| /* |
| * 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); |
