Tausworthe 223 implementation in java similar to LuaJIT

Tausworthe223.java

/*
** LuaJIT -- a Just-In-Time Compiler for Lua. https://luajit.org/
**
** Copyright (C) 2005-2022 Mike Pall. All rights reserved.
** Copyright (C) 2023 Mason Daniels.
**
** Permission is hereby granted, free of charge, to any person obtaining
** a copy of this software and associated documentation files (the
** "Software"), to deal in the Software without restriction, including
** without limitation the rights to use, copy, modify, merge, publish,
** distribute, sublicense, and/or sell copies of the Software, and to
** permit persons to whom the Software is furnished to do so, subject to
** the following conditions:
**
** The above copyright notice and this permission notice shall be
** included in all copies or substantial portions of the Software.
**
** THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
** EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
** MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
** IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
** CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
** TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
** SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
**
** [ MIT license: https://www.opensource.org/licenses/mit-license.php ]
*/

/*
** Basically, this is a java equivalent to the Tausworthe PRNG implementation found in LuaJIT.
** https://github.com/LuaJIT/LuaJIT/blob/v2.1/src/lj_prng.c
** 
*/

public class Tausworthe223 {

	public static void main(String[] args) {

		Tausworthe223 prng = new Tausworthe223(144);
		for (int i = 0; i < 100000; i++) {
			prng.nextDouble();
		}
		System.out.println(prng.nextDouble()); // prints 0.587154017020378

		/*
		 ** Equal LuaJIT code:
		 ** 
		 ** function j(i)
		 ** math.randomseed(i)
		 ** for i=0,99999,1 do math.random() end
		 ** print(math.random())
		 ** end
		 ** 
		 ** j(144)
		 **
		 ** This prints 0.58715401702038 (rounds)
		 **/

	}

	private static final int[] R = { 18, 28, 7, 8 }; // This is actually called R iirc
	private static final int[] U = { 63, 58, 55, 47 }; // Didn't know what to name this
	private static final int[] N = { 31, 19, 24, 21 }; // Or this

	private long[] state = new long[4];
	private long seed;

	public Tausworthe223(long seed) {
		this.seed = seed;
		seed();

	}

	private static long pi = 4614256656552045848L;
	private static long e = 4613303445314885481L;

	// TODO: Ensure MSB is not empty.
	public void seed() {
		
		// Set up seed
		double result = seed;
		for (int i = 0; i < 4; i++) {
			result = result * Double.longBitsToDouble(pi) + Double.longBitsToDouble(e);
			state[i] = Double.doubleToLongBits(result);
		}

		// Iterate over steps
		for (int i = 0; i < 10; i++) {
			nextStep();
		}
	}

	public long nextStep() {
		long result = 0;
		for (int i = 0; i < 4; i++) {
			state[i] = (((state[i] << N[i]) ^ state[i]) >>> (U[i] - R[i]))
					^ ((state[i] & 0xFFFFFFFFFFFFFFFFL << (64 - U[i]))) << R[i];
			result ^= state[i];
		}
		return result;
	}

	public double nextDouble() {
		long mask = (0x000fffffL << 32L) | 0xffffffffL;
		long exponent = 0x3ff00000L << 32L;
		long bits = (nextStep() & mask) | exponent;
		return Double.longBitsToDouble(bits) - 1d;
	}

}