165 lines
3.9 KiB
C
165 lines
3.9 KiB
C
#ifdef sccsid
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static char sccsid[] = "@(#)_Qfmul.c 1.1 94/10/31 SMI";
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#endif
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/*
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* Copyright (c) 1988 by Sun Microsystems, Inc.
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*/
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#include "_Qquad.h"
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#include "_Qglobals.h"
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void
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_fp_mul(px, py, pz)
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unpacked *px, *py, *pz;
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{
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unpacked *pt;
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unsigned acc[4]; /* Product accumulator. */
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unsigned i,j,y,*x,s,r,c;
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if ((int) px->fpclass < (int) py->fpclass) {
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pt = px;
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px = py;
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py = pt;
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}
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/* Now class(x) >= class(y). */
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*pz = *px;
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pz->sign = px->sign ^ py->sign;
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switch (px->fpclass) {
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case fp_quiet:
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case fp_signaling:
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case fp_zero:
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return;
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case fp_infinity:
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if (py->fpclass == fp_zero) {
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fpu_error_nan(pz);
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pz->fpclass = fp_quiet;
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}
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return;
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case fp_normal:
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if (py->fpclass == fp_zero) {
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pz->fpclass = fp_zero;
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return;
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}
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}
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/* Now x and y are both normal or subnormal. */
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x = px->significand; /* save typing */
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s=r=acc[0]=acc[1]=acc[2]=acc[3]=0; /* intialize acc to zero */
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y = py->significand[3]; /* py->significand[3] * x */
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if(y!=0) {
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j=1;
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do {
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s |= r; /* shift acc right one bit */
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r = acc[3]&1;
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acc[3] = ((acc[2]&1)<<31)|(acc[3]>>1);
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acc[2] = ((acc[1]&1)<<31)|(acc[2]>>1);
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acc[1] = ((acc[0]&1)<<31)|(acc[1]>>1);
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acc[0] = (acc[0]>>1);
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if(j&y) { /* bit i of y != 0, add x to acc */
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c = 0;
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c = fpu_add3wc(&acc[3],acc[3],x[3],c);
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c = fpu_add3wc(&acc[2],acc[2],x[2],c);
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c = fpu_add3wc(&acc[1],acc[1],x[1],c);
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c = fpu_add3wc(&acc[0],acc[0],x[0],c);
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}
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j += j;
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} while (j!=0);
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}
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y = py->significand[2]; /* py->significand[2] * x */
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if(y!=0) {
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j=1;
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do {
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s |= r; /* shift acc right one bit */
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r = acc[3]&1;
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acc[3] = ((acc[2]&1)<<31)|(acc[3]>>1);
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acc[2] = ((acc[1]&1)<<31)|(acc[2]>>1);
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acc[1] = ((acc[0]&1)<<31)|(acc[1]>>1);
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acc[0] = (acc[0]>>1);
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if(j&y) { /* bit i of y != 0, add x to acc */
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c = 0;
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c = fpu_add3wc(&acc[3],acc[3],x[3],c);
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c = fpu_add3wc(&acc[2],acc[2],x[2],c);
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c = fpu_add3wc(&acc[1],acc[1],x[1],c);
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c = fpu_add3wc(&acc[0],acc[0],x[0],c);
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}
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j += j;
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} while (j!=0);
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} else {
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s |= r|(acc[3]&0x7fffffff);
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r = (acc[3]&0x80000000)>>31;
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acc[3]=acc[2];acc[2]=acc[1];acc[1]=acc[0];acc[0]=0;
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}
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y = py->significand[1]; /* py->significand[1] * x */
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if(y!=0) {
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j=1;
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do {
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s |= r; /* shift acc right one bit */
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r = acc[3]&1;
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acc[3] = ((acc[2]&1)<<31)|(acc[3]>>1);
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acc[2] = ((acc[1]&1)<<31)|(acc[2]>>1);
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acc[1] = ((acc[0]&1)<<31)|(acc[1]>>1);
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acc[0] = (acc[0]>>1);
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if(j&y) { /* bit i of y != 0, add x to acc */
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c = 0;
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c = fpu_add3wc(&acc[3],acc[3],x[3],c);
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c = fpu_add3wc(&acc[2],acc[2],x[2],c);
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c = fpu_add3wc(&acc[1],acc[1],x[1],c);
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c = fpu_add3wc(&acc[0],acc[0],x[0],c);
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}
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j += j;
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} while (j!=0);
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} else {
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s |= r|(acc[3]&0x7fffffff);
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r = (acc[3]&0x80000000)>>31;
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acc[3]=acc[2];acc[2]=acc[1];acc[1]=acc[0];acc[0]=0;
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}
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/* py->significand[0] * x */
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y = py->significand[0]; /* y is of form 0x0001???? */
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j=1;
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do {
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s |= r; /* shift acc right one bit */
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r = acc[3]&1;
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acc[3] = ((acc[2]&1)<<31)|(acc[3]>>1);
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acc[2] = ((acc[1]&1)<<31)|(acc[2]>>1);
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acc[1] = ((acc[0]&1)<<31)|(acc[1]>>1);
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acc[0] = (acc[0]>>1);
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if(j&y) { /* bit i of y != 0, add x to acc */
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c = 0;
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c = fpu_add3wc(&acc[3],acc[3],x[3],c);
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c = fpu_add3wc(&acc[2],acc[2],x[2],c);
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c = fpu_add3wc(&acc[1],acc[1],x[1],c);
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c = fpu_add3wc(&acc[0],acc[0],x[0],c);
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}
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j += j;
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} while (j<=y);
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if(acc[0]>=0x20000) { /* right shift one bit to normalize */
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pz->exponent = px->exponent + py->exponent + 1;
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pz->sticky = s|r;
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pz->rounded = acc[3]&1;
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pz->significand[3]=((acc[2]&1)<<31)|(acc[3]>>1);
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pz->significand[2]=((acc[1]&1)<<31)|(acc[2]>>1);
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pz->significand[1]=((acc[0]&1)<<31)|(acc[1]>>1);
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pz->significand[0]=(acc[0]>>1);
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} else {
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pz->exponent = px->exponent + py->exponent;
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pz->sticky = s;
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pz->rounded = r;
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pz->significand[3]=acc[3];
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pz->significand[2]=acc[2];
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pz->significand[1]=acc[1];
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pz->significand[0]=acc[0];
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}
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}
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