prandom.h 1.4 KB

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  1. /* SPDX-License-Identifier: GPL-2.0 */
  2. /*
  3. * include/linux/prandom.h
  4. *
  5. * Include file for the fast pseudo-random 32-bit
  6. * generation.
  7. */
  8. #ifndef _LINUX_PRANDOM_H
  9. #define _LINUX_PRANDOM_H
  10. #include <linux/types.h>
  11. #include <linux/percpu.h>
  12. #include <linux/random.h>
  13. struct rnd_state {
  14. __u32 s1, s2, s3, s4;
  15. };
  16. u32 prandom_u32_state(struct rnd_state *state);
  17. void prandom_bytes_state(struct rnd_state *state, void *buf, size_t nbytes);
  18. void prandom_seed_full_state(struct rnd_state __percpu *pcpu_state);
  19. #define prandom_init_once(pcpu_state) \
  20. DO_ONCE(prandom_seed_full_state, (pcpu_state))
  21. /* Deprecated: use get_random_u32_below() instead. */
  22. static inline u32 prandom_u32_max(u32 ep_ro)
  23. {
  24. return get_random_u32_below(ep_ro);
  25. }
  26. /*
  27. * Handle minimum values for seeds
  28. */
  29. static inline u32 __seed(u32 x, u32 m)
  30. {
  31. return (x < m) ? x + m : x;
  32. }
  33. /**
  34. * prandom_seed_state - set seed for prandom_u32_state().
  35. * @state: pointer to state structure to receive the seed.
  36. * @seed: arbitrary 64-bit value to use as a seed.
  37. */
  38. static inline void prandom_seed_state(struct rnd_state *state, u64 seed)
  39. {
  40. u32 i = ((seed >> 32) ^ (seed << 10) ^ seed) & 0xffffffffUL;
  41. state->s1 = __seed(i, 2U);
  42. state->s2 = __seed(i, 8U);
  43. state->s3 = __seed(i, 16U);
  44. state->s4 = __seed(i, 128U);
  45. }
  46. /* Pseudo random number generator from numerical recipes. */
  47. static inline u32 next_pseudo_random32(u32 seed)
  48. {
  49. return seed * 1664525 + 1013904223;
  50. }
  51. #endif