1/* Truncate argument to nearest integral value not larger than the argument.
2 Copyright (C) 1997-2017 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
24
25double
26__trunc (double x)
27{
28 int64_t i0, j0;
29 int64_t sx;
30
31 EXTRACT_WORDS64 (i0, x);
32 sx = i0 & UINT64_C(0x8000000000000000);
33 j0 = ((i0 >> 52) & 0x7ff) - 0x3ff;
34 if (j0 < 52)
35 {
36 if (j0 < 0)
37 /* The magnitude of the number is < 1 so the result is +-0. */
38 INSERT_WORDS64 (x, sx);
39 else
40 INSERT_WORDS64 (x, sx | (i0 & ~(UINT64_C(0x000fffffffffffff) >> j0)));
41 }
42 else
43 {
44 if (j0 == 0x400)
45 /* x is inf or NaN. */
46 return x + x;
47 }
48
49 return x;
50}
51#ifndef __trunc
52weak_alias (__trunc, trunc)
53# ifdef NO_LONG_DOUBLE
54strong_alias (__trunc, __truncl)
55weak_alias (__trunc, truncl)
56# endif
57#endif
58