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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/xoroshiro64starstar.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>
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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_u32_into;
+use rand_core::impls::{fill_bytes_via_next, next_u64_via_u32};
+use rand_core::{RngCore, SeedableRng};
+
+/// A xoroshiro64** random number generator.
+///
+/// The xoshiro64** algorithm is not suitable for cryptographic purposes, but
+/// is very fast and has excellent statistical properties.
+///
+/// The algorithm used here is translated from [the `xoroshiro64starstar.c`
+/// reference source code](http://xoshiro.di.unimi.it/xoroshiro64starstar.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 Xoroshiro64StarStar {
+ s0: u32,
+ s1: u32,
+}
+
+impl RngCore for Xoroshiro64StarStar {
+ #[inline]
+ fn next_u32(&mut self) -> u32 {
+ let r = starstar_u32!(self.s0);
+ impl_xoroshiro_u32!(self);
+ r
+ }
+
+ #[inline]
+ fn next_u64(&mut self) -> u64 {
+ next_u64_via_u32(self)
+ }
+
+ #[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 Xoroshiro64StarStar {
+ type Seed = [u8; 8];
+
+ /// Create a new `Xoroshiro64StarStar`. If `seed` is entirely 0, it will be
+ /// mapped to a different seed.
+ fn from_seed(seed: [u8; 8]) -> Xoroshiro64StarStar {
+ deal_with_zero_seed!(seed, Self);
+ let mut s = [0; 2];
+ read_u32_into(&seed, &mut s);
+
+ Xoroshiro64StarStar {
+ s0: s[0],
+ s1: s[1],
+ }
+ }
+
+ /// Seed a `Xoroshiro64StarStar` from a `u64` using `SplitMix64`.
+ fn seed_from_u64(seed: u64) -> Xoroshiro64StarStar {
+ from_splitmix!(seed)
+ }
+}
+
+#[cfg(test)]
+mod tests {
+ use super::*;
+
+ #[test]
+ fn reference() {
+ let mut rng = Xoroshiro64StarStar::from_seed([1, 0, 0, 0, 2, 0, 0, 0]);
+ // These values were produced with the reference implementation:
+ // http://xoshiro.di.unimi.it/xoshiro64starstar.c
+ let expected = [
+ 3802928447, 813792938, 1618621494, 2955957307, 3252880261,
+ 1129983909, 2539651700, 1327610908, 1757650787, 2763843748,
+ ];
+ for &e in &expected {
+ assert_eq!(rng.next_u32(), e);
+ }
+ }
+
+ #[test]
+ fn zero_seed() {
+ let mut rng = Xoroshiro64StarStar::seed_from_u64(0);
+ assert_ne!(rng.next_u64(), 0);
+ }
+}