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review.evervolv.com / android_kernel_htc_msm8960 / 22e9cd9dc9b51f5ad96588ecbfde5f3221e0e6dd / . / arch / mips / math-emu / dp_div.c
blob: a1bce1b7c09c8a116d079d4d86adc4ad2fb86039 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700[diff] [blame]1/* IEEE754 floating point arithmetic
2 * double precision: common utilities
3 */
4/*
5 * MIPS floating point support
6 * Copyright (C) 1994-2000 Algorithmics Ltd.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700[diff] [blame]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#include "ieee754dp.h"
28
29ieee754dp ieee754dp_div(ieee754dp x, ieee754dp y)
30{
31 COMPXDP;
32 COMPYDP;
33
34 EXPLODEXDP;
35 EXPLODEYDP;
36
37 CLEARCX;
38
39 FLUSHXDP;
40 FLUSHYDP;
41
42 switch (CLPAIR(xc, yc)) {
43 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):
44 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN):
45 case CLPAIR(IEEE754_CLASS_SNAN, 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 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO):
51 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM):
52 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM):
53 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
54 SETCX(IEEE754_INVALID_OPERATION);
55 return ieee754dp_nanxcpt(ieee754dp_indef(), "div", x, y);
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 /* Infinity handling
72 */
73
74 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF):
75 SETCX(IEEE754_INVALID_OPERATION);
76 return ieee754dp_xcpt(ieee754dp_indef(), "div", x, y);
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 /* Zero handling
89 */
90
91 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
92 SETCX(IEEE754_INVALID_OPERATION);
93 return ieee754dp_xcpt(ieee754dp_indef(), "div", x, y);
94
95 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO):
96 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO):
97 SETCX(IEEE754_ZERO_DIVIDE);
98 return ieee754dp_xcpt(ieee754dp_inf(xs ^ ys), "div", x, y);
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
107 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM):
108 DPDNORMY;
109 break;
110
111 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM):
112 DPDNORMX;
113 break;
114
115 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_NORM):
116 break;
117 }
118 assert(xm & DP_HIDDEN_BIT);
119 assert(ym & DP_HIDDEN_BIT);
120
121 /* provide rounding space */
122 xm <<= 3;
123 ym <<= 3;
124
125 {
126 /* now the dirty work */
127
128 u64 rm = 0;
129 int re = xe - ye;
130 u64 bm;
131
132 for (bm = DP_MBIT(DP_MBITS + 2); bm; bm >>= 1) {
133 if (xm >= ym) {
134 xm -= ym;
135 rm |= bm;
136 if (xm == 0)
137 break;
138 }
139 xm <<= 1;
140 }
141 rm <<= 1;
142 if (xm)
143 rm |= 1; /* have remainder, set sticky */
144
145 assert(rm);
146
147 /* normalise rm to rounding precision ?
148 */
149 while ((rm >> (DP_MBITS + 3)) == 0) {
150 rm <<= 1;
151 re--;
152 }
153
154 DPNORMRET2(xs == ys ? 0 : 1, re, rm, "div", x, y);
155 }
156}