1 /* IEEE754 floating point arithmetic
2 * single precision
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 "ieee754sp.h"
23
ieee754sp_div(union ieee754sp x,union ieee754sp y)24 union ieee754sp ieee754sp_div(union ieee754sp x, union ieee754sp y)
25 {
26 unsigned rm;
27 int re;
28 unsigned bm;
29
30 COMPXSP;
31 COMPYSP;
32
33 EXPLODEXSP;
34 EXPLODEYSP;
35
36 ieee754_clearcx();
37
38 FLUSHXSP;
39 FLUSHYSP;
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 ieee754sp_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 ieee754sp_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 ieee754sp_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 ieee754sp_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 ieee754sp_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 ieee754sp_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 ieee754sp_inf(xs ^ ys);
99
100 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM):
101 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM):
102 return ieee754sp_zero(xs == ys ? 0 : 1);
103
104 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
105 SPDNORMX;
106
107 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM):
108 SPDNORMY;
109 break;
110
111 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM):
112 SPDNORMX;
113 break;
114
115 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_NORM):
116 break;
117 }
118 assert(xm & SP_HIDDEN_BIT);
119 assert(ym & SP_HIDDEN_BIT);
120
121 /* provide rounding space */
122 xm <<= 3;
123 ym <<= 3;
124
125 /* now the dirty work */
126
127 rm = 0;
128 re = xe - ye;
129
130 for (bm = SP_MBIT(SP_FBITS + 2); bm; bm >>= 1) {
131 if (xm >= ym) {
132 xm -= ym;
133 rm |= bm;
134 if (xm == 0)
135 break;
136 }
137 xm <<= 1;
138 }
139
140 rm <<= 1;
141 if (xm)
142 rm |= 1; /* have remainder, set sticky */
143
144 assert(rm);
145
146 /* normalise rm to rounding precision ?
147 */
148 while ((rm >> (SP_FBITS + 3)) == 0) {
149 rm <<= 1;
150 re--;
151 }
152
153 return ieee754sp_format(xs == ys ? 0 : 1, re, rm);
154 }
155