1 | /* Round to integer type. ldbl-96 version. |
2 | Copyright (C) 2016-2017 Free Software Foundation, Inc. |
3 | This file is part of the GNU C Library. |
4 | |
5 | The GNU C Library is free software; you can redistribute it and/or |
6 | modify it under the terms of the GNU Lesser General Public |
7 | License as published by the Free Software Foundation; either |
8 | version 2.1 of the License, or (at your option) any later version. |
9 | |
10 | The GNU C Library is distributed in the hope that it will be useful, |
11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
13 | Lesser General Public License for more details. |
14 | |
15 | You should have received a copy of the GNU Lesser General Public |
16 | License along with the GNU C Library; if not, see |
17 | <http://www.gnu.org/licenses/>. */ |
18 | |
19 | #include <errno.h> |
20 | #include <fenv.h> |
21 | #include <math.h> |
22 | #include <math_private.h> |
23 | #include <stdbool.h> |
24 | #include <stdint.h> |
25 | |
26 | #define BIAS 0x3fff |
27 | #define MANT_DIG 64 |
28 | |
29 | #if UNSIGNED |
30 | # define RET_TYPE uintmax_t |
31 | #else |
32 | # define RET_TYPE intmax_t |
33 | #endif |
34 | |
35 | #include <fromfp.h> |
36 | |
37 | RET_TYPE |
38 | FUNC (long double x, int round, unsigned int width) |
39 | { |
40 | if (width > INTMAX_WIDTH) |
41 | width = INTMAX_WIDTH; |
42 | uint16_t se; |
43 | uint32_t hx, lx; |
44 | GET_LDOUBLE_WORDS (se, hx, lx, x); |
45 | bool negative = (se & 0x8000) != 0; |
46 | if (width == 0) |
47 | return fromfp_domain_error (negative, width); |
48 | if ((hx | lx) == 0) |
49 | return 0; |
50 | int exponent = se & 0x7fff; |
51 | exponent -= BIAS; |
52 | int max_exponent = fromfp_max_exponent (negative, width); |
53 | if (exponent > max_exponent) |
54 | return fromfp_domain_error (negative, width); |
55 | |
56 | uint64_t ix = (((uint64_t) hx) << 32) | lx; |
57 | uintmax_t uret; |
58 | bool half_bit, more_bits; |
59 | if (exponent >= MANT_DIG - 1) |
60 | { |
61 | uret = ix; |
62 | /* Exponent 63; no shifting required. */ |
63 | half_bit = false; |
64 | more_bits = false; |
65 | } |
66 | else if (exponent >= -1) |
67 | { |
68 | uint64_t h = 1ULL << (MANT_DIG - 2 - exponent); |
69 | half_bit = (ix & h) != 0; |
70 | more_bits = (ix & (h - 1)) != 0; |
71 | if (exponent == -1) |
72 | uret = 0; |
73 | else |
74 | uret = ix >> (MANT_DIG - 1 - exponent); |
75 | } |
76 | else |
77 | { |
78 | uret = 0; |
79 | half_bit = false; |
80 | more_bits = true; |
81 | } |
82 | return fromfp_round_and_return (negative, uret, half_bit, more_bits, round, |
83 | exponent, max_exponent, width); |
84 | } |
85 | |