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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/xoshiro512starstar.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/xoshiro512starstar.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::impls::fill_bytes_via_next;
+use rand_core::le::read_u64_into;
+use rand_core::{SeedableRng, RngCore, Error};
+
+use crate::Seed512;
+
+/// A xoshiro512** random number generator.
+///
+/// The xoshiro512** algorithm is not suitable for cryptographic purposes, but
+/// is very fast and has excellent statistical properties.
+///
+/// The algorithm used here is translated from [the `xoshiro512starstar.c`
+/// reference source code](http://xoshiro.di.unimi.it/xoshiro512starstar.c) by
+/// David Blackman and Sebastiano Vigna.
+#[derive(Debug, Clone, PartialEq, Eq)]
+#[cfg_attr(feature="serde1", derive(Serialize, Deserialize))]
+pub struct Xoshiro512StarStar {
+ s: [u64; 8],
+}
+
+impl Xoshiro512StarStar {
+ /// Jump forward, equivalently to 2^256 calls to `next_u64()`.
+ ///
+ /// This can be used to generate 2^256 non-overlapping subsequences for
+ /// parallel computations.
+ ///
+ /// ```
+ /// use rand_xoshiro::rand_core::SeedableRng;
+ /// use rand_xoshiro::Xoshiro512StarStar;
+ ///
+ /// let rng1 = Xoshiro512StarStar::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, [
+ 0x33ed89b6e7a353f9, 0x760083d7955323be, 0x2837f2fbb5f22fae,
+ 0x4b8c5674d309511c, 0xb11ac47a7ba28c25, 0xf1be7667092bcc1c,
+ 0x53851efdb6df0aaf, 0x1ebbc8b23eaf25db
+ ]);
+ }
+
+ /// Jump forward, equivalently to 2^384 calls to `next_u64()`.
+ ///
+ /// This can be used to generate 2^128 starting points, from each of which
+ /// `jump()` will generate 2^128 non-overlapping subsequences for parallel
+ /// distributed computations.
+ pub fn long_jump(&mut self) {
+ impl_jump!(u64, self, [
+ 0x11467fef8f921d28, 0xa2a819f2e79c8ea8, 0xa8299fc284b3959a,
+ 0xb4d347340ca63ee1, 0x1cb0940bedbff6ce, 0xd956c5c4fa1f8e17,
+ 0x915e38fd4eda93bc, 0x5b3ccdfa5d7daca5
+ ]);
+ }
+}
+
+
+impl SeedableRng for Xoshiro512StarStar {
+ type Seed = Seed512;
+
+ /// Create a new `Xoshiro512StarStar`. If `seed` is entirely 0, it will be
+ /// mapped to a different seed.
+ #[inline]
+ fn from_seed(seed: Seed512) -> Xoshiro512StarStar {
+ deal_with_zero_seed!(seed, Self);
+ let mut state = [0; 8];
+ read_u64_into(&seed.0, &mut state);
+ Xoshiro512StarStar { s: state }
+ }
+
+ /// Seed a `Xoshiro512StarStar` from a `u64` using `SplitMix64`.
+ fn seed_from_u64(seed: u64) -> Xoshiro512StarStar {
+ from_splitmix!(seed)
+ }
+}
+
+impl RngCore for Xoshiro512StarStar {
+ #[inline]
+ fn next_u32(&mut self) -> u32 {
+ // The 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 result_starstar = starstar_u64!(self.s[1]);
+ impl_xoshiro_large!(self);
+ result_starstar
+ }
+
+ #[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<(), Error> {
+ self.fill_bytes(dest);
+ Ok(())
+ }
+}
+
+#[cfg(test)]
+mod tests {
+ use super::*;
+
+ #[test]
+ fn reference() {
+ let mut rng = Xoshiro512StarStar::from_seed(Seed512(
+ [1, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0,
+ 3, 0, 0, 0, 0, 0, 0, 0, 4, 0, 0, 0, 0, 0, 0, 0,
+ 5, 0, 0, 0, 0, 0, 0, 0, 6, 0, 0, 0, 0, 0, 0, 0,
+ 7, 0, 0, 0, 0, 0, 0, 0, 8, 0, 0, 0, 0, 0, 0, 0]));
+ // These values were produced with the reference implementation:
+ // http://xoshiro.di.unimi.it/xoshiro512starstar.c
+ let expected = [
+ 11520, 0, 23040, 23667840, 144955163520, 303992986974289920,
+ 25332796375735680, 296904390158016, 13911081092387501979,
+ 15304787717237593024,
+ ];
+ for &e in &expected {
+ assert_eq!(rng.next_u64(), e);
+ }
+ }
+}