blob: c4eb44c133bb836e4b6d30ba497639444f49610b
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 |