x_fline.s

RTEMS (Real-Time Executive for Multiprocessor Systems) is a free open source real-time operating sys

//
//      $Id: x_fline.S,v 1.1 1998/12/14 23:15:31 joel Exp $
//
//	x_fline.sa 3.3 1/10/91
//
//	fpsp_fline --- FPSP handler for fline exception
//
//	First determine if the exception is one of the unimplemented
//	floating point instructions.  If so, let fpsp_unimp handle it.
//	Next, determine if the instruction is an fmovecr with a non-zero
//	<ea> field.  If so, handle here and return.  Otherwise, it
//	must be a real F-line exception.
//

//		Copyright (C) Motorola, Inc. 1990
//			All Rights Reserved
//
//	THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF MOTOROLA 
//	The copyright notice above does not evidence any  
//	actual or intended publication of such source code.

X_FLINE:	//idnt    2,1 | Motorola 040 Floating Point Software Package

	|section	8

#include "fpsp.defs"

	|xref	real_fline
	|xref	fpsp_unimp
	|xref	uni_2
	|xref	mem_read
	|xref	fpsp_fmt_error

	.global	fpsp_fline
fpsp_fline:
//
//	check for unimplemented vector first.  Use EXC_VEC-4 because
//	the equate is valid only after a 'link a6' has pushed one more
//	long onto the stack.
//
	cmpw	#UNIMP_VEC,EXC_VEC-4(%a7)
	beql	fpsp_unimp

//
//	fmovecr with non-zero <ea> handling here
//
	subl	#4,%a7		//4 accounts for 2-word difference
//				;between six word frame (unimp) and
//				;four word frame
	link	%a6,#-LOCAL_SIZE
	fsave	-(%a7)
	moveml	%d0-%d1/%a0-%a1,USER_DA(%a6)
	moveal	EXC_PC+4(%a6),%a0	//get address of fline instruction
	leal	L_SCR1(%a6),%a1	//use L_SCR1 as scratch
	movel	#4,%d0
	addl	#4,%a6		//to offset the sub.l #4,a7 above so that
//				;a6 can point correctly to the stack frame 
//				;before branching to mem_read
	bsrl	mem_read
	subl	#4,%a6
	movel	L_SCR1(%a6),%d0	//d0 contains the fline and command word
	bfextu	%d0{#4:#3},%d1	//extract coprocessor id
	cmpib	#1,%d1		//check if cpid=1
	bne	not_mvcr	//exit if not
	bfextu	%d0{#16:#6},%d1
	cmpib	#0x17,%d1		//check if it is an FMOVECR encoding
	bne	not_mvcr	
//				;if an FMOVECR instruction, fix stack
//				;and go to FPSP_UNIMP
fix_stack:
	cmpib	#VER_40,(%a7)	//test for orig unimp frame
	bnes	ck_rev
	subl	#UNIMP_40_SIZE-4,%a7 //emulate an orig fsave
	moveb	#VER_40,(%a7)
	moveb	#UNIMP_40_SIZE-4,1(%a7)
	clrw	2(%a7)
	bras	fix_con
ck_rev:
	cmpib	#VER_41,(%a7)	//test for rev unimp frame
	bnel	fpsp_fmt_error	//if not $40 or $41, exit with error
	subl	#UNIMP_41_SIZE-4,%a7 //emulate a rev fsave
	moveb	#VER_41,(%a7)
	moveb	#UNIMP_41_SIZE-4,1(%a7)
	clrw	2(%a7)
fix_con:
	movew	EXC_SR+4(%a6),EXC_SR(%a6) //move stacked sr to new position
	movel	EXC_PC+4(%a6),EXC_PC(%a6) //move stacked pc to new position
	fmovel	EXC_PC(%a6),%FPIAR //point FPIAR to fline inst
	movel	#4,%d1
	addl	%d1,EXC_PC(%a6)	//increment stacked pc value to next inst
	movew	#0x202c,EXC_VEC(%a6) //reformat vector to unimp
	clrl	EXC_EA(%a6)	//clear the EXC_EA field
	movew	%d0,CMDREG1B(%a6) //move the lower word into CMDREG1B
	clrl	E_BYTE(%a6)
	bsetb	#UFLAG,T_BYTE(%a6)
	moveml	USER_DA(%a6),%d0-%d1/%a0-%a1 //restore data registers
	bral	uni_2

not_mvcr:
	moveml	USER_DA(%a6),%d0-%d1/%a0-%a1 //restore data registers
	frestore (%a7)+
	unlk	%a6
	addl	#4,%a7
	bral	real_fline

	|end