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63551311 | 1 | /* Round double to integer away from zero. |
d7826aa1 | 2 | Copyright (C) 1997, 2011 Free Software Foundation, Inc. |
63551311 UD |
3 | This file is part of the GNU C Library. |
4 | Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997. | |
5 | ||
6 | The GNU C Library is free software; you can redistribute it and/or | |
41bdb6e2 AJ |
7 | modify it under the terms of the GNU Lesser General Public |
8 | License as published by the Free Software Foundation; either | |
9 | version 2.1 of the License, or (at your option) any later version. | |
63551311 UD |
10 | |
11 | The GNU C Library is distributed in the hope that it will be useful, | |
12 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
41bdb6e2 | 14 | Lesser General Public License for more details. |
63551311 | 15 | |
41bdb6e2 | 16 | You should have received a copy of the GNU Lesser General Public |
59ba27a6 PE |
17 | License along with the GNU C Library; if not, see |
18 | <http://www.gnu.org/licenses/>. */ | |
63551311 UD |
19 | |
20 | #include <math.h> | |
21 | ||
22 | #include "math_private.h" | |
23 | ||
24 | ||
25 | static const double huge = 1.0e300; | |
26 | ||
27 | ||
28 | double | |
29 | __round (double x) | |
30 | { | |
31 | int32_t i0, j0; | |
32 | u_int32_t i1; | |
33 | ||
34 | EXTRACT_WORDS (i0, i1, x); | |
35 | j0 = ((i0 >> 20) & 0x7ff) - 0x3ff; | |
36 | if (j0 < 20) | |
37 | { | |
38 | if (j0 < 0) | |
39 | { | |
80479147 | 40 | math_force_eval (huge + x); |
d7826aa1 UD |
41 | |
42 | i0 &= 0x80000000; | |
43 | if (j0 == -1) | |
44 | i0 |= 0x3ff00000; | |
45 | i1 = 0; | |
63551311 UD |
46 | } |
47 | else | |
48 | { | |
49 | u_int32_t i = 0x000fffff >> j0; | |
50 | if (((i0 & i) | i1) == 0) | |
51 | /* X is integral. */ | |
52 | return x; | |
80479147 | 53 | math_force_eval (huge + x); |
d7826aa1 UD |
54 | |
55 | /* Raise inexact if x != 0. */ | |
56 | i0 += 0x00080000 >> j0; | |
57 | i0 &= ~i; | |
58 | i1 = 0; | |
63551311 UD |
59 | } |
60 | } | |
61 | else if (j0 > 51) | |
62 | { | |
63 | if (j0 == 0x400) | |
64 | /* Inf or NaN. */ | |
65 | return x + x; | |
66 | else | |
67 | return x; | |
68 | } | |
69 | else | |
70 | { | |
71 | u_int32_t i = 0xffffffff >> (j0 - 20); | |
72 | if ((i1 & i) == 0) | |
73 | /* X is integral. */ | |
74 | return x; | |
75 | ||
80479147 | 76 | math_force_eval (huge + x); |
d7826aa1 UD |
77 | |
78 | /* Raise inexact if x != 0. */ | |
79 | u_int32_t j = i1 + (1 << (51 - j0)); | |
80 | if (j < i1) | |
81 | i0 += 1; | |
82 | i1 = j; | |
63551311 UD |
83 | i1 &= ~i; |
84 | } | |
85 | ||
86 | INSERT_WORDS (x, i0, i1); | |
87 | return x; | |
88 | } | |
89 | weak_alias (__round, round) | |
90 | #ifdef NO_LONG_DOUBLE | |
91 | strong_alias (__round, __roundl) | |
92 | weak_alias (__round, roundl) | |
93 | #endif |