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 42