1/* Round double to integer away from zero.
2 Copyright (C) 1997-2016 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 <stdint.h>
24
25static const double huge = 1.0e300;
26
27
28double
29__round (double x)
30{
31 int64_t i0, j0;
32
33 EXTRACT_WORDS64 (i0, x);
34 j0 = ((i0 >> 52) & 0x7ff) - 0x3ff;
35 if (__glibc_likely (j0 < 52))
36 {
37 if (j0 < 0)
38 {
39 math_force_eval (huge + x);
40
41 i0 &= UINT64_C(0x8000000000000000);
42 if (j0 == -1)
43 i0 |= UINT64_C(0x3ff0000000000000);
44 }
45 else
46 {
47 uint64_t i = UINT64_C(0x000fffffffffffff) >> j0;
48 if ((i0 & i) == 0)
49 /* X is integral. */
50 return x;
51 math_force_eval (huge + x);
52
53 /* Raise inexact if x != 0. */
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}
70weak_alias (__round, round)
71#ifdef NO_LONG_DOUBLE
72strong_alias (__round, __roundl)
73weak_alias (__round, roundl)
74#endif
75