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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_div(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(), "div", 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 | ||
75 | case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF): | |
76 | SETCX(IEEE754_INVALID_OPERATION); | |
77 | return ieee754sp_xcpt(ieee754sp_indef(), "div", x, y); | |
78 | ||
79 | case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF): | |
80 | case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF): | |
81 | case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF): | |
82 | return ieee754sp_zero(xs ^ ys); | |
83 | ||
84 | case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO): | |
85 | case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM): | |
86 | case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM): | |
87 | return ieee754sp_inf(xs ^ ys); | |
88 | ||
89 | /* Zero handling | |
90 | */ | |
91 | ||
92 | case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO): | |
93 | SETCX(IEEE754_INVALID_OPERATION); | |
94 | return ieee754sp_xcpt(ieee754sp_indef(), "div", x, y); | |
95 | ||
96 | case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO): | |
97 | case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO): | |
98 | SETCX(IEEE754_ZERO_DIVIDE); | |
99 | return ieee754sp_xcpt(ieee754sp_inf(xs ^ ys), "div", x, y); | |
100 | ||
101 | case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM): | |
102 | case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM): | |
103 | return ieee754sp_zero(xs == ys ? 0 : 1); | |
104 | ||
105 | case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM): | |
106 | SPDNORMX; | |
107 | ||
108 | case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM): | |
109 | SPDNORMY; | |
110 | break; | |
111 | ||
112 | case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM): | |
113 | SPDNORMX; | |
114 | break; | |
115 | ||
116 | case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_NORM): | |
117 | break; | |
118 | } | |
119 | assert(xm & SP_HIDDEN_BIT); | |
120 | assert(ym & SP_HIDDEN_BIT); | |
121 | ||
122 | /* provide rounding space */ | |
123 | xm <<= 3; | |
124 | ym <<= 3; | |
125 | ||
126 | { | |
127 | /* now the dirty work */ | |
128 | ||
129 | unsigned rm = 0; | |
130 | int re = xe - ye; | |
131 | unsigned bm; | |
132 | ||
133 | for (bm = SP_MBIT(SP_MBITS + 2); bm; bm >>= 1) { | |
134 | if (xm >= ym) { | |
135 | xm -= ym; | |
136 | rm |= bm; | |
137 | if (xm == 0) | |
138 | break; | |
139 | } | |
140 | xm <<= 1; | |
141 | } | |
142 | rm <<= 1; | |
143 | if (xm) | |
144 | rm |= 1; /* have remainder, set sticky */ | |
145 | ||
146 | assert(rm); | |
147 | ||
148 | /* normalise rm to rounding precision ? | |
149 | */ | |
150 | while ((rm >> (SP_MBITS + 3)) == 0) { | |
151 | rm <<= 1; | |
152 | re--; | |
153 | } | |
154 | ||
155 | SPNORMRET2(xs == ys ? 0 : 1, re, rm, "div", x, y); | |
156 | } | |
157 | } |