glibc/stdlib/erand48_r.c

53 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 <errno.h>
#include <math.h>
#include <stdlib.h>
int
erand48_r (xsubi, buffer, result)
unsigned short int xsubi[3];
struct drand48_data *buffer;
double *result;
{
int i;
/* Be generous for the arguments, detect some errors. */
if (result == NULL)
{
errno = EFAULT;
return -1;
}
/* Compute next state. */
if (__drand48_iterate (xsubi, buffer) < 0)
return -1;
*result = 0.0;
for (i = 4 / sizeof (unsigned short int); i >= 0; --i)
{
double factor = ldexp (1.0, (i - 6) * sizeof (unsigned short int));
*result += factor * (double) xsubi[i];
}
return 0;
}