lib/rand.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Simple xorshift PRNG
   4  *   see http://www.jstatsoft.org/v08/i14/paper
   5  *
   6  * Copyright (c) 2012 Michael Walle
   7  * Michael Walle <michael@walle.cc>
   8  */
   9
  10 #include <common.h>
  11
  12 static unsigned int y = 1U;
  13
  14 unsigned int rand_r(unsigned int *seedp)
  15 {
  16         *seedp ^= (*seedp << 13);
  17         *seedp ^= (*seedp >> 17);
  18         *seedp ^= (*seedp << 5);
  19
  20         return *seedp;
  21 }
  22
  23 unsigned int rand(void)
  24 {
  25         return rand_r(&y);
  26 }
  27
  28 void srand(unsigned int seed)
  29 {
  30         y = seed;
  31 }