1 | /* Round argument to nearest integral value according to current rounding |
2 | direction. |
3 | Copyright (C) 1997-2024 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 <fenv.h> |
21 | #include <limits.h> |
22 | #include <math.h> |
23 | |
24 | #include <math-narrow-eval.h> |
25 | #include <math_private.h> |
26 | #include <libm-alias-double.h> |
27 | #include <fix-fp-int-convert-overflow.h> |
28 | #include <math-use-builtins.h> |
29 | |
30 | |
31 | long int |
32 | __lrint (double x) |
33 | { |
34 | #if USE_LRINT_BUILTIN |
35 | return __builtin_lrint (x); |
36 | #else |
37 | /* Use generic implementation. */ |
38 | static const double two52[2] = |
39 | { |
40 | 4.50359962737049600000e+15, /* 0x43300000, 0x00000000 */ |
41 | -4.50359962737049600000e+15, /* 0xC3300000, 0x00000000 */ |
42 | }; |
43 | |
44 | int32_t j0; |
45 | uint32_t i0, i1; |
46 | double w; |
47 | double t; |
48 | long int result; |
49 | int sx; |
50 | |
51 | EXTRACT_WORDS (i0, i1, x); |
52 | j0 = ((i0 >> 20) & 0x7ff) - 0x3ff; |
53 | sx = i0 >> 31; |
54 | i0 &= 0xfffff; |
55 | i0 |= 0x100000; |
56 | |
57 | if (j0 < 20) |
58 | { |
59 | w = math_narrow_eval (two52[sx] + x); |
60 | t = w - two52[sx]; |
61 | EXTRACT_WORDS (i0, i1, t); |
62 | j0 = ((i0 >> 20) & 0x7ff) - 0x3ff; |
63 | i0 &= 0xfffff; |
64 | i0 |= 0x100000; |
65 | |
66 | result = (j0 < 0 ? 0 : i0 >> (20 - j0)); |
67 | } |
68 | else if (j0 < (int32_t) (8 * sizeof (long int)) - 1) |
69 | { |
70 | if (j0 >= 52) |
71 | result = ((long int) i0 << (j0 - 20)) | ((long int) i1 << (j0 - 52)); |
72 | else |
73 | { |
74 | #if defined FE_INVALID || defined FE_INEXACT |
75 | /* X < LONG_MAX + 1 implied by J0 < 31. */ |
76 | if (sizeof (long int) == 4 |
77 | && x > (double) LONG_MAX) |
78 | { |
79 | /* In the event of overflow we must raise the "invalid" |
80 | exception, but not "inexact". */ |
81 | t = __nearbyint (x: x); |
82 | feraiseexcept (excepts: t == LONG_MAX ? FE_INEXACT : FE_INVALID); |
83 | } |
84 | else |
85 | #endif |
86 | { |
87 | w = math_narrow_eval (two52[sx] + x); |
88 | t = w - two52[sx]; |
89 | } |
90 | EXTRACT_WORDS (i0, i1, t); |
91 | j0 = ((i0 >> 20) & 0x7ff) - 0x3ff; |
92 | i0 &= 0xfffff; |
93 | i0 |= 0x100000; |
94 | |
95 | if (j0 == 20) |
96 | result = (long int) i0; |
97 | else |
98 | result = ((long int) i0 << (j0 - 20)) | (i1 >> (52 - j0)); |
99 | } |
100 | } |
101 | else |
102 | { |
103 | /* The number is too large. Unless it rounds to LONG_MIN, |
104 | FE_INVALID must be raised and the return value is |
105 | unspecified. */ |
106 | #if defined FE_INVALID || defined FE_INEXACT |
107 | if (sizeof (long int) == 4 |
108 | && x < (double) LONG_MIN |
109 | && x > (double) LONG_MIN - 1.0) |
110 | { |
111 | /* If truncation produces LONG_MIN, the cast will not raise |
112 | the exception, but may raise "inexact". */ |
113 | t = __nearbyint (x: x); |
114 | feraiseexcept (excepts: t == LONG_MIN ? FE_INEXACT : FE_INVALID); |
115 | return LONG_MIN; |
116 | } |
117 | else if (FIX_DBL_LONG_CONVERT_OVERFLOW && x != (double) LONG_MIN) |
118 | { |
119 | feraiseexcept (FE_INVALID); |
120 | return sx == 0 ? LONG_MAX : LONG_MIN; |
121 | } |
122 | #endif |
123 | return (long int) x; |
124 | } |
125 | |
126 | return sx ? -result : result; |
127 | #endif /* ! USE_LRINT_BUILTIN */ |
128 | } |
129 | |
130 | libm_alias_double (__lrint, lrint) |
131 | |