1/* Round double to integer away from zero.
2 Copyright (C) 2011-2023 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/* Based on a version which carries the following copyright: */
20
21/*
22 * ====================================================
23 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
24 *
25 * Developed at SunPro, a Sun Microsystems, Inc. business.
26 * Permission to use, copy, modify, and distribute this
27 * software is freely granted, provided that this notice
28 * is preserved.
29 * ====================================================
30 */
31
32#define NO_MATH_REDIRECT
33#include <math.h>
34#include <math_private.h>
35#include <stdint.h>
36#include <libm-alias-double.h>
37#include <math-use-builtins.h>
38
39/*
40 * floor(x)
41 * Return x rounded toward -inf to integral value
42 * Method:
43 * Bit twiddling.
44 */
45
46
47double
48__floor (double x)
49{
50#if USE_FLOOR_BUILTIN
51 return __builtin_floor (x);
52#else
53 /* Use generic implementation. */
54 int64_t i0;
55 EXTRACT_WORDS64 (i0, x);
56 int32_t j0 = ((i0 >> 52) & 0x7ff) - 0x3ff;
57 if (__glibc_likely (j0 < 52))
58 {
59 if (j0 < 0)
60 {
61 /* return 0 * sign (x) if |x| < 1 */
62 if (i0 >= 0)
63 i0 = 0;
64 else if ((i0 & 0x7fffffffffffffffl) != 0)
65 i0 = 0xbff0000000000000l;
66 }
67 else
68 {
69 uint64_t i = 0x000fffffffffffffl >> j0;
70 if ((i0 & i) == 0)
71 return x; /* x is integral */
72 if (i0 < 0)
73 i0 += 0x0010000000000000l >> j0;
74 i0 &= ~i;
75 }
76 INSERT_WORDS64 (x, i0);
77 }
78 else if (j0 == 0x400)
79 return x + x; /* inf or NaN */
80 return x;
81#endif /* ! USE_FLOOR_BUILTIN */
82}
83#ifndef __floor
84libm_alias_double (__floor, floor)
85#endif
86