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diff --git a/rand/rand_pcg/src/pcg64.rs b/rand/rand_pcg/src/pcg64.rs
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-// Copyright 2018 Developers of the Rand project.
-// Copyright 2017 Paul Dicker.
-// Copyright 2014-2017 Melissa O'Neill and PCG Project contributors
-//
-// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
-// https://www.apache.org/licenses/LICENSE-2.0> or the MIT license
-// <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your
-// option. This file may not be copied, modified, or distributed
-// except according to those terms.
-
-//! PCG random number generators
-
-use core::fmt;
-use rand_core::{RngCore, SeedableRng, Error, le, impls};
-#[cfg(feature="serde1")] use serde::{Serialize, Deserialize};
-
-// This is the default multiplier used by PCG for 64-bit state.
-const MULTIPLIER: u64 = 6364136223846793005;
-
-/// A PCG random number generator (XSH RR 64/32 (LCG) variant).
-///
-/// Permuted Congruential Generator with 64-bit state, internal Linear
-/// Congruential Generator, and 32-bit output via "xorshift high (bits),
-/// random rotation" output function.
-///
-/// This is a 64-bit LCG with explicitly chosen stream with the PCG-XSH-RR
-/// output function. This combination is the standard `pcg32`.
-///
-/// Despite the name, this implementation uses 16 bytes (128 bit) space
-/// comprising 64 bits of state and 64 bits stream selector. These are both set
-/// by `SeedableRng`, using a 128-bit seed.
-#[derive(Clone)]
-#[cfg_attr(feature="serde1", derive(Serialize,Deserialize))]
-pub struct Lcg64Xsh32 {
- state: u64,
- increment: u64,
-}
-
-/// `Lcg64Xsh32` is also officially known as `pcg32`.
-pub type Pcg32 = Lcg64Xsh32;
-
-impl Lcg64Xsh32 {
- /// Construct an instance compatible with PCG seed and stream.
- ///
- /// Note that PCG specifies default values for both parameters:
- ///
- /// - `state = 0xcafef00dd15ea5e5`
- /// - `stream = 0xa02bdbf7bb3c0a7`
- // Note: stream is 1442695040888963407u64 >> 1
- pub fn new(state: u64, stream: u64) -> Self {
- // The increment must be odd, hence we discard one bit:
- 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 };
- // Move away from inital value:
- pcg.state = pcg.state.wrapping_add(pcg.increment);
- pcg.step();
- pcg
- }
-
- #[inline]
- fn step(&mut self) {
- // prepare the LCG for the next round
- self.state = self.state
- .wrapping_mul(MULTIPLIER)
- .wrapping_add(self.increment);
- }
-}
-
-// Custom Debug implementation that does not expose the internal state
-impl fmt::Debug for Lcg64Xsh32 {
- fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
- write!(f, "Lcg64Xsh32 {{}}")
- }
-}
-
-/// We use a single 127-bit seed to initialise the state and select a stream.
-/// One `seed` bit (lowest bit of `seed[8]`) is ignored.
-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);
-
- // The increment must be odd, hence we discard one bit:
- 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();
-
- // Output function XSH RR: xorshift high (bits), followed by a random rotate
- // Constants are for 64-bit state, 32-bit output
- const ROTATE: u32 = 59; // 64 - 5
- const XSHIFT: u32 = 18; // (5 + 32) / 2
- const SPARE: u32 = 27; // 64 - 32 - 5
-
- 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(())
- }
-}