1/* Truncate argument to nearest integral value not larger than the argument.
2 Copyright (C) 1997-2023 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 <math-use-builtins.h>
25
26
27double
28__trunc (double x)
29{
30#if USE_TRUNC_BUILTIN
31 return __builtin_trunc (x);
32#else
33 /* Use generic implementation. */
34 int64_t i0, j0;
35 int64_t sx;
36
37 EXTRACT_WORDS64 (i0, x);
38 sx = i0 & UINT64_C (0x8000000000000000);
39 j0 = ((i0 >> 52) & 0x7ff) - 0x3ff;
40 if (j0 < 52)
41 {
42 if (j0 < 0)
43 /* The magnitude of the number is < 1 so the result is +-0. */
44 INSERT_WORDS64 (x, sx);
45 else
46 INSERT_WORDS64 (x, sx | (i0 & ~(UINT64_C (0x000fffffffffffff) >> j0)));
47 }
48 else
49 {
50 if (j0 == 0x400)
51 /* x is inf or NaN. */
52 return x + x;
53 }
54
55 return x;
56#endif /* ! USE_TRUNC_BUILTIN */
57}
58#ifndef __trunc
59libm_alias_double (__trunc, trunc)
60#endif
61