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Diffstat (limited to 'rand/src/prng/xorshift.rs')
-rw-r--r-- | rand/src/prng/xorshift.rs | 101 |
1 files changed, 0 insertions, 101 deletions
diff --git a/rand/src/prng/xorshift.rs b/rand/src/prng/xorshift.rs deleted file mode 100644 index dd367e9..0000000 --- a/rand/src/prng/xorshift.rs +++ /dev/null @@ -1,101 +0,0 @@ -// 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_) } - } -} |