GNU Linux-libre 4.19.286-gnu1
[releases.git] / arch / mips / math-emu / dp_div.c
1 /* IEEE754 floating point arithmetic
2  * double precision: common utilities
3  */
4 /*
5  * MIPS floating point support
6  * Copyright (C) 1994-2000 Algorithmics Ltd.
7  *
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.,
19  *  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA.
20  */
21
22 #include "ieee754dp.h"
23
24 union ieee754dp ieee754dp_div(union ieee754dp x, union ieee754dp y)
25 {
26         u64 rm;
27         int re;
28         u64 bm;
29
30         COMPXDP;
31         COMPYDP;
32
33         EXPLODEXDP;
34         EXPLODEYDP;
35
36         ieee754_clearcx();
37
38         FLUSHXDP;
39         FLUSHYDP;
40
41         switch (CLPAIR(xc, yc)) {
42         case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN):
43         case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN):
44         case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN):
45         case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN):
46         case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN):
47                 return ieee754dp_nanxcpt(y);
48
49         case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):
50         case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):
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                 return ieee754dp_nanxcpt(x);
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         /*
72          * Infinity handling
73          */
74         case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF):
75                 ieee754_setcx(IEEE754_INVALID_OPERATION);
76                 return ieee754dp_indef();
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 ieee754dp_zero(xs ^ ys);
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 ieee754dp_inf(xs ^ ys);
87
88         /*
89          * Zero handling
90          */
91         case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
92                 ieee754_setcx(IEEE754_INVALID_OPERATION);
93                 return ieee754dp_indef();
94
95         case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO):
96         case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO):
97                 ieee754_setcx(IEEE754_ZERO_DIVIDE);
98                 return ieee754dp_inf(xs ^ ys);
99
100         case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM):
101         case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM):
102                 return ieee754dp_zero(xs == ys ? 0 : 1);
103
104         case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
105                 DPDNORMX;
106                 /* fall through */
107
108         case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM):
109                 DPDNORMY;
110                 break;
111
112         case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM):
113                 DPDNORMX;
114                 break;
115
116         case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_NORM):
117                 break;
118         }
119         assert(xm & DP_HIDDEN_BIT);
120         assert(ym & DP_HIDDEN_BIT);
121
122         /* provide rounding space */
123         xm <<= 3;
124         ym <<= 3;
125
126         /* now the dirty work */
127
128         rm = 0;
129         re = xe - ye;
130
131         for (bm = DP_MBIT(DP_FBITS + 2); bm; bm >>= 1) {
132                 if (xm >= ym) {
133                         xm -= ym;
134                         rm |= bm;
135                         if (xm == 0)
136                                 break;
137                 }
138                 xm <<= 1;
139         }
140
141         rm <<= 1;
142         if (xm)
143                 rm |= 1;        /* have remainder, set sticky */
144
145         assert(rm);
146
147         /*
148          * Normalise rm to rounding precision ?
149          */
150         while ((rm >> (DP_FBITS + 3)) == 0) {
151                 rm <<= 1;
152                 re--;
153         }
154
155         return ieee754dp_format(xs == ys ? 0 : 1, re, rm);
156 }