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1da177e4 LT |
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 <linux/kernel.h> | |
29 | #include "ieee754sp.h" | |
30 | ||
31 | int 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 | ||
118 | unsigned 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 | } |