1/* Round argument to nearest integral value according to current rounding
2 direction.
3 Copyright (C) 1997-2024 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-narrow-eval.h>
25#include <math_private.h>
26#include <libm-alias-float.h>
27#include <fix-fp-int-convert-overflow.h>
28#include <math-use-builtins.h>
29
30
31long long int
32__llrintf (float x)
33{
34#if USE_LLRINTF_BUILTIN
35 return __builtin_llrintf (x);
36#else
37 /* Use generic implementation. */
38 static const float two23[2] =
39 {
40 8.3886080000e+06, /* 0x4B000000 */
41 -8.3886080000e+06, /* 0xCB000000 */
42 };
43
44 int32_t j0;
45 uint32_t i0;
46 float w;
47 float t;
48 long long int result;
49 int sx;
50
51 GET_FLOAT_WORD (i0, x);
52
53 sx = i0 >> 31;
54 j0 = ((i0 >> 23) & 0xff) - 0x7f;
55 i0 &= 0x7fffff;
56 i0 |= 0x800000;
57
58 if (j0 < (int32_t) (sizeof (long long int) * 8) - 1)
59 {
60 if (j0 >= 23)
61 result = (long long int) i0 << (j0 - 23);
62 else
63 {
64 w = math_narrow_eval (two23[sx] + x);
65 t = w - two23[sx];
66 GET_FLOAT_WORD (i0, t);
67 j0 = ((i0 >> 23) & 0xff) - 0x7f;
68 i0 &= 0x7fffff;
69 i0 |= 0x800000;
70
71 result = (j0 < 0 ? 0 : i0 >> (23 - j0));
72 }
73 }
74 else
75 {
76#ifdef FE_INVALID
77 /* The number is too large. Unless it rounds to LLONG_MIN,
78 FE_INVALID must be raised and the return value is
79 unspecified. */
80 if (FIX_FLT_LLONG_CONVERT_OVERFLOW && x != (float) LLONG_MIN)
81 {
82 feraiseexcept (FE_INVALID);
83 return sx == 0 ? LLONG_MAX : LLONG_MIN;
84 }
85#endif
86 return (long long int) x;
87 }
88
89 return sx ? -result : result;
90#endif /* ! USE_LLRINTF_BUILTIN */
91}
92
93libm_alias_float (__llrint, llrint)
94

source code of glibc/sysdeps/ieee754/flt-32/s_llrintf.c