![Linus Torvalds](/assets/img/avatar_default.png)
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
178 lines
4.7 KiB
C
178 lines
4.7 KiB
C
/* IEEE754 floating point arithmetic
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* double precision: common utilities
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*/
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/*
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* MIPS floating point support
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* Copyright (C) 1994-2000 Algorithmics Ltd.
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* http://www.algor.co.uk
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*
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* ########################################################################
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*
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* This program is free software; you can distribute it and/or modify it
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* under the terms of the GNU General Public License (Version 2) as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 59 Temple Place - Suite 330, Boston MA 02111-1307, USA.
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*
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* ########################################################################
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*/
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#include "ieee754dp.h"
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ieee754dp ieee754dp_mul(ieee754dp x, ieee754dp y)
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{
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COMPXDP;
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COMPYDP;
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EXPLODEXDP;
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EXPLODEYDP;
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CLEARCX;
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FLUSHXDP;
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FLUSHYDP;
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switch (CLPAIR(xc, yc)) {
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case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):
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case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN):
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case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):
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case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN):
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case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN):
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case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN):
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case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN):
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case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO):
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case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM):
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case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM):
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case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
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SETCX(IEEE754_INVALID_OPERATION);
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return ieee754dp_nanxcpt(ieee754dp_indef(), "mul", x, y);
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case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN):
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case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN):
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case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_QNAN):
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case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_QNAN):
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return y;
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case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
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case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_ZERO):
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case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_NORM):
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case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_DNORM):
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case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_INF):
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return x;
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/* Infinity handling */
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case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO):
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case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF):
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SETCX(IEEE754_INVALID_OPERATION);
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return ieee754dp_xcpt(ieee754dp_indef(), "mul", x, y);
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case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF):
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case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF):
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case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM):
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case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM):
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case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF):
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return ieee754dp_inf(xs ^ ys);
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case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
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case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM):
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case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM):
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case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO):
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case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO):
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return ieee754dp_zero(xs ^ ys);
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case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
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DPDNORMX;
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case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM):
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DPDNORMY;
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break;
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case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM):
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DPDNORMX;
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break;
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case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_NORM):
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break;
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}
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/* rm = xm * ym, re = xe+ye basicly */
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assert(xm & DP_HIDDEN_BIT);
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assert(ym & DP_HIDDEN_BIT);
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{
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int re = xe + ye;
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int rs = xs ^ ys;
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u64 rm;
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/* shunt to top of word */
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xm <<= 64 - (DP_MBITS + 1);
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ym <<= 64 - (DP_MBITS + 1);
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/* multiply 32bits xm,ym to give high 32bits rm with stickness
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*/
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/* 32 * 32 => 64 */
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#define DPXMULT(x,y) ((u64)(x) * (u64)y)
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{
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unsigned lxm = xm;
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unsigned hxm = xm >> 32;
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unsigned lym = ym;
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unsigned hym = ym >> 32;
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u64 lrm;
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u64 hrm;
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lrm = DPXMULT(lxm, lym);
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hrm = DPXMULT(hxm, hym);
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{
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u64 t = DPXMULT(lxm, hym);
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{
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u64 at =
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lrm + (t << 32);
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hrm += at < lrm;
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lrm = at;
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}
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hrm = hrm + (t >> 32);
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}
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{
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u64 t = DPXMULT(hxm, lym);
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{
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u64 at =
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lrm + (t << 32);
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hrm += at < lrm;
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lrm = at;
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}
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hrm = hrm + (t >> 32);
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}
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rm = hrm | (lrm != 0);
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}
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/*
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* sticky shift down to normal rounding precision
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*/
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if ((s64) rm < 0) {
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rm =
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(rm >> (64 - (DP_MBITS + 1 + 3))) |
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((rm << (DP_MBITS + 1 + 3)) != 0);
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re++;
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} else {
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rm =
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(rm >> (64 - (DP_MBITS + 1 + 3 + 1))) |
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((rm << (DP_MBITS + 1 + 3 + 1)) != 0);
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}
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assert(rm & (DP_HIDDEN_BIT << 3));
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DPNORMRET2(rs, re, rm, "mul", x, y);
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}
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}
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