1 /* Round float value to long long int.
2 Copyright (C) 1997-2021 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 #include <math.h>
20 #include <math_private.h>
21 #include <stdint.h>
22 #include <libm-alias-float.h>
23
24 /* Round to the nearest integer, with values exactly on a 0.5 boundary
25 rounded away from zero, regardless of the current rounding mode.
26 If (long long)x, when x is out of range of a long long, clips at
27 LLONG_MAX or LLONG_MIN, then this implementation also clips. */
28
29 long long int
__llroundf(float x)30 __llroundf (float x)
31 {
32 long long xr;
33 if (HAVE_PPC_FCTIDZ)
34 xr = (long long) x;
35 else
36 {
37 float ax = fabsf (x);
38 /* Avoid incorrect exceptions from libgcc conversions (as of GCC
39 5): <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59412>. */
40 if (ax < 0x1p31f)
41 xr = (long long int) (long int) x;
42 else if (!(ax < 0x1p55f))
43 xr = (long long int) (long int) (x * 0x1p-32f) << 32;
44 else
45 {
46 uint32_t i0;
47 GET_FLOAT_WORD (i0, x);
48 int exponent = ((i0 >> 23) & 0xff) - 0x7f;
49 unsigned long long int mant = (i0 & 0x7fffff) | 0x800000;
50 mant <<= exponent - 23;
51 xr = (long long int) ((i0 & 0x80000000) != 0 ? -mant : mant);
52 }
53 }
54 /* Avoid spurious "inexact" converting LLONG_MAX to float, and from
55 subtraction when the result is out of range, by returning early
56 for arguments large enough that no rounding is needed. */
57 if (!(fabsf (x) < 0x1p23f))
58 return xr;
59 float xrf = (float) xr;
60
61 if (x >= 0.0)
62 {
63 if (x - xrf >= 0.5)
64 xr += (long long) ((unsigned long long) xr + 1) > 0;
65 }
66 else
67 {
68 if (xrf - x >= 0.5)
69 xr -= (long long) ((unsigned long long) xr - 1) < 0;
70 }
71 return xr;
72 }
73 libm_alias_float (__llround, llround)
74