1/* Copyright (C) 1995-2022 Free Software Foundation, Inc.
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
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.
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
12 Lesser General Public License for more details.
13
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library; if not, see
16 <https://www.gnu.org/licenses/>. */
17
18#include <ieee754.h>
19#include <stdlib.h>
20#include <limits.h>
21
22
23int
24__erand48_r (unsigned short int xsubi[3], struct drand48_data *buffer,
25 double *result)
26{
27 union ieee754_double temp;
28
29 /* Compute next state. */
30 if (__drand48_iterate (xsubi, buffer) < 0)
31 return -1;
32
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). */
35
36 temp.ieee.negative = 0;
37 temp.ieee.exponent = IEEE754_DOUBLE_BIAS;
38 temp.ieee.mantissa0 = (xsubi[2] << 4) | (xsubi[1] >> 12);
39 temp.ieee.mantissa1 = ((xsubi[1] & 0xfff) << 20) | (xsubi[0] << 4);
40
41 /* Please note the lower 4 bits of mantissa1 are always 0. */
42 *result = temp.d - 1.0;
43
44 return 0;
45}
46weak_alias (__erand48_r, erand48_r)
47