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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. | |
1da177e4 | 7 | * |
1da177e4 LT |
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. | |
11 | * | |
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 | |
15 | * for more details. | |
16 | * | |
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., | |
3f7cac41 | 19 | * 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
1da177e4 LT |
20 | */ |
21 | ||
1da177e4 LT |
22 | #include "ieee754sp.h" |
23 | ||
2209bcb1 | 24 | union ieee754sp ieee754sp_add(union ieee754sp x, union ieee754sp y) |
1da177e4 | 25 | { |
3f7cac41 RB |
26 | int s; |
27 | ||
1da177e4 LT |
28 | COMPXSP; |
29 | COMPYSP; | |
30 | ||
31 | EXPLODEXSP; | |
32 | EXPLODEYSP; | |
33 | ||
9e8bad1f | 34 | ieee754_clearcx(); |
1da177e4 LT |
35 | |
36 | FLUSHXSP; | |
37 | FLUSHYSP; | |
38 | ||
39 | switch (CLPAIR(xc, yc)) { | |
1da177e4 | 40 | case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN): |
1da177e4 LT |
41 | case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN): |
42 | case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN): | |
43 | case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN): | |
44 | case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN): | |
d5afa7e9 MR |
45 | return ieee754sp_nanxcpt(y); |
46 | ||
47 | case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN): | |
48 | case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN): | |
1da177e4 LT |
49 | case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO): |
50 | case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM): | |
51 | case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM): | |
52 | case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF): | |
d5afa7e9 | 53 | return ieee754sp_nanxcpt(x); |
1da177e4 LT |
54 | |
55 | case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN): | |
56 | case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN): | |
57 | case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_QNAN): | |
58 | case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_QNAN): | |
59 | return y; | |
60 | ||
61 | case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN): | |
62 | case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_ZERO): | |
63 | case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_NORM): | |
64 | case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_DNORM): | |
65 | case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_INF): | |
66 | return x; | |
67 | ||
68 | ||
3f7cac41 RB |
69 | /* |
70 | * Infinity handling | |
71 | */ | |
1da177e4 LT |
72 | case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF): |
73 | if (xs == ys) | |
74 | return x; | |
9e8bad1f | 75 | ieee754_setcx(IEEE754_INVALID_OPERATION); |
90efba36 | 76 | return ieee754sp_indef(); |
1da177e4 LT |
77 | |
78 | case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF): | |
79 | case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF): | |
80 | case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF): | |
81 | return y; | |
82 | ||
83 | case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO): | |
84 | case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM): | |
85 | case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM): | |
86 | return x; | |
87 | ||
3f7cac41 RB |
88 | /* |
89 | * Zero handling | |
90 | */ | |
1da177e4 LT |
91 | case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO): |
92 | if (xs == ys) | |
93 | return x; | |
94 | else | |
56a64733 | 95 | return ieee754sp_zero(ieee754_csr.rm == FPU_CSR_RD); |
1da177e4 LT |
96 | |
97 | case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO): | |
98 | case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO): | |
99 | return x; | |
100 | ||
101 | case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM): | |
102 | case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM): | |
103 | return y; | |
104 | ||
105 | case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM): | |
106 | SPDNORMX; | |
107 | ||
3f7cac41 RB |
108 | /* FALL THROUGH */ |
109 | ||
1da177e4 LT |
110 | case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM): |
111 | SPDNORMY; | |
112 | break; | |
113 | ||
114 | case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM): | |
115 | SPDNORMX; | |
116 | break; | |
117 | ||
118 | case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_NORM): | |
119 | break; | |
120 | } | |
121 | assert(xm & SP_HIDDEN_BIT); | |
122 | assert(ym & SP_HIDDEN_BIT); | |
123 | ||
3f7cac41 RB |
124 | /* |
125 | * Provide guard, round and stick bit space. | |
126 | */ | |
1da177e4 LT |
127 | xm <<= 3; |
128 | ym <<= 3; | |
129 | ||
130 | if (xe > ye) { | |
3f7cac41 RB |
131 | /* |
132 | * Have to shift y fraction right to align. | |
1da177e4 | 133 | */ |
3f7cac41 | 134 | s = xe - ye; |
db57f29d PB |
135 | ym = XSPSRS(ym, s); |
136 | ye += s; | |
1da177e4 | 137 | } else if (ye > xe) { |
3f7cac41 RB |
138 | /* |
139 | * Have to shift x fraction right to align. | |
1da177e4 | 140 | */ |
3f7cac41 | 141 | s = ye - xe; |
db57f29d PB |
142 | xm = XSPSRS(xm, s); |
143 | xe += s; | |
1da177e4 LT |
144 | } |
145 | assert(xe == ye); | |
146 | assert(xe <= SP_EMAX); | |
147 | ||
148 | if (xs == ys) { | |
3f7cac41 RB |
149 | /* |
150 | * Generate 28 bit result of adding two 27 bit numbers | |
151 | * leaving result in xm, xs and xe. | |
1da177e4 LT |
152 | */ |
153 | xm = xm + ym; | |
1da177e4 | 154 | |
ad8fb553 | 155 | if (xm >> (SP_FBITS + 1 + 3)) { /* carry out */ |
1da177e4 LT |
156 | SPXSRSX1(); |
157 | } | |
158 | } else { | |
159 | if (xm >= ym) { | |
160 | xm = xm - ym; | |
1da177e4 LT |
161 | } else { |
162 | xm = ym - xm; | |
1da177e4 LT |
163 | xs = ys; |
164 | } | |
165 | if (xm == 0) | |
56a64733 | 166 | return ieee754sp_zero(ieee754_csr.rm == FPU_CSR_RD); |
1da177e4 | 167 | |
3f7cac41 RB |
168 | /* |
169 | * Normalize in extended single precision | |
170 | */ | |
ad8fb553 | 171 | while ((xm >> (SP_FBITS + 3)) == 0) { |
1da177e4 LT |
172 | xm <<= 1; |
173 | xe--; | |
174 | } | |
1da177e4 | 175 | } |
90efba36 RB |
176 | |
177 | return ieee754sp_format(xs, xe, xm); | |
1da177e4 | 178 | } |