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/* cpu_asm.c ===> cpu_asm.S or cpu_asm.s
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*
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* This file contains the basic algorithms for all assembly code used
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* in an specific CPU port of RTEMS. These algorithms must be implemented
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* in assembly language
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*
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* NOTE: This is supposed to be a .S or .s file NOT a C file.
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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 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: cpu_asm.c,v 1.2 2001-09-27 11:59:28 chris Exp $
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*/
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/*
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* This is supposed to be an assembly file. This means that system.h
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* and cpu.h should not be included in a "real" cpu_asm file. An
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* implementation in assembly should include "cpu_asm.h>
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*/
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#include <rtems/system.h>
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#include <rtems/score/cpu.h>
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/* #include "cpu_asm.h> */
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/*
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* _CPU_Context_save_fp_context
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*
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* This routine is responsible for saving the FP context
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* at *fp_context_ptr. If the point to load the FP context
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* from is changed then the pointer is modified by this routine.
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*
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* Sometimes a macro implementation of this is in cpu.h which dereferences
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* the ** and a similarly named routine in this file is passed something
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* like a (Context_Control_fp *). The general rule on making this decision
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* is to avoid writing assembly language.
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*
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* NO_CPU Specific Information:
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*
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* XXX document implementation including references if appropriate
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*/
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void _CPU_Context_save_fp(
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void **fp_context_ptr
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)
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{
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}
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/*
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* _CPU_Context_restore_fp_context
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*
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* This routine is responsible for restoring the FP context
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* at *fp_context_ptr. If the point to load the FP context
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* from is changed then the pointer is modified by this routine.
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*
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* Sometimes a macro implementation of this is in cpu.h which dereferences
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* the ** and a similarly named routine in this file is passed something
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* like a (Context_Control_fp *). The general rule on making this decision
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* is to avoid writing assembly language.
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*
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* NO_CPU Specific Information:
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*
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* XXX document implementation including references if appropriate
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*/
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void _CPU_Context_restore_fp(
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void **fp_context_ptr
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)
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{
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}
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/* _CPU_Context_switch
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*
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* This routine performs a normal non-FP context switch.
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*
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* NO_CPU Specific Information:
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*
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* XXX document implementation including references if appropriate
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*/
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void _CPU_Context_switch(
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Context_Control *run,
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Context_Control *heir
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)
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{
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}
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/*
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* _CPU_Context_restore
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*
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* This routine is generally used only to restart self in an
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* efficient manner. It may simply be a label in _CPU_Context_switch.
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*
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* NOTE: May be unnecessary to reload some registers.
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*
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* NO_CPU Specific Information:
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*
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* XXX document implementation including references if appropriate
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*/
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void _CPU_Context_restore(
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Context_Control *new_context
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)
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{
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}
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/* void __ISR_Handler()
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*
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* This routine provides the RTEMS interrupt management.
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*
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* NO_CPU Specific Information:
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*
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* XXX document implementation including references if appropriate
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*/
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void _ISR_Handler()
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{
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/*
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* This discussion ignores a lot of the ugly details in a real
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* implementation such as saving enough registers/state to be
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* able to do something real. Keep in mind that the goal is
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* to invoke a user's ISR handler which is written in C and
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* uses a certain set of registers.
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*
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* Also note that the exact order is to a large extent flexible.
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* Hardware will dictate a sequence for a certain subset of
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* _ISR_Handler while requirements for setting
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*/
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/*
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* At entry to "common" _ISR_Handler, the vector number must be
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* available. On some CPUs the hardware puts either the vector
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* number or the offset into the vector table for this ISR in a
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* known place. If the hardware does not give us this information,
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* then the assembly portion of RTEMS for this port will contain
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* a set of distinct interrupt entry points which somehow place
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* the vector number in a known place (which is safe if another
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* interrupt nests this one) and branches to _ISR_Handler.
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*
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* save some or all context on stack
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* may need to save some special interrupt information for exit
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*
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* #if ( CPU_HAS_SOFTWARE_INTERRUPT_STACK == TRUE )
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* if ( _ISR_Nest_level == 0 )
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* switch to software interrupt stack
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* #endif
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*
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* _ISR_Nest_level++;
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*
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* _Thread_Dispatch_disable_level++;
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*
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* (*_ISR_Vector_table[ vector ])( vector );
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*
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* --_ISR_Nest_level;
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*
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* if ( _ISR_Nest_level )
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* goto the label "exit interrupt (simple case)"
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*
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* #if ( CPU_HAS_SOFTWARE_INTERRUPT_STACK == TRUE )
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* restore stack
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* #endif
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*
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* if ( !_Context_Switch_necessary )
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* goto the label "exit interrupt (simple case)"
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*
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* if ( !_ISR_Signals_to_thread_executing )
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* _ISR_Signals_to_thread_executing = FALSE;
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* goto the label "exit interrupt (simple case)"
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*
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* call _Thread_Dispatch() or prepare to return to _ISR_Dispatch
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*
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* prepare to get out of interrupt
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* return from interrupt (maybe to _ISR_Dispatch)
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*
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* LABEL "exit interrupt (simple case):
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* prepare to get out of interrupt
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* return from interrupt
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*/
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}
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