1/* Round argument to nearest integral value according to current rounding
2 direction.
3 Copyright (C) 1997-2022 Free Software Foundation, Inc.
4 This file is part of the GNU C Library.
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#include <fenv.h>
21#include <limits.h>
22#include <math.h>
23
24#include <math_private.h>
25#include <libm-alias-ldouble.h>
26
27static const long double two63[2] =
28{
29 9.223372036854775808000000e+18, /* 0x403E, 0x00000000, 0x00000000 */
30 -9.223372036854775808000000e+18 /* 0xC03E, 0x00000000, 0x00000000 */
31};
32
33
34long long int
35__llrintl (long double x)
36{
37 int32_t se,j0;
38 uint32_t i0, i1;
39 long long int result;
40 long double w;
41 long double t;
42 int sx;
43
44 GET_LDOUBLE_WORDS (se, i0, i1, x);
45
46 sx = (se >> 15) & 1;
47 j0 = (se & 0x7fff) - 0x3fff;
48
49 if (j0 < (int32_t) (8 * sizeof (long long int)) - 1)
50 {
51 if (j0 >= 63)
52 result = (((long long int) i0 << 32) | i1) << (j0 - 63);
53 else
54 {
55#if defined FE_INVALID || defined FE_INEXACT
56 /* X < LLONG_MAX + 1 implied by J0 < 63. */
57 if (x > (long double) LLONG_MAX)
58 {
59 /* In the event of overflow we must raise the "invalid"
60 exception, but not "inexact". */
61 t = __nearbyintl (x: x);
62 feraiseexcept (excepts: t == LLONG_MAX ? FE_INEXACT : FE_INVALID);
63 }
64 else
65#endif
66 {
67 w = two63[sx] + x;
68 t = w - two63[sx];
69 }
70 GET_LDOUBLE_WORDS (se, i0, i1, t);
71 j0 = (se & 0x7fff) - 0x3fff;
72
73 if (j0 < 0)
74 result = 0;
75 else if (j0 <= 31)
76 result = i0 >> (31 - j0);
77 else
78 result = ((long long int) i0 << (j0 - 31)) | (i1 >> (63 - j0));
79 }
80 }
81 else
82 {
83 /* The number is too large. It is left implementation defined
84 what happens. */
85 return (long long int) x;
86 }
87
88 return sx ? -result : result;
89}
90
91libm_alias_ldouble (__llrint, llrint)
92

source code of glibc/sysdeps/ieee754/ldbl-96/s_llrintl.c