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awilliam
GitHub Repository: awilliam/linux-vfio
 Path: blob/master/arch/m68k/fpsp040/x_fline.S
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|	x_fline.sa 3.3 1/10/91

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|

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|	fpsp_fline --- FPSP handler for fline exception

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|

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|	First determine if the exception is one of the unimplemented

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|	floating point instructions.  If so, let fpsp_unimp handle it.

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|	Next, determine if the instruction is an fmovecr with a non-zero

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|	<ea> field.  If so, handle here and return.  Otherwise, it

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|	must be a real F-line exception.

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|

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|		Copyright (C) Motorola, Inc. 1990

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|			All Rights Reserved

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|

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|       For details on the license for this file, please see the

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|       file, README, in this same directory.

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

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	|section	8

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#include "fpsp.h"

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	|xref	real_fline

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	|xref	fpsp_unimp

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	|xref	uni_2

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	|xref	mem_read

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	|xref	fpsp_fmt_error

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	.global	fpsp_fline

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fpsp_fline:

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|

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|	check for unimplemented vector first.  Use EXC_VEC-4 because

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|	the equate is valid only after a 'link a6' has pushed one more

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|	long onto the stack.

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|

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	cmpw	#UNIMP_VEC,EXC_VEC-4(%a7)

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	beql	fpsp_unimp

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|

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|	fmovecr with non-zero <ea> handling here

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|

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	subl	#4,%a7		|4 accounts for 2-word difference

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|				;between six word frame (unimp) and

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|				;four word frame

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	link	%a6,#-LOCAL_SIZE

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	fsave	-(%a7)

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	moveml	%d0-%d1/%a0-%a1,USER_DA(%a6)

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	moveal	EXC_PC+4(%a6),%a0	|get address of fline instruction

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	leal	L_SCR1(%a6),%a1	|use L_SCR1 as scratch

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	movel	#4,%d0

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	addl	#4,%a6		|to offset the sub.l #4,a7 above so that

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|				;a6 can point correctly to the stack frame

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|				;before branching to mem_read

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	bsrl	mem_read

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	subl	#4,%a6

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	movel	L_SCR1(%a6),%d0	|d0 contains the fline and command word

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	bfextu	%d0{#4:#3},%d1	|extract coprocessor id

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	cmpib	#1,%d1		|check if cpid=1

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	bne	not_mvcr	|exit if not

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	bfextu	%d0{#16:#6},%d1

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	cmpib	#0x17,%d1		|check if it is an FMOVECR encoding

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	bne	not_mvcr

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|				;if an FMOVECR instruction, fix stack

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|				;and go to FPSP_UNIMP

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fix_stack:

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	cmpib	#VER_40,(%a7)	|test for orig unimp frame

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	bnes	ck_rev

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	subl	#UNIMP_40_SIZE-4,%a7 |emulate an orig fsave

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	moveb	#VER_40,(%a7)

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	moveb	#UNIMP_40_SIZE-4,1(%a7)

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	clrw	2(%a7)

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	bras	fix_con

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ck_rev:

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	cmpib	#VER_41,(%a7)	|test for rev unimp frame

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	bnel	fpsp_fmt_error	|if not $40 or $41, exit with error

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	subl	#UNIMP_41_SIZE-4,%a7 |emulate a rev fsave

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	moveb	#VER_41,(%a7)

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	moveb	#UNIMP_41_SIZE-4,1(%a7)

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	clrw	2(%a7)

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fix_con:

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	movew	EXC_SR+4(%a6),EXC_SR(%a6) |move stacked sr to new position

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	movel	EXC_PC+4(%a6),EXC_PC(%a6) |move stacked pc to new position

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	fmovel	EXC_PC(%a6),%FPIAR |point FPIAR to fline inst

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	movel	#4,%d1

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	addl	%d1,EXC_PC(%a6)	|increment stacked pc value to next inst

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	movew	#0x202c,EXC_VEC(%a6) |reformat vector to unimp

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	clrl	EXC_EA(%a6)	|clear the EXC_EA field

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	movew	%d0,CMDREG1B(%a6) |move the lower word into CMDREG1B

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	clrl	E_BYTE(%a6)

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	bsetb	#UFLAG,T_BYTE(%a6)

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	moveml	USER_DA(%a6),%d0-%d1/%a0-%a1 |restore data registers

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	bral	uni_2

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not_mvcr:

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	moveml	USER_DA(%a6),%d0-%d1/%a0-%a1 |restore data registers

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	frestore (%a7)+

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	unlk	%a6

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	addl	#4,%a7

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	bral	real_fline

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	|end

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