161 lines
3.8 KiB
C
161 lines
3.8 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/* 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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*/
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#include "ieee754dp.h"
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union ieee754dp ieee754dp_mul(union ieee754dp x, union ieee754dp y)
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{
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int re;
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int rs;
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u64 rm;
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unsigned int lxm;
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unsigned int hxm;
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unsigned int lym;
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unsigned int hym;
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u64 lrm;
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u64 hrm;
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u64 t;
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u64 at;
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COMPXDP;
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COMPYDP;
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EXPLODEXDP;
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EXPLODEYDP;
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ieee754_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_QNAN, 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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return ieee754dp_nanxcpt(y);
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case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):
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case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):
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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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return ieee754dp_nanxcpt(x);
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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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/*
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* Infinity handling
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*/
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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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ieee754_setcx(IEEE754_INVALID_OPERATION);
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return ieee754dp_indef();
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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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/* fall through */
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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 basically */
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assert(xm & DP_HIDDEN_BIT);
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assert(ym & DP_HIDDEN_BIT);
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re = xe + ye;
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rs = xs ^ ys;
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/* shunt to top of word */
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xm <<= 64 - (DP_FBITS + 1);
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ym <<= 64 - (DP_FBITS + 1);
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/*
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* Multiply 64 bits xm, ym to give high 64 bits rm with stickness.
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*/
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lxm = xm;
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hxm = xm >> 32;
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lym = ym;
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hym = ym >> 32;
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lrm = DPXMULT(lxm, lym);
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hrm = DPXMULT(hxm, hym);
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t = DPXMULT(lxm, hym);
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at = lrm + (t << 32);
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hrm += at < lrm;
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lrm = at;
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hrm = hrm + (t >> 32);
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t = DPXMULT(hxm, lym);
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at = lrm + (t << 32);
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hrm += at < lrm;
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lrm = at;
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hrm = hrm + (t >> 32);
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rm = hrm | (lrm != 0);
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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 = (rm >> (64 - (DP_FBITS + 1 + 3))) |
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((rm << (DP_FBITS + 1 + 3)) != 0);
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re++;
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} else {
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rm = (rm >> (64 - (DP_FBITS + 1 + 3 + 1))) |
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((rm << (DP_FBITS + 1 + 3 + 1)) != 0);
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}
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assert(rm & (DP_HIDDEN_BIT << 3));
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return ieee754dp_format(rs, re, rm);
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}
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