1 | /* Round to long int long double floating-point values. |
2 | IBM extended format long double version. |
3 | Copyright (C) 2006-2024 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 |
28 | __lroundl (long double x) |
29 | { |
30 | double xh, xl; |
31 | long res, hi, lo; |
32 | |
33 | ldbl_unpack (x, &xh, &xl); |
34 | |
35 | /* Limit the range of values handled by the conversion to long. |
36 | We do this because we aren't sure whether that conversion properly |
37 | raises FE_INVALID. */ |
38 | if ( |
39 | #if __LONG_MAX__ == 2147483647 |
40 | __builtin_expect |
41 | ((__builtin_fabs (xh) <= (double) __LONG_MAX__ + 2), 1) |
42 | #else |
43 | __builtin_expect |
44 | ((__builtin_fabs (xh) <= -(double) (-__LONG_MAX__ - 1)), 1) |
45 | #endif |
46 | #if !defined (FE_INVALID) |
47 | || 1 |
48 | #endif |
49 | ) |
50 | { |
51 | #if __LONG_MAX__ == 2147483647 |
52 | long long llhi = (long long) xh; |
53 | if (llhi != (long) llhi) |
54 | hi = llhi < 0 ? -__LONG_MAX__ - 1 : __LONG_MAX__; |
55 | else |
56 | hi = llhi; |
57 | xh -= hi; |
58 | #else |
59 | if (__glibc_unlikely ((xh == -(double) (-__LONG_MAX__ - 1)))) |
60 | { |
61 | /* When XH is 9223372036854775808.0, converting to long long will |
62 | overflow, resulting in an invalid operation. However, XL might |
63 | be negative and of sufficient magnitude that the overall long |
64 | double is in fact in range. Avoid raising an exception. In any |
65 | case we need to convert this value specially, because |
66 | the converted value is not exactly represented as a double |
67 | thus subtracting HI from XH suffers rounding error. */ |
68 | hi = __LONG_MAX__; |
69 | xh = 1.0; |
70 | } |
71 | else |
72 | { |
73 | hi = (long) xh; |
74 | xh -= hi; |
75 | } |
76 | #endif |
77 | ldbl_canonicalize (&xh, &xl); |
78 | |
79 | lo = (long) xh; |
80 | |
81 | /* Peg at max/min values, assuming that the above conversions do so. |
82 | Strictly speaking, we can return anything for values that overflow, |
83 | but this is more useful. */ |
84 | res = (long int) ((unsigned long int) hi + (unsigned long int) lo); |
85 | |
86 | /* This is just sign(hi) == sign(lo) && sign(res) != sign(hi). */ |
87 | if (__glibc_unlikely (((~(hi ^ lo) & (res ^ hi)) < 0))) |
88 | goto overflow; |
89 | |
90 | xh -= lo; |
91 | ldbl_canonicalize (&xh, &xl); |
92 | |
93 | hi = res; |
94 | if (xh > 0.5) |
95 | { |
96 | res += 1UL; |
97 | } |
98 | else if (xh == 0.5) |
99 | { |
100 | if (xl > 0.0 || (xl == 0.0 && res >= 0)) |
101 | res += 1UL; |
102 | } |
103 | else if (-xh > 0.5) |
104 | { |
105 | res -= 1UL; |
106 | } |
107 | else if (-xh == 0.5) |
108 | { |
109 | if (xl < 0.0 || (xl == 0.0 && res <= 0)) |
110 | res -= 1UL; |
111 | } |
112 | |
113 | if (__glibc_unlikely (((~(hi ^ (res - hi)) & (res ^ hi)) < 0))) |
114 | goto overflow; |
115 | |
116 | return res; |
117 | } |
118 | else |
119 | { |
120 | if (xh > 0.0) |
121 | hi = __LONG_MAX__; |
122 | else if (xh < 0.0) |
123 | hi = -__LONG_MAX__ - 1; |
124 | else |
125 | /* Nan */ |
126 | hi = 0; |
127 | } |
128 | |
129 | overflow: |
130 | #ifdef FE_INVALID |
131 | feraiseexcept (FE_INVALID); |
132 | #endif |
133 | return hi; |
134 | } |
135 | |
136 | long_double_symbol (libm, __lroundl, lroundl); |
137 | |