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1da177e4 LT |
1 | /* IEEE754 floating point arithmetic |
2 | * double precision: common utilities | |
3 | */ | |
4 | /* | |
5 | * MIPS floating point support | |
6 | * Copyright (C) 1994-2000 Algorithmics Ltd. | |
1da177e4 LT |
7 | * |
8 | * ######################################################################## | |
9 | * | |
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. | |
13 | * | |
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 | |
17 | * for more details. | |
18 | * | |
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. | |
22 | * | |
23 | * ######################################################################## | |
24 | */ | |
25 | ||
26 | ||
27 | #include "ieee754dp.h" | |
28 | ||
29 | ieee754dp ieee754dp_mul(ieee754dp x, ieee754dp y) | |
30 | { | |
31 | COMPXDP; | |
32 | COMPYDP; | |
33 | ||
34 | EXPLODEXDP; | |
35 | EXPLODEYDP; | |
36 | ||
37 | CLEARCX; | |
38 | ||
39 | FLUSHXDP; | |
40 | FLUSHYDP; | |
41 | ||
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); | |
56 | ||
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): | |
61 | return y; | |
62 | ||
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): | |
68 | return x; | |
69 | ||
70 | ||
71 | /* Infinity handling */ | |
72 | ||
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); | |
77 | ||
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); | |
84 | ||
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); | |
91 | ||
92 | ||
93 | case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM): | |
94 | DPDNORMX; | |
95 | ||
96 | case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM): | |
97 | DPDNORMY; | |
98 | break; | |
99 | ||
100 | case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM): | |
101 | DPDNORMX; | |
102 | break; | |
103 | ||
104 | case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_NORM): | |
105 | break; | |
106 | } | |
25985edc | 107 | /* rm = xm * ym, re = xe+ye basically */ |
1da177e4 LT |
108 | assert(xm & DP_HIDDEN_BIT); |
109 | assert(ym & DP_HIDDEN_BIT); | |
110 | { | |
111 | int re = xe + ye; | |
112 | int rs = xs ^ ys; | |
113 | u64 rm; | |
114 | ||
115 | /* shunt to top of word */ | |
116 | xm <<= 64 - (DP_MBITS + 1); | |
117 | ym <<= 64 - (DP_MBITS + 1); | |
118 | ||
119 | /* multiply 32bits xm,ym to give high 32bits rm with stickness | |
120 | */ | |
121 | ||
122 | /* 32 * 32 => 64 */ | |
21a151d8 | 123 | #define DPXMULT(x, y) ((u64)(x) * (u64)y) |
1da177e4 LT |
124 | |
125 | { | |
126 | unsigned lxm = xm; | |
127 | unsigned hxm = xm >> 32; | |
128 | unsigned lym = ym; | |
129 | unsigned hym = ym >> 32; | |
130 | u64 lrm; | |
131 | u64 hrm; | |
132 | ||
133 | lrm = DPXMULT(lxm, lym); | |
134 | hrm = DPXMULT(hxm, hym); | |
135 | ||
136 | { | |
137 | u64 t = DPXMULT(lxm, hym); | |
138 | { | |
139 | u64 at = | |
140 | lrm + (t << 32); | |
141 | hrm += at < lrm; | |
142 | lrm = at; | |
143 | } | |
144 | hrm = hrm + (t >> 32); | |
145 | } | |
146 | ||
147 | { | |
148 | u64 t = DPXMULT(hxm, lym); | |
149 | { | |
150 | u64 at = | |
151 | lrm + (t << 32); | |
152 | hrm += at < lrm; | |
153 | lrm = at; | |
154 | } | |
155 | hrm = hrm + (t >> 32); | |
156 | } | |
157 | rm = hrm | (lrm != 0); | |
158 | } | |
159 | ||
160 | /* | |
161 | * sticky shift down to normal rounding precision | |
162 | */ | |
163 | if ((s64) rm < 0) { | |
164 | rm = | |
165 | (rm >> (64 - (DP_MBITS + 1 + 3))) | | |
166 | ((rm << (DP_MBITS + 1 + 3)) != 0); | |
167 | re++; | |
168 | } else { | |
169 | rm = | |
170 | (rm >> (64 - (DP_MBITS + 1 + 3 + 1))) | | |
171 | ((rm << (DP_MBITS + 1 + 3 + 1)) != 0); | |
172 | } | |
173 | assert(rm & (DP_HIDDEN_BIT << 3)); | |
174 | DPNORMRET2(rs, re, rm, "mul", x, y); | |
175 | } | |
176 | } |