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

|
|	gen_except.sa 3.7 1/16/92
|
|	gen_except --- FPSP routine to detect reportable exceptions
|
|	This routine compares the exception enable byte of the
|	user_fpcr on the stack with the exception status byte
|	of the user_fpsr.
|
|	Any routine which may report an exceptions must load
|	the stack frame in memory with the exceptional operand(s).
|
|	Priority for exceptions is:
|
|	Highest:	bsun
|			snan
|			operr
|			ovfl
|			unfl
|			dz
|			inex2
|	Lowest:		inex1
|
|	Note: The IEEE standard specifies that inex2 is to be
|	reported if ovfl occurs and the ovfl enable bit is not
|	set but the inex2 enable bit is.
|
|
|		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.

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

	|section 8

#include "fpsp.h"

	|xref	real_trace
	|xref	fpsp_done
	|xref	fpsp_fmt_error

exc_tbl:
	.long	bsun_exc
	.long	commonE1
	.long	commonE1
	.long	ovfl_unfl
	.long	ovfl_unfl
	.long	commonE1
	.long	commonE3
	.long	commonE3
	.long	no_match

	.global	gen_except
gen_except:
	cmpib	#IDLE_SIZE-4,1(%a7)	|test for idle frame
	beq	do_check		|go handle idle frame
	cmpib	#UNIMP_40_SIZE-4,1(%a7)	|test for orig unimp frame
	beqs	unimp_x			|go handle unimp frame
	cmpib	#UNIMP_41_SIZE-4,1(%a7)	|test for rev unimp frame
	beqs	unimp_x			|go handle unimp frame
	cmpib	#BUSY_SIZE-4,1(%a7)	|if size <> $60, fmt error
	bnel	fpsp_fmt_error
	leal	BUSY_SIZE+LOCAL_SIZE(%a7),%a1 |init a1 so fpsp.h
|					;equates will work
| Fix up the new busy frame with entries from the unimp frame
|
	movel	ETEMP_EX(%a6),ETEMP_EX(%a1) |copy etemp from unimp
	movel	ETEMP_HI(%a6),ETEMP_HI(%a1) |frame to busy frame
	movel	ETEMP_LO(%a6),ETEMP_LO(%a1)
	movel	CMDREG1B(%a6),CMDREG1B(%a1) |set inst in frame to unimp
	movel	CMDREG1B(%a6),%d0		|fix cmd1b to make it
	andl	#0x03c30000,%d0		|work for cmd3b
	bfextu	CMDREG1B(%a6){#13:#1},%d1	|extract bit 2
	lsll	#5,%d1
	swap	%d1
	orl	%d1,%d0			|put it in the right place
	bfextu	CMDREG1B(%a6){#10:#3},%d1	|extract bit 3,4,5
	lsll	#2,%d1
	swap	%d1
	orl	%d1,%d0			|put them in the right place
	movel	%d0,CMDREG3B(%a1)		|in the busy frame
|
| Or in the FPSR from the emulation with the USER_FPSR on the stack.
|
	fmovel	%FPSR,%d0
	orl	%d0,USER_FPSR(%a6)
	movel	USER_FPSR(%a6),FPSR_SHADOW(%a1) |set exc bits
	orl	#sx_mask,E_BYTE(%a1)
	bra	do_clean

|
| Frame is an unimp frame possible resulting from an fmove <ea>,fp0
| that caused an exception
|
| a1 is modified to point into the new frame allowing fpsp equates
| to be valid.
|
unimp_x:
	cmpib	#UNIMP_40_SIZE-4,1(%a7)	|test for orig unimp frame
	bnes	test_rev
	leal	UNIMP_40_SIZE+LOCAL_SIZE(%a7),%a1
	bras	unimp_con
test_rev:
	cmpib	#UNIMP_41_SIZE-4,1(%a7)	|test for rev unimp frame
	bnel	fpsp_fmt_error		|if not $28 or $30
	leal	UNIMP_41_SIZE+LOCAL_SIZE(%a7),%a1

unimp_con:
|
| Fix up the new unimp frame with entries from the old unimp frame
|
	movel	CMDREG1B(%a6),CMDREG1B(%a1) |set inst in frame to unimp
|
| Or in the FPSR from the emulation with the USER_FPSR on the stack.
|
	fmovel	%FPSR,%d0
	orl	%d0,USER_FPSR(%a6)
	bra	do_clean

|
| Frame is idle, so check for exceptions reported through
| USER_FPSR and set the unimp frame accordingly.
| A7 must be incremented to the point before the
| idle fsave vector to the unimp vector.
|

do_check:
	addl	#4,%a7			|point A7 back to unimp frame
|
| Or in the FPSR from the emulation with the USER_FPSR on the stack.
|
	fmovel	%FPSR,%d0
	orl	%d0,USER_FPSR(%a6)
|
| On a busy frame, we must clear the nmnexc bits.
|
	cmpib	#BUSY_SIZE-4,1(%a7)	|check frame type
	bnes	check_fr		|if busy, clr nmnexc
	clrw	NMNEXC(%a6)		|clr nmnexc & nmcexc
	btstb	#5,CMDREG1B(%a6)		|test for fmove out
	bnes	frame_com
	movel	USER_FPSR(%a6),FPSR_SHADOW(%a6) |set exc bits
	orl	#sx_mask,E_BYTE(%a6)
	bras	frame_com
check_fr:
	cmpb	#UNIMP_40_SIZE-4,1(%a7)
	beqs	frame_com
	clrw	NMNEXC(%a6)
frame_com:
	moveb	FPCR_ENABLE(%a6),%d0	|get fpcr enable byte
	andb	FPSR_EXCEPT(%a6),%d0	|and in the fpsr exc byte
	bfffo	%d0{#24:#8},%d1		|test for first set bit
	leal	exc_tbl,%a0		|load jmp table address
	subib	#24,%d1			|normalize bit offset to 0-8
	movel	(%a0,%d1.w*4),%a0		|load routine address based
|					;based on first enabled exc
	jmp	(%a0)			|jump to routine
|
| Bsun is not possible in unimp or unsupp
|
bsun_exc:
	bra	do_clean
|
| The typical work to be done to the unimp frame to report an
| exception is to set the E1/E3 byte and clr the U flag.
| commonE1 does this for E1 exceptions, which are snan,
| operr, and dz.  commonE3 does this for E3 exceptions, which
| are inex2 and inex1, and also clears the E1 exception bit
| left over from the unimp exception.
|
commonE1:
	bsetb	#E1,E_BYTE(%a6)		|set E1 flag
	bra	commonE			|go clean and exit

commonE3:
	tstb	UFLG_TMP(%a6)		|test flag for unsup/unimp state
	bnes	unsE3
uniE3:
	bsetb	#E3,E_BYTE(%a6)		|set E3 flag
	bclrb	#E1,E_BYTE(%a6)		|clr E1 from unimp
	bra	commonE

unsE3:
	tstb	RES_FLG(%a6)
	bnes	unsE3_0
unsE3_1:
	bsetb	#E3,E_BYTE(%a6)		|set E3 flag
unsE3_0:
	bclrb	#E1,E_BYTE(%a6)		|clr E1 flag
	movel	CMDREG1B(%a6),%d0
	andl	#0x03c30000,%d0		|work for cmd3b
	bfextu	CMDREG1B(%a6){#13:#1},%d1	|extract bit 2
	lsll	#5,%d1
	swap	%d1
	orl	%d1,%d0			|put it in the right place
	bfextu	CMDREG1B(%a6){#10:#3},%d1	|extract bit 3,4,5
	lsll	#2,%d1
	swap	%d1
	orl	%d1,%d0			|put them in the right place
	movel	%d0,CMDREG3B(%a6)		|in the busy frame

commonE:
	bclrb	#UFLAG,T_BYTE(%a6)	|clr U flag from unimp
	bra	do_clean		|go clean and exit
|
| No bits in the enable byte match existing exceptions.  Check for
| the case of the ovfl exc without the ovfl enabled, but with
| inex2 enabled.
|
no_match:
	btstb	#inex2_bit,FPCR_ENABLE(%a6) |check for ovfl/inex2 case
	beqs	no_exc			|if