_Qfmul.c revision 7c478bd95313f5f23a4c958a745db2134aa03244
/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License, Version 1.0 only
* (the "License"). You may not use this file except in compliance
* with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
#pragma ident "%Z%%M% %I% %E% SMI"
/*
* Copyright (c) 1988 by Sun Microsystems, Inc.
*/
#include "_Qquad.h"
#include "_Qglobals.h"
void
_fp_mul(px, py, pz)
unpacked *px, *py, *pz;
{
unpacked *pt;
unsigned acc[4]; /* Product accumulator. */
unsigned i,j,y,*x,s,r,c;
if ((int) px->fpclass < (int) py->fpclass) {
pt = px;
px = py;
py = pt;
}
/* Now class(x) >= class(y). */
*pz = *px;
pz->sign = px->sign ^ py->sign;
switch (px->fpclass) {
case fp_quiet:
case fp_signaling:
case fp_zero:
return;
case fp_infinity:
if (py->fpclass == fp_zero) {
fpu_error_nan(pz);
pz->fpclass = fp_quiet;
}
return;
case fp_normal:
if (py->fpclass == fp_zero) {
pz->fpclass = fp_zero;
return;
}
}
/* Now x and y are both normal or subnormal. */
x = px->significand; /* save typing */
s=r=acc[0]=acc[1]=acc[2]=acc[3]=0; /* intialize acc to zero */
y = py->significand[3]; /* py->significand[3] * x */
if(y!=0) {
j=1;
do {
s |= r; /* shift acc right one bit */
r = acc[3]&1;
acc[3] = ((acc[2]&1)<<31)|(acc[3]>>1);
acc[2] = ((acc[1]&1)<<31)|(acc[2]>>1);
acc[1] = ((acc[0]&1)<<31)|(acc[1]>>1);
acc[0] = (acc[0]>>1);
if(j&y) { /* bit i of y != 0, add x to acc */
c = 0;
c = fpu_add3wc(&acc[3],acc[3],x[3],c);
c = fpu_add3wc(&acc[2],acc[2],x[2],c);
c = fpu_add3wc(&acc[1],acc[1],x[1],c);
c = fpu_add3wc(&acc[0],acc[0],x[0],c);
}
j += j;
} while (j!=0);
}
y = py->significand[2]; /* py->significand[2] * x */
if(y!=0) {
j=1;
do {
s |= r; /* shift acc right one bit */
r = acc[3]&1;
acc[3] = ((acc[2]&1)<<31)|(acc[3]>>1);
acc[2] = ((acc[1]&1)<<31)|(acc[2]>>1);
acc[1] = ((acc[0]&1)<<31)|(acc[1]>>1);
acc[0] = (acc[0]>>1);
if(j&y) { /* bit i of y != 0, add x to acc */
c = 0;
c = fpu_add3wc(&acc[3],acc[3],x[3],c);
c = fpu_add3wc(&acc[2],acc[2],x[2],c);
c = fpu_add3wc(&acc[1],acc[1],x[1],c);
c = fpu_add3wc(&acc[0],acc[0],x[0],c);
}
j += j;
} while (j!=0);
} else {
s |= r|(acc[3]&0x7fffffff);
r = (acc[3]&0x80000000)>>31;
acc[3]=acc[2];acc[2]=acc[1];acc[1]=acc[0];acc[0]=0;
}
y = py->significand[1]; /* py->significand[1] * x */
if(y!=0) {
j=1;
do {
s |= r; /* shift acc right one bit */
r = acc[3]&1;
acc[3] = ((acc[2]&1)<<31)|(acc[3]>>1);
acc[2] = ((acc[1]&1)<<31)|(acc[2]>>1);
acc[1] = ((acc[0]&1)<<31)|(acc[1]>>1);
acc[0] = (acc[0]>>1);
if(j&y) { /* bit i of y != 0, add x to acc */
c = 0;
c = fpu_add3wc(&acc[3],acc[3],x[3],c);
c = fpu_add3wc(&acc[2],acc[2],x[2],c);
c = fpu_add3wc(&acc[1],acc[1],x[1],c);
c = fpu_add3wc(&acc[0],acc[0],x[0],c);
}
j += j;
} while (j!=0);
} else {
s |= r|(acc[3]&0x7fffffff);
r = (acc[3]&0x80000000)>>31;
acc[3]=acc[2];acc[2]=acc[1];acc[1]=acc[0];acc[0]=0;
}
/* py->significand[0] * x */
y = py->significand[0]; /* y is of form 0x0001???? */
j=1;
do {
s |= r; /* shift acc right one bit */
r = acc[3]&1;
acc[3] = ((acc[2]&1)<<31)|(acc[3]>>1);
acc[2] = ((acc[1]&1)<<31)|(acc[2]>>1);
acc[1] = ((acc[0]&1)<<31)|(acc[1]>>1);
acc[0] = (acc[0]>>1);
if(j&y) { /* bit i of y != 0, add x to acc */
c = 0;
c = fpu_add3wc(&acc[3],acc[3],x[3],c);
c = fpu_add3wc(&acc[2],acc[2],x[2],c);
c = fpu_add3wc(&acc[1],acc[1],x[1],c);
c = fpu_add3wc(&acc[0],acc[0],x[0],c);
}
j += j;
} while (j<=y);
if(acc[0]>=0x20000) { /* right shift one bit to normalize */
pz->exponent = px->exponent + py->exponent + 1;
pz->sticky = s|r;
pz->rounded = acc[3]&1;
pz->significand[3]=((acc[2]&1)<<31)|(acc[3]>>1);
pz->significand[2]=((acc[1]&1)<<31)|(acc[2]>>1);
pz->significand[1]=((acc[0]&1)<<31)|(acc[1]>>1);
pz->significand[0]=(acc[0]>>1);
} else {
pz->exponent = px->exponent + py->exponent;
pz->sticky = s;
pz->rounded = r;
pz->significand[3]=acc[3];
pz->significand[2]=acc[2];
pz->significand[1]=acc[1];
pz->significand[0]=acc[0];
}
}