LXR busybox/shell/random.h

   1/* vi: set sw=4 ts=4: */
   2/*
   3 * $RANDOM support.
   4 *
   5 * Copyright (C) 2009 Denys Vlasenko
   6 *
   7 * Licensed under GPLv2, see file LICENSE in this source tree.
   8 */
   9#ifndef SHELL_RANDOM_H
  10#define SHELL_RANDOM_H 1
  11
  12PUSH_AND_SET_FUNCTION_VISIBILITY_TO_HIDDEN
  13
  14typedef struct random_t {
  15        /* State of random number generators: */
  16
  17        /* Galois LFSR (fast but weak) */
  18        int32_t galois_LFSR; /* must be signed! */
  19
  20        /* LCG (fast but weak) */
  21        uint32_t LCG;
  22
  23        /* 64-bit xorshift (fast, moderate strength) */
  24        uint32_t xs64_x;
  25        uint32_t xs64_y;
  26} random_t;
  27
  28#define UNINITED_RANDOM_T(rnd) \
  29        ((rnd)->galois_LFSR == 0)
  30
  31#define INIT_RANDOM_T(rnd, nonzero, v) \
  32        ((rnd)->galois_LFSR = (rnd)->xs64_x = (nonzero), (rnd)->LCG = (rnd)->xs64_y = (v))
  33
  34#define CLEAR_RANDOM_T(rnd) \
  35        ((rnd)->galois_LFSR = 0)
  36
  37uint32_t next_random(random_t *rnd) FAST_FUNC;
  38
  39POP_SAVED_FUNCTION_VISIBILITY
  40
  41#endif
  42