rand.c 1.2 KB

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  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. #include <common.h>
  27. static unsigned int y = 1U;
  28. unsigned int rand_r(unsigned int *seedp)
  29. {
  30. *seedp ^= (*seedp << 13);
  31. *seedp ^= (*seedp >> 17);
  32. *seedp ^= (*seedp << 5);
  33. return *seedp;
  34. }
  35. unsigned int rand(void)
  36. {
  37. return rand_r(&y);
  38. }
  39. void srand(unsigned int seed)
  40. {
  41. y = seed;
  42. }