projects / thirdparty / glibc.git / blame
| Commit | Line | Data |
|---|---|---|
| 41c67149 JM |
1 | /* Round to nearest integer value, rounding halfway cases to even. |
| 2 | ldbl-128ibm version. | |
| 2b778ceb | 3 | Copyright (C) 2016-2021 Free Software Foundation, Inc. |
| 41c67149 JM |
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 | |
| 5a82c748 | 18 | <https://www.gnu.org/licenses/>. */ |
| 41c67149 JM |
19 | |
| 20 | #include <math.h> | |
| 21 | #include <math_private.h> | |
| 22 | ||
| 23 | long double | |
| 01f28812 | 24 | __roundevenl (long double x) |
| 41c67149 JM |
25 | { |
| 26 | double xh, xl, hi; | |
| 27 | ||
| 28 | ldbl_unpack (x, &xh, &xl); | |
| 29 | ||
| 30 | if (xh != 0 && isfinite (xh)) | |
| 31 | { | |
| 01f28812 | 32 | hi = __roundeven (xh); |
| 41c67149 JM |
33 | if (hi != xh) |
| 34 | { | |
| 35 | /* The high part is not an integer; the low part only | |
| 36 | affects the result if the high part is exactly half way | |
| 37 | between two integers and the low part is nonzero in the | |
| 38 | opposite direction to the rounding of the high part. */ | |
| 39 | double diff = hi - xh; | |
| 40 | if (fabs (diff) == 0.5) | |
| 41 | { | |
| 42 | if (xl < 0 && diff > 0) | |
| 43 | xh = hi - 1; | |
| 44 | else if (xl > 0 && diff < 0) | |
| 45 | xh = hi + 1; | |
| 46 | else | |
| 47 | xh = hi; | |
| 48 | } | |
| 49 | else | |
| 50 | xh = hi; | |
| 51 | xl = 0; | |
| 52 | } | |
| 53 | else | |
| 54 | { | |
| 55 | /* The high part is a nonzero integer. Rounding the low | |
| 56 | part to nearest, ties round to even, is always correct, | |
| 57 | as a high part that is an odd integer together with a low | |
| 58 | part with magnitude 0.5 is not a valid long double. */ | |
| 01f28812 | 59 | xl = __roundeven (xl); |
| 41c67149 JM |
60 | xh = hi; |
| 61 | ldbl_canonicalize_int (&xh, &xl); | |
| 62 | } | |
| 63 | } | |
| 64 | else | |
| 65 | /* Quiet signaling NaN arguments. */ | |
| 66 | xh += xh; | |
| 67 | ||
| 68 | return ldbl_pack (xh, xl); | |
| 69 | } | |
| 01f28812 | 70 | weak_alias (__roundevenl, roundevenl) |