1 | /* Truncate argument to nearest integral value not larger than the argument. |
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 | |
25 | |
26 | double |
27 | __trunc (double x) |
28 | { |
29 | int64_t i0, j0; |
30 | int64_t sx; |
31 | |
32 | EXTRACT_WORDS64 (i0, x); |
33 | sx = i0 & UINT64_C(0x8000000000000000); |
34 | j0 = ((i0 >> 52) & 0x7ff) - 0x3ff; |
35 | if (j0 < 52) |
36 | { |
37 | if (j0 < 0) |
38 | /* The magnitude of the number is < 1 so the result is +-0. */ |
39 | INSERT_WORDS64 (x, sx); |
40 | else |
41 | INSERT_WORDS64 (x, sx | (i0 & ~(UINT64_C(0x000fffffffffffff) >> j0))); |
42 | } |
43 | else |
44 | { |
45 | if (j0 == 0x400) |
46 | /* x is inf or NaN. */ |
47 | return x + x; |
48 | } |
49 | |
50 | return x; |
51 | } |
52 | #ifndef __trunc |
53 | libm_alias_double (__trunc, trunc) |
54 | #endif |
55 | |