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bfff8b1b | 1 | /* Copyright (C) 1995-2017 Free Software Foundation, Inc. |
377a515b UD |
2 | This file is part of the GNU C Library. |
3 | ||
4 | The GNU C Library is free software; you can redistribute it and/or | |
41bdb6e2 AJ |
5 | modify it under the terms of the GNU Lesser General Public |
6 | License as published by the Free Software Foundation; either | |
7 | version 2.1 of the License, or (at your option) any later version. | |
377a515b UD |
8 | |
9 | The GNU C Library is distributed in the hope that it will be useful, | |
10 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
41bdb6e2 | 12 | Lesser General Public License for more details. |
377a515b | 13 | |
41bdb6e2 | 14 | You should have received a copy of the GNU Lesser General Public |
59ba27a6 PE |
15 | License along with the GNU C Library; if not, see |
16 | <http://www.gnu.org/licenses/>. */ | |
28f540f4 RM |
17 | |
18 | #include "gmp.h" | |
19 | #include "gmp-impl.h" | |
20 | #include "longlong.h" | |
981993e1 | 21 | #include <ieee754.h> |
28f540f4 | 22 | #include <float.h> |
abfbdde1 | 23 | #include <math.h> |
28f540f4 RM |
24 | #include <stdlib.h> |
25 | ||
abfbdde1 | 26 | /* Convert a `long double' in IEEE854 quad-precision format to a |
28f540f4 | 27 | multi-precision integer representing the significand scaled up by its |
abfbdde1 UD |
28 | number of bits (113 for long double) and an integral power of two |
29 | (MPN frexpl). */ | |
28f540f4 RM |
30 | |
31 | mp_size_t | |
abfbdde1 UD |
32 | __mpn_extract_long_double (mp_ptr res_ptr, mp_size_t size, |
33 | int *expt, int *is_neg, | |
34 | long double value) | |
28f540f4 | 35 | { |
abfbdde1 | 36 | union ieee854_long_double u; |
28f540f4 RM |
37 | u.d = value; |
38 | ||
39 | *is_neg = u.ieee.negative; | |
abfbdde1 | 40 | *expt = (int) u.ieee.exponent - IEEE854_LONG_DOUBLE_BIAS; |
28f540f4 RM |
41 | |
42 | #if BITS_PER_MP_LIMB == 32 | |
abfbdde1 UD |
43 | res_ptr[0] = u.ieee.mantissa3; /* Low-order 32 bits of fraction. */ |
44 | res_ptr[1] = u.ieee.mantissa2; | |
45 | res_ptr[2] = u.ieee.mantissa1; | |
46 | res_ptr[3] = u.ieee.mantissa0; /* High-order 32 bits. */ | |
47 | #define N 4 | |
28f540f4 RM |
48 | #elif BITS_PER_MP_LIMB == 64 |
49 | /* Hopefully the compiler will combine the two bitfield extracts | |
50 | and this composition into just the original quadword extract. */ | |
d8a5edc2 RM |
51 | res_ptr[0] = ((mp_limb_t) u.ieee.mantissa2 << 32) | u.ieee.mantissa3; |
52 | res_ptr[1] = ((mp_limb_t) u.ieee.mantissa0 << 32) | u.ieee.mantissa1; | |
abfbdde1 | 53 | #define N 2 |
28f540f4 RM |
54 | #else |
55 | #error "mp_limb size " BITS_PER_MP_LIMB "not accounted for" | |
56 | #endif | |
57 | /* The format does not fill the last limb. There are some zeros. */ | |
58 | #define NUM_LEADING_ZEROS (BITS_PER_MP_LIMB \ | |
abfbdde1 | 59 | - (LDBL_MANT_DIG - ((N - 1) * BITS_PER_MP_LIMB))) |
28f540f4 RM |
60 | |
61 | if (u.ieee.exponent == 0) | |
62 | { | |
63 | /* A biased exponent of zero is a special case. | |
64 | Either it is a zero or it is a denormal number. */ | |
abfbdde1 UD |
65 | if (res_ptr[0] == 0 && res_ptr[1] == 0 |
66 | && res_ptr[N - 2] == 0 && res_ptr[N - 1] == 0) /* Assumes N<=4. */ | |
28f540f4 RM |
67 | /* It's zero. */ |
68 | *expt = 0; | |
69 | else | |
70 | { | |
71 | /* It is a denormal number, meaning it has no implicit leading | |
350635a5 | 72 | one bit, and its exponent is in fact the format minimum. */ |
28f540f4 RM |
73 | int cnt; |
74 | ||
abfbdde1 | 75 | #if N == 2 |
28f540f4 RM |
76 | if (res_ptr[N - 1] != 0) |
77 | { | |
78 | count_leading_zeros (cnt, res_ptr[N - 1]); | |
79 | cnt -= NUM_LEADING_ZEROS; | |
abfbdde1 UD |
80 | res_ptr[N - 1] = res_ptr[N - 1] << cnt |
81 | | (res_ptr[0] >> (BITS_PER_MP_LIMB - cnt)); | |
28f540f4 | 82 | res_ptr[0] <<= cnt; |
abfbdde1 | 83 | *expt = LDBL_MIN_EXP - 1 - cnt; |
28f540f4 RM |
84 | } |
85 | else | |
86 | { | |
87 | count_leading_zeros (cnt, res_ptr[0]); | |
88 | if (cnt >= NUM_LEADING_ZEROS) | |
89 | { | |
90 | res_ptr[N - 1] = res_ptr[0] << (cnt - NUM_LEADING_ZEROS); | |
a182affd | 91 | res_ptr[0] = 0; |
28f540f4 RM |
92 | } |
93 | else | |
94 | { | |
95 | res_ptr[N - 1] = res_ptr[0] >> (NUM_LEADING_ZEROS - cnt); | |
96 | res_ptr[0] <<= BITS_PER_MP_LIMB - (NUM_LEADING_ZEROS - cnt); | |
97 | } | |
abfbdde1 UD |
98 | *expt = LDBL_MIN_EXP - 1 |
99 | - (BITS_PER_MP_LIMB - NUM_LEADING_ZEROS) - cnt; | |
100 | } | |
101 | #else | |
102 | int j, k, l; | |
103 | ||
52e1b618 | 104 | for (j = N - 1; j > 0; j--) |
abfbdde1 UD |
105 | if (res_ptr[j] != 0) |
106 | break; | |
107 | ||
108 | count_leading_zeros (cnt, res_ptr[j]); | |
109 | cnt -= NUM_LEADING_ZEROS; | |
110 | l = N - 1 - j; | |
111 | if (cnt < 0) | |
112 | { | |
113 | cnt += BITS_PER_MP_LIMB; | |
52e1b618 | 114 | l--; |
28f540f4 | 115 | } |
abfbdde1 UD |
116 | if (!cnt) |
117 | for (k = N - 1; k >= l; k--) | |
118 | res_ptr[k] = res_ptr[k-l]; | |
119 | else | |
52e1b618 UD |
120 | { |
121 | for (k = N - 1; k > l; k--) | |
122 | res_ptr[k] = res_ptr[k-l] << cnt | |
123 | | res_ptr[k-l-1] >> (BITS_PER_MP_LIMB - cnt); | |
124 | res_ptr[k--] = res_ptr[0] << cnt; | |
125 | } | |
abfbdde1 UD |
126 | |
127 | for (; k >= 0; k--) | |
128 | res_ptr[k] = 0; | |
52e1b618 | 129 | *expt = LDBL_MIN_EXP - 1 - l * BITS_PER_MP_LIMB - cnt; |
abfbdde1 | 130 | #endif |
28f540f4 RM |
131 | } |
132 | } | |
133 | else | |
134 | /* Add the implicit leading one bit for a normalized number. */ | |
d8a5edc2 RM |
135 | res_ptr[N - 1] |= (mp_limb_t) 1 << (LDBL_MANT_DIG - 1 |
136 | - ((N - 1) * BITS_PER_MP_LIMB)); | |
28f540f4 RM |
137 | |
138 | return N; | |
139 | } |