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1 | /* lround function. PowerPC32 version. |
2 | Copyright (C) 2004-2019 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 | |
5a82c748 | 17 | <https://www.gnu.org/licenses/>. */ |
9d5d214e AZ |
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); | |
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 (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 |