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gerrit-public.fairphone.software / kernel / msm-4.9 / c273625b42dc93094b9f5db64944a0a8c6775c99 / . / arch / mips / math-emu / dp_tlong.c
blob: 0f07ec2be3f93198198f29940345dc613484a107 [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 "ieee754dp.h"
29
30s64 ieee754dp_tlong(ieee754dp x)
31{
32 COMPXDP;
33
34 CLEARCX;
35
36 EXPLODEXDP;
37 FLUSHXDP;
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(), "dp_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 == DP_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(), "dp_tlong", x);
59 }
60 /* oh gawd */
61 if (xe > DP_MBITS) {
62 xm <<= xe - DP_MBITS;
63 } else if (xe < DP_MBITS) {
64 u64 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;
Andrea Gelminic2736252010-05-23 21:52:07 +0200[diff] [blame^]74 } else {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700[diff] [blame]75 /* Shifting a u64 64 times does not work,
76 * so we do it in two steps. Be aware that xe
77 * may be -1 */
78 residue = xm << (xe + 1);
79 residue <<= 63 - DP_MBITS;
80 round = (residue >> 63) != 0;
81 sticky = (residue << 1) != 0;
82 xm >>= DP_MBITS - xe;
83 }
84 odd = (xm & 0x1) != 0x0;
85 switch (ieee754_csr.rm) {
86 case IEEE754_RN:
87 if (round && (sticky || odd))
88 xm++;
89 break;
90 case IEEE754_RZ:
91 break;
92 case IEEE754_RU: /* toward +Infinity */
93 if ((round || sticky) && !xs)
94 xm++;
95 break;
96 case IEEE754_RD: /* toward -Infinity */
97 if ((round || sticky) && xs)
98 xm++;
99 break;
100 }
101 if ((xm >> 63) != 0) {
102 /* This can happen after rounding */
103 SETCX(IEEE754_INVALID_OPERATION);
104 return ieee754di_xcpt(ieee754di_indef(), "dp_tlong", x);
105 }
106 if (round || sticky)
107 SETCX(IEEE754_INEXACT);
108 }
109 if (xs)
110 return -xm;
111 else
112 return xm;
113}
114
115
116u64 ieee754dp_tulong(ieee754dp x)
117{
118 ieee754dp hb = ieee754dp_1e63();
119
120 /* what if x < 0 ?? */
121 if (ieee754dp_lt(x, hb))
122 return (u64) ieee754dp_tlong(x);
123
124 return (u64) ieee754dp_tlong(ieee754dp_sub(x, hb)) |
125 (1ULL << 63);
126}