1 | /* lround function. PowerPC32 version. |
2 | Copyright (C) 2004-2024 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 | #define lroundf __redirect_lroundf |
20 | #define __lroundf __redirect___lroundf |
21 | #include <math.h> |
22 | #undef lroundf |
23 | #undef __lroundf |
24 | #include <libm-alias-float.h> |
25 | #include <libm-alias-double.h> |
26 | |
27 | long int |
28 | __lround (double x) |
29 | { |
30 | #ifdef _ARCH_PWR5X |
31 | x = round (x); |
32 | #else |
33 | /* Ieee 1003.1 lround function. ieee specifies "round to the nearest |
34 | integer value, rounding halfway cases away from zero, regardless of |
35 | the current rounding mode." however powerpc architecture defines |
36 | "round to nearest" as "choose the best approximation. in case of a |
37 | tie, choose the one that is even (least significant bit o).". |
38 | so we can't use the powerpc "round to nearest" mode. instead we set |
39 | "round toward zero" mode and round by adding +-0.5 before rounding |
40 | to the integer value. it is necessary to detect when x is |
41 | (+-)0x1.fffffffffffffp-2 because adding +-0.5 in this case will |
42 | cause an erroneous shift, carry and round. we simply return 0 if |
43 | 0.5 > x > -0.5. */ |
44 | |
45 | double ax = fabs (x: x); |
46 | |
47 | if (ax < 0.5) |
48 | return 0; |
49 | |
50 | if (x >= 0x7fffffff.8p0 || x <= -0x80000000.8p0) |
51 | x = (x < 0.0) ? -0x1p+52 : 0x1p+52; |
52 | else |
53 | { |
54 | /* Test whether an integer to avoid spurious "inexact". */ |
55 | double t = ax + 0x1p+52; |
56 | t = t - 0x1p+52; |
57 | if (ax != t) |
58 | { |
59 | ax = ax + 0.5; |
60 | if (x < 0.0) |
61 | ax = -fabs (x: ax); |
62 | x = ax; |
63 | } |
64 | } |
65 | #endif |
66 | /* Force evaluation of values larger than long int, so invalid |
67 | exceptions are raise. */ |
68 | long long int ret; |
69 | asm ("fctiwz %0, %1" : "=d" (ret) : "d" (x)); |
70 | return ret; |
71 | } |
72 | #ifndef __lround |
73 | libm_alias_double (__lround, lround) |
74 | |
75 | strong_alias (__lround, __lroundf) |
76 | libm_alias_float (__lround, lround) |
77 | #endif |
78 | |