1/* Round double to integer away from zero.
2 Copyright (C) 1997-2022 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19#define NO_MATH_REDIRECT
20#include <math.h>
21
22#include <math_private.h>
23#include <libm-alias-double.h>
24#include <stdint.h>
25#include <math-use-builtins.h>
26
27
28double
29__round (double x)
30{
31#if USE_ROUND_BUILTIN
32 return __builtin_round (x);
33#else
34 /* Use generic implementation. */
35 int64_t i0, j0;
36
37 EXTRACT_WORDS64 (i0, x);
38 j0 = ((i0 >> 52) & 0x7ff) - 0x3ff;
39 if (__glibc_likely (j0 < 52))
40 {
41 if (j0 < 0)
42 {
43 i0 &= UINT64_C (0x8000000000000000);
44 if (j0 == -1)
45 i0 |= UINT64_C (0x3ff0000000000000);
46 }
47 else
48 {
49 uint64_t i = UINT64_C (0x000fffffffffffff) >> j0;
50 if ((i0 & i) == 0)
51 /* X is integral. */
52 return x;
53
54 i0 += UINT64_C (0x0008000000000000) >> j0;
55 i0 &= ~i;
56 }
57 }
58 else
59 {
60 if (j0 == 0x400)
61 /* Inf or NaN. */
62 return x + x;
63 else
64 return x;
65 }
66
67 INSERT_WORDS64 (x, i0);
68 return x;
69#endif /* ! USE_ROUND_BUILTIN */
70}
71libm_alias_double (__round, round)
72