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f964490f RM |
1 | /* Round to int long double floating-point values. |
2 | IBM extended format long double version. | |
2b778ceb | 3 | Copyright (C) 2006-2021 Free Software Foundation, Inc. |
f964490f RM |
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 | 17 | License along with the GNU C Library; if not, see |
5a82c748 | 18 | <https://www.gnu.org/licenses/>. */ |
f964490f RM |
19 | |
20 | /* This has been coded in assembler because GCC makes such a mess of it | |
21 | when it's coded in C. */ | |
22 | ||
f29b6f17 | 23 | #define NO_MATH_REDIRECT |
f964490f | 24 | #include <math.h> |
4a3d3999 | 25 | #include <fenv.h> |
b4d5b8b0 | 26 | #include <math-barriers.h> |
0d13dfa1 | 27 | #include <math_private.h> |
70e2ba33 | 28 | #include <fenv_private.h> |
f964490f RM |
29 | #include <math_ldbl_opt.h> |
30 | #include <float.h> | |
31 | #include <ieee754.h> | |
32 | ||
613c92b3 JM |
33 | #ifdef USE_AS_NEARBYINTL |
34 | # define rintl nearbyintl | |
35 | # define __rintl __nearbyintl | |
36 | #endif | |
37 | ||
f964490f | 38 | |
f964490f RM |
39 | long double |
40 | __rintl (long double x) | |
f964490f | 41 | { |
5c68d401 | 42 | double xh, xl, hi, lo; |
f964490f | 43 | |
5c68d401 RM |
44 | ldbl_unpack (x, &xh, &xl); |
45 | ||
46 | /* Return Inf, Nan, +/-0 unchanged. */ | |
47 | if (__builtin_expect (xh != 0.0 | |
48 | && __builtin_isless (__builtin_fabs (xh), | |
49 | __builtin_inf ()), 1)) | |
f964490f | 50 | { |
5c68d401 | 51 | double orig_xh; |
4a3d3999 | 52 | int save_round = fegetround (); |
5c68d401 RM |
53 | |
54 | /* Long double arithmetic, including the canonicalisation below, | |
55 | only works in round-to-nearest mode. */ | |
613c92b3 JM |
56 | #ifdef USE_AS_NEARBYINTL |
57 | SET_RESTORE_ROUND_NOEX (FE_TONEAREST); | |
58 | #else | |
5c68d401 | 59 | fesetround (FE_TONEAREST); |
613c92b3 | 60 | #endif |
5c68d401 RM |
61 | |
62 | /* Convert the high double to integer. */ | |
63 | orig_xh = xh; | |
64 | hi = ldbl_nearbyint (xh); | |
65 | ||
66 | /* Subtract integral high part from the value. If the low double | |
67 | happens to be exactly 0.5 or -0.5, you might think that this | |
68 | subtraction could result in an incorrect conversion. For | |
69 | instance, subtracting an odd number would cause this function | |
70 | to round in the wrong direction. However, if we have a | |
71 | canonical long double with the low double 0.5 or -0.5, then the | |
72 | high double must be even. */ | |
73 | xh -= hi; | |
74 | ldbl_canonicalize (&xh, &xl); | |
75 | ||
76 | /* Now convert the low double, adjusted for any remainder from the | |
77 | high double. */ | |
78 | lo = ldbl_nearbyint (xh); | |
79 | ||
80 | xh -= lo; | |
81 | ldbl_canonicalize (&xh, &xl); | |
82 | ||
83 | switch (save_round) | |
f964490f | 84 | { |
5c68d401 RM |
85 | case FE_TONEAREST: |
86 | if (xl > 0.0 && xh == 0.5) | |
87 | lo += 1.0; | |
88 | else if (xl < 0.0 && -xh == 0.5) | |
89 | lo -= 1.0; | |
90 | break; | |
91 | ||
92 | case FE_TOWARDZERO: | |
93 | if (orig_xh < 0.0) | |
94 | goto do_up; | |
95 | /* Fall thru */ | |
96 | ||
97 | case FE_DOWNWARD: | |
98 | if (xh < 0.0 || (xh == 0.0 && xl < 0.0)) | |
99 | lo -= 1.0; | |
100 | break; | |
101 | ||
102 | case FE_UPWARD: | |
103 | do_up: | |
104 | if (xh > 0.0 || (xh == 0.0 && xl > 0.0)) | |
105 | lo += 1.0; | |
106 | break; | |
f964490f | 107 | } |
5c68d401 RM |
108 | |
109 | /* Ensure the final value is canonical. In certain cases, | |
110 | rounding causes hi,lo calculated so far to be non-canonical. */ | |
111 | xh = hi; | |
112 | xl = lo; | |
113 | ldbl_canonicalize (&xh, &xl); | |
114 | ||
115 | /* Ensure we return -0 rather than +0 when appropriate. */ | |
116 | if (orig_xh < 0.0) | |
117 | xh = -__builtin_fabs (xh); | |
118 | ||
613c92b3 JM |
119 | #ifdef USE_AS_NEARBYINTL |
120 | math_force_eval (xh); | |
121 | math_force_eval (xl); | |
122 | #else | |
5c68d401 | 123 | fesetround (save_round); |
613c92b3 | 124 | #endif |
f964490f | 125 | } |
bba14195 JM |
126 | else |
127 | /* Quiet signaling NaN arguments. */ | |
128 | xh += xh; | |
f964490f | 129 | |
5c68d401 | 130 | return ldbl_pack (xh, xl); |
f964490f RM |
131 | } |
132 | ||
133 | long_double_symbol (libm, __rintl, rintl); |