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 int
35__lrintl (long double x)
36{
37 int32_t se,j0;
38 uint32_t i0, i1;
39 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 < 31)
50 {
51#if defined FE_INVALID || defined FE_INEXACT
52 /* X < LONG_MAX + 1 implied by J0 < 31. */
53 if (sizeof (long int) == 4
54 && x > (long double) LONG_MAX)
55 {
56 /* In the event of overflow we must raise the "invalid"
57 exception, but not "inexact". */
58 t = __nearbyintl (x: x);
59 feraiseexcept (excepts: t == LONG_MAX ? FE_INEXACT : FE_INVALID);
60 }
61 else
62#endif
63 {
64 w = two63[sx] + x;
65 t = w - two63[sx];
66 }
67 GET_LDOUBLE_WORDS (se, i0, i1, t);
68 j0 = (se & 0x7fff) - 0x3fff;
69
70 result = (j0 < 0 ? 0 : i0 >> (31 - j0));
71 }
72 else if (j0 < (int32_t) (8 * sizeof (long int)) - 1)
73 {
74 if (j0 >= 63)
75 result = ((long int) i0 << (j0 - 31)) | (i1 << (j0 - 63));
76 else
77 {
78#if defined FE_INVALID || defined FE_INEXACT
79 /* X < LONG_MAX + 1 implied by J0 < 63. */
80 if (sizeof (long int) == 8
81 && x > (long double) LONG_MAX)
82 {
83 /* In the event of overflow we must raise the "invalid"
84 exception, but not "inexact". */
85 t = __nearbyintl (x: x);
86 feraiseexcept (excepts: t == LONG_MAX ? FE_INEXACT : FE_INVALID);
87 }
88 else
89#endif
90 {
91 w = two63[sx] + x;
92 t = w - two63[sx];
93 }
94 GET_LDOUBLE_WORDS (se, i0, i1, t);
95 j0 = (se & 0x7fff) - 0x3fff;
96
97 if (j0 == 31)
98 result = (long int) i0;
99 else
100 result = ((long int) i0 << (j0 - 31)) | (i1 >> (63 - j0));
101 }
102 }
103 else
104 {
105 /* The number is too large. Unless it rounds to LONG_MIN,
106 FE_INVALID must be raised and the return value is
107 unspecified. */
108#if defined FE_INVALID || defined FE_INEXACT
109 if (sizeof (long int) == 4
110 && x < (long double) LONG_MIN
111 && x > (long double) LONG_MIN - 1.0L)
112 {
113 /* If truncation produces LONG_MIN, the cast will not raise
114 the exception, but may raise "inexact". */
115 t = __nearbyintl (x: x);
116 feraiseexcept (excepts: t == LONG_MIN ? FE_INEXACT : FE_INVALID);
117 return LONG_MIN;
118 }
119#endif
120 return (long int) x;
121 }
122
123 return sx ? -result : result;
124}
125
126libm_alias_ldouble (__lrint, lrint)
127

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