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[/] [openrisc/] [trunk/] [rtos/] [rtems/] [c/] [src/] [exec/] [score/] [src/] [threaddispatch.c] - Rev 30
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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: threaddispatch.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_Dispatch * * This kernel routine determines if a dispatch is needed, and if so * dispatches to the heir thread. Once the heir is running an attempt * is made to dispatch any ASRs. * * ALTERNATE ENTRY POINTS: * void _Thread_Enable_dispatch(); * * Input parameters: NONE * * Output parameters: NONE * * INTERRUPT LATENCY: * dispatch thread * no dispatch thread */ #if ( CPU_INLINE_ENABLE_DISPATCH == FALSE ) void _Thread_Enable_dispatch( void ) { if ( --_Thread_Dispatch_disable_level ) return; _Thread_Dispatch(); } #endif void _Thread_Dispatch( void ) { Thread_Control *executing; Thread_Control *heir; ISR_Level level; executing = _Thread_Executing; _ISR_Disable( level ); while ( _Context_Switch_necessary == TRUE ) { heir = _Thread_Heir; _Thread_Dispatch_disable_level = 1; _Context_Switch_necessary = FALSE; _Thread_Executing = heir; executing->rtems_ada_self = rtems_ada_self; rtems_ada_self = heir->rtems_ada_self; _ISR_Enable( level ); heir->ticks_executed++; _User_extensions_Thread_switch( executing, heir ); if ( heir->budget_algorithm == THREAD_CPU_BUDGET_ALGORITHM_RESET_TIMESLICE ) heir->cpu_time_budget = _Thread_Ticks_per_timeslice; /* * If the CPU has hardware floating point, then we must address saving * and restoring it as part of the context switch. * * The second conditional compilation section selects the algorithm used * to context switch between floating point tasks. The deferred algorithm * can be significantly better in a system with few floating point tasks * because it reduces the total number of save and restore FP context * operations. However, this algorithm can not be used on all CPUs due * to unpredictable use of FP registers by some compilers for integer * operations. */ #if ( CPU_HARDWARE_FP == TRUE ) #if ( CPU_USE_DEFERRED_FP_SWITCH == TRUE ) if ( (heir->fp_context != NULL) && !_Thread_Is_allocated_fp( heir ) ) { if ( _Thread_Allocated_fp != NULL ) _Context_Save_fp( &_Thread_Allocated_fp->fp_context ); _Context_Restore_fp( &heir->fp_context ); _Thread_Allocated_fp = heir; } #else if ( executing->fp_context != NULL ) _Context_Save_fp( &executing->fp_context ); if ( heir->fp_context != NULL ) _Context_Restore_fp( &heir->fp_context ); #endif #endif _Context_Switch( &executing->Registers, &heir->Registers ); executing = _Thread_Executing; _ISR_Disable( level ); } _Thread_Dispatch_disable_level = 0; _ISR_Enable( level ); if ( _Thread_Do_post_task_switch_extension || executing->do_post_task_switch_extension ) { executing->do_post_task_switch_extension = FALSE; _API_extensions_Run_postswitch(); } }
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