1/* Copyright (C) 1995-2021 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3 Contributed by Ulrich Drepper <drepper@gnu.ai.mit.edu>, August 1995.
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
17 <https://www.gnu.org/licenses/>. */
18
19#include <ieee754.h>
20#include <stdlib.h>
21#include <limits.h>
22
23
24int
25__erand48_r (unsigned short int xsubi[3], struct drand48_data *buffer,
26 double *result)
27{
28 union ieee754_double temp;
29
30 /* Compute next state. */
31 if (__drand48_iterate (xsubi, buffer) < 0)
32 return -1;
33
34 /* Construct a positive double with the 48 random bits distributed over
35 its fractional part so the resulting FP number is [0.0,1.0). */
36
37 temp.ieee.negative = 0;
38 temp.ieee.exponent = IEEE754_DOUBLE_BIAS;
39 temp.ieee.mantissa0 = (xsubi[2] << 4) | (xsubi[1] >> 12);
40 temp.ieee.mantissa1 = ((xsubi[1] & 0xfff) << 20) | (xsubi[0] << 4);
41
42 /* Please note the lower 4 bits of mantissa1 are always 0. */
43 *result = temp.d - 1.0;
44
45 return 0;
46}
47weak_alias (__erand48_r, erand48_r)
48