* Copyright (c) 1986 Regents of the University of California.
* This code is derived from software contributed to Berkeley by
* %sccs.include.redist.c%
#if defined(SYSLIBC_SCCS) && !defined(lint)
.asciz "@(#)muld.s 1.3 (Berkeley) %G%"
#endif /* SYSLIBC_SCCS and not lint */
#include <tahoemath/fp.h>
#define HIDDEN 23 /* here we count from 0 not from 1 as in fp.h */
XENTRY(muld, R2|R3|R4|R5|R6|R7|R8|R9)
clrl r3 /* r3 - sign: 0 for positive,1 for negative. */
bbc $0,r3,1f /* seconed operand is negative. */
clrl r3 /* if first was negative, make result positive. */
1: movl $1,r3 /* if first was positive, make result negative. */
2: andl2 $EXPMASK,r0 /* compute first 'pure'exponent. */
andl2 $EXPMASK,r2 /* compute seconed 'pure'exponent. */
addl2 r0,r2 /* add the exponents. */
cmpl r2,$258 /* normalization can make the exp. smaller. */
* We have the sign in r3,the exponent in r2,now is the time to
* perform the multiplication...
/* fetch first fraction: (r0,r1) */
andl3 $(0!(EXPMASK | SIGNBIT)),4(fp),r0
shlq $7,r0,r0 /* leave the sign bit cleared. */
/* fetch seconed fraction: (r4,r5) */
andl3 $(0!(EXPMASK | SIGNBIT)),12(fp),r4
shlq $7,r4,r4 /* leave the sign bit cleared. */
/* in the following lp1 stands for least significant part of operand 1,
* lp2 for least significant part of operand 2,
* mp1 for most significant part of operand 1,
* mp2 for most significant part of operand 2.
shrl $1,r1,r1 /* clear the sign bit of the lp1. */
emul r1,r4,$0,r6 /* r6,r7 <-- lp1*mp2 */
shlq $1,r6,r6 /* to compensate for the shift we did to clear the sign bit. */
1: shrl $1,r5,r5 /* clear the sign bit of the lp2. */
emul r0,r5,$0,r8 /* r8,r9 <-- mp1*lp2 */
addl2 r9,r7 /* r6,r7 <-- the sum of the products. */
1: emul r0,r4,$0,r0 /* r0,r1 <-- mp1*mp2 */
addl2 r6,r1 /* add the most sig. part of the sum. */
movl r0,r4 /* to see how much we realy need to shift. */
movl $6,r5 /* r5 - shift counter. */
shrl $7,r4,r4 /* dummy shift. */
1: bbs $HIDDEN,r4,realshift
decl r2 /* update exponent. */
decl r5 /* update shift counter. */