1 /* IEEE754 floating point arithmetic
5 * MIPS floating point support
6 * Copyright (C) 1994-2000 Algorithmics Ltd.
8 * This program is free software; you can distribute it and/or modify it
9 * under the terms of the GNU General Public License (Version 2) as
10 * published by the Free Software Foundation.
12 * This program is distributed in the hope it will be useful, but WITHOUT
13 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
17 * You should have received a copy of the GNU General Public License along
18 * with this program; if not, write to the Free Software Foundation, Inc.,
19 * 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
22 #include "ieee754sp.h"
24 union ieee754sp ieee754sp_mul(union ieee754sp x, union ieee754sp y)
49 switch (CLPAIR(xc, yc)) {
50 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):
51 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN):
52 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):
53 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN):
54 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN):
55 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN):
56 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN):
57 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO):
58 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM):
59 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM):
60 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
61 ieee754_setcx(IEEE754_INVALID_OPERATION);
62 return ieee754sp_nanxcpt(ieee754sp_indef());
64 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN):
65 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN):
66 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_QNAN):
67 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_QNAN):
70 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
71 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_ZERO):
72 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_NORM):
73 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_DNORM):
74 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_INF):
81 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO):
82 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF):
83 ieee754_setcx(IEEE754_INVALID_OPERATION);
84 return ieee754sp_indef();
86 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF):
87 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF):
88 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM):
89 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM):
90 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF):
91 return ieee754sp_inf(xs ^ ys);
93 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
94 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM):
95 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM):
96 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO):
97 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO):
98 return ieee754sp_zero(xs ^ ys);
101 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
104 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM):
108 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM):
112 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_NORM):
115 /* rm = xm * ym, re = xe+ye basically */
116 assert(xm & SP_HIDDEN_BIT);
117 assert(ym & SP_HIDDEN_BIT);
122 /* shunt to top of word */
123 xm <<= 32 - (SP_FBITS + 1);
124 ym <<= 32 - (SP_FBITS + 1);
127 * Multiply 32 bits xm, ym to give high 32 bits rm with stickness.
134 lrm = lxm * lym; /* 16 * 16 => 32 */
135 hrm = hxm * hym; /* 16 * 16 => 32 */
137 t = lxm * hym; /* 16 * 16 => 32 */
138 at = lrm + (t << 16);
141 hrm = hrm + (t >> 16);
143 t = hxm * lym; /* 16 * 16 => 32 */
144 at = lrm + (t << 16);
147 hrm = hrm + (t >> 16);
149 rm = hrm | (lrm != 0);
152 * Sticky shift down to normal rounding precision.
155 rm = (rm >> (32 - (SP_FBITS + 1 + 3))) |
156 ((rm << (SP_FBITS + 1 + 3)) != 0);
159 rm = (rm >> (32 - (SP_FBITS + 1 + 3 + 1))) |
160 ((rm << (SP_FBITS + 1 + 3 + 1)) != 0);
162 assert(rm & (SP_HIDDEN_BIT << 3));
164 return ieee754sp_format(rs, re, rm);