xref: /csrg-svn/sys/tahoe/math/Kdivd.s (revision 25693)
1*25693Ssam/*	Kdivd.s	1.3	86/01/05	*/
224119Ssam
3*25693Ssam#include "../tahoemath/fp.h"
4*25693Ssam#include "../tahoemath/Kfp.h"
5*25693Ssam#include "../tahoe/SYS.h"
624119Ssam
725664Ssam#define	HIDDEN	23		# here we count from 0 not from 1 as in fp.h
824119Ssam
924119Ssam	.text
1025664SsamENTRY(Kdivd, R9|R8|R7|R6|R5|R4|R3|R2)
1124119Ssam	clrl	r3		# r3 - sign: 0 for positive,1 for negative.
1224119Ssam	movl	4(fp),r0
1324119Ssam	jgeq	1f
1424119Ssam	movl	$1,r3
1524119Ssam1:	movl	12(fp),r2
1624119Ssam	jgeq	2f
1724119Ssam	bbc	$0,r3,1f	# seconed operand is negative.
1824119Ssam	clrl	r3		# if first was negative, make result positive.
1924119Ssam	jmp	2f
2024119Ssam1:	movl	$1,r3		# if first was positive, make result negative.
2124119Ssam2:	andl2	$EXPMASK,r0	# compute first 'pure'exponent.
2224119Ssam	jeql	retz
2324119Ssam	shrl	$EXPSHIFT,r0,r0
2424119Ssam	subl2	$BIAS,r0
2524119Ssam	andl2	$EXPMASK,r2	# compute seconed 'pure'exponent.
2624119Ssam	jeql	retz2
2724119Ssam	shrl	$EXPSHIFT,r2,r2
2824119Ssam	subl2	$BIAS,r2
2924119Ssam	subl3	r2,r0,r2	# subtruct the exponents.
3024119Ssam	addl2	$BIAS,r2
3124119Ssam	jleq	underf
3224119Ssam				# normalization can make the exp. smaller.
3324119Ssam #
3424119Ssam #	We have the sign in r3,the exponent in r2,now is the time to
3524119Ssam # 	perform the division...
3624119Ssam #
3724119Ssam	# fetch dividend. (r4,r5)
3824119Ssam	andl3	$(0!(EXPMASK | SIGNBIT)),4(fp),r4
3924119Ssam	orl2	$(0!CLEARHID),r4
4024119Ssam	movl	8(fp),r5
4124119Ssam
4224119Ssam	# fetch divisor : (r6,r7)
4324119Ssam	andl3	$(0!(EXPMASK | SIGNBIT)),12(fp),r6
4424119Ssam	orl2	$(0!CLEARHID),r6
4524119Ssam	movl	16(fp),r7
4624119Ssam
4724119Ssam	movl	$0,r0		# init r0,r1 to be zeros
4824119Ssam	movl	$0,r1
4924119Ssam	movl	$(0!CLEARHID),r8# r8 first bit to set (if).
5024119Ssam	shll	$1,r8,r8	# to have one more bit,because we might
5124119Ssam				# have to shift left to normelize.
5224119Ssam	movl	$0,r9
5324119Ssam
5424119Ssam2:
5524119Ssam	subl2	r7,r5
5624119Ssam	sbwc	r6,r4
5724119Ssam	jgeq	1f
5824119Ssam	addl2	r7,r5
5924119Ssam	adwc	r6,r4
6024119Ssam	shlq	$1,r4,r4
6124119Ssam	shrq	$1,r8,r8
6224119Ssam	jeql	over
6324119Ssam	jmp	2b
6424119Ssam1:
6524119Ssam	orl2	r8,r0
6624119Ssam	orl2	r9,r1
6724119Ssam	shlq	$1,r4,r4
6824119Ssam	shrq	$1,r8,r8
6924119Ssam	jneq	2b
7024119Ssam
7124119Ssamover:
7224119Ssam	pushl 	20(fp)
7325664Ssam	callf	$8,_Kfnorm
7424119Ssamsign:
7524119Ssam1:	bbc	$0,r3,done
7624119Ssam	orl2	$SIGNBIT,r0
7724119Ssamdone:	ret
7824119Ssam
7924119Ssamretz:
8024119Ssam	  clrl	r0
8124119Ssam	  clrl	r1
8224119Ssam	  ret
8324119Ssam
8424119Ssamretz2:	bbc	$31,12(fp),z_div
8524119Ssam	  clrl	r0
8624119Ssam	  clrl	r1
8724119Ssam	  ret
8824119Ssamunderf:
8924119Ssam	orl2	$HFS_UNDF,*20(fp)
9024119Ssam	ret
9124119Ssamz_div:
9224119Ssam	orl2	$HFS_DIVZ,*20(fp)
9324119Ssam	ret
94