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diff --git a/rand/rand_xoshiro/src/splitmix64.rs b/rand/rand_xoshiro/src/splitmix64.rs
new file mode 100644
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+++ b/rand/rand_xoshiro/src/splitmix64.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.
+
+use byteorder::{ByteOrder, LittleEndian};
+use rand_core::le::read_u64_into;
+use rand_core::impls::fill_bytes_via_next;
+use rand_core::{RngCore, SeedableRng, Error};
+
+/// A splitmix64 random number generator.
+///
+/// The splitmix algorithm is not suitable for cryptographic purposes, but is
+/// very fast and has a 64 bit state.
+///
+/// The algorithm used here is translated from [the `splitmix64.c`
+/// reference source code](http://xoshiro.di.unimi.it/splitmix64.c) by
+/// Sebastiano Vigna. For `next_u32`, a more efficient mixing function taken
+/// from [`dsiutils`](http://dsiutils.di.unimi.it/) is used.
+#[allow(missing_copy_implementations)]
+#[derive(Debug, Clone)]
+pub struct SplitMix64 {
+    x: u64,
+}
+
+const PHI: u64 = 0x9e3779b97f4a7c15;
+
+impl RngCore for SplitMix64 {
+    #[inline]
+    fn next_u32(&mut self) -> u32 {
+        self.x = self.x.wrapping_add(PHI);
+        let mut z = self.x;
+        // David Stafford's
+        // (http://zimbry.blogspot.com/2011/09/better-bit-mixing-improving-on.html)
+        // "Mix4" variant of the 64-bit finalizer in Austin Appleby's
+        // MurmurHash3 algorithm.
+        z = (z ^ (z >> 33)).wrapping_mul(0x62A9D9ED799705F5);
+        z = (z ^ (z >> 28)).wrapping_mul(0xCB24D0A5C88C35B3);
+        (z >> 32) as u32
+    }
+
+    #[inline]
+    fn next_u64(&mut self) -> u64 {
+        self.x = self.x.wrapping_add(PHI);
+        let mut z = self.x;
+        z = (z ^ (z >> 30)).wrapping_mul(0xbf58476d1ce4e5b9);
+        z = (z ^ (z >> 27)).wrapping_mul(0x94d049bb133111eb);
+        z ^ (z >> 31)
+    }
+
+    #[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(())
+    }
+}
+
+impl SeedableRng for SplitMix64 {
+    type Seed = [u8; 8];
+
+    /// Create a new `SplitMix64`.
+    fn from_seed(seed: [u8; 8]) -> SplitMix64 {
+        let mut state = [0; 1];
+        read_u64_into(&seed, &mut state);
+        SplitMix64 {
+            x: state[0],
+        }
+    }
+
+    /// Seed a `SplitMix64` from a `u64`.
+    fn seed_from_u64(seed: u64) -> SplitMix64 {
+        let mut x = [0; 8];
+        LittleEndian::write_u64(&mut x, seed);
+        SplitMix64::from_seed(x)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn reference() {
+        let mut rng = SplitMix64::seed_from_u64(1477776061723855037);
+        // These values were produced with the reference implementation:
+        // http://xoshiro.di.unimi.it/splitmix64.c
+        let expected : [u64 ; 50]= [
+            1985237415132408290, 2979275885539914483, 13511426838097143398,
+            8488337342461049707, 15141737807933549159, 17093170987380407015,
+            16389528042912955399, 13177319091862933652, 10841969400225389492,
+            17094824097954834098, 3336622647361835228, 9678412372263018368,
+            11111587619974030187, 7882215801036322410, 5709234165213761869,
+            7799681907651786826, 4616320717312661886, 4251077652075509767,
+            7836757050122171900, 5054003328188417616, 12919285918354108358,
+            16477564761813870717, 5124667218451240549, 18099554314556827626,
+            7603784838804469118, 6358551455431362471, 3037176434532249502,
+            3217550417701719149, 9958699920490216947, 5965803675992506258,
+            12000828378049868312, 12720568162811471118, 245696019213873792,
+            8351371993958923852, 14378754021282935786, 5655432093647472106,
+            5508031680350692005, 8515198786865082103, 6287793597487164412,
+            14963046237722101617, 3630795823534910476, 8422285279403485710,
+            10554287778700714153, 10871906555720704584, 8659066966120258468,
+            9420238805069527062, 10338115333623340156, 13514802760105037173,
+            14635952304031724449, 15419692541594102413,
+        ];
+        for &e in expected.iter() {
+            assert_eq!(rng.next_u64(), e);
+        }
+    }
+
+    #[test]
+    fn next_u32() {
+        let mut rng = SplitMix64::seed_from_u64(10);
+        // These values were produced with the reference implementation:
+        // http://dsiutils.di.unimi.it/dsiutils-2.5.1-src.tar.gz
+        let expected : [u32 ; 100]= [
+            3930361779, 4016923089, 4113052479, 925926767, 1755287528,
+            802865554, 954171070, 3724185978, 173676273, 1414488795, 12664133,
+            1784889697, 1303817078, 261610523, 941280008, 2571813643,
+            2954453492, 378291111, 2546873158, 3923319175, 645257028,
+            3881821278, 2681538690, 3037029984, 1999958137, 1853970361,
+            2989951788, 2126166628, 839962987, 3989679659, 3656977858,
+            684284364, 1673258011, 170979192, 3037622326, 1600748179,
+            1780764218, 1141430714, 4139736875, 3336905707, 2262051600,
+            3830850262, 2430765325, 1073032139, 1668888979, 2716938970,
+            4102420032, 40305196, 386350562, 2754480591, 622869439, 2129598760,
+            2306038241, 4218338739, 412298926, 3453855056, 3061469690,
+            4284292697, 994843708, 1591016681, 414726151, 1238182607, 18073498,
+            1237631493, 351884714, 2347486264, 2488990876, 802846256, 645670443,
+            957607012, 3126589776, 1966356370, 3036485766, 868696717,
+            2808613630, 2070968151, 1025536863, 1743949425, 466212687,
+            2994327271, 209776458, 1246125124, 3344380309, 2203947859,
+            968313105, 2805485302, 197484837, 3472483632, 3931823935,
+            3288490351, 4165666529, 3671080416, 689542830, 1272555356,
+            1039141475, 3984640460, 4142959054, 2252788890, 2459379590,
+            991872507,
+        ];
+        for &e in expected.iter() {
+            assert_eq!(rng.next_u32(), e);
+        }
+    }
+}