File: /usr/src/linux/arch/mips64/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. All rights reserved.
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 "ieee754dp.h"
29
30 ieee754dp ieee754dp_div(ieee754dp x, ieee754dp y)
31 {
32 COMPXDP;
33 COMPYDP;
34
35 CLEARCX;
36
37 EXPLODEXDP;
38 EXPLODEYDP;
39
40 switch (CLPAIR(xc, yc)) {
41 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):
42 return ieee754dp_nanxcpt(ieee754dp_bestnan(x, y), "div", x,
43 y);
44
45 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN):
46 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN):
47 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN):
48 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN):
49 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN):
50 return ieee754dp_nanxcpt(y, "div", x, y);
51
52 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):
53 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO):
54 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM):
55 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM):
56 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
57 return ieee754dp_nanxcpt(x, "div", x, y);
58
59 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
60 return ieee754dp_bestnan(x, y);
61
62 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN):
63 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN):
64 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_QNAN):
65 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_QNAN):
66 return y;
67
68 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_ZERO):
69 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_NORM):
70 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_DNORM):
71 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_INF):
72 return x;
73
74
75 /* Infinity handeling
76 */
77
78 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF):
79 SETCX(IEEE754_INVALID_OPERATION);
80 return ieee754dp_xcpt(ieee754dp_indef(), "div", x, y);
81
82 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF):
83 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF):
84 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF):
85 return ieee754dp_zero(xs ^ ys);
86
87 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO):
88 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM):
89 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM):
90 return ieee754dp_inf(xs ^ ys);
91
92 /* Zero handeling
93 */
94
95 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
96 SETCX(IEEE754_INVALID_OPERATION);
97 return ieee754dp_xcpt(ieee754dp_indef(), "div", x, y);
98
99 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO):
100 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO):
101 SETCX(IEEE754_ZERO_DIVIDE);
102 return ieee754dp_xcpt(ieee754dp_inf(xs ^ ys), "div", x, y);
103
104 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM):
105 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM):
106 return ieee754dp_zero(xs == ys ? 0 : 1);
107
108 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
109 DPDNORMX;
110
111 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM):
112 DPDNORMY;
113 break;
114
115 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM):
116 DPDNORMX;
117 break;
118
119 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_NORM):
120 break;
121 }
122 assert(xm & DP_HIDDEN_BIT);
123 assert(ym & DP_HIDDEN_BIT);
124
125 /* provide rounding space */
126 xm <<= 3;
127 ym <<= 3;
128
129 {
130 /* now the dirty work */
131
132 unsigned long long rm = 0;
133 int re = xe - ye;
134 unsigned long long bm;
135
136 for (bm = DP_MBIT(DP_MBITS + 2); bm; bm >>= 1) {
137 if (xm >= ym) {
138 xm -= ym;
139 rm |= bm;
140 if (xm == 0)
141 break;
142 }
143 xm <<= 1;
144 }
145 rm <<= 1;
146 if (xm)
147 rm |= 1; /* have remainder, set sticky */
148
149 assert(rm);
150
151 /* normalise rm to rounding precision ?
152 */
153 while ((rm >> (DP_MBITS + 3)) == 0) {
154 rm <<= 1;
155 re--;
156 }
157
158 DPNORMRET2(xs == ys ? 0 : 1, re, rm, "div", x, y);
159 }
160 }
161