From 698f8c2f01ea549d77d7dc3338a12e04c11057b9 Mon Sep 17 00:00:00 2001
From: Daniel Baumann <daniel.baumann@progress-linux.org>
Date: Wed, 17 Apr 2024 14:02:58 +0200
Subject: Adding upstream version 1.64.0+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
---
 vendor/rand_xoshiro/src/xoshiro256plus.rs | 131 ++++++++++++++++++++++++++++++
 1 file changed, 131 insertions(+)
 create mode 100644 vendor/rand_xoshiro/src/xoshiro256plus.rs

(limited to 'vendor/rand_xoshiro/src/xoshiro256plus.rs')

diff --git a/vendor/rand_xoshiro/src/xoshiro256plus.rs b/vendor/rand_xoshiro/src/xoshiro256plus.rs
new file mode 100644
index 000000000..67ce8ab8a
--- /dev/null
+++ b/vendor/rand_xoshiro/src/xoshiro256plus.rs
@@ -0,0 +1,131 @@
+// 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};
+
+/// A xoshiro256+ random number generator.
+///
+/// The xoshiro256+ 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 `xoshiro256plus.c`
+/// reference source code](http://xoshiro.di.unimi.it/xoshiro256plus.c) by
+/// David Blackman and Sebastiano Vigna.
+#[derive(Debug, Clone, PartialEq, Eq)]
+#[cfg_attr(feature="serde1", derive(Serialize, Deserialize))]
+pub struct Xoshiro256Plus {
+    s: [u64; 4],
+}
+
+impl Xoshiro256Plus {
+    /// Jump forward, equivalently to 2^128 calls to `next_u64()`.
+    ///
+    /// This can be used to generate 2^128 non-overlapping subsequences for
+    /// parallel computations.
+    ///
+    /// ```
+    /// use rand_xoshiro::rand_core::SeedableRng;
+    /// use rand_xoshiro::Xoshiro256Plus;
+    ///
+    /// let rng1 = Xoshiro256Plus::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, [
+            0x180ec6d33cfd0aba, 0xd5a61266f0c9392c,
+            0xa9582618e03fc9aa, 0x39abdc4529b1661c
+        ]);
+    }
+
+    /// Jump forward, equivalently to 2^192 calls to `next_u64()`.
+    ///
+    /// This can be used to generate 2^64 starting points, from each of which
+    /// `jump()` will generate 2^64 non-overlapping subsequences for parallel
+    /// distributed computations.
+    pub fn long_jump(&mut self) {
+        impl_jump!(u64, self, [
+            0x76e15d3efefdcbbf, 0xc5004e441c522fb3,
+            0x77710069854ee241, 0x39109bb02acbe635
+        ]);
+    }
+}
+
+impl SeedableRng for Xoshiro256Plus {
+    type Seed = [u8; 32];
+
+    /// Create a new `Xoshiro256Plus`.  If `seed` is entirely 0, it will be
+    /// mapped to a different seed.
+    #[inline]
+    fn from_seed(seed: [u8; 32]) -> Xoshiro256Plus {
+        deal_with_zero_seed!(seed, Self);
+        let mut state = [0; 4];
+        read_u64_into(&seed, &mut state);
+        Xoshiro256Plus { s: state }
+    }
+
+    /// Seed a `Xoshiro256Plus` from a `u64` using `SplitMix64`.
+    fn seed_from_u64(seed: u64) -> Xoshiro256Plus {
+        from_splitmix!(seed)
+    }
+}
+
+impl RngCore for Xoshiro256Plus {
+    #[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_plus = self.s[0].wrapping_add(self.s[3]);
+        impl_xoshiro_u64!(self);
+        result_plus
+    }
+
+    #[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 = Xoshiro256Plus::from_seed(
+            [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]);
+        // These values were produced with the reference implementation:
+        // http://xoshiro.di.unimi.it/xoshiro256plus.c
+        let expected = [
+            5, 211106232532999, 211106635186183, 9223759065350669058,
+            9250833439874351877, 13862484359527728515, 2346507365006083650,
+            1168864526675804870, 34095955243042024, 3466914240207415127,
+        ];
+        for &e in &expected {
+            assert_eq!(rng.next_u64(), e);
+        }
+    }
+}
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