RAND31 random number generator in Rust. Suitable for generating white noise for audio applications.

rand31.rs

/*
 * rand31.rs
 * Copyright (C) 2013 Adrian Perez <[email protected]>
 *
 * Implements the rand31 random number generation algorithm, which is
 * particularly suitable for use as white noise for sound applications.
 *
 * For more information on the algorithm, please refer to:
 * http://www.firstptr.com.au/dsp/rand31/
 *
 * Distributed under terms of the MIT license.
 */

static constapmc: u64 = 16807;

pub struct Rand31 {
	priv seed: u64
}

impl Rand31 {
	pub fn next(&mut self) -> u64 {
		let mut lo: u64 = constapmc * (self.seed & 0xFFFF);
		let hi: u64 = constapmc * (self.seed >> 16);
		lo += (hi & 0x7FFF) << 16;
		lo += hi >> 15;
		if lo > 0x7FFFFFFF {
			lo -= 0x7FFFFFFF;
		}
		self.seed = lo;
		self.seed
	}

	pub fn nextf(&mut self) -> f64 {
		(self.next() as f64) / 2147483647.0
	}
}

pub fn new_with_seed(seed: u64) -> Rand31 { Rand31 { seed: seed } }
pub fn new() -> Rand31 { new_with_seed(1) }


// This main() functions is for testing.
fn main () {
	let mut r = new();
	loop {
		println(format!("{:u}", r.next()));
	}
}