get_op.s

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

	orb	#0x10,DTAG(%a6)
	bras	end_getop

//
// At this point, it is either an fmoveout packed, unnorm or denorm
//
opclass3:
	clrb	DY_MO_FLG(%a6)	//set dyadic/monadic flag to monadic
	bfextu	CMDREG1B(%a6){#4:#2},%d0
	cmpib	#3,%d0
	bne	src_ex_dnrm	//if not equal, must be unnorm or denorm
//				;else it is a packed move out
//				;exit
end_getop:
	rts

//
// Sets the DY_MO_FLG correctly. This is used only on if it is an
// unsupported data type exception.  Set if dyadic.
//
chk_dy_mo:
	movew	CMDREG1B(%a6),%d0	
	btstl	#5,%d0		//testing extension command word
	beqs	set_mon		//if bit 5 = 0 then monadic
	btstl	#4,%d0		//know that bit 5 = 1
	beqs	set_dya		//if bit 4 = 0 then dyadic
	andiw	#0x007f,%d0	//get rid of all but extension bits {6:0}
	cmpiw 	#0x0038,%d0	//if extension = $38 then fcmp (dyadic)
	bnes	set_mon
set_dya:
	st	DY_MO_FLG(%a6)	//set the inst flag type to dyadic
	rts
set_mon:
	clrb	DY_MO_FLG(%a6)	//set the inst flag type to monadic
	rts
//
//	MK_NORM
//
// Normalizes unnormalized numbers, sets tag to norm or denorm, sets unfl
// exception if denorm.
//
// CASE opclass 0x0 unsupp
//	mk_norm till msb set
//	set tag = norm
//
// CASE opclass 0x0 unimp
//	mk_norm till msb set or exp = 0
//	if integer bit = 0
//	   tag = denorm
//	else
//	   tag = norm
//
// CASE opclass 011 unsupp
//	mk_norm till msb set or exp = 0
//	if integer bit = 0
//	   tag = denorm
//	   set unfl_nmcexe = 1
//	else
//	   tag = norm
//
// if exp <= $3fff
//   set ete15 or fpte15 = 1
// else set ete15 or fpte15 = 0

// input:
//	a0 = points to operand to be normalized
// output:
//	L_SCR1{7:5} = operand tag (000 = norm, 100 = denorm)
//	L_SCR1{4}   = fpte15 or ete15 (0 = exp > $3fff, 1 = exp <=$3fff)
//	the normalized operand is placed back on the fsave stack
mk_norm:	
	clrl	L_SCR1(%a6)
	bclrb	#sign_bit,LOCAL_EX(%a0)
	sne	LOCAL_SGN(%a0)	//transform into internal extended format

	cmpib	#0x2c,1+EXC_VEC(%a6) //check if unimp
	bnes	uns_data	//branch if unsupp
	bsr	uni_inst	//call if unimp (opclass 0x0)
	bras	reload
uns_data:
	btstb	#direction_bit,CMDREG1B(%a6) //check transfer direction
	bnes	bit_set		//branch if set (opclass 011)
	bsr	uns_opx		//call if opclass 0x0
	bras	reload
bit_set:
	bsr	uns_op3		//opclass 011
reload:
	cmpw	#0x3fff,LOCAL_EX(%a0) //if exp > $3fff
	bgts	end_mk		//   fpte15/ete15 already set to 0
	bsetb	#4,L_SCR1(%a6)	//else set fpte15/ete15 to 1
//				;calling routine actually sets the 
//				;value on the stack (along with the 
//				;tag), since this routine doesn't 
//				;know if it should set ete15 or fpte15
//				;ie, it doesn't know if this is the 
//				;src op or dest op.
end_mk:
	bfclr	LOCAL_SGN(%a0){#0:#8}
	beqs	end_mk_pos
	bsetb	#sign_bit,LOCAL_EX(%a0) //convert back to IEEE format
end_mk_pos:
	rts
//
//     CASE opclass 011 unsupp
//
uns_op3:
	bsr	nrm_zero	//normalize till msb = 1 or exp = zero
	btstb	#7,LOCAL_HI(%a0)	//if msb = 1
	bnes	no_unfl		//then branch
set_unfl:
	orw	#dnrm_tag,L_SCR1(%a6) //set denorm tag
	bsetb	#unfl_bit,FPSR_EXCEPT(%a6) //set unfl exception bit
no_unfl:
	rts
//
//     CASE opclass 0x0 unsupp
//
uns_opx:
	bsr	nrm_zero	//normalize the number
	btstb	#7,LOCAL_HI(%a0)	//check if integer bit (j-bit) is set 
	beqs	uns_den		//if clear then now have a denorm
uns_nrm:
	orb	#norm_tag,L_SCR1(%a6) //set tag to norm
	rts
uns_den:
	orb	#dnrm_tag,L_SCR1(%a6) //set tag to denorm
	rts
//
//     CASE opclass 0x0 unimp
//
uni_inst:
	bsr	nrm_zero
	btstb	#7,LOCAL_HI(%a0)	//check if integer bit (j-bit) is set 
	beqs	uni_den		//if clear then now have a denorm
uni_nrm:
	orb	#norm_tag,L_SCR1(%a6) //set tag to norm
	rts
uni_den:
	orb	#dnrm_tag,L_SCR1(%a6) //set tag to denorm
	rts

//
//	Decimal to binary conversion
//
// Special cases of inf and NaNs are completed outside of decbin.  
// If the input is an snan, the snan bit is not set.
// 
// input:
//	ETEMP(a6)	- points to packed decimal string in memory
// output:
//	fp0	- contains packed string converted to extended precision
//	ETEMP	- same as fp0
unpack:
	movew	CMDREG1B(%a6),%d0	//examine command word, looking for fmove's
	andw	#0x3b,%d0
	beq	move_unpack	//special handling for fmove: must set FPSR_CC

	movew	ETEMP(%a6),%d0	//get word with inf information
	bfextu	%d0{#20:#12},%d1	//get exponent into d1
	cmpiw	#0x0fff,%d1	//test for inf or NaN
	bnes	try_zero	//if not equal, it is not special
	bfextu	%d0{#17:#3},%d1	//get SE and y bits into d1
	cmpiw	#7,%d1		//SE and y bits must be on for special
	bnes	try_zero	//if not on, it is not special
//input is of the special cases of inf and NaN
	tstl	ETEMP_HI(%a6)	//check ms mantissa
	bnes	fix_nan		//if non-zero, it is a NaN
	tstl	ETEMP_LO(%a6)	//check ls mantissa
	bnes	fix_nan		//if non-zero, it is a NaN
	bra	finish		//special already on stack
fix_nan:
	btstb	#signan_bit,ETEMP_HI(%a6) //test for snan
	bne	finish
	orl	#snaniop_mask,USER_FPSR(%a6) //always set snan if it is so
	bra	finish
try_zero:
	movew	ETEMP_EX+2(%a6),%d0 //get word 4
	andiw	#0x000f,%d0	//clear all but last ni(y)bble
	tstw	%d0		//check for zero.
	bne	not_spec
	tstl	ETEMP_HI(%a6)	//check words 3 and 2
	bne	not_spec
	tstl	ETEMP_LO(%a6)	//check words 1 and 0
	bne	not_spec
	tstl	ETEMP(%a6)	//test sign of the zero
	bges	pos_zero
	movel	#0x80000000,ETEMP(%a6) //write neg zero to etemp
	clrl	ETEMP_HI(%a6)
	clrl	ETEMP_LO(%a6)
	bra	finish
pos_zero:
	clrl	ETEMP(%a6)
	clrl	ETEMP_HI(%a6)
	clrl	ETEMP_LO(%a6)
	bra	finish

not_spec:
	fmovemx %fp0-%fp1,-(%a7)	//save fp0 - decbin returns in it
	bsr	decbin
	fmovex %fp0,ETEMP(%a6)	//put the unpacked sop in the fsave stack
	fmovemx (%a7)+,%fp0-%fp1
	fmovel	#0,%FPSR		//clr fpsr from decbin
	bra	finish

//
// Special handling for packed move in:  Same results as all other
// packed cases, but we must set the FPSR condition codes properly.
//
move_unpack:
	movew	ETEMP(%a6),%d0	//get word with inf information
	bfextu	%d0{#20:#12},%d1	//get exponent into d1
	cmpiw	#0x0fff,%d1	//test for inf or NaN
	bnes	mtry_zero	//if not equal, it is not special
	bfextu	%d0{#17:#3},%d1	//get SE and y bits into d1
	cmpiw	#7,%d1		//SE and y bits must be on for special
	bnes	mtry_zero	//if not on, it is not special
//input is of the special cases of inf and NaN
	tstl	ETEMP_HI(%a6)	//check ms mantissa
	bnes	mfix_nan		//if non-zero, it is a NaN
	tstl	ETEMP_LO(%a6)	//check ls mantissa
	bnes	mfix_nan		//if non-zero, it is a NaN
//input is inf
	orl	#inf_mask,USER_FPSR(%a6) //set I bit
	tstl	ETEMP(%a6)	//check sign
	bge	finish
	orl	#neg_mask,USER_FPSR(%a6) //set N bit
	bra	finish		//special already on stack
mfix_nan:
	orl	#nan_mask,USER_FPSR(%a6) //set NaN bit
	moveb	#nan_tag,STAG(%a6)	//set stag to NaN
	btstb	#signan_bit,ETEMP_HI(%a6) //test for snan
	bnes	mn_snan
	orl	#snaniop_mask,USER_FPSR(%a6) //set snan bit
	btstb	#snan_bit,FPCR_ENABLE(%a6) //test for snan enabled
	bnes	mn_snan
	bsetb	#signan_bit,ETEMP_HI(%a6) //force snans to qnans
mn_snan:
	tstl	ETEMP(%a6)	//check for sign
	bge	finish		//if clr, go on
	orl	#neg_mask,USER_FPSR(%a6) //set N bit
	bra	finish

mtry_zero:
	movew	ETEMP_EX+2(%a6),%d0 //get word 4
	andiw	#0x000f,%d0	//clear all but last ni(y)bble
	tstw	%d0		//check for zero.
	bnes	mnot_spec
	tstl	ETEMP_HI(%a6)	//check words 3 and 2
	bnes	mnot_spec
	tstl	ETEMP_LO(%a6)	//check words 1 and 0
	bnes	mnot_spec
	tstl	ETEMP(%a6)	//test sign of the zero
	bges	mpos_zero
	orl	#neg_mask+z_mask,USER_FPSR(%a6) //set N and Z
	movel	#0x80000000,ETEMP(%a6) //write neg zero to etemp
	clrl	ETEMP_HI(%a6)
	clrl	ETEMP_LO(%a6)
	bras	finish
mpos_zero:
	orl	#z_mask,USER_FPSR(%a6) //set Z
	clrl	ETEMP(%a6)
	clrl	ETEMP_HI(%a6)
	clrl	ETEMP_LO(%a6)
	bras	finish

mnot_spec:
	fmovemx %fp0-%fp1,-(%a7)	//save fp0 ,fp1 - decbin returns in fp0
	bsr	decbin
	fmovex %fp0,ETEMP(%a6)
//				;put the unpacked sop in the fsave stack
	fmovemx (%a7)+,%fp0-%fp1

finish:
	movew	CMDREG1B(%a6),%d0	//get the command word
	andw	#0xfbff,%d0	//change the source specifier field to 
//				;extended (was packed).
	movew	%d0,CMDREG1B(%a6)	//write command word back to fsave stack
//				;we need to do this so the 040 will 
//				;re-execute the inst. without taking 
//				;another packed trap.

fix_stag:
//Converted result is now in etemp on fsave stack, now set the source 
//tag (stag) 
//	if (ete =$7fff) then INF or NAN
//		if (etemp = $x.0----0) then
//			stag = INF
//		else
//			stag = NAN
//	else
//		if (ete = $0000) then
//			stag = ZERO
//		else
//			stag = NORM
//
// Note also that the etemp_15 bit (just right of the stag) must
// be set accordingly.  
//
	movew		ETEMP_EX(%a6),%d1
	andiw		#0x7fff,%d1   //strip sign
	cmpw  		#0x7fff,%d1
	bnes  		z_or_nrm
	movel		ETEMP_HI(%a6),%d1
	bnes		is_nan
	movel		ETEMP_LO(%a6),%d1
	bnes		is_nan
is_inf:
	moveb		#0x40,STAG(%a6)
	movel		#0x40,%d0
	rts
is_nan:
	moveb		#0x60,STAG(%a6)
	movel		#0x60,%d0
	rts
z_or_nrm:
	tstw		%d1  
	bnes		is_nrm
is_zro:
// For a zero, set etemp_15
	moveb		#0x30,STAG(%a6)
	movel		#0x20,%d0
	rts
is_nrm:
// For a norm, check if the exp <= $3fff; if so, set etemp_15
	cmpiw		#0x3fff,%d1
	bles		set_bit15
	moveb		#0,STAG(%a6)
	bras		end_is_nrm
set_bit15:
	moveb		#0x10,STAG(%a6)
end_is_nrm:
	movel		#0,%d0
end_fix:
	rts
 
end_get:
	rts
	|end