1 /* Round double to integer away from zero.
2    Copyright (C) 2011-2022 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 
47 double
__floor(double x)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
84 libm_alias_double (__floor, floor)
85 #endif
86