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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 | ||
28 | #include "ieee754dp.h" | |
29 | ||
2209bcb1 | 30 | union ieee754dp ieee754dp_add(union ieee754dp x, union ieee754dp y) |
1da177e4 LT |
31 | { |
32 | COMPXDP; | |
33 | COMPYDP; | |
34 | ||
35 | EXPLODEXDP; | |
36 | EXPLODEYDP; | |
37 | ||
9e8bad1f | 38 | ieee754_clearcx(); |
1da177e4 LT |
39 | |
40 | FLUSHXDP; | |
41 | FLUSHYDP; | |
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): | |
9e8bad1f | 55 | ieee754_setcx(IEEE754_INVALID_OPERATION); |
90efba36 | 56 | return ieee754dp_nanxcpt(ieee754dp_indef()); |
1da177e4 LT |
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 | ||
75 | case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF): | |
76 | if (xs == ys) | |
77 | return x; | |
9e8bad1f | 78 | ieee754_setcx(IEEE754_INVALID_OPERATION); |
90efba36 | 79 | return ieee754dp_indef(); |
1da177e4 LT |
80 | |
81 | case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF): | |
82 | case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF): | |
83 | case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF): | |
84 | return y; | |
85 | ||
86 | case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO): | |
87 | case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM): | |
88 | case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM): | |
89 | return x; | |
90 | ||
91 | /* Zero handling | |
92 | */ | |
93 | ||
94 | case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO): | |
95 | if (xs == ys) | |
96 | return x; | |
97 | else | |
98 | return ieee754dp_zero(ieee754_csr.rm == | |
99 | IEEE754_RD); | |
100 | ||
101 | case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO): | |
102 | case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO): | |
103 | return x; | |
104 | ||
105 | case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM): | |
106 | case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM): | |
107 | return y; | |
108 | ||
109 | case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM): | |
110 | DPDNORMX; | |
111 | ||
112 | /* FALL THROUGH */ | |
113 | ||
114 | case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM): | |
115 | DPDNORMY; | |
116 | break; | |
117 | ||
118 | case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM): | |
119 | DPDNORMX; | |
120 | break; | |
121 | ||
122 | case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_NORM): | |
123 | break; | |
124 | } | |
125 | assert(xm & DP_HIDDEN_BIT); | |
126 | assert(ym & DP_HIDDEN_BIT); | |
127 | ||
128 | /* provide guard,round and stick bit space */ | |
129 | xm <<= 3; | |
130 | ym <<= 3; | |
131 | ||
132 | if (xe > ye) { | |
133 | /* have to shift y fraction right to align | |
134 | */ | |
135 | int s = xe - ye; | |
136 | ym = XDPSRS(ym, s); | |
137 | ye += s; | |
138 | } else if (ye > xe) { | |
139 | /* have to shift x fraction right to align | |
140 | */ | |
141 | int s = ye - xe; | |
142 | xm = XDPSRS(xm, s); | |
143 | xe += s; | |
144 | } | |
145 | assert(xe == ye); | |
146 | assert(xe <= DP_EMAX); | |
147 | ||
148 | if (xs == ys) { | |
149 | /* generate 28 bit result of adding two 27 bit numbers | |
150 | * leaving result in xm,xs,xe | |
151 | */ | |
152 | xm = xm + ym; | |
153 | xe = xe; | |
154 | xs = xs; | |
155 | ||
ad8fb553 | 156 | if (xm >> (DP_FBITS + 1 + 3)) { /* carry out */ |
1da177e4 LT |
157 | xm = XDPSRS1(xm); |
158 | xe++; | |
159 | } | |
160 | } else { | |
161 | if (xm >= ym) { | |
162 | xm = xm - ym; | |
163 | xe = xe; | |
164 | xs = xs; | |
165 | } else { | |
166 | xm = ym - xm; | |
167 | xe = xe; | |
168 | xs = ys; | |
169 | } | |
170 | if (xm == 0) | |
171 | return ieee754dp_zero(ieee754_csr.rm == | |
172 | IEEE754_RD); | |
173 | ||
174 | /* normalize to rounding precision */ | |
ad8fb553 | 175 | while ((xm >> (DP_FBITS + 3)) == 0) { |
1da177e4 LT |
176 | xm <<= 1; |
177 | xe--; | |
178 | } | |
179 | ||
180 | } | |
90efba36 RB |
181 | |
182 | return ieee754dp_format(xs, xe, xm); | |
1da177e4 | 183 | } |