Linux-2.6.12-rc2
[linux-2.6.git] / arch / mips / math-emu / sp_tlong.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 s64 ieee754sp_tlong(ieee754sp x)
31 {
32         COMPXDP;                /* <-- need 64-bit mantissa tmp */
33
34         CLEARCX;
35
36         EXPLODEXSP;
37         FLUSHXSP;
38
39         switch (xc) {
40         case IEEE754_CLASS_SNAN:
41         case IEEE754_CLASS_QNAN:
42         case IEEE754_CLASS_INF:
43                 SETCX(IEEE754_INVALID_OPERATION);
44                 return ieee754di_xcpt(ieee754di_indef(), "sp_tlong", x);
45         case IEEE754_CLASS_ZERO:
46                 return 0;
47         case IEEE754_CLASS_DNORM:
48         case IEEE754_CLASS_NORM:
49                 break;
50         }
51         if (xe >= 63) {
52                 /* look for valid corner case */
53                 if (xe == 63 && xs && xm == SP_HIDDEN_BIT)
54                         return -0x8000000000000000LL;
55                 /* Set invalid. We will only use overflow for floating
56                    point overflow */
57                 SETCX(IEEE754_INVALID_OPERATION);
58                 return ieee754di_xcpt(ieee754di_indef(), "sp_tlong", x);
59         }
60         /* oh gawd */
61         if (xe > SP_MBITS) {
62                 xm <<= xe - SP_MBITS;
63         } else if (xe < SP_MBITS) {
64                 u32 residue;
65                 int round;
66                 int sticky;
67                 int odd;
68
69                 if (xe < -1) {
70                         residue = xm;
71                         round = 0;
72                         sticky = residue != 0;
73                         xm = 0;
74                 }
75                 else {
76                         residue = xm << (32 - SP_MBITS + xe);
77                         round = (residue >> 31) != 0;
78                         sticky = (residue << 1) != 0;
79                         xm >>= SP_MBITS - xe;
80                 }
81                 odd = (xm & 0x1) != 0x0;
82                 switch (ieee754_csr.rm) {
83                 case IEEE754_RN:
84                         if (round && (sticky || odd))
85                                 xm++;
86                         break;
87                 case IEEE754_RZ:
88                         break;
89                 case IEEE754_RU:        /* toward +Infinity */
90                         if ((round || sticky) && !xs)
91                                 xm++;
92                         break;
93                 case IEEE754_RD:        /* toward -Infinity */
94                         if ((round || sticky) && xs)
95                                 xm++;
96                         break;
97                 }
98                 if ((xm >> 63) != 0) {
99                         /* This can happen after rounding */
100                         SETCX(IEEE754_INVALID_OPERATION);
101                         return ieee754di_xcpt(ieee754di_indef(), "sp_tlong", x);
102                 }
103                 if (round || sticky)
104                         SETCX(IEEE754_INEXACT);
105         }
106         if (xs)
107                 return -xm;
108         else
109                 return xm;
110 }
111
112
113 u64 ieee754sp_tulong(ieee754sp x)
114 {
115         ieee754sp hb = ieee754sp_1e63();
116
117         /* what if x < 0 ?? */
118         if (ieee754sp_lt(x, hb))
119                 return (u64) ieee754sp_tlong(x);
120
121         return (u64) ieee754sp_tlong(ieee754sp_sub(x, hb)) |
122             (1ULL << 63);
123 }