blob: 1d73d2abe0b5a516198c2c0bc622c7a9b29e6414 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/* 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 <linux/kernel.h>
29#include "ieee754sp.h"
30
31int ieee754sp_tint(ieee754sp x)
32{
33 COMPXSP;
34
35 CLEARCX;
36
37 EXPLODEXSP;
38 FLUSHXSP;
39
40 switch (xc) {
41 case IEEE754_CLASS_SNAN:
42 case IEEE754_CLASS_QNAN:
43 case IEEE754_CLASS_INF:
44 SETCX(IEEE754_INVALID_OPERATION);
45 return ieee754si_xcpt(ieee754si_indef(), "sp_tint", x);
46 case IEEE754_CLASS_ZERO:
47 return 0;
48 case IEEE754_CLASS_DNORM:
49 case IEEE754_CLASS_NORM:
50 break;
51 }
52 if (xe >= 31) {
53 /* look for valid corner case */
54 if (xe == 31 && xs && xm == SP_HIDDEN_BIT)
55 return -0x80000000;
56 /* Set invalid. We will only use overflow for floating
57 point overflow */
58 SETCX(IEEE754_INVALID_OPERATION);
59 return ieee754si_xcpt(ieee754si_indef(), "sp_tint", x);
60 }
61 /* oh gawd */
62 if (xe > SP_MBITS) {
63 xm <<= xe - SP_MBITS;
64 } else {
65 u32 residue;
66 int round;
67 int sticky;
68 int odd;
69
70 if (xe < -1) {
71 residue = xm;
72 round = 0;
73 sticky = residue != 0;
74 xm = 0;
75 }
76 else {
77 /* Shifting a u32 32 times does not work,
78 * so we do it in two steps. Be aware that xe
79 * may be -1 */
80 residue = xm << (xe + 1);
81 residue <<= 31 - SP_MBITS;
82 round = (residue >> 31) != 0;
83 sticky = (residue << 1) != 0;
84 xm >>= SP_MBITS - xe;
85 }
86 odd = (xm & 0x1) != 0x0;
87 switch (ieee754_csr.rm) {
88 case IEEE754_RN:
89 if (round && (sticky || odd))
90 xm++;
91 break;
92 case IEEE754_RZ:
93 break;
94 case IEEE754_RU: /* toward +Infinity */
95 if ((round || sticky) && !xs)
96 xm++;
97 break;
98 case IEEE754_RD: /* toward -Infinity */
99 if ((round || sticky) && xs)
100 xm++;
101 break;
102 }
103 if ((xm >> 31) != 0) {
104 /* This can happen after rounding */
105 SETCX(IEEE754_INVALID_OPERATION);
106 return ieee754si_xcpt(ieee754si_indef(), "sp_tint", x);
107 }
108 if (round || sticky)
109 SETCX(IEEE754_INEXACT);
110 }
111 if (xs)
112 return -xm;
113 else
114 return xm;
115}
116
117
118unsigned int ieee754sp_tuns(ieee754sp x)
119{
120 ieee754sp hb = ieee754sp_1e31();
121
122 /* what if x < 0 ?? */
123 if (ieee754sp_lt(x, hb))
124 return (unsigned) ieee754sp_tint(x);
125
126 return (unsigned) ieee754sp_tint(ieee754sp_sub(x, hb)) |
127 ((unsigned) 1 << 31);
128}