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1da177e4 LT |
1 | /* IEEE754 floating point arithmetic |
2 | * single precision | |
3 | */ | |
4 | /* | |
5 | * MIPS floating point support | |
6 | * Copyright (C) 1994-2000 Algorithmics Ltd. | |
7 | * http://www.algor.co.uk | |
8 | * | |
9 | * ######################################################################## | |
10 | * | |
11 | * This program is free software; you can distribute it and/or modify it | |
12 | * under the terms of the GNU General Public License (Version 2) as | |
13 | * published by the Free Software Foundation. | |
14 | * | |
15 | * This program is distributed in the hope it will be useful, but WITHOUT | |
16 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
17 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
18 | * for more details. | |
19 | * | |
20 | * You should have received a copy of the GNU General Public License along | |
21 | * with this program; if not, write to the Free Software Foundation, Inc., | |
22 | * 59 Temple Place - Suite 330, Boston MA 02111-1307, USA. | |
23 | * | |
24 | * ######################################################################## | |
25 | */ | |
26 | ||
27 | ||
28 | #include "ieee754sp.h" | |
29 | ||
30 | ieee754sp ieee754sp_mul(ieee754sp x, ieee754sp y) | |
31 | { | |
32 | COMPXSP; | |
33 | COMPYSP; | |
34 | ||
35 | EXPLODEXSP; | |
36 | EXPLODEYSP; | |
37 | ||
38 | CLEARCX; | |
39 | ||
40 | FLUSHXSP; | |
41 | FLUSHYSP; | |
42 | ||
43 | switch (CLPAIR(xc, yc)) { | |
44 | case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN): | |
45 | case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN): | |
46 | case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN): | |
47 | case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN): | |
48 | case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN): | |
49 | case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN): | |
50 | case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN): | |
51 | case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO): | |
52 | case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM): | |
53 | case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM): | |
54 | case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF): | |
55 | SETCX(IEEE754_INVALID_OPERATION); | |
56 | return ieee754sp_nanxcpt(ieee754sp_indef(), "mul", x, y); | |
57 | ||
58 | case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN): | |
59 | case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN): | |
60 | case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_QNAN): | |
61 | case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_QNAN): | |
62 | return y; | |
63 | ||
64 | case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN): | |
65 | case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_ZERO): | |
66 | case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_NORM): | |
67 | case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_DNORM): | |
68 | case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_INF): | |
69 | return x; | |
70 | ||
71 | ||
72 | /* Infinity handling */ | |
73 | ||
74 | case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO): | |
75 | case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF): | |
76 | SETCX(IEEE754_INVALID_OPERATION); | |
77 | return ieee754sp_xcpt(ieee754sp_indef(), "mul", x, y); | |
78 | ||
79 | case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF): | |
80 | case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF): | |
81 | case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM): | |
82 | case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM): | |
83 | case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF): | |
84 | return ieee754sp_inf(xs ^ ys); | |
85 | ||
86 | case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO): | |
87 | case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM): | |
88 | case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM): | |
89 | case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO): | |
90 | case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO): | |
91 | return ieee754sp_zero(xs ^ ys); | |
92 | ||
93 | ||
94 | case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM): | |
95 | SPDNORMX; | |
96 | ||
97 | case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM): | |
98 | SPDNORMY; | |
99 | break; | |
100 | ||
101 | case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM): | |
102 | SPDNORMX; | |
103 | break; | |
104 | ||
105 | case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_NORM): | |
106 | break; | |
107 | } | |
108 | /* rm = xm * ym, re = xe+ye basicly */ | |
109 | assert(xm & SP_HIDDEN_BIT); | |
110 | assert(ym & SP_HIDDEN_BIT); | |
111 | ||
112 | { | |
113 | int re = xe + ye; | |
114 | int rs = xs ^ ys; | |
115 | unsigned rm; | |
116 | ||
117 | /* shunt to top of word */ | |
118 | xm <<= 32 - (SP_MBITS + 1); | |
119 | ym <<= 32 - (SP_MBITS + 1); | |
120 | ||
121 | /* multiply 32bits xm,ym to give high 32bits rm with stickness | |
122 | */ | |
123 | { | |
124 | unsigned short lxm = xm & 0xffff; | |
125 | unsigned short hxm = xm >> 16; | |
126 | unsigned short lym = ym & 0xffff; | |
127 | unsigned short hym = ym >> 16; | |
128 | unsigned lrm; | |
129 | unsigned hrm; | |
130 | ||
131 | lrm = lxm * lym; /* 16 * 16 => 32 */ | |
132 | hrm = hxm * hym; /* 16 * 16 => 32 */ | |
133 | ||
134 | { | |
135 | unsigned t = lxm * hym; /* 16 * 16 => 32 */ | |
136 | { | |
137 | unsigned at = lrm + (t << 16); | |
138 | hrm += at < lrm; | |
139 | lrm = at; | |
140 | } | |
141 | hrm = hrm + (t >> 16); | |
142 | } | |
143 | ||
144 | { | |
145 | unsigned t = hxm * lym; /* 16 * 16 => 32 */ | |
146 | { | |
147 | unsigned at = lrm + (t << 16); | |
148 | hrm += at < lrm; | |
149 | lrm = at; | |
150 | } | |
151 | hrm = hrm + (t >> 16); | |
152 | } | |
153 | rm = hrm | (lrm != 0); | |
154 | } | |
155 | ||
156 | /* | |
157 | * sticky shift down to normal rounding precision | |
158 | */ | |
159 | if ((int) rm < 0) { | |
160 | rm = (rm >> (32 - (SP_MBITS + 1 + 3))) | | |
161 | ((rm << (SP_MBITS + 1 + 3)) != 0); | |
162 | re++; | |
163 | } else { | |
164 | rm = (rm >> (32 - (SP_MBITS + 1 + 3 + 1))) | | |
165 | ((rm << (SP_MBITS + 1 + 3 + 1)) != 0); | |
166 | } | |
167 | assert(rm & (SP_HIDDEN_BIT << 3)); | |
168 | ||
169 | SPNORMRET2(rs, re, rm, "mul", x, y); | |
170 | } | |
171 | } |