1 | /* Round to long long int long double floating-point values. |
2 | IBM extended format long double version. |
3 | Copyright (C) 2006-2022 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 <math.h> |
21 | #include <fenv.h> |
22 | #include <math_private.h> |
23 | #include <math_ldbl_opt.h> |
24 | #include <float.h> |
25 | #include <ieee754.h> |
26 | |
27 | long long |
28 | __llroundl (long double x) |
29 | { |
30 | double xh, xl; |
31 | long long res, hi, lo; |
32 | |
33 | ldbl_unpack (x, &xh, &xl); |
34 | |
35 | /* Limit the range of values handled by the conversion to long long. |
36 | We do this because we aren't sure whether that conversion properly |
37 | raises FE_INVALID. */ |
38 | if (__builtin_expect |
39 | ((__builtin_fabs (xh) <= -(double) (-__LONG_LONG_MAX__ - 1)), 1) |
40 | #if !defined (FE_INVALID) |
41 | || 1 |
42 | #endif |
43 | ) |
44 | { |
45 | if (__glibc_unlikely ((xh == -(double) (-__LONG_LONG_MAX__ - 1)))) |
46 | { |
47 | /* When XH is 9223372036854775808.0, converting to long long will |
48 | overflow, resulting in an invalid operation. However, XL might |
49 | be negative and of sufficient magnitude that the overall long |
50 | double is in fact in range. Avoid raising an exception. In any |
51 | case we need to convert this value specially, because |
52 | the converted value is not exactly represented as a double |
53 | thus subtracting HI from XH suffers rounding error. */ |
54 | hi = __LONG_LONG_MAX__; |
55 | xh = 1.0; |
56 | } |
57 | else |
58 | { |
59 | hi = (long long) xh; |
60 | xh -= hi; |
61 | } |
62 | ldbl_canonicalize (&xh, &xl); |
63 | |
64 | lo = (long long) xh; |
65 | |
66 | /* Peg at max/min values, assuming that the above conversions do so. |
67 | Strictly speaking, we can return anything for values that overflow, |
68 | but this is more useful. */ |
69 | res = hi + lo; |
70 | |
71 | /* This is just sign(hi) == sign(lo) && sign(res) != sign(hi). */ |
72 | if (__glibc_unlikely (((~(hi ^ lo) & (res ^ hi)) < 0))) |
73 | goto overflow; |
74 | |
75 | xh -= lo; |
76 | ldbl_canonicalize (&xh, &xl); |
77 | |
78 | hi = res; |
79 | if (xh > 0.5) |
80 | { |
81 | res += 1; |
82 | } |
83 | else if (xh == 0.5) |
84 | { |
85 | if (xl > 0.0 || (xl == 0.0 && res >= 0)) |
86 | res += 1; |
87 | } |
88 | else if (-xh > 0.5) |
89 | { |
90 | res -= 1; |
91 | } |
92 | else if (-xh == 0.5) |
93 | { |
94 | if (xl < 0.0 || (xl == 0.0 && res <= 0)) |
95 | res -= 1; |
96 | } |
97 | |
98 | if (__glibc_unlikely (((~(hi ^ (res - hi)) & (res ^ hi)) < 0))) |
99 | goto overflow; |
100 | |
101 | return res; |
102 | } |
103 | else |
104 | { |
105 | if (xh > 0.0) |
106 | hi = __LONG_LONG_MAX__; |
107 | else if (xh < 0.0) |
108 | hi = -__LONG_LONG_MAX__ - 1; |
109 | else |
110 | /* Nan */ |
111 | hi = 0; |
112 | } |
113 | |
114 | overflow: |
115 | #ifdef FE_INVALID |
116 | feraiseexcept (FE_INVALID); |
117 | #endif |
118 | return hi; |
119 | } |
120 | |
121 | long_double_symbol (libm, __llroundl, llroundl); |
122 | |