168 lines
4.5 KiB
C
168 lines
4.5 KiB
C
/* IEEE754 floating point arithmetic
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* single precision
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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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* 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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* 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#include "ieee754sp.h"
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union ieee754sp ieee754sp_mul(union ieee754sp x, union ieee754sp y)
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{
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int re;
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int rs;
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unsigned int rm;
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unsigned short lxm;
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unsigned short hxm;
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unsigned short lym;
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unsigned short hym;
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unsigned int lrm;
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unsigned int hrm;
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unsigned int t;
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unsigned int at;
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COMPXSP;
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COMPYSP;
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EXPLODEXSP;
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EXPLODEYSP;
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ieee754_clearcx();
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FLUSHXSP;
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FLUSHYSP;
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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 ieee754sp_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 ieee754sp_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 ieee754sp_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 ieee754sp_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 ieee754sp_zero(xs ^ ys);
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case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
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SPDNORMX;
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/* fall through */
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case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM):
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SPDNORMY;
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break;
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case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM):
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SPDNORMX;
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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 & SP_HIDDEN_BIT);
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assert(ym & SP_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 <<= 32 - (SP_FBITS + 1);
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ym <<= 32 - (SP_FBITS + 1);
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/*
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* Multiply 32 bits xm, ym to give high 32 bits rm with stickness.
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*/
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lxm = xm & 0xffff;
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hxm = xm >> 16;
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lym = ym & 0xffff;
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hym = ym >> 16;
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lrm = lxm * lym; /* 16 * 16 => 32 */
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hrm = hxm * hym; /* 16 * 16 => 32 */
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t = lxm * hym; /* 16 * 16 => 32 */
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at = lrm + (t << 16);
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hrm += at < lrm;
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lrm = at;
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hrm = hrm + (t >> 16);
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t = hxm * lym; /* 16 * 16 => 32 */
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at = lrm + (t << 16);
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hrm += at < lrm;
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lrm = at;
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hrm = hrm + (t >> 16);
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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 ((int) rm < 0) {
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rm = (rm >> (32 - (SP_FBITS + 1 + 3))) |
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((rm << (SP_FBITS + 1 + 3)) != 0);
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re++;
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} else {
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rm = (rm >> (32 - (SP_FBITS + 1 + 3 + 1))) |
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((rm << (SP_FBITS + 1 + 3 + 1)) != 0);
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}
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assert(rm & (SP_HIDDEN_BIT << 3));
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return ieee754sp_format(rs, re, rm);
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}
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