added random seed check

2020-01-30 13:25:18 -05:00
parent 15b4601e95
commit 6fb15ca0c5
1 changed files with 24 additions and 0 deletions
@@ -0,0 +1,24 @@
+package kaptainwutax.seedcracker.magic;
+
+import kaptainwutax.seedcracker.util.Rand;
+import kaptainwutax.seedcracker.util.math.LCG;
+
+public class RandomSeed {
+
+	private static final LCG INVERSE_LCG = Rand.JAVA_LCG.combine(-1);
+
+	/**
+	 * Source: https://twitter.com/Geosquare_/status/1169623192153010176
+	 * */
+	public static boolean isRandomSeed(long worldSeed) {
+		long upperBits = worldSeed >>> 32;
+		long lowerBits = worldSeed & MagicMath.MASK_32;
+
+		long a = (24667315 * upperBits + 18218081 * lowerBits + 67552711) >> 32;
+		long b = (-4824621 * upperBits + 7847617 * lowerBits + 7847617) >> 32;
+		long seed = INVERSE_LCG.nextSeed(7847617 * a - 18218081 * b);
+		return new Rand(seed, false).nextLong() == worldSeed;
+	}
+
+
+}