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c0842fbc LT |
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 | ||
11 | #include <linux/types.h> | |
3e6743e2 | 12 | #include <linux/once.h> |
d4150779 | 13 | #include <linux/random.h> |
c0842fbc | 14 | |
c0842fbc LT |
15 | struct rnd_state { |
16 | __u32 s1, s2, s3, s4; | |
17 | }; | |
18 | ||
c0842fbc LT |
19 | u32 prandom_u32_state(struct rnd_state *state); |
20 | void prandom_bytes_state(struct rnd_state *state, void *buf, size_t nbytes); | |
21 | void prandom_seed_full_state(struct rnd_state __percpu *pcpu_state); | |
22 | ||
23 | #define prandom_init_once(pcpu_state) \ | |
24 | DO_ONCE(prandom_seed_full_state, (pcpu_state)) | |
25 | ||
c0842fbc LT |
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 | /** | |
35 | * prandom_seed_state - set seed for prandom_u32_state(). | |
36 | * @state: pointer to state structure to receive the seed. | |
37 | * @seed: arbitrary 64-bit value to use as a seed. | |
38 | */ | |
39 | static inline void prandom_seed_state(struct rnd_state *state, u64 seed) | |
40 | { | |
d327ea15 | 41 | u32 i = ((seed >> 32) ^ (seed << 10) ^ seed) & 0xffffffffUL; |
c0842fbc LT |
42 | |
43 | state->s1 = __seed(i, 2U); | |
44 | state->s2 = __seed(i, 8U); | |
45 | state->s3 = __seed(i, 16U); | |
46 | state->s4 = __seed(i, 128U); | |
47 | } | |
48 | ||
49 | /* Pseudo random number generator from numerical recipes. */ | |
50 | static inline u32 next_pseudo_random32(u32 seed) | |
51 | { | |
52 | return seed * 1664525 + 1013904223; | |
53 | } | |
54 | ||
55 | #endif |