1*9acf1ca5SMichael Walle /* 2*9acf1ca5SMichael Walle * Simple xorshift PRNG 3*9acf1ca5SMichael Walle * see http://www.jstatsoft.org/v08/i14/paper 4*9acf1ca5SMichael Walle * 5*9acf1ca5SMichael Walle * Copyright (c) 2012 Michael Walle 6*9acf1ca5SMichael Walle * Michael Walle <michael@walle.cc> 7*9acf1ca5SMichael Walle * 8*9acf1ca5SMichael Walle * See file CREDITS for list of people who contributed to this 9*9acf1ca5SMichael Walle * project. 10*9acf1ca5SMichael Walle * 11*9acf1ca5SMichael Walle * This program is free software; you can redistribute it and/or 12*9acf1ca5SMichael Walle * modify it under the terms of the GNU General Public License as 13*9acf1ca5SMichael Walle * published by the Free Software Foundation; either version 2 of 14*9acf1ca5SMichael Walle * the License, or (at your option) any later version. 15*9acf1ca5SMichael Walle * 16*9acf1ca5SMichael Walle * This program is distributed in the hope that it will be useful, 17*9acf1ca5SMichael Walle * but WITHOUT ANY WARRANTY; without even the implied warranty of 18*9acf1ca5SMichael Walle * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 19*9acf1ca5SMichael Walle * GNU General Public License for more details. 20*9acf1ca5SMichael Walle * 21*9acf1ca5SMichael Walle * You should have received a copy of the GNU General Public License 22*9acf1ca5SMichael Walle * along with this program; if not, write to the Free Software 23*9acf1ca5SMichael Walle * Foundation, Inc., 59 Temple Place, Suite 330, Boston, 24*9acf1ca5SMichael Walle * MA 02111-1307 USA 25*9acf1ca5SMichael Walle */ 26*9acf1ca5SMichael Walle 27*9acf1ca5SMichael Walle #include <common.h> 28*9acf1ca5SMichael Walle 29*9acf1ca5SMichael Walle static unsigned int y = 1U; 30*9acf1ca5SMichael Walle 31*9acf1ca5SMichael Walle unsigned int rand_r(unsigned int *seedp) 32*9acf1ca5SMichael Walle { 33*9acf1ca5SMichael Walle *seedp ^= (*seedp << 13); 34*9acf1ca5SMichael Walle *seedp ^= (*seedp >> 17); 35*9acf1ca5SMichael Walle *seedp ^= (*seedp << 5); 36*9acf1ca5SMichael Walle 37*9acf1ca5SMichael Walle return *seedp; 38*9acf1ca5SMichael Walle } 39*9acf1ca5SMichael Walle 40*9acf1ca5SMichael Walle unsigned int rand(void) 41*9acf1ca5SMichael Walle { 42*9acf1ca5SMichael Walle return rand_r(&y); 43*9acf1ca5SMichael Walle } 44*9acf1ca5SMichael Walle 45*9acf1ca5SMichael Walle void srand(unsigned int seed) 46*9acf1ca5SMichael Walle { 47*9acf1ca5SMichael Walle y = seed; 48*9acf1ca5SMichael Walle } 49