42 строки
1.4 KiB
C
42 строки
1.4 KiB
C
/*
|
|
* Copyright (c) 2002-2006 Hewlett-Packard Development Company, L.P.
|
|
* Contributed by David Mosberger-Tang <davidm@hpl.hp.com>
|
|
*
|
|
* This program is free software; you can redistribute it and/or
|
|
* modify it under the terms of version 2 of the GNU General Public
|
|
* License as published by the Free Software Foundation.
|
|
*
|
|
* This program 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
|
|
* General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with this program; if not, write to the Free Software
|
|
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
|
|
* 02111-1307 USA
|
|
*/
|
|
#include <linux/types.h>
|
|
#include <linux/module.h>
|
|
|
|
/*
|
|
* Fast, simple, yet decent quality random number generator based on
|
|
* a paper by David G. Carta ("Two Fast Implementations of the
|
|
* `Minimal Standard' Random Number Generator," Communications of the
|
|
* ACM, January, 1990).
|
|
*/
|
|
u64 carta_random32 (u64 seed)
|
|
{
|
|
# define A 16807
|
|
# define M ((u32) 1 << 31)
|
|
u64 s, prod = A * seed, p, q;
|
|
|
|
p = (prod >> 31) & (M - 1);
|
|
q = (prod >> 0) & (M - 1);
|
|
s = p + q;
|
|
if (s >= M)
|
|
s -= M - 1;
|
|
return s;
|
|
}
|
|
EXPORT_SYMBOL_GPL(carta_random32);
|