Merge branch 'sh/for-2.6.28' of git://git.kernel.org/pub/scm/linux/kernel/git/lethal...
[linux-2.6] / arch / mips / math-emu / sp_div.c
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
30 ieee754sp 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 }