */ #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 ); }