blob: 3cdc8a2535a898ad2ca31faa9e3658035afb2221 [file] [log] [blame]
lh9ed821d2023-04-07 01:36:19 -07001/* Round argument to nearest integral value according to current rounding
2 direction.
3 Copyright (C) 1997, 2004 Free Software Foundation, Inc.
4 This file is part of the GNU C Library.
5 Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
6
7 The GNU C Library is free software; you can redistribute it and/or
8 modify it under the terms of the GNU Lesser General Public
9 License as published by the Free Software Foundation; either
10 version 2.1 of the License, or (at your option) any later version.
11
12 The GNU C Library is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 Lesser General Public License for more details.
16
17 You should have received a copy of the GNU Lesser General Public
18 License along with the GNU C Library; if not, write to the Free
19 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
20 02111-1307 USA. */
21
22#include <features.h>
23/* Prevent math.h from defining a colliding inline */
24#undef __USE_EXTERN_INLINES
25#include <math.h>
26#include "math_private.h"
27
28static const double two52[2] =
29{
30 4.50359962737049600000e+15, /* 0x43300000, 0x00000000 */
31 -4.50359962737049600000e+15, /* 0xC3300000, 0x00000000 */
32};
33
34
35long int
36lrint (double x)
37{
38 int32_t j0;
39 u_int32_t i0,i1;
40 volatile double w;
41 double t;
42 long int result;
43 int sx;
44
45 EXTRACT_WORDS (i0, i1, x);
46 j0 = ((i0 >> 20) & 0x7ff) - 0x3ff;
47 sx = i0 >> 31;
48 i0 &= 0xfffff;
49 i0 |= 0x100000;
50
51 if (j0 < 20)
52 {
53 if (j0 < -1)
54 return 0;
55 else
56 {
57 w = two52[sx] + x;
58 t = w - two52[sx];
59 EXTRACT_WORDS (i0, i1, t);
60 j0 = ((i0 >> 20) & 0x7ff) - 0x3ff;
61 i0 &= 0xfffff;
62 i0 |= 0x100000;
63
64 result = i0 >> (20 - j0);
65 }
66 }
67 else if (j0 < (int32_t) (8 * sizeof (long int)) - 1)
68 {
69 if (j0 >= 52)
70 result = ((long int) i0 << (j0 - 20)) | (i1 << (j0 - 52));
71 else
72 {
73 w = two52[sx] + x;
74 t = w - two52[sx];
75 EXTRACT_WORDS (i0, i1, t);
76 j0 = ((i0 >> 20) & 0x7ff) - 0x3ff;
77 i0 &= 0xfffff;
78 i0 |= 0x100000;
79
80 if (j0 == 20)
81 result = (long int) i0;
82 else
83 result = ((long int) i0 << (j0 - 20)) | (i1 >> (52 - j0));
84 }
85 }
86 else
87 {
88 /* The number is too large. It is left implementation defined
89 what happens. */
90 return (long int) x;
91 }
92
93 return sx ? -result : result;
94}
95libm_hidden_def(lrint)