release/src/router/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
  12 PUSH_AND_SET_FUNCTION_VISIBILITY_TO_HIDDEN
  13
  14 typedef 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
  37 uint32_t next_random(random_t *rnd) FAST_FUNC;
  38
  39 POP_SAVED_FUNCTION_VISIBILITY
  40
  41 #endif