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423c2b9d | 1 | /* Round to integer type. ldbl-128ibm version. |
04277e02 | 2 | Copyright (C) 2016-2019 Free Software Foundation, Inc. |
423c2b9d JM |
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 | |
5a82c748 | 17 | <https://www.gnu.org/licenses/>. */ |
423c2b9d JM |
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 0x3ff | |
27 | #define MANT_DIG 53 | |
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 | double hi, lo; | |
41 | if (width > INTMAX_WIDTH) | |
42 | width = INTMAX_WIDTH; | |
43 | uint64_t hx, lx; | |
44 | ldbl_unpack (x, &hi, &lo); | |
45 | EXTRACT_WORDS64 (hx, hi); | |
46 | EXTRACT_WORDS64 (lx, lo); | |
47 | bool negative = (hx & 0x8000000000000000ULL) != 0; | |
48 | bool lo_negative = (lx & 0x8000000000000000ULL) != 0; | |
49 | if (width == 0) | |
50 | return fromfp_domain_error (negative, width); | |
51 | hx &= 0x7fffffffffffffffULL; | |
52 | lx &= 0x7fffffffffffffffULL; | |
53 | if ((hx | lx) == 0) | |
54 | return 0; | |
55 | int hi_exponent = hx >> (MANT_DIG - 1); | |
56 | hi_exponent -= BIAS; | |
57 | int exponent = hi_exponent; | |
58 | hx &= ((1ULL << (MANT_DIG - 1)) - 1); | |
59 | if (hx == 0 && lx != 0 && lo_negative != negative) | |
60 | exponent--; | |
61 | int max_exponent = fromfp_max_exponent (negative, width); | |
62 | if (exponent > max_exponent) | |
63 | return fromfp_domain_error (negative, width); | |
64 | int lo_exponent = lx >> (MANT_DIG - 1); | |
65 | lo_exponent -= BIAS; | |
66 | ||
67 | /* Convert the high part to integer. */ | |
68 | hx |= 1ULL << (MANT_DIG - 1); | |
69 | uintmax_t uret; | |
70 | bool half_bit, more_bits; | |
71 | if (hi_exponent >= MANT_DIG - 1) | |
72 | { | |
73 | uret = hx; | |
74 | uret <<= hi_exponent - (MANT_DIG - 1); | |
75 | half_bit = false; | |
76 | more_bits = false; | |
77 | } | |
78 | else if (hi_exponent >= -1) | |
79 | { | |
80 | uint64_t h = 1ULL << (MANT_DIG - 2 - hi_exponent); | |
81 | half_bit = (hx & h) != 0; | |
82 | more_bits = (hx & (h - 1)) != 0; | |
83 | uret = hx >> (MANT_DIG - 1 - hi_exponent); | |
84 | } | |
85 | else | |
86 | { | |
87 | uret = 0; | |
88 | half_bit = false; | |
89 | more_bits = true; | |
90 | } | |
91 | ||
92 | /* Likewise, the low part. */ | |
93 | if (lx != 0) | |
94 | { | |
95 | uintmax_t lo_uret; | |
96 | bool lo_half_bit, lo_more_bits; | |
97 | lx &= ((1ULL << (MANT_DIG - 1)) - 1); | |
98 | lx |= 1ULL << (MANT_DIG - 1); | |
99 | /* The high part exponent is at most 64, so the low part | |
100 | exponent is at most 11. */ | |
101 | if (lo_exponent >= -1) | |
102 | { | |
103 | uint64_t h = 1ULL << (MANT_DIG - 2 - lo_exponent); | |
104 | lo_half_bit = (lx & h) != 0; | |
105 | lo_more_bits = (lx & (h - 1)) != 0; | |
106 | lo_uret = lx >> (MANT_DIG - 1 - lo_exponent); | |
107 | } | |
108 | else | |
109 | { | |
110 | lo_uret = 0; | |
111 | lo_half_bit = false; | |
112 | lo_more_bits = true; | |
113 | } | |
114 | if (lo_negative == negative) | |
115 | { | |
116 | uret += lo_uret; | |
117 | half_bit |= lo_half_bit; | |
118 | more_bits |= lo_more_bits; | |
119 | } | |
120 | else | |
121 | { | |
122 | uret -= lo_uret; | |
123 | if (lo_half_bit) | |
124 | { | |
125 | uret--; | |
126 | half_bit = true; | |
127 | } | |
128 | if (lo_more_bits && !more_bits) | |
129 | { | |
130 | if (half_bit) | |
131 | { | |
132 | half_bit = false; | |
133 | more_bits = true; | |
134 | } | |
135 | else | |
136 | { | |
137 | uret--; | |
138 | half_bit = true; | |
139 | more_bits = true; | |
140 | } | |
141 | } | |
142 | } | |
143 | } | |
144 | ||
145 | return fromfp_round_and_return (negative, uret, half_bit, more_bits, round, | |
146 | exponent, max_exponent, width); | |
147 | } |