1 /* IEEE754 floating point arithmetic
2 * double precision: common utilities
5 * MIPS floating point support
6 * Copyright (C) 1994-2000 Algorithmics Ltd.
8 * ########################################################################
10 * This program is free software; you can distribute it and/or modify it
11 * under the terms of the GNU General Public License (Version 2) as
12 * published by the Free Software Foundation.
14 * This program is distributed in the hope it will be useful, but WITHOUT
15 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
16 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
19 * You should have received a copy of the GNU General Public License along
20 * with this program; if not, write to the Free Software Foundation, Inc.,
21 * 59 Temple Place - Suite 330, Boston MA 02111-1307, USA.
23 * ########################################################################
27 #include "ieee754dp.h"
29 ieee754dp ieee754dp_mul(ieee754dp x, ieee754dp y)
42 switch (CLPAIR(xc, yc)) {
43 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):
44 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN):
45 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):
46 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN):
47 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN):
48 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN):
49 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN):
50 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO):
51 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM):
52 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM):
53 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
54 SETCX(IEEE754_INVALID_OPERATION);
55 return ieee754dp_nanxcpt(ieee754dp_indef(), "mul", x, y);
57 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN):
58 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN):
59 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_QNAN):
60 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_QNAN):
63 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
64 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_ZERO):
65 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_NORM):
66 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_DNORM):
67 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_INF):
71 /* Infinity handling */
73 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO):
74 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF):
75 SETCX(IEEE754_INVALID_OPERATION);
76 return ieee754dp_xcpt(ieee754dp_indef(), "mul", x, y);
78 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF):
79 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF):
80 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM):
81 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM):
82 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF):
83 return ieee754dp_inf(xs ^ ys);
85 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
86 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM):
87 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM):
88 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO):
89 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO):
90 return ieee754dp_zero(xs ^ ys);
93 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
96 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM):
100 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM):
104 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_NORM):
107 /* rm = xm * ym, re = xe+ye basically */
108 assert(xm & DP_HIDDEN_BIT);
109 assert(ym & DP_HIDDEN_BIT);
115 /* shunt to top of word */
116 xm <<= 64 - (DP_MBITS + 1);
117 ym <<= 64 - (DP_MBITS + 1);
119 /* multiply 32bits xm,ym to give high 32bits rm with stickness
123 #define DPXMULT(x, y) ((u64)(x) * (u64)y)
127 unsigned hxm = xm >> 32;
129 unsigned hym = ym >> 32;
133 lrm = DPXMULT(lxm, lym);
134 hrm = DPXMULT(hxm, hym);
137 u64 t = DPXMULT(lxm, hym);
144 hrm = hrm + (t >> 32);
148 u64 t = DPXMULT(hxm, lym);
155 hrm = hrm + (t >> 32);
157 rm = hrm | (lrm != 0);
161 * sticky shift down to normal rounding precision
165 (rm >> (64 - (DP_MBITS + 1 + 3))) |
166 ((rm << (DP_MBITS + 1 + 3)) != 0);
170 (rm >> (64 - (DP_MBITS + 1 + 3 + 1))) |
171 ((rm << (DP_MBITS + 1 + 3 + 1)) != 0);
173 assert(rm & (DP_HIDDEN_BIT << 3));
174 DPNORMRET2(rs, re, rm, "mul", x, y);