86 lines
2.5 KiB
Java
86 lines
2.5 KiB
Java
/*
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* This file is part of Baritone.
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*
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* Baritone is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* Baritone is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with Baritone. If not, see <https://www.gnu.org/licenses/>.
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*/
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package baritone.behavior.look;
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import java.util.Arrays;
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import java.util.concurrent.atomic.AtomicLong;
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import java.util.function.LongSupplier;
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/**
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* Implementation of Xoroshiro256++
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* <p>
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* Extended to produce random double-precision floating point numbers, and allow copies to be spawned via {@link #fork},
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* which share the same internal state as the source object.
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*
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* @author Brady
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*/
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public final class ForkableRandom {
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private static final double DOUBLE_UNIT = 0x1.0p-53;
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private final long[] s;
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public ForkableRandom() {
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this(System.nanoTime() ^ System.currentTimeMillis());
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}
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public ForkableRandom(long seedIn) {
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final AtomicLong seed = new AtomicLong(seedIn);
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final LongSupplier splitmix64 = () -> {
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long z = seed.addAndGet(0x9e3779b97f4a7c15L);
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z = (z ^ (z >>> 30)) * 0xbf58476d1ce4e5b9L;
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z = (z ^ (z >>> 27)) * 0x94d049bb133111ebL;
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return z ^ (z >>> 31);
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};
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this.s = new long[] {
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splitmix64.getAsLong(),
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splitmix64.getAsLong(),
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splitmix64.getAsLong(),
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splitmix64.getAsLong()
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};
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}
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private ForkableRandom(long[] s) {
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this.s = s;
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}
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public double nextDouble() {
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return (this.next() >>> 11) * DOUBLE_UNIT;
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}
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public long next() {
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final long result = rotl(this.s[0] + this.s[3], 23) + this.s[0];
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final long t = this.s[1] << 17;
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this.s[2] ^= this.s[0];
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this.s[3] ^= this.s[1];
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this.s[1] ^= this.s[2];
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this.s[0] ^= this.s[3];
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this.s[2] ^= t;
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this.s[3] = rotl(this.s[3], 45);
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return result;
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}
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public ForkableRandom fork() {
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return new ForkableRandom(Arrays.copyOf(this.s, 4));
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}
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private static long rotl(long x, int k) {
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return (x << k) | (x >>> (64 - k));
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}
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}
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