[unix-history] / usr / src / sys / tahoe / math / Kaddd.s

/*	Kaddd.s	1.3	86/01/05	*/

#include "../tahoemath/fp.h"
#include "../tahoe/SYS.h"

/*
 * _Kaddd(acc_most,acc_least,op_most,op_least,hfs)
 */

ENTRY(Kaddd, R10|R9|R8|R7|R6|R5|R4|R3|R2)
/*
 * see which operand has a greater exponent
 * The greater one will be fetched into r0,r1,r2,r3.
 * r0,r1 - 'pure' fraction, r2 - exponent, r3 - sign).
 * The smaller operand will be fetched into r4,r5,r6,r7.
 */
	tstl	4(fp)	# handle (a+b) where a and/or b = 0.0
	jneq	next
	movl	16(fp),r1
	movl	12(fp),r0
	ret
next:
	tstl	12(fp)
	jneq	doit
	movl	8(fp),r1
	movl	4(fp),r0
	ret
doit:
	andl3	$EXPMASK,4(fp),r0
	andl3	$EXPMASK,12(fp),r1
	cmpl	r0,r1
	jgtr	first_greater

	movl	12(fp),r0	# bigger operand to r0,r1
	movl	16(fp),r1

	movl	4(fp),r4	# smaller operand to r4,r5
	movl	8(fp),r5
	jmp	expo

first_greater:
	movl	4(fp),r0	# bigger operand to r0,r1
	movl	8(fp),r1

	movl	12(fp),r4	# smaller operand to r4,r5
	movl	16(fp),r5


/*
 * Compute exponents:
 */
expo:
	andl3	$EXPMASK,r0,r2	# r2 will hold the exponent.
	shrl	$EXPSHIFT,r2,r2
	andl3	$EXPMASK,r4,r6	# r6 will hold the exponent.
	shrl	$EXPSHIFT,r6,r6
/*
 * Compare the exponents:
 */
	subl3	r6,r2,r8
	jeql	signs
	cmpl	r8,$MAX_EXP_DIF
	jleq	signs
	ret			# return the bigger number.
 
/*
 * Remember the signs:
 */
signs:
	clrl	r3
	bbc	$31,r0,sign2	# if negative remember it.
	incl	r3
sign2:
	clrl	r7
	bbc	$31,r4,frac	# if negative remember it.
	incl	r7
/*
 * Compute 'pure' fraction:
 */
frac:
				# clear the non fraction parts.
	andl2	$(0!(EXPMASK | SIGNBIT)),r0
				# add the hidden bit.
	orl2	$(0!CLEARHID),r0
				# clear the non fraction parts.
	andl2	$(0!(EXPMASK | SIGNBIT)),r4
				# add the hidden bit.
	orl2	$(0!CLEARHID),r4

/*
 * Shift the smaller operand:
 */
	shrq	r8,r4,r4
eql_exps:
	cmpl 	r3,r7
	jeql	add
	bbc	$0,r3,negr4r5
/*
 * Negate the pair r0,r1:
 */
	clrl	r3
	mcoml	r1,r1
	clrl	r9		# r9 - carry flag.
	incl	r1
	bcc	comr0
	incl	r9		# remember the carry.
comr0:	mcoml	r0,r0
	bbc	$0,r9,add
	incl	r0

/*
 * Add the fractions:
 */
add:
	clrl	r10 		# to remember the sign of the result.
	addl2	r5,r1
	adwc	r4,r0
	jgeq	norm		# if positive go to normelize.
	incl	r10		# else remember it and negate the result.
/*
 * Negate the pair r0,r1:
 */
	clrl	r3
	mcoml	r1,r1
	clrl	r9		# r9 - carry flag.
	incl	r1
	bcc	comr00
	incl	r9		# remember the carry.
comr00:	mcoml	r0,r0
	bbc	$0,r9,norm
	incl	r0
norm:	pushl	20(fp)		# addr of returnen exception.
	callf	$8,_Kfnorm
 
/*
 * Add the sign bit
 */
	bbs	$0,r10,negative
	bbs	$0,r3,negative
	ret
negative:
	orl2	$SIGNBIT,r0
	ret
 
 
/*
 * Negate the pair r4,r5:
 */
negr4r5:
	clrl	r7
	mcoml	r5,r5
	clrl	r9		# r9 - carry flag.
	incl	r5
	bcc	comr4
	incl	r9		# remember the carry.
comr4:	mcoml	r4,r4
	bbc	$0,r9,add
	incl	r4
	jmp	add
 
	movl	r4,r0		# return the  smaller operand.
	movl	r5,r1
	ret
Commit	Line	Data
9d1834ba	1	/* Kaddd.s 1.3 86/01/05 */
e1e5361b	2
9d1834ba SL	3	#include "../tahoemath/fp.h"
9d1834ba SL	4	#include "../tahoe/SYS.h"
e1e5361b	5
2b252132 SL	6	/*
	7	* _Kaddd(acc_most,acc_least,op_most,op_least,hfs)
	8	*/
e1e5361b	9
2b252132 SL	10	ENTRY(Kaddd, R10\|R9\|R8\|R7\|R6\|R5\|R4\|R3\|R2)
	11	/*
	12	* see which operand has a greater exponent
	13	* The greater one will be fetched into r0,r1,r2,r3.
	14	* r0,r1 - 'pure' fraction, r2 - exponent, r3 - sign).
	15	* The smaller operand will be fetched into r4,r5,r6,r7.
	16	*/
e1e5361b SL	17	tstl 4(fp) # handle (a+b) where a and/or b = 0.0
	18	jneq next
	19	movl 16(fp),r1
	20	movl 12(fp),r0
	21	ret
	22	next:
	23	tstl 12(fp)
	24	jneq doit
	25	movl 8(fp),r1
	26	movl 4(fp),r0
	27	ret
	28	doit:
	29	andl3 $EXPMASK,4(fp),r0
	30	andl3 $EXPMASK,12(fp),r1
	31	cmpl r0,r1
	32	jgtr first_greater
	33
	34	movl 12(fp),r0 # bigger operand to r0,r1
	35	movl 16(fp),r1
	36
	37	movl 4(fp),r4 # smaller operand to r4,r5
	38	movl 8(fp),r5
	39	jmp expo
	40
	41	first_greater:
	42	movl 4(fp),r0 # bigger operand to r0,r1
	43	movl 8(fp),r1
	44
	45	movl 12(fp),r4 # smaller operand to r4,r5
	46	movl 16(fp),r5
	47
	48
2b252132 SL	49	/*
	50	* Compute exponents:
	51	*/
e1e5361b SL	52	expo:
	53	andl3 $EXPMASK,r0,r2 # r2 will hold the exponent.
	54	shrl $EXPSHIFT,r2,r2
	55	andl3 $EXPMASK,r4,r6 # r6 will hold the exponent.
	56	shrl $EXPSHIFT,r6,r6
2b252132 SL	57	/*
	58	* Compare the exponents:
	59	*/
e1e5361b SL	60	subl3 r6,r2,r8
	61	jeql signs
	62	cmpl r8,$MAX_EXP_DIF
	63	jleq signs
	64	ret # return the bigger number.
	65
2b252132 SL	66	/*
	67	* Remember the signs:
	68	*/
e1e5361b SL	69	signs:
	70	clrl r3
	71	bbc $31,r0,sign2 # if negative remember it.
	72	incl r3
	73	sign2:
	74	clrl r7
	75	bbc $31,r4,frac # if negative remember it.
	76	incl r7
2b252132 SL	77	/*
	78	* Compute 'pure' fraction:
	79	*/
e1e5361b SL	80	frac:
	81	# clear the non fraction parts.
	82	andl2 $(0!(EXPMASK \| SIGNBIT)),r0
	83	# add the hidden bit.
	84	orl2 $(0!CLEARHID),r0
	85	# clear the non fraction parts.
	86	andl2 $(0!(EXPMASK \| SIGNBIT)),r4
	87	# add the hidden bit.
	88	orl2 $(0!CLEARHID),r4
	89
2b252132 SL	90	/*
	91	* Shift the smaller operand:
	92	*/
e1e5361b SL	93	shrq r8,r4,r4
	94	eql_exps:
	95	cmpl r3,r7
	96	jeql add
	97	bbc $0,r3,negr4r5
2b252132 SL	98	/*
	99	* Negate the pair r0,r1:
	100	*/
e1e5361b SL	101	clrl r3
	102	mcoml r1,r1
	103	clrl r9 # r9 - carry flag.
	104	incl r1
	105	bcc comr0
	106	incl r9 # remember the carry.
	107	comr0: mcoml r0,r0
	108	bbc $0,r9,add
	109	incl r0
	110
2b252132 SL	111	/*
	112	* Add the fractions:
	113	*/
e1e5361b SL	114	add:
	115	clrl r10 # to remember the sign of the result.
	116	addl2 r5,r1
	117	adwc r4,r0
	118	jgeq norm # if positive go to normelize.
	119	incl r10 # else remember it and negate the result.
2b252132 SL	120	/*
	121	* Negate the pair r0,r1:
	122	*/
e1e5361b SL	123	clrl r3
	124	mcoml r1,r1
	125	clrl r9 # r9 - carry flag.
	126	incl r1
	127	bcc comr00
	128	incl r9 # remember the carry.
	129	comr00: mcoml r0,r0
	130	bbc $0,r9,norm
	131	incl r0
	132	norm: pushl 20(fp) # addr of returnen exception.
2b252132	133	callf $8,_Kfnorm
e1e5361b	134
2b252132 SL	135	/*
	136	* Add the sign bit
	137	*/
e1e5361b SL	138	bbs $0,r10,negative
	139	bbs $0,r3,negative
	140	ret
	141	negative:
	142	orl2 $SIGNBIT,r0
	143	ret
	144
	145
2b252132 SL	146	/*
	147	* Negate the pair r4,r5:
	148	*/
e1e5361b SL	149	negr4r5:
	150	clrl r7
	151	mcoml r5,r5
	152	clrl r9 # r9 - carry flag.
	153	incl r5
	154	bcc comr4
	155	incl r9 # remember the carry.
	156	comr4: mcoml r4,r4
	157	bbc $0,r9,add
	158	incl r4
	159	jmp add
	160
e1e5361b SL	161	movl r4,r0 # return the smaller operand.
	162	movl r5,r1
	163	ret