m68k/fpsp/kernel_ex.sa

*	MOTOROLA MICROPROCESSOR & MEMORY TECHNOLOGY GROUP
*	M68000 Hi-Performance Microprocessor Division
*	M68040 Software Package
*
*	M68040 Software Package Copyright (c) 1993, 1994 Motorola Inc.
*	All rights reserved.
*
*	THE SOFTWARE is provided on an "AS IS" basis and without warranty.
*	To the maximum extent permitted by applicable law,
*	MOTOROLA DISCLAIMS ALL WARRANTIES WHETHER EXPRESS OR IMPLIED,
*	INCLUDING IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A
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*	regard to the SOFTWARE (INCLUDING ANY MODIFIED VERSIONS THEREOF)
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*
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*	PROFITS, BUSINESS INTERRUPTION, LOSS OF BUSINESS INFORMATION, OR
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*
*	You are hereby granted a copyright license to use, modify, and
*	distribute the SOFTWARE so long as this entire notice is retained
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*	No licenses are granted by implication, estoppel or otherwise
*	under any patents or trademarks of Motorola, Inc.

*
*	kernel_ex.sa 3.3 12/19/90
*
* This file contains routines to force exception status in the
* fpu for exceptional cases detected or reported within the
* transcendental functions.  Typically, the t_xx routine will
* set the appropriate bits in the USER_FPSR word on the stack.
* The bits are tested in gen_except.sa to determine if an exceptional
* situation needs to be created on return from the FPSP.
*

KERNEL_EX    IDNT    2,1 Motorola 040 Floating Point Software Package

	section    8

	include	fpsp.h

mns_inf  dc.l $ffff0000,$00000000,$00000000
pls_inf  dc.l $7fff0000,$00000000,$00000000
nan      dc.l $7fff0000,$ffffffff,$ffffffff
huge     dc.l $7ffe0000,$ffffffff,$ffffffff

	xref	  ovf_r_k
	xref	  unf_sub
	xref	  nrm_set

	xdef   	  t_dz
	xdef      t_dz2
	xdef      t_operr
	xdef      t_unfl
	xdef      t_ovfl
	xdef      t_ovfl2
	xdef      t_inx2
	xdef	  t_frcinx
	xdef	  t_extdnrm
	xdef	  t_resdnrm
	xdef	  dst_nan
	xdef	  src_nan
*
*	DZ exception
*
*
*	if dz trap disabled
*		store properly signed inf (use sign of etemp) into fp0
*		set FPSR exception status dz bit, condition code
*		inf bit, and accrued dz bit
*		return
*		frestore the frame into the machine (done by unimp_hd)
*
*	else dz trap enabled
*		set exception status bit & accrued bits in FPSR
*		set flag to disable sto_res from corrupting fp register
*		return
*		frestore the frame into the machine (done by unimp_hd)
*
* t_dz2 is used by monadic functions such as flogn (from do_func).
* t_dz is used by monadic functions such as satanh (from the
* transcendental function).
*
t_dz2:
	bset.b	#neg_bit,FPSR_CC(a6)	;set neg bit in FPSR
	fmove.l	#0,FPSR			;clr status bits (Z set)
	btst.b	#dz_bit,FPCR_ENABLE(a6)	;test FPCR for dz exc enabled
	bne.b	dz_ena_end
	bra.b	m_inf			;flogx always returns -inf
t_dz:
	fmove.l	#0,FPSR			;clr status bits (Z set)
	btst.b	#dz_bit,FPCR_ENABLE(a6)	;test FPCR for dz exc enabled
	bne.b	dz_ena
*
*	dz disabled
*
	btst.b	#sign_bit,ETEMP_EX(a6)	;check sign for neg or pos
	beq.b	p_inf			;branch if pos sign

m_inf:
	fmovem.x mns_inf,fp0		;load -inf
	bset.b	#neg_bit,FPSR_CC(a6)	;set neg bit in FPSR
	bra.b	set_fpsr
p_inf:
	fmovem.x pls_inf,fp0		;load +inf
set_fpsr:
	or.l	#dzinf_mask,USER_FPSR(a6) ;set I,DZ,ADZ
	rts
*
*	dz enabled
*
dz_ena:
	btst.b	#sign_bit,ETEMP_EX(a6)	;check sign for neg or pos
	beq.b	dz_ena_end
	bset.b	#neg_bit,FPSR_CC(a6)	;set neg bit in FPSR
dz_ena_end:
	or.l	#dzinf_mask,USER_FPSR(a6) ;set I,DZ,ADZ
	st.b	STORE_FLG(a6)
	rts
*
*	OPERR exception
*
*	if (operr trap disabled)
*		set FPSR exception status operr bit, condition code
*		nan bit; Store default NAN into fp0
*		frestore the frame into the machine (done by unimp_hd)
*
*	else (operr trap enabled)
*		set FPSR exception status operr bit, accrued operr bit
*		set flag to disable sto_res from corrupting fp register
*		frestore the frame into the machine (done by unimp_hd)
*
t_operr:
	or.l	#opnan_mask,USER_FPSR(a6) ;set NaN, OPERR, AIOP

	btst.b	#operr_bit,FPCR_ENABLE(a6) ;test FPCR for operr enabled
	bne.b	op_ena

	fmovem.x nan,fp0		;load default nan
	rts
op_ena:
	st.b	STORE_FLG(a6)		;do not corrupt destination
	rts

*
*	t_unfl --- UNFL exception
*
* This entry point is used by all routines requiring unfl, inex2,
* aunfl, and ainex to be set on exit.
*
* On entry, a0 points to the exceptional operand.  The final exceptional
* operand is built in FP_SCR1 and only the sign from the original operand
* is used.
*
t_unfl:
	clr.l	FP_SCR1(a6)		;set exceptional operand to zero
	clr.l	FP_SCR1+4(a6)
	clr.l	FP_SCR1+8(a6)
	tst.b	(a0)			;extract sign from caller's exop
	bpl.b	unfl_signok
	bset	#sign_bit,FP_SCR1(a6)
unfl_signok:
	lea.l	FP_SCR1(a6),a0
	or.l	#unfinx_mask,USER_FPSR(a6)
*					;set UNFL, INEX2, AUNFL, AINEX
unfl_con:
	btst.b	#unfl_bit,FPCR_ENABLE(a6)
	beq.b	unfl_dis

unfl_ena:
	bfclr	STAG(a6){5:3}		;clear wbtm66,wbtm1,wbtm0
	bset.b	#wbtemp15_bit,WB_BYTE(a6) ;set wbtemp15
	bset.b	#sticky_bit,STICKY(a6)	;set sticky bit

	bclr.b	#E1,E_BYTE(a6)

unfl_dis:
	bfextu	FPCR_MODE(a6){0:2},d0	;get round precision

	bclr.b	#sign_bit,LOCAL_EX(a0)
	sne	LOCAL_SGN(a0)		;convert to internal ext format

	bsr	unf_sub			;returns IEEE result at a0
*					;and sets FPSR_CC accordingly

	bfclr	LOCAL_SGN(a0){0:8}	;convert back to IEEE ext format
	beq.b	unfl_fin

	bset.b	#sign_bit,LOCAL_EX(a0)
	bset.b	#sign_bit,FP_SCR1(a6)	;set sign bit of exc operand

unfl_fin:
	fmovem.x (a0),fp0		;store result in fp0
	rts


*
*	t_ovfl2 --- OVFL exception (without inex2 returned)
*
* This entry is used by scale to force catastrophic overflow.  The
* ovfl, aovfl, and ainex bits are set, but not the inex2 bit.
*
t_ovfl2:
	or.l	#ovfl_inx_mask,USER_FPSR(a6)
	move.l	ETEMP(a6),FP_SCR1(a6)
	move.l	ETEMP_HI(a6),FP_SCR1+4(a6)
	move.l	ETEMP_LO(a6),FP_SCR1+8(a6)
*
* Check for single or double round precision.  If single, check if
* the lower 40 bits of ETEMP are zero; if not, set inex2.  If double,
* check if the lower 21 bits are zero; if not, set inex2.
*
	move.b	FPCR_MODE(a6),d0
	andi.b	#$c0,d0
	beq.w	t_work		;if extended, finish ovfl processing
	cmpi.b	#$40,d0		;test for single
	bne.b	t_dbl
t_sgl:
	tst.b	ETEMP_LO(a6)
	bne.b	t_setinx2
	move.l	ETEMP_HI(a6),d0
	andi.l	#$ff,d0		;look at only lower 8 bits
	bne.b	t_setinx2
	bra.w	t_work
t_dbl:
	move.l	ETEMP_LO(a6),d0
	andi.l	#$7ff,d0	;look at only lower 11 bits
	beq.w	t_work
t_setinx2:
	or.l	#inex2_mask,USER_FPSR(a6)
	bra.b	t_work
*
*	t_ovfl --- OVFL exception
*
*** Note: the exc operand is returned in ETEMP.
*
t_ovfl:
	or.l	#ovfinx_mask,USER_FPSR(a6)
t_work:
	btst.b	#ovfl_bit,FPCR_ENABLE(a6) ;test FPCR for ovfl enabled
	beq.b	ovf_dis

ovf_ena:
	clr.l	FP_SCR1(a6)		;set exceptional operand
	clr.l	FP_SCR1+4(a6)
	clr.l	FP_SCR1+8(a6)

	bfclr	STAG(a6){5:3}		;clear wbtm66,wbtm1,wbtm0
	bclr.b	#wbtemp15_bit,WB_BYTE(a6) ;clear wbtemp15
	bset.b	#sticky_bit,STICKY(a6)	;set sticky bit

	bclr.b	#E1,E_BYTE(a6)
*					;fall through to disabled case

* For disabled overflow call 'ovf_r_k'.  This routine loads the
* correct result based on the rounding precision, destination
* format, rounding mode and sign.
*
ovf_dis:
	bsr	ovf_r_k			;returns unsigned ETEMP_EX
*					;and sets FPSR_CC accordingly.
	bfclr	ETEMP_SGN(a6){0:8}	;fix sign
	beq.b	ovf_pos
	bset.b	#sign_bit,ETEMP_EX(a6)
	bset.b	#sign_bit,FP_SCR1(a6)	;set exceptional operand sign
ovf_pos:
	fmovem.x ETEMP(a6),fp0		;move the result to fp0
	rts


*
*	INEX2 exception
*
* The inex2 and ainex bits are set.
*
t_inx2:
	or.l	#inx2a_mask,USER_FPSR(a6) ;set INEX2, AINEX
	rts

*
*	Force Inex2
*
* This routine is called by the transcendental routines to force
* the inex2 exception bits set in the FPSR.  If the underflow bit
* is set, but the underflow trap was not taken, the aunfl bit in
* the FPSR must be set.
*
t_frcinx:
	or.l	#inx2a_mask,USER_FPSR(a6) ;set INEX2, AINEX
	btst.b	#unfl_bit,FPSR_EXCEPT(a6) ;test for unfl bit set
	beq.b	no_uacc1		;if clear, do not set aunfl
	bset.b	#aunfl_bit,FPSR_AEXCEPT(a6)
no_uacc1:
	rts

*
*	DST_NAN
*
* Determine if the destination nan is signalling or non-signalling,
* and set the FPSR bits accordingly.  See the MC68040 User's Manual
* section 3.2.2.5 NOT-A-NUMBERS.
*
dst_nan:
	btst.b	#sign_bit,FPTEMP_EX(a6) ;test sign of nan
	beq.b	dst_pos			;if clr, it was positive
	bset.b	#neg_bit,FPSR_CC(a6)	;set N bit
dst_pos:
	btst.b	#signan_bit,FPTEMP_HI(a6) ;check if signalling
	beq.b	dst_snan		;branch if signalling

	fmove.l	d1,fpcr			;restore user's rmode/prec
	fmove.x FPTEMP(a6),fp0		;return the non-signalling nan
*
* Check the source nan.  If it is signalling, snan will be reported.
*
	move.b	STAG(a6),d0
	andi.b	#$e0,d0
	cmpi.b	#$60,d0
	bne.b	no_snan
	btst.b	#signan_bit,ETEMP_HI(a6) ;check if signalling
	bne.b	no_snan
	or.l	#snaniop_mask,USER_FPSR(a6) ;set NAN, SNAN, AIOP
no_snan:
	rts

dst_snan:
	btst.b	#snan_bit,FPCR_ENABLE(a6) ;check if trap enabled
	beq.b	dst_dis			;branch if disabled

	or.b	#nan_tag,DTAG(a6)	;set up dtag for nan
	st.b	STORE_FLG(a6)		;do not store a result
	or.l	#snaniop_mask,USER_FPSR(a6) ;set NAN, SNAN, AIOP
	rts

dst_dis:
	bset.b	#signan_bit,FPTEMP_HI(a6) ;set SNAN bit in sop
	fmove.l	d1,fpcr			;restore user's rmode/prec
	fmove.x FPTEMP(a6),fp0		;load non-sign. nan
	or.l	#snaniop_mask,USER_FPSR(a6) ;set NAN, SNAN, AIOP
	rts

*
*	SRC_NAN
*
* Determine if the source nan is signalling or non-signalling,
* and set the FPSR bits accordingly.  See the MC68040 User's Manual
* section 3.2.2.5 NOT-A-NUMBERS.
*
src_nan:
	btst.b	#sign_bit,ETEMP_EX(a6) ;test sign of nan
	beq.b	src_pos			;if clr, it was positive
	bset.b	#neg_bit,FPSR_CC(a6)	;set N bit
src_pos:
	btst.b	#signan_bit,ETEMP_HI(a6) ;check if signalling
	beq.b	src_snan		;branch if signalling
	fmove.l	d1,fpcr			;restore user's rmode/prec
	fmove.x ETEMP(a6),fp0		;return the non-signalling nan
	rts

src_snan:
	btst.b	#snan_bit,FPCR_ENABLE(a6) ;check if trap enabled
	beq.b	src_dis			;branch if disabled
	bset.b	#signan_bit,ETEMP_HI(a6) ;set SNAN bit in sop
	or.b	#norm_tag,DTAG(a6)	;set up dtag for norm
	or.b	#nan_tag,STAG(a6)	;set up stag for nan
	st.b	STORE_FLG(a6)		;do not store a result
	or.l	#snaniop_mask,USER_FPSR(a6) ;set NAN, SNAN, AIOP
	rts

src_dis:
	bset.b	#signan_bit,ETEMP_HI(a6) ;set SNAN bit in sop
	fmove.l	d1,fpcr			;restore user's rmode/prec
	fmove.x ETEMP(a6),fp0		;load non-sign. nan
	or.l	#snaniop_mask,USER_FPSR(a6) ;set NAN, SNAN, AIOP
	rts

*
* For all functions that have a denormalized input and that f(x)=x,
* this is the entry point
*
t_extdnrm:
	or.l	#unfinx_mask,USER_FPSR(a6)
*					;set UNFL, INEX2, AUNFL, AINEX
	bra.b	xdnrm_con
*
* Entry point for scale with extended denorm.  The function does
* not set inex2, aunfl, or ainex.
*
t_resdnrm:
	or.l	#unfl_mask,USER_FPSR(a6)

xdnrm_con:
	btst.b	#unfl_bit,FPCR_ENABLE(a6)
	beq.b	xdnrm_dis

*
* If exceptions are enabled, the additional task of setting up WBTEMP
* is needed so that when the underflow exception handler is entered,
* the user perceives no difference between what the 040 provides vs.
* what the FPSP provides.
*
xdnrm_ena:
	move.l	a0,-(a7)

	move.l	LOCAL_EX(a0),FP_SCR1(a6)
	move.l	LOCAL_HI(a0),FP_SCR1+4(a6)
	move.l	LOCAL_LO(a0),FP_SCR1+8(a6)

	lea	FP_SCR1(a6),a0

	bclr.b	#sign_bit,LOCAL_EX(a0)
	sne	LOCAL_SGN(a0)		;convert to internal ext format
	tst.w	LOCAL_EX(a0)		;check if input is denorm
	beq.b	xdnrm_dn		;if so, skip nrm_set
	bsr	nrm_set			;normalize the result (exponent
*					;will be negative
xdnrm_dn:
	bclr.b	#sign_bit,LOCAL_EX(a0)	;take off false sign
	bfclr	LOCAL_SGN(a0){0:8}	;change back to IEEE ext format
	beq.b	xdep
	bset.b	#sign_bit,LOCAL_EX(a0)
xdep:
	bfclr	STAG(a6){5:3}		;clear wbtm66,wbtm1,wbtm0
	bset.b	#wbtemp15_bit,WB_BYTE(a6) ;set wbtemp15
	bclr.b	#sticky_bit,STICKY(a6)	;clear sticky bit
	bclr.b	#E1,E_BYTE(a6)
	move.l	(a7)+,a0
xdnrm_dis:
	bfextu	FPCR_MODE(a6){0:2},d0	;get round precision
	bne.b	not_ext			;if not round extended, store
*					;IEEE defaults
is_ext:
	btst.b	#sign_bit,LOCAL_EX(a0)
	beq.b	xdnrm_store

	bset.b	#neg_bit,FPSR_CC(a6)	;set N bit in FPSR_CC

	bra.b	xdnrm_store

not_ext:
	bclr.b	#sign_bit,LOCAL_EX(a0)
	sne	LOCAL_SGN(a0)		;convert to internal ext format
	bsr	unf_sub			;returns IEEE result pointed by
*					;a0; sets FPSR_CC accordingly
	bfclr	LOCAL_SGN(a0){0:8}	;convert back to IEEE ext format
	beq.b	xdnrm_store
	bset.b	#sign_bit,LOCAL_EX(a0)
xdnrm_store:
	fmovem.x (a0),fp0		;store result in fp0
	rts

*
* This subroutine is used for dyadic operations that use an extended
* denorm within the kernel. The approach used is to capture the frame,
* fix/restore.
*
	xdef	t_avoid_unsupp
t_avoid_unsupp:
	link	a2,#-LOCAL_SIZE		;so that a2 fpsp.h negative
*					;offsets may be used
	fsave	-(a7)
	tst.b	1(a7)			;check if idle, exit if so
	beq.w	idle_end
	btst.b	#E1,E_BYTE(a2)		;check for an E1 exception if
*					;enabled, there is an unsupp
	beq.w	end_avun		;else, exit
	btst.b	#7,DTAG(a2)		;check for denorm destination
	beq.b	src_den			;else, must be a source denorm
*
* handle destination denorm
*
	lea	FPTEMP(a2),a0
	btst.b	#sign_bit,LOCAL_EX(a0)
	sne	LOCAL_SGN(a0)		;convert to internal ext format
	bclr.b	#7,DTAG(a2)		;set DTAG to norm
	bsr	nrm_set			;normalize result, exponent
*					;will become negative
	bclr.b	#sign_bit,LOCAL_EX(a0)	;get rid of fake sign
	bfclr	LOCAL_SGN(a0){0:8}	;convert back to IEEE ext format
	beq.b	ck_src_den		;check if source is also denorm
	bset.b	#sign_bit,LOCAL_EX(a0)
ck_src_den:
	btst.b	#7,STAG(a2)
	beq.b	end_avun
src_den:
	lea	ETEMP(a2),a0
	btst.b	#sign_bit,LOCAL_EX(a0)
	sne	LOCAL_SGN(a0)		;convert to internal ext format
	bclr.b	#7,STAG(a2)		;set STAG to norm
	bsr	nrm_set			;normalize result, exponent
*					;will become negative
	bclr.b	#sign_bit,LOCAL_EX(a0)	;get rid of fake sign
	bfclr	LOCAL_SGN(a0){0:8}	;convert back to IEEE ext format
	beq.b	den_com
	bset.b	#sign_bit,LOCAL_EX(a0)
den_com:
	move.b	#$fe,CU_SAVEPC(a2)	;set continue frame
	clr.w	NMNEXC(a2)		;clear NMNEXC
	bclr.b	#E1,E_BYTE(a2)
*	fmove.l	FPSR,FPSR_SHADOW(a2)
*	bset.b	#SFLAG,E_BYTE(a2)
*	bset.b	#XFLAG,T_BYTE(a2)
end_avun:
	frestore (a7)+
	unlk	a2
	rts
idle_end:
	add.l	#4,a7
	unlk	a2
	rts
	end