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Diffstat (limited to 'rand/rand_xoshiro/src/splitmix64.rs')
| -rw-r--r-- | rand/rand_xoshiro/src/splitmix64.rs | 149 |
1 files changed, 0 insertions, 149 deletions
diff --git a/rand/rand_xoshiro/src/splitmix64.rs b/rand/rand_xoshiro/src/splitmix64.rs deleted file mode 100644 index 3a41450..0000000 --- a/rand/rand_xoshiro/src/splitmix64.rs +++ /dev/null @@ -1,149 +0,0 @@ -// 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_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)] -#[cfg_attr(feature="serde1", derive(Serialize, Deserialize))] -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 { - SplitMix64::from_seed(seed.to_le_bytes()) - } -} - -#[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); - } - } -} |