1/* Truncate argument to nearest integral value not larger than the argument.
2 Copyright (C) 1997-2021 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 <https://www.gnu.org/licenses/>. */
19
20#define NO_MATH_REDIRECT
21#include <math.h>
22
23#include <math_private.h>
24#include <libm-alias-double.h>
25#include <math-use-builtins.h>
26
27
28double
29__trunc (double x)
30{
31#if USE_TRUNC_BUILTIN
32 return __builtin_trunc (x);
33#else
34 /* Use generic implementation. */
35 int64_t i0, j0;
36 int64_t sx;
37
38 EXTRACT_WORDS64 (i0, x);
39 sx = i0 & UINT64_C (0x8000000000000000);
40 j0 = ((i0 >> 52) & 0x7ff) - 0x3ff;
41 if (j0 < 52)
42 {
43 if (j0 < 0)
44 /* The magnitude of the number is < 1 so the result is +-0. */
45 INSERT_WORDS64 (x, sx);
46 else
47 INSERT_WORDS64 (x, sx | (i0 & ~(UINT64_C (0x000fffffffffffff) >> j0)));
48 }
49 else
50 {
51 if (j0 == 0x400)
52 /* x is inf or NaN. */
53 return x + x;
54 }
55
56 return x;
57#endif /* ! USE_TRUNC_BUILTIN */
58}
59#ifndef __trunc
60libm_alias_double (__trunc, trunc)
61#endif
62