lib/rand.c

   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  * SPDX-License-Identifier:     GPL-2.0+
   9  */
  10
  11 #include <common.h>
  12
  13 static unsigned int y = 1U;
  14
  15 unsigned int rand_r(unsigned int *seedp)
  16 {
  17         *seedp ^= (*seedp << 13);
  18         *seedp ^= (*seedp >> 17);
  19         *seedp ^= (*seedp << 5);
  20
  21         return *seedp;
  22 }
  23
  24 unsigned int rand(void)
  25 {
  26         return rand_r(&y);
  27 }
  28
  29 void srand(unsigned int seed)
  30 {
  31         y = seed;
  32 }