1/* Round double to integer away from zero.
2 Copyright (C) 2011-2021 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4 Contributed by Ulrich Drepper <drepper@cygnus.com>, 2011.
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/* Based on a version which carries the following copyright: */
21
22/*
23 * ====================================================
24 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
25 *
26 * Developed at SunPro, a Sun Microsystems, Inc. business.
27 * Permission to use, copy, modify, and distribute this
28 * software is freely granted, provided that this notice
29 * is preserved.
30 * ====================================================
31 */
32
33#define NO_MATH_REDIRECT
34#include <math.h>
35#include <math_private.h>
36#include <stdint.h>
37#include <libm-alias-double.h>
38#include <math-use-builtins.h>
39
40/*
41 * floor(x)
42 * Return x rounded toward -inf to integral value
43 * Method:
44 * Bit twiddling.
45 */
46
47
48double
49__floor (double x)
50{
51#if USE_FLOOR_BUILTIN
52 return __builtin_floor (x);
53#else
54 /* Use generic implementation. */
55 int64_t i0;
56 EXTRACT_WORDS64 (i0, x);
57 int32_t j0 = ((i0 >> 52) & 0x7ff) - 0x3ff;
58 if (__glibc_likely (j0 < 52))
59 {
60 if (j0 < 0)
61 {
62 /* return 0 * sign (x) if |x| < 1 */
63 if (i0 >= 0)
64 i0 = 0;
65 else if ((i0 & 0x7fffffffffffffffl) != 0)
66 i0 = 0xbff0000000000000l;
67 }
68 else
69 {
70 uint64_t i = 0x000fffffffffffffl >> j0;
71 if ((i0 & i) == 0)
72 return x; /* x is integral */
73 if (i0 < 0)
74 i0 += 0x0010000000000000l >> j0;
75 i0 &= ~i;
76 }
77 INSERT_WORDS64 (x, i0);
78 }
79 else if (j0 == 0x400)
80 return x + x; /* inf or NaN */
81 return x;
82#endif /* ! USE_FLOOR_BUILTIN */
83}
84#ifndef __floor
85libm_alias_double (__floor, floor)
86#endif
87