From 49f76c7bddad53dda407c3dfd577eafacdaa7061 Mon Sep 17 00:00:00 2001
From: DBotThePony <dbotthepony@yandex.ru>
Date: Wed, 5 Mar 2025 09:06:44 +0700
Subject: [PATCH] Provide Xoshiro256StarStar random

---
 .../mc/otm/core/util/Xoshiro256SSRandom.kt    | 110 ++++++++++++++++++
 1 file changed, 110 insertions(+)
 create mode 100644 src/main/kotlin/ru/dbotthepony/mc/otm/core/util/Xoshiro256SSRandom.kt

diff --git a/src/main/kotlin/ru/dbotthepony/mc/otm/core/util/Xoshiro256SSRandom.kt b/src/main/kotlin/ru/dbotthepony/mc/otm/core/util/Xoshiro256SSRandom.kt
new file mode 100644
index 000000000..e14e7ed02
--- /dev/null
+++ b/src/main/kotlin/ru/dbotthepony/mc/otm/core/util/Xoshiro256SSRandom.kt
@@ -0,0 +1,110 @@
+package ru.dbotthepony.mc.otm.core.util
+
+import it.unimi.dsi.fastutil.HashCommon
+import net.minecraft.util.Mth
+import net.minecraft.util.RandomSource
+import net.minecraft.world.level.levelgen.MarsagliaPolarGaussian
+import net.minecraft.world.level.levelgen.PositionalRandomFactory
+import java.lang.StringBuilder
+import java.util.random.RandomGenerator
+
+class Xoshiro256SSRandom(
+	private var s0: Long,
+	private var s1: Long,
+	private var s2: Long,
+	private var s3: Long,
+) : RandomGenerator, RandomSource {
+	private val gaussian = MarsagliaPolarGaussian(this)
+
+	constructor(seed: Long = System.nanoTime()) : this(1L, 2L, 3L, 4L) {
+		setSeed(seed)
+	}
+
+	override fun setSeed(seed: Long) {
+		val rng = LCG64Random(seed)
+		s0 = rng.nextLong()
+		s1 = rng.nextLong()
+		s2 = rng.nextLong()
+		s3 = rng.nextLong()
+		gaussian.reset()
+	}
+
+	override fun nextInt(): Int {
+		// sample upper bits
+		return nextLong().ushr(32).toInt()
+	}
+
+	override fun nextLong(): Long {
+		val result = (s1 * 5).rotateLeft(7) * 9
+		val t = s1.shl(17)
+		s2 = s2.xor(s0)
+		s3 = s3.xor(s1)
+		s1 = s1.xor(s2)
+		s0 = s0.xor(s3)
+		s2 = s2.xor(t)
+		s3 = s3.rotateLeft(45)
+		return result
+	}
+
+	override fun nextInt(bound: Int): Int {
+		return super<RandomGenerator>.nextInt(bound)
+	}
+
+	override fun nextInt(origin: Int, bound: Int): Int {
+		return super<RandomGenerator>.nextInt(origin, bound)
+	}
+
+	override fun nextBoolean(): Boolean {
+		return super.nextBoolean()
+	}
+
+	override fun nextFloat(): Float {
+		return super.nextFloat()
+	}
+
+	override fun nextDouble(): Double {
+		return super.nextDouble()
+	}
+
+	override fun nextGaussian(): Double {
+		return gaussian.nextGaussian()
+	}
+
+	override fun fork(): RandomSource {
+		return Xoshiro256SSRandom(nextLong(), nextLong(), nextLong(), nextLong())
+	}
+
+	override fun forkPositional(): PositionalRandomFactory {
+		return Positional(nextLong(), nextLong(), nextLong(), nextLong())
+	}
+
+	class Positional(
+		val s0: Long,
+		val s1: Long,
+		val s2: Long,
+		val s3: Long,
+	) : PositionalRandomFactory {
+		override fun at(x: Int, y: Int, z: Int): RandomSource {
+			val rng = LCG64Random(Mth.getSeed(x, y, z))
+
+			return Xoshiro256SSRandom(
+				s0.rotateLeft(11).xor(rng.nextLong()),
+				s1.rotateLeft(22).xor(rng.nextLong()),
+				s2.rotateLeft(33).xor(rng.nextLong()),
+				s3.rotateLeft(44).xor(rng.nextLong()),
+			)
+		}
+
+		override fun fromHashOf(name: String): RandomSource {
+			return Xoshiro256SSRandom(s0, HashCommon.murmurHash3(name.hashCode().toLong()).xor(s1), s2, s3)
+		}
+
+		override fun fromSeed(seed: Long): RandomSource {
+			return Xoshiro256SSRandom(seed)
+		}
+
+		override fun parityConfigString(builder: StringBuilder) {
+			throw UnsupportedOperationException()
+		}
+	}
+}