1 | /* Round to 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 | /* This has been coded in assembler because GCC makes such a mess of it |
21 | when it's coded in C. */ |
22 | |
23 | #define NO_MATH_REDIRECT |
24 | #include <math.h> |
25 | #include <fenv.h> |
26 | #include <math-barriers.h> |
27 | #include <math_private.h> |
28 | #include <fenv_private.h> |
29 | #include <math_ldbl_opt.h> |
30 | #include <float.h> |
31 | #include <ieee754.h> |
32 | |
33 | #ifdef USE_AS_NEARBYINTL |
34 | # define rintl nearbyintl |
35 | # define __rintl __nearbyintl |
36 | #endif |
37 | |
38 | |
39 | long double |
40 | __rintl (long double x) |
41 | { |
42 | double xh, xl, hi, lo; |
43 | |
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)) |
50 | { |
51 | double orig_xh; |
52 | int save_round = fegetround (); |
53 | |
54 | /* Long double arithmetic, including the canonicalisation below, |
55 | only works in round-to-nearest mode. */ |
56 | #ifdef USE_AS_NEARBYINTL |
57 | SET_RESTORE_ROUND_NOEX (FE_TONEAREST); |
58 | #else |
59 | fesetround (FE_TONEAREST); |
60 | #endif |
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) |
84 | { |
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; |
107 | } |
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 | |
119 | #ifdef USE_AS_NEARBYINTL |
120 | math_force_eval (xh); |
121 | math_force_eval (xl); |
122 | #else |
123 | fesetround (save_round); |
124 | #endif |
125 | } |
126 | else |
127 | /* Quiet signaling NaN arguments. */ |
128 | xh += xh; |
129 | |
130 | return ldbl_pack (xh, xl); |
131 | } |
132 | |
133 | long_double_symbol (libm, __rintl, rintl); |
134 | |