1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
|
/* Round to integer type. ldbl-128ibm version.
Copyright (C) 2016-2019 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <errno.h>
#include <fenv.h>
#include <math.h>
#include <math_private.h>
#include <stdbool.h>
#include <stdint.h>
#define BIAS 0x3ff
#define MANT_DIG 53
#if UNSIGNED
# define RET_TYPE uintmax_t
#else
# define RET_TYPE intmax_t
#endif
#include <fromfp.h>
RET_TYPE
FUNC (long double x, int round, unsigned int width)
{
double hi, lo;
if (width > INTMAX_WIDTH)
width = INTMAX_WIDTH;
uint64_t hx, lx;
ldbl_unpack (x, &hi, &lo);
EXTRACT_WORDS64 (hx, hi);
EXTRACT_WORDS64 (lx, lo);
bool negative = (hx & 0x8000000000000000ULL) != 0;
bool lo_negative = (lx & 0x8000000000000000ULL) != 0;
if (width == 0)
return fromfp_domain_error (negative, width);
hx &= 0x7fffffffffffffffULL;
lx &= 0x7fffffffffffffffULL;
if ((hx | lx) == 0)
return 0;
int hi_exponent = hx >> (MANT_DIG - 1);
hi_exponent -= BIAS;
int exponent = hi_exponent;
hx &= ((1ULL << (MANT_DIG - 1)) - 1);
if (hx == 0 && lx != 0 && lo_negative != negative)
exponent--;
int max_exponent = fromfp_max_exponent (negative, width);
if (exponent > max_exponent)
return fromfp_domain_error (negative, width);
int lo_exponent = lx >> (MANT_DIG - 1);
lo_exponent -= BIAS;
/* Convert the high part to integer. */
hx |= 1ULL << (MANT_DIG - 1);
uintmax_t uret;
bool half_bit, more_bits;
if (hi_exponent >= MANT_DIG - 1)
{
uret = hx;
uret <<= hi_exponent - (MANT_DIG - 1);
half_bit = false;
more_bits = false;
}
else if (hi_exponent >= -1)
{
uint64_t h = 1ULL << (MANT_DIG - 2 - hi_exponent);
half_bit = (hx & h) != 0;
more_bits = (hx & (h - 1)) != 0;
uret = hx >> (MANT_DIG - 1 - hi_exponent);
}
else
{
uret = 0;
half_bit = false;
more_bits = true;
}
/* Likewise, the low part. */
if (lx != 0)
{
uintmax_t lo_uret;
bool lo_half_bit, lo_more_bits;
lx &= ((1ULL << (MANT_DIG - 1)) - 1);
lx |= 1ULL << (MANT_DIG - 1);
/* The high part exponent is at most 64, so the low part
exponent is at most 11. */
if (lo_exponent >= -1)
{
uint64_t h = 1ULL << (MANT_DIG - 2 - lo_exponent);
lo_half_bit = (lx & h) != 0;
lo_more_bits = (lx & (h - 1)) != 0;
lo_uret = lx >> (MANT_DIG - 1 - lo_exponent);
}
else
{
lo_uret = 0;
lo_half_bit = false;
lo_more_bits = true;
}
if (lo_negative == negative)
{
uret += lo_uret;
half_bit |= lo_half_bit;
more_bits |= lo_more_bits;
}
else
{
uret -= lo_uret;
if (lo_half_bit)
{
uret--;
half_bit = true;
}
if (lo_more_bits && !more_bits)
{
if (half_bit)
{
half_bit = false;
more_bits = true;
}
else
{
uret--;
half_bit = true;
more_bits = true;
}
}
}
}
return fromfp_round_and_return (negative, uret, half_bit, more_bits, round,
exponent, max_exponent, width);
}
|
