1 | /* Round double to integer away from zero. |
2 | Copyright (C) 1997-2018 Free Software Foundation, Inc. |
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 |
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. |
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 |
14 | Lesser General Public License for more details. |
15 | |
16 | You should have received a copy of the GNU Lesser General Public |
17 | License along with the GNU C Library; if not, see |
18 | <http://www.gnu.org/licenses/>. */ |
19 | |
20 | #include <math.h> |
21 | |
22 | #include <math_private.h> |
23 | #include <libm-alias-double.h> |
24 | #include <stdint.h> |
25 | |
26 | |
27 | double |
28 | __round (double x) |
29 | { |
30 | int64_t i0, j0; |
31 | |
32 | EXTRACT_WORDS64 (i0, x); |
33 | j0 = ((i0 >> 52) & 0x7ff) - 0x3ff; |
34 | if (__glibc_likely (j0 < 52)) |
35 | { |
36 | if (j0 < 0) |
37 | { |
38 | i0 &= UINT64_C(0x8000000000000000); |
39 | if (j0 == -1) |
40 | i0 |= UINT64_C(0x3ff0000000000000); |
41 | } |
42 | else |
43 | { |
44 | uint64_t i = UINT64_C(0x000fffffffffffff) >> j0; |
45 | if ((i0 & i) == 0) |
46 | /* X is integral. */ |
47 | return x; |
48 | |
49 | i0 += UINT64_C(0x0008000000000000) >> j0; |
50 | i0 &= ~i; |
51 | } |
52 | } |
53 | else |
54 | { |
55 | if (j0 == 0x400) |
56 | /* Inf or NaN. */ |
57 | return x + x; |
58 | else |
59 | return x; |
60 | } |
61 | |
62 | INSERT_WORDS64 (x, i0); |
63 | return x; |
64 | } |
65 | libm_alias_double (__round, round) |
66 | |