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6d7e8eda | 1 | /* Copyright (C) 1995-2023 Free Software Foundation, Inc. |
c84142e8 | 2 | This file is part of the GNU C Library. |
c84142e8 UD |
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. | |
c84142e8 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. |
c84142e8 | 13 | |
41bdb6e2 | 14 | You should have received a copy of the GNU Lesser General Public |
59ba27a6 | 15 | License along with the GNU C Library; if not, see |
5a82c748 | 16 | <https://www.gnu.org/licenses/>. */ |
60478656 | 17 | |
c131718c | 18 | #include <ieee754.h> |
60478656 | 19 | #include <stdlib.h> |
5aab07eb | 20 | #include <limits.h> |
52e9a9d1 RM |
21 | |
22 | ||
60478656 | 23 | int |
a72ddc14 JM |
24 | __erand48_r (unsigned short int xsubi[3], struct drand48_data *buffer, |
25 | double *result) | |
60478656 | 26 | { |
c131718c UD |
27 | union ieee754_double temp; |
28 | ||
60478656 RM |
29 | /* Compute next state. */ |
30 | if (__drand48_iterate (xsubi, buffer) < 0) | |
31 | return -1; | |
32 | ||
5aab07eb RM |
33 | /* Construct a positive double with the 48 random bits distributed over |
34 | its fractional part so the resulting FP number is [0.0,1.0). */ | |
52e9a9d1 | 35 | |
c131718c | 36 | temp.ieee.negative = 0; |
ebbad4cc | 37 | temp.ieee.exponent = IEEE754_DOUBLE_BIAS; |
c131718c UD |
38 | temp.ieee.mantissa0 = (xsubi[2] << 4) | (xsubi[1] >> 12); |
39 | temp.ieee.mantissa1 = ((xsubi[1] & 0xfff) << 20) | (xsubi[0] << 4); | |
52e9a9d1 | 40 | |
6973fc01 UD |
41 | /* Please note the lower 4 bits of mantissa1 are always 0. */ |
42 | *result = temp.d - 1.0; | |
43 | ||
60478656 RM |
44 | return 0; |
45 | } | |
47f13fd4 | 46 | weak_alias (__erand48_r, erand48_r) |