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review.evervolv.com / android_kernel_htc_msm8960 / af9deabeb0298559227fd9b481d33aefcb15ca54 / . / arch / mips / math-emu / sp_div.c
blob: 2b437fcfdad94f4d3d2ff8ce824323e083f53efc [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700[diff] [blame]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
30ieee754sp 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}