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423c2b9d JM |
1 | /* Round to integer type. ldbl-128 version. |
2 | Copyright (C) 2016 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 113 | |
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 (_Float128 x, int round, unsigned int width) | |
39 | { | |
40 | if (width > INTMAX_WIDTH) | |
41 | width = INTMAX_WIDTH; | |
42 | uint64_t hx, lx; | |
43 | GET_LDOUBLE_WORDS64 (hx, lx, x); | |
44 | bool negative = (hx & 0x8000000000000000ULL) != 0; | |
45 | if (width == 0) | |
46 | return fromfp_domain_error (negative, width); | |
47 | hx &= 0x7fffffffffffffffULL; | |
48 | if ((hx | lx) == 0) | |
49 | return 0; | |
50 | int exponent = hx >> (MANT_DIG - 1 - 64); | |
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 | hx &= ((1ULL << (MANT_DIG - 1 - 64)) - 1); | |
57 | hx |= 1ULL << (MANT_DIG - 1 - 64); | |
58 | uintmax_t uret; | |
59 | bool half_bit, more_bits; | |
60 | /* The exponent is at most 63, so we are shifting right by at least | |
61 | 49 bits. */ | |
62 | if (exponent >= -1) | |
63 | { | |
64 | int shift = MANT_DIG - 1 - exponent; | |
65 | if (shift <= 64) | |
66 | { | |
67 | uint64_t h = 1ULL << (shift - 1); | |
68 | half_bit = (lx & h) != 0; | |
69 | more_bits = (lx & (h - 1)) != 0; | |
70 | uret = hx << (64 - shift); | |
71 | if (shift != 64) | |
72 | uret |= lx >> shift; | |
73 | } | |
74 | else | |
75 | { | |
76 | uint64_t h = 1ULL << (shift - 1 - 64); | |
77 | half_bit = (hx & h) != 0; | |
78 | more_bits = ((hx & (h - 1)) | lx) != 0; | |
79 | uret = hx >> (shift - 64); | |
80 | } | |
81 | } | |
82 | else | |
83 | { | |
84 | uret = 0; | |
85 | half_bit = false; | |
86 | more_bits = true; | |
87 | } | |
88 | return fromfp_round_and_return (negative, uret, half_bit, more_bits, round, | |
89 | exponent, max_exponent, width); | |
90 | } |