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/* Copyright (C) 1995, 1996 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 <stdlib.h>
#include <limits.h>
/* Global state for non-reentrent functions. */
struct drand48_data __libc_drand48_data;
int
__drand48_iterate (xsubi, buffer)
unsigned short int xsubi[3];
struct drand48_data *buffer;
{
/* Be generous for the arguments, detect some errors. */
if (xsubi == NULL || buffer == NULL)
{
errno = EFAULT;
return -1;
}
/* Initialize buffer, if not yet done. */
if (!buffer->init)
{
#if (USHRT_MAX == 0xffffU)
buffer->a[2] = 0x5;
buffer->a[1] = 0xdeec;
buffer->a[0] = 0xe66d;
#else
buffer->a[2] = 0x5deecUL;
buffer->a[1] = 0xe66d0000UL;
buffer->a[0] = 0;
#endif
buffer->c = 0xb;
buffer->init = 1;
}
/* Do the real work. We choose a data type which contains at least
48 bits. Because we compute the modulus it does not care how
many bits really are computed. */
if (sizeof (long int) >= 6)
{
/* The `long' data type is sufficent. */
unsigned long int X, a, result;
#define ONE_STEP \
if (sizeof (unsigned short int) == 2) \
{ \
X = (xsubi[2] << 16 | xsubi[1]) << 16 | xsubi[0]; \
a = (buffer->a[2] << 16 | buffer->a[1]) << 16 | buffer->a[0]; \
\
result = X * a + buffer->c; \
\
xsubi[0] = result & 0xffff; \
result >>= 16; \
xsubi[1] = result & 0xffff; \
result >>= 16; \
xsubi[2] = result & 0xffff; \
} \
else \
{ \
X = xsubi[2] << 16 | xsubi[1] >> 16; \
a = buffer->a[2] << 16 | buffer->a[1] >> 16; \
\
result = X * a + buffer->c; \
\
xsubi[0] = result >> 16 & 0xffffffffl; \
xsubi[1] = result << 16 & 0xffff0000l; \
}
ONE_STEP;
}
else
{
/* We have to use the `long long' data type. */
unsigned long long int X, a, result;
ONE_STEP;
}
return 0;
}
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