mirror of
https://sourceware.org/git/glibc.git
synced 2024-11-25 14:30:06 +00:00
5aab07eb56
* stdlib/erand48_r.c: Use FP division by powers of two to distribute short bits into double.
47 lines
1.5 KiB
C
47 lines
1.5 KiB
C
/* Copyright (C) 1995 Free Software Foundation, Inc.
|
|
This file is part of the GNU C Library.
|
|
Contributed by Ulrich Drepper <drepper@gnu.ai.mit.edu>, August 1995.
|
|
|
|
The GNU C Library is free software; you can redistribute it and/or
|
|
modify it under the terms of the GNU Library General Public License as
|
|
published by the Free Software Foundation; either version 2 of the
|
|
License, or (at your option) any later version.
|
|
|
|
The GNU C Library is distributed in the hope that it will be useful,
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
Library General Public License for more details.
|
|
|
|
You should have received a copy of the GNU Library General Public
|
|
License along with the GNU C Library; see the file COPYING.LIB. If
|
|
not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
|
|
Boston, MA 02111-1307, USA. */
|
|
|
|
#include <stdlib.h>
|
|
#include <limits.h>
|
|
|
|
|
|
int
|
|
erand48_r (xsubi, buffer, result)
|
|
unsigned short int xsubi[3];
|
|
struct drand48_data *buffer;
|
|
double *result;
|
|
{
|
|
/* Compute next state. */
|
|
if (__drand48_iterate (xsubi, buffer) < 0)
|
|
return -1;
|
|
|
|
/* Construct a positive double with the 48 random bits distributed over
|
|
its fractional part so the resulting FP number is [0.0,1.0). */
|
|
|
|
#if USHRT_MAX == 65535
|
|
*result = ((double) xsubi[2] / (1ULL << 48) +
|
|
(double) xsubi[1] / (1ULL << 32) +
|
|
(double) xsubi[0] / (1ULL << 16));
|
|
#else
|
|
# error Unsupported size of short int
|
|
#endif
|
|
|
|
return 0;
|
|
}
|