1 /* 2 * Simple xorshift PRNG 3 * see http://www.jstatsoft.org/v08/i14/paper 4 * 5 * Copyright (c) 2012 Michael Walle 6 * Michael Walle <michael@walle.cc> 7 * 8 * See file CREDITS for list of people who contributed to this 9 * project. 10 * 11 * This program is free software; you can redistribute it and/or 12 * modify it under the terms of the GNU General Public License as 13 * published by the Free Software Foundation; either version 2 of 14 * the License, or (at your option) any later version. 15 * 16 * This program is distributed in the hope that it will be useful, 17 * but WITHOUT ANY WARRANTY; without even the implied warranty of 18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 19 * GNU General Public License for more details. 20 * 21 * You should have received a copy of the GNU General Public License 22 * along with this program; if not, write to the Free Software 23 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, 24 * MA 02111-1307 USA 25 */ 26 27 #include <common.h> 28 29 static unsigned int y = 1U; 30 31 unsigned int rand_r(unsigned int *seedp) 32 { 33 *seedp ^= (*seedp << 13); 34 *seedp ^= (*seedp >> 17); 35 *seedp ^= (*seedp << 5); 36 37 return *seedp; 38 } 39 40 unsigned int rand(void) 41 { 42 return rand_r(&y); 43 } 44 45 void srand(unsigned int seed) 46 { 47 y = seed; 48 } 49