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Diffstat (limited to 'rand/rand_xoshiro/src/xoroshiro128plus.rs')
-rw-r--r-- | rand/rand_xoshiro/src/xoroshiro128plus.rs | 130 |
1 files changed, 0 insertions, 130 deletions
diff --git a/rand/rand_xoshiro/src/xoroshiro128plus.rs b/rand/rand_xoshiro/src/xoroshiro128plus.rs deleted file mode 100644 index a7b4ebc..0000000 --- a/rand/rand_xoshiro/src/xoroshiro128plus.rs +++ /dev/null @@ -1,130 +0,0 @@ -// Copyright 2018 Developers of the Rand project. -// -// 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. - -#[cfg(feature="serde1")] use serde::{Serialize, Deserialize}; -use rand_core; -use rand_core::le::read_u64_into; -use rand_core::impls::fill_bytes_via_next; -use rand_core::{RngCore, SeedableRng}; - -/// A xoroshiro128+ random number generator. -/// -/// The xoroshiro128+ algorithm is not suitable for cryptographic purposes, but -/// is very fast and has good statistical properties, besides a low linear -/// complexity in the lowest bits. -/// -/// The algorithm used here is translated from [the `xoroshiro128plus.c` -/// reference source code](http://xoshiro.di.unimi.it/xoroshiro128plus.c) by -/// David Blackman and Sebastiano Vigna. -#[allow(missing_copy_implementations)] -#[derive(Debug, Clone)] -#[cfg_attr(feature="serde1", derive(Serialize, Deserialize))] -pub struct Xoroshiro128Plus { - s0: u64, - s1: u64, -} - -impl Xoroshiro128Plus { - /// Jump forward, equivalently to 2^64 calls to `next_u64()`. - /// - /// This can be used to generate 2^64 non-overlapping subsequences for - /// parallel computations. - /// - /// ``` - /// use rand_xoshiro::rand_core::SeedableRng; - /// use rand_xoshiro::Xoroshiro128Plus; - /// - /// let rng1 = Xoroshiro128Plus::seed_from_u64(0); - /// let mut rng2 = rng1.clone(); - /// rng2.jump(); - /// let mut rng3 = rng2.clone(); - /// rng3.jump(); - /// ``` - pub fn jump(&mut self) { - impl_jump!(u64, self, [0xdf900294d8f554a5, 0x170865df4b3201fc]); - } - - /// Jump forward, equivalently to 2^96 calls to `next_u64()`. - /// - /// This can be used to generate 2^32 starting points, from each of which - /// `jump()` will generate 2^32 non-overlapping subsequences for parallel - /// distributed computations. - pub fn long_jump(&mut self) { - impl_jump!(u64, self, [0xd2a98b26625eee7b, 0xdddf9b1090aa7ac1]); - } -} - -impl RngCore for Xoroshiro128Plus { - #[inline] - fn next_u32(&mut self) -> u32 { - // The two lowest bits have some linear dependencies, so we use the - // upper bits instead. - (self.next_u64() >> 32) as u32 - } - - #[inline] - fn next_u64(&mut self) -> u64 { - let r = self.s0.wrapping_add(self.s1); - impl_xoroshiro_u64!(self); - r - } - - #[inline] - fn fill_bytes(&mut self, dest: &mut [u8]) { - fill_bytes_via_next(self, dest); - } - - #[inline] - fn try_fill_bytes(&mut self, dest: &mut [u8]) -> Result<(), rand_core::Error> { - self.fill_bytes(dest); - Ok(()) - } -} - -impl SeedableRng for Xoroshiro128Plus { - type Seed = [u8; 16]; - - /// Create a new `Xoroshiro128Plus`. If `seed` is entirely 0, it will be - /// mapped to a different seed. - fn from_seed(seed: [u8; 16]) -> Xoroshiro128Plus { - deal_with_zero_seed!(seed, Self); - let mut s = [0; 2]; - read_u64_into(&seed, &mut s); - - Xoroshiro128Plus { - s0: s[0], - s1: s[1], - } - } - - /// Seed a `Xoroshiro128Plus` from a `u64` using `SplitMix64`. - fn seed_from_u64(seed: u64) -> Xoroshiro128Plus { - from_splitmix!(seed) - } -} - -#[cfg(test)] -mod tests { - use super::*; - - #[test] - fn reference() { - let mut rng = Xoroshiro128Plus::from_seed( - [1, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0]); - // These values were produced with the reference implementation: - // http://xoshiro.di.unimi.it/xoshiro128starstar.c - let expected = [ - 3, 412333834243, 2360170716294286339, 9295852285959843169, - 2797080929874688578, 6019711933173041966, 3076529664176959358, - 3521761819100106140, 7493067640054542992, 920801338098114767, - ]; - for &e in &expected { - assert_eq!(rng.next_u64(), e); - } - } -} |