path: root/arch/m68k/fpsp040/skeleton.S

|
|	skeleton.sa 3.2 4/26/91
|
|	This file contains code that is system dependent and will
|	need to be modified to install the FPSP.
|
|	Each entry point for exception 'xxxx' begins with a 'jmp fpsp_xxxx'.
|	Put any target system specific handling that must be done immediately
|	before the jump instruction.  If there no handling necessary, then
|	the 'fpsp_xxxx' handler entry point should be placed in the exception
|	table so that the 'jmp' can be eliminated. If the FPSP determines that the
|	exception is one that must be reported then there will be a
|	return from the package by a 'jmp real_xxxx'.  At that point
|	the machine state will be identical to the state before
|	the FPSP was entered.  In particular, whatever condition
|	that caused the exception will still be pending when the FPSP
|	package returns.  Thus, there will be system specific code
|	to handle the exception.
|
|	If the exception was completely handled by the package, then
|	the return will be via a 'jmp fpsp_done'.  Unless there is
|	OS specific work to be done (such as handling a context switch or
|	interrupt) the user program can be resumed via 'rte'.
|
|	In the following skeleton code, some typical 'real_xxxx' handling
|	code is shown.  This code may need to be moved to an appropriate
|	place in the target system, or rewritten.
|

|		Copyright (C) Motorola, Inc. 1990
|			All Rights Reserved
|
|       For details on the license for this file, please see the
|       file, README, in this same directory.

|
|	Modified for Linux-1.3.x by Jes Sorensen (jds@kom.auc.dk)
|

#include <linux/linkage.h>
#include <asm/entry.h>
#include <asm/asm-offsets.h>

|SKELETON	idnt    2,1 | Motorola 040 Floating Point Software Package

	|section 15
|
|	The following counters are used for standalone testing
|

	|section 8

#include "fpsp.h"

	|xref	b1238_fix

|
|	Divide by Zero exception
|
|	All dz exceptions are 'real', hence no fpsp_dz entry point.
|
	.global	dz
	.global	real_dz
dz:
real_dz:
	link		%a6,#-LOCAL_SIZE
	fsave		-(%sp)
	bclrb		#E1,E_BYTE(%a6)
	frestore	(%sp)+
	unlk		%a6

	SAVE_ALL_INT
	GET_CURRENT(%d0)
	movel	%sp,%sp@-		| stack frame pointer argument
	bsrl	trap_c
	addql	#4,%sp
	bral	ret_from_exception

|
|	Inexact exception
|
|	All inexact exceptions are real, but the 'real' handler
|	will probably want to clear the pending exception.
|	The provided code will clear the E3 exception (if pending),
|	otherwise clear the E1 exception.  The frestore is not really
|	necessary for E1 exceptions.
|
| Code following the 'inex' label is to handle bug #1232.  In this
| bug, if an E1 snan, ovfl, or unfl occurred, and the process was
| swapped out before taking the exception, the exception taken on
| return was inex, rather than the correct exception.  The snan, ovfl,
| and unfl exception to be taken must not have been enabled.  The
| fix is to check for E1, and the existence of one of snan, ovfl,
| or unfl bits set in the fpsr.  If any of these are set, branch
| to the appropriate  handler for the exception in the fpsr.  Note
| that this fix is only for d43b parts, and is skipped if the
| version number is not $40.
|
|
	.global	real_inex
	.global	inex
inex:
	link		%a6,#-LOCAL_SIZE
	fsave		-(%sp)
	cmpib		#VER_40,(%sp)		|test version number
	bnes		not_fmt40
	fmovel		%fpsr,-(%sp)
	btstb		#E1,E_BYTE(%a6)		|test for E1 set
	beqs		not_b1232
	btstb		#snan_bit,2(%sp) |test for snan
	beq		inex_ckofl
	addl		#4,%sp
	frestore	(%sp)+
	unlk		%a6
	bra		snan
inex_ckofl:
	btstb		#ovfl_bit,2(%sp) |test for ovfl
	beq		inex_ckufl
	addl		#4,%sp
	frestore	(%sp)+
	unlk		%a6
	bra		ovfl
inex_ckufl:
	btstb		#unfl_bit,2(%sp) |test for unfl
	beq		not_b1232
	addl		#4,%sp
	frestore	(%sp)+
	unlk		%a6
	bra		unfl

|
| We do not have the bug 1232 case.  Clean up the stack and call
| real_inex.
|
not_b1232:
	addl		#4,%sp
	frestore	(%sp)+
	unlk		%a6

real_inex:

	link		%a6,#-LOCAL_SIZE
	fsave		-(%sp)
not_fmt40:
	bclrb		#E3,E_BYTE(%a6)		|clear and test E3 flag
	beqs		inex_cke1
|
| Clear dirty bit on dest resister in the frame before branching
| to b1238_fix.
|
	moveml		%d0/%d1,USER_DA(%a6)
	bfextu		CMDREG1B(%a6){#6:#3},%d0		|get dest reg no
	bclrb		%d0,FPR_DIRTY_BITS(%a6)	|clr dest dirty bit
	bsrl		b1238_fix		|test for bug1238 case
	moveml		USER_DA(%a6),%d0/%d1
	bras		inex_done
inex_cke1:
	bclrb		#E1,E_BYTE(%a6)
inex_done:
	frestore	(%sp)+
	unlk		%a6

	SAVE_ALL_INT
	GET_CURRENT(%d0)
	movel	%sp,%sp@-		| stack frame pointer argument
	bsrl	trap_c
	addql	#4,%sp
	bral	ret_from_exception

|
|	Overflow exception