const MULTIPLIER: u128 = 0x2360_ED05_1FC6_5DA4_4385_DF64_9FCC_F645;
use core::fmt;
use rand_core::{le, Error, RngCore, SeedableRng};
#[cfg(feature = "serde1")] use serde::{Deserialize, Serialize};
#[derive(Clone, PartialEq, Eq)]
#[cfg_attr(feature = "serde1", derive(Serialize, Deserialize))]
pub struct Lcg128Xsl64 {
state: u128,
increment: u128,
}
pub type Pcg64 = Lcg128Xsl64;
impl Lcg128Xsl64 {
pub fn new(state: u128, stream: u128) -> Self {
let increment = (stream << 1) | 1;
Lcg128Xsl64::from_state_incr(state, increment)
}
#[inline]
fn from_state_incr(state: u128, increment: u128) -> Self {
let mut pcg = Lcg128Xsl64 { 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 Lcg128Xsl64 {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(f, "Lcg128Xsl64 {{}}")
}
}
impl SeedableRng for Lcg128Xsl64 {
type Seed = [u8; 32];
fn from_seed(seed: Self::Seed) -> Self {
let mut seed_u64 = [0u64; 4];
le::read_u64_into(&seed, &mut seed_u64);
let state = u128::from(seed_u64[0]) | (u128::from(seed_u64[1]) << 64);
let incr = u128::from(seed_u64[2]) | (u128::from(seed_u64[3]) << 64);
Lcg128Xsl64::from_state_incr(state, incr | 1)
}
}
impl RngCore for Lcg128Xsl64 {
#[inline]
fn next_u32(&mut self) -> u32 {
self.next_u64() as u32
}
#[inline]
fn next_u64(&mut self) -> u64 {
self.step();
output_xsl_rr(self.state)
}
#[inline]
fn fill_bytes(&mut self, dest: &mut [u8]) {
fill_bytes_impl(self, dest)
}
#[inline]
fn try_fill_bytes(&mut self, dest: &mut [u8]) -> Result<(), Error> {
self.fill_bytes(dest);
Ok(())
}
}
#[derive(Clone, PartialEq, Eq)]
#[cfg_attr(feature = "serde1", derive(Serialize, Deserialize))]
pub struct Mcg128Xsl64 {
state: u128,
}
pub type Pcg64Mcg = Mcg128Xsl64;
impl Mcg128Xsl64 {
pub fn new(state: u128) -> Self {
Mcg128Xsl64 { state: state | 1 }
}
}
impl fmt::Debug for Mcg128Xsl64 {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(f, "Mcg128Xsl64 {{}}")
}
}
impl SeedableRng for Mcg128Xsl64 {
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);
let state = u128::from(seed_u64[0]) |
u128::from(seed_u64[1]) << 64;
Mcg128Xsl64::new(state)
}
}
impl RngCore for Mcg128Xsl64 {
#[inline]
fn next_u32(&mut self) -> u32 {
self.next_u64() as u32
}
#[inline]
fn next_u64(&mut self) -> u64 {
self.state = self.state.wrapping_mul(MULTIPLIER);
output_xsl_rr(self.state)
}
#[inline]
fn fill_bytes(&mut self, dest: &mut [u8]) {
fill_bytes_impl(self, dest)
}
#[inline]
fn try_fill_bytes(&mut self, dest: &mut [u8]) -> Result<(), Error> {
self.fill_bytes(dest);
Ok(())
}
}
#[inline(always)]
fn output_xsl_rr(state: u128) -> u64 {
const XSHIFT: u32 = 64; const ROTATE: u32 = 122;
let rot = (state >> ROTATE) as u32;
let xsl = ((state >> XSHIFT) as u64) ^ (state as u64);
xsl.rotate_right(rot)
}
#[inline(always)]
fn fill_bytes_impl<R: RngCore + ?Sized>(rng: &mut R, dest: &mut [u8]) {
let mut left = dest;
while left.len() >= 8 {
let (l, r) = { left }.split_at_mut(8);
left = r;
let chunk: [u8; 8] = rng.next_u64().to_le_bytes();
l.copy_from_slice(&chunk);
}
let n = left.len();
if n > 0 {
let chunk: [u8; 8] = rng.next_u64().to_le_bytes();
left.copy_from_slice(&chunk[..n]);
}
}