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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-17 12:02:58 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-17 12:02:58 +0000
commit698f8c2f01ea549d77d7dc3338a12e04c11057b9 (patch)
tree173a775858bd501c378080a10dca74132f05bc50 /vendor/rand_xoshiro/src/xoroshiro128plusplus.rs
parentInitial commit. (diff)
downloadrustc-698f8c2f01ea549d77d7dc3338a12e04c11057b9.tar.xz
rustc-698f8c2f01ea549d77d7dc3338a12e04c11057b9.zip
Adding upstream version 1.64.0+dfsg1.upstream/1.64.0+dfsg1
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'vendor/rand_xoshiro/src/xoroshiro128plusplus.rs')
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+// 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::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 excellent statistical properties.
+///
+/// The algorithm used here is translated from [the `xoroshiro128plusplus.c`
+/// reference source code](http://xoshiro.di.unimi.it/xoroshiro128plusplus.c) by
+/// David Blackman and Sebastiano Vigna.
+#[allow(missing_copy_implementations)]
+#[derive(Debug, Clone, PartialEq, Eq)]
+#[cfg_attr(feature="serde1", derive(Serialize, Deserialize))]
+pub struct Xoroshiro128PlusPlus {
+ s0: u64,
+ s1: u64,
+}
+
+impl Xoroshiro128PlusPlus {
+ /// 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::Xoroshiro128PlusPlus;
+ ///
+ /// let rng1 = Xoroshiro128PlusPlus::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, [0x2bd7a6a6e99c2ddc, 0x0992ccaf6a6fca05]);
+ }
+
+ /// 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, [0x360fd5f2cf8d5d99, 0x9c6e6877736c46e3]);
+ }
+}
+
+impl RngCore for Xoroshiro128PlusPlus {
+ #[inline]
+ fn next_u32(&mut self) -> u32 {
+ self.next_u64() as u32
+ }
+
+ #[inline]
+ fn next_u64(&mut self) -> u64 {
+ let r = plusplus_u64!(self.s0, self.s1, 17);
+ impl_xoroshiro_u64_plusplus!(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 Xoroshiro128PlusPlus {
+ type Seed = [u8; 16];
+
+ /// Create a new `Xoroshiro128PlusPlus`. If `seed` is entirely 0, it will be
+ /// mapped to a different seed.
+ fn from_seed(seed: [u8; 16]) -> Xoroshiro128PlusPlus {
+ deal_with_zero_seed!(seed, Self);
+ let mut s = [0; 2];
+ read_u64_into(&seed, &mut s);
+
+ Xoroshiro128PlusPlus {
+ s0: s[0],
+ s1: s[1],
+ }
+ }
+
+ /// Seed a `Xoroshiro128PlusPlus` from a `u64` using `SplitMix64`.
+ fn seed_from_u64(seed: u64) -> Xoroshiro128PlusPlus {
+ from_splitmix!(seed)
+ }
+}
+
+#[cfg(test)]
+mod tests {
+ use super::*;
+
+ #[test]
+ fn reference() {
+ let mut rng = Xoroshiro128PlusPlus::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/xoshiro128plusplus.c
+ let expected = [
+ 393217, 669327710093319, 1732421326133921491, 11394790081659126983,
+ 9555452776773192676, 3586421180005889563, 1691397964866707553,
+ 10735626796753111697, 15216282715349408991, 14247243556711267923,
+ ];
+ for &e in &expected {
+ assert_eq!(rng.next_u64(), e);
+ }
+ }
+}