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gerrit-public.fairphone.software / kernel / msm / 6337f5e5aab7faf6029d9ac4eba7496295bdf93c / . / arch / mips / math-emu / dp_tint.c
blob: 24478623c117446d9c394204dbd5a18e811b6206 [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.
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 "ieee754dp.h"
30
31int ieee754dp_tint(ieee754dp x)
32{
33 COMPXDP;
34
35 CLEARCX;
36
37 EXPLODEXDP;
38 FLUSHXDP;
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(), "dp_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 /* Set invalid. We will only use overflow for floating
54 point overflow */
55 SETCX(IEEE754_INVALID_OPERATION);
56 return ieee754si_xcpt(ieee754si_indef(), "dp_tint", x);
57 }
58 /* oh gawd */
59 if (xe > DP_MBITS) {
60 xm <<= xe - DP_MBITS;
61 } else if (xe < DP_MBITS) {
62 u64 residue;
63 int round;
64 int sticky;
65 int odd;
66
67 if (xe < -1) {
68 residue = xm;
69 round = 0;
70 sticky = residue != 0;
71 xm = 0;
Andrea Gelmini6337f5e2010-05-23 21:52:06 +0200[diff] [blame^]72 } else {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700[diff] [blame]73 residue = xm << (64 - DP_MBITS + xe);
74 round = (residue >> 63) != 0;
75 sticky = (residue << 1) != 0;
76 xm >>= DP_MBITS - xe;
77 }
78 /* Note: At this point upper 32 bits of xm are guaranteed
79 to be zero */
80 odd = (xm & 0x1) != 0x0;
81 switch (ieee754_csr.rm) {
82 case IEEE754_RN:
83 if (round && (sticky || odd))
84 xm++;
85 break;
86 case IEEE754_RZ:
87 break;
88 case IEEE754_RU: /* toward +Infinity */
89 if ((round || sticky) && !xs)
90 xm++;
91 break;
92 case IEEE754_RD: /* toward -Infinity */
93 if ((round || sticky) && xs)
94 xm++;
95 break;
96 }
97 /* look for valid corner case 0x80000000 */
98 if ((xm >> 31) != 0 && (xs == 0 || xm != 0x80000000)) {
99 /* This can happen after rounding */
100 SETCX(IEEE754_INVALID_OPERATION);
101 return ieee754si_xcpt(ieee754si_indef(), "dp_tint", 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
113unsigned int ieee754dp_tuns(ieee754dp x)
114{
115 ieee754dp hb = ieee754dp_1e31();
116
117 /* what if x < 0 ?? */
118 if (ieee754dp_lt(x, hb))
119 return (unsigned) ieee754dp_tint(x);
120
121 return (unsigned) ieee754dp_tint(ieee754dp_sub(x, hb)) |
122 ((unsigned) 1 << 31);
123}