1/* Round to integer type. ldbl-128 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 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
37RET_TYPE
38FUNC (_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}
91