1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
use core::fmt;
use rand_core::{impls, le, Error, RngCore, SeedableRng};
#[cfg(feature = "serde1")] use serde::{Deserialize, Serialize};
const MULTIPLIER: u64 = 6364136223846793005;
#[derive(Clone, PartialEq, Eq)]
#[cfg_attr(feature = "serde1", derive(Serialize, Deserialize))]
pub struct Lcg64Xsh32 {
state: u64,
increment: u64,
}
pub type Pcg32 = Lcg64Xsh32;
impl Lcg64Xsh32 {
pub fn new(state: u64, stream: u64) -> Self {
let increment = (stream << 1) | 1;
Lcg64Xsh32::from_state_incr(state, increment)
}
#[inline]
fn from_state_incr(state: u64, increment: u64) -> Self {
let mut pcg = Lcg64Xsh32 { state, increment };
pcg.state = pcg.state.wrapping_add(pcg.increment);
pcg.step();
pcg
}
#[inline]
fn step(&mut self) {
self.state = self
.state
.wrapping_mul(MULTIPLIER)
.wrapping_add(self.increment);
}
}
impl fmt::Debug for Lcg64Xsh32 {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(f, "Lcg64Xsh32 {{}}")
}
}
impl SeedableRng for Lcg64Xsh32 {
type Seed = [u8; 16];
fn from_seed(seed: Self::Seed) -> Self {
let mut seed_u64 = [0u64; 2];
le::read_u64_into(&seed, &mut seed_u64);
Lcg64Xsh32::from_state_incr(seed_u64[0], seed_u64[1] | 1)
}
}
impl RngCore for Lcg64Xsh32 {
#[inline]
fn next_u32(&mut self) -> u32 {
let state = self.state;
self.step();
const ROTATE: u32 = 59;
const XSHIFT: u32 = 18;
const SPARE: u32 = 27;
let rot = (state >> ROTATE) as u32;
let xsh = (((state >> XSHIFT) ^ state) >> SPARE) as u32;
xsh.rotate_right(rot)
}
#[inline]
fn next_u64(&mut self) -> u64 {
impls::next_u64_via_u32(self)
}
#[inline]
fn fill_bytes(&mut self, dest: &mut [u8]) {
impls::fill_bytes_via_next(self, dest)
}
#[inline]
fn try_fill_bytes(&mut self, dest: &mut [u8]) -> Result<(), Error> {
self.fill_bytes(dest);
Ok(())
}
}