From 1b6a04ca5504955c571d1c97504fb45ea0befee4 Mon Sep 17 00:00:00 2001
From: Valentin Popov <valentin@popov.link>
Date: Mon, 8 Jan 2024 01:21:28 +0400
Subject: Initial vendor packages

Signed-off-by: Valentin Popov <valentin@popov.link>
---
 vendor/rand/src/prng/xorshift.rs | 101 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 101 insertions(+)
 create mode 100644 vendor/rand/src/prng/xorshift.rs

(limited to 'vendor/rand/src/prng/xorshift.rs')

diff --git a/vendor/rand/src/prng/xorshift.rs b/vendor/rand/src/prng/xorshift.rs
new file mode 100644
index 0000000..dd367e9
--- /dev/null
+++ b/vendor/rand/src/prng/xorshift.rs
@@ -0,0 +1,101 @@
+// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+//! Xorshift generators
+
+use core::num::Wrapping as w;
+use {Rng, SeedableRng, Rand};
+
+/// An Xorshift[1] random number
+/// generator.
+///
+/// The Xorshift algorithm is not suitable for cryptographic purposes
+/// but is very fast. If you do not know for sure that it fits your
+/// requirements, use a more secure one such as `IsaacRng` or `OsRng`.
+///
+/// [1]: Marsaglia, George (July 2003). ["Xorshift
+/// RNGs"](http://www.jstatsoft.org/v08/i14/paper). *Journal of
+/// Statistical Software*. Vol. 8 (Issue 14).
+#[allow(missing_copy_implementations)]
+#[derive(Clone, Debug)]
+pub struct XorShiftRng {
+    x: w<u32>,
+    y: w<u32>,
+    z: w<u32>,
+    w: w<u32>,
+}
+
+impl XorShiftRng {
+    /// Creates a new XorShiftRng instance which is not seeded.
+    ///
+    /// The initial values of this RNG are constants, so all generators created
+    /// by this function will yield the same stream of random numbers. It is
+    /// highly recommended that this is created through `SeedableRng` instead of
+    /// this function
+    pub fn new_unseeded() -> XorShiftRng {
+        XorShiftRng {
+            x: w(0x193a6754),
+            y: w(0xa8a7d469),
+            z: w(0x97830e05),
+            w: w(0x113ba7bb),
+        }
+    }
+}
+
+impl Rng for XorShiftRng {
+    #[inline]
+    fn next_u32(&mut self) -> u32 {
+        let x = self.x;
+        let t = x ^ (x << 11);
+        self.x = self.y;
+        self.y = self.z;
+        self.z = self.w;
+        let w_ = self.w;
+        self.w = w_ ^ (w_ >> 19) ^ (t ^ (t >> 8));
+        self.w.0
+    }
+}
+
+impl SeedableRng<[u32; 4]> for XorShiftRng {
+    /// Reseed an XorShiftRng. This will panic if `seed` is entirely 0.
+    fn reseed(&mut self, seed: [u32; 4]) {
+        assert!(!seed.iter().all(|&x| x == 0),
+                "XorShiftRng.reseed called with an all zero seed.");
+
+        self.x = w(seed[0]);
+        self.y = w(seed[1]);
+        self.z = w(seed[2]);
+        self.w = w(seed[3]);
+    }
+
+    /// Create a new XorShiftRng. This will panic if `seed` is entirely 0.
+    fn from_seed(seed: [u32; 4]) -> XorShiftRng {
+        assert!(!seed.iter().all(|&x| x == 0),
+                "XorShiftRng::from_seed called with an all zero seed.");
+
+        XorShiftRng {
+            x: w(seed[0]),
+            y: w(seed[1]),
+            z: w(seed[2]),
+            w: w(seed[3]),
+        }
+    }
+}
+
+impl Rand for XorShiftRng {
+    fn rand<R: Rng>(rng: &mut R) -> XorShiftRng {
+        let mut tuple: (u32, u32, u32, u32) = rng.gen();
+        while tuple == (0, 0, 0, 0) {
+            tuple = rng.gen();
+        }
+        let (x, y, z, w_) = tuple;
+        XorShiftRng { x: w(x), y: w(y), z: w(z), w: w(w_) }
+    }
+}
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