1 /* Copyright (C) 1995, 1997, 2001 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3 Contributed by Ulrich Drepper <drepper@gnu.ai.mit.edu <mailto:drepper@gnu.ai.mit.edu>>, August 1995.
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.
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.
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, write to the Free
17 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
24 extern int __drand48_iterate(unsigned short xsubi[3],
25 struct drand48_data *buffer);
28 int erand48_r (xsubi, buffer, result)
29 unsigned short int xsubi[3];
30 struct drand48_data *buffer;
33 union ieee754_double temp;
35 /* Compute next state. */
36 if (__drand48_iterate (xsubi, buffer) < 0)
39 /* Construct a positive double with the 48 random bits distributed over
40 its fractional part so the resulting FP number is [0.0,1.0). */
42 temp.ieee.negative = 0;
43 temp.ieee.exponent = IEEE754_DOUBLE_BIAS;
44 temp.ieee.mantissa0 = (xsubi[2] << 4) | (xsubi[1] >> 12);
45 temp.ieee.mantissa1 = ((xsubi[1] & 0xfff) << 20) | (xsubi[0] << 4);
47 /* Please note the lower 4 bits of mantissa1 are always 0. */
48 *result = temp.d - 1.0;