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fb146a76 UD |
1 | /* Round to long int long double floating-point values. |
2 | IBM extended format long double version. | |
688903eb | 3 | Copyright (C) 2006-2018 Free Software Foundation, Inc. |
fb146a76 UD |
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 | |
59ba27a6 PE |
17 | License along with the GNU C Library; if not, see |
18 | <http://www.gnu.org/licenses/>. */ | |
fb146a76 | 19 | |
f964490f | 20 | #include <math.h> |
4a3d3999 | 21 | #include <fenv.h> |
0d13dfa1 | 22 | #include <math_private.h> |
f964490f | 23 | #include <math_ldbl_opt.h> |
fb146a76 UD |
24 | #include <float.h> |
25 | #include <ieee754.h> | |
26 | ||
f964490f | 27 | |
fb146a76 UD |
28 | long |
29 | __lrintl (long double x) | |
f964490f | 30 | { |
fb146a76 UD |
31 | double xh, xl; |
32 | long res, hi, lo; | |
33 | int save_round; | |
34 | ||
35 | ldbl_unpack (x, &xh, &xl); | |
36 | ||
37 | /* Limit the range of values handled by the conversion to long. | |
38 | We do this because we aren't sure whether that conversion properly | |
39 | raises FE_INVALID. */ | |
40 | if ( | |
41 | #if __LONG_MAX__ == 2147483647 | |
42 | __builtin_expect | |
43 | ((__builtin_fabs (xh) <= (double) __LONG_MAX__ + 2), 1) | |
44 | #else | |
45 | __builtin_expect | |
46 | ((__builtin_fabs (xh) <= -(double) (-__LONG_MAX__ - 1)), 1) | |
47 | #endif | |
48 | #if !defined (FE_INVALID) | |
49 | || 1 | |
50 | #endif | |
51 | ) | |
52 | { | |
4a3d3999 | 53 | save_round = fegetround (); |
fb146a76 UD |
54 | |
55 | #if __LONG_MAX__ == 2147483647 | |
56 | long long llhi = (long long) xh; | |
57 | if (llhi != (long) llhi) | |
58 | hi = llhi < 0 ? -__LONG_MAX__ - 1 : __LONG_MAX__; | |
59 | else | |
60 | hi = llhi; | |
61 | xh -= hi; | |
62 | #else | |
a1ffb40e | 63 | if (__glibc_unlikely ((xh == -(double) (-__LONG_MAX__ - 1)))) |
fb146a76 UD |
64 | { |
65 | /* When XH is 9223372036854775808.0, converting to long long will | |
66 | overflow, resulting in an invalid operation. However, XL might | |
67 | be negative and of sufficient magnitude that the overall long | |
68 | double is in fact in range. Avoid raising an exception. In any | |
69 | case we need to convert this value specially, because | |
70 | the converted value is not exactly represented as a double | |
71 | thus subtracting HI from XH suffers rounding error. */ | |
72 | hi = __LONG_MAX__; | |
73 | xh = 1.0; | |
74 | } | |
75 | else | |
76 | { | |
77 | hi = (long) xh; | |
78 | xh -= hi; | |
79 | } | |
80 | #endif | |
81 | ldbl_canonicalize (&xh, &xl); | |
82 | ||
83 | lo = (long) xh; | |
84 | ||
85 | /* Peg at max/min values, assuming that the above conversions do so. | |
86 | Strictly speaking, we can return anything for values that overflow, | |
87 | but this is more useful. */ | |
12727488 | 88 | res = (long int) ((unsigned long int) hi + (unsigned long int) lo); |
fb146a76 UD |
89 | |
90 | /* This is just sign(hi) == sign(lo) && sign(res) != sign(hi). */ | |
a1ffb40e | 91 | if (__glibc_unlikely (((~(hi ^ lo) & (res ^ hi)) < 0))) |
fb146a76 UD |
92 | goto overflow; |
93 | ||
94 | xh -= lo; | |
95 | ldbl_canonicalize (&xh, &xl); | |
96 | ||
97 | hi = res; | |
98 | switch (save_round) | |
99 | { | |
100 | case FE_TONEAREST: | |
101 | if (fabs (xh) < 0.5 | |
102 | || (fabs (xh) == 0.5 | |
103 | && ((xh > 0.0 && xl < 0.0) | |
104 | || (xh < 0.0 && xl > 0.0) | |
105 | || (xl == 0.0 && (res & 1) == 0)))) | |
106 | return res; | |
107 | ||
108 | if (xh < 0.0) | |
12727488 | 109 | res -= 1UL; |
fb146a76 | 110 | else |
12727488 | 111 | res += 1UL; |
fb146a76 UD |
112 | break; |
113 | ||
114 | case FE_TOWARDZERO: | |
115 | if (res > 0 && (xh < 0.0 || (xh == 0.0 && xl < 0.0))) | |
12727488 | 116 | res -= 1UL; |
fb146a76 | 117 | else if (res < 0 && (xh > 0.0 || (xh == 0.0 && xl > 0.0))) |
12727488 | 118 | res += 1UL; |
fb146a76 UD |
119 | return res; |
120 | break; | |
121 | ||
122 | case FE_UPWARD: | |
123 | if (xh > 0.0 || (xh == 0.0 && xl > 0.0)) | |
12727488 | 124 | res += 1UL; |
fb146a76 UD |
125 | break; |
126 | ||
127 | case FE_DOWNWARD: | |
128 | if (xh < 0.0 || (xh == 0.0 && xl < 0.0)) | |
12727488 | 129 | res -= 1UL; |
fb146a76 UD |
130 | break; |
131 | } | |
132 | ||
a1ffb40e | 133 | if (__glibc_unlikely (((~(hi ^ (res - hi)) & (res ^ hi)) < 0))) |
fb146a76 UD |
134 | goto overflow; |
135 | ||
136 | return res; | |
137 | } | |
138 | else | |
139 | { | |
140 | if (xh > 0.0) | |
141 | hi = __LONG_MAX__; | |
142 | else if (xh < 0.0) | |
143 | hi = -__LONG_MAX__ - 1; | |
144 | else | |
145 | /* Nan */ | |
146 | hi = 0; | |
147 | } | |
148 | ||
149 | overflow: | |
150 | #ifdef FE_INVALID | |
151 | feraiseexcept (FE_INVALID); | |
152 | #endif | |
153 | return hi; | |
f964490f | 154 | } |
fb146a76 | 155 | |
f964490f | 156 | long_double_symbol (libm, __lrintl, lrintl); |