Tidy up some chunkloading math

BlueMapCore/src/main/java/de/bluecolored/bluemap/core/mca/ChunkAnvil113.java

@@ -198,20 +198,8 @@ public BlockState getBlockState(Vector3i pos) {
 			int y = pos.getY() & 0xF;
 			int z = pos.getZ() & 0xF;
 			int blockIndex = y * 256 + z * 16 + x;
-			int index = blockIndex * bitsPerBlock;
-			int firstLong = index >> 6; // index / 64
-			int bitoffset = index & 0x3F; // Math.floorMod(index, 64)
-			
-			long value = blocks[firstLong] >>> bitoffset;
-			
-			if (bitoffset > 0 && firstLong + 1 < blocks.length) {
-				long value2 = blocks[firstLong + 1];
-				value2 = value2 << -bitoffset;
-				value = value | value2;
-			}
-			
-			value = value & (0xFFFFFFFFFFFFFFFFL >>> -bitsPerBlock);
 			
+			long value = MCAMath.getValueFromLongStream(blocks, blockIndex, bitsPerBlock);
 			if (value >= palette.length) {
 				Logger.global.noFloodWarning("palettewarning", "Got palette value " + value + " but palette has size of " + palette.length + " (Future occasions of this error will not be logged)");
 				return BlockState.MISSING;
@@ -230,24 +218,11 @@ public LightData getLightData(Vector3i pos) {
 			int blockHalfByteIndex = blockByteIndex >> 1; // blockByteIndex / 2 
 			boolean largeHalf = (blockByteIndex & 0x1) != 0; // (blockByteIndex % 2) == 0
 
-			int blockLight = this.blockLight.length > 0 ? getByteHalf(this.blockLight[blockHalfByteIndex], largeHalf) : 0;
+			int blockLight = this.blockLight.length > 0 ? MCAMath.getByteHalf(this.blockLight[blockHalfByteIndex], largeHalf) : 0;
-			int skyLight = this.skyLight.length > 0 ? getByteHalf(this.skyLight[blockHalfByteIndex], largeHalf) : 0;
+			int skyLight = this.skyLight.length > 0 ? MCAMath.getByteHalf(this.skyLight[blockHalfByteIndex], largeHalf) : 0;
 			
 			return new LightData(skyLight, blockLight);
 		}
-		
-		/**
-		 * Extracts the 4 bits of the left (largeHalf = <code>true</code>) or the right (largeHalf = <code>false</code>) side of the byte stored in <code>value</code>.<br> 
-		 * The value is treated as an unsigned byte.
-		 */
-		private int getByteHalf(int value, boolean largeHalf) {
-			value = value & 0xFF;
-			if (largeHalf) {
-				value = value >> 4;
-			}
-			value = value & 0xF;
-			return value;
-		}
 	}
 	
 }

BlueMapCore/src/main/java/de/bluecolored/bluemap/core/mca/ChunkAnvil115.java

@@ -199,20 +199,8 @@ public BlockState getBlockState(Vector3i pos) {
 			int y = pos.getY() & 0xF;
 			int z = pos.getZ() & 0xF;
 			int blockIndex = y * 256 + z * 16 + x;
-			int index = blockIndex * bitsPerBlock;
-			int firstLong = index >> 6; // index / 64
-			int bitoffset = index & 0x3F; // Math.floorMod(index, 64)
-			
-			long value = blocks[firstLong] >>> bitoffset;
-			
-			if (bitoffset > 0 && firstLong + 1 < blocks.length) {
-				long value2 = blocks[firstLong + 1];
-				value2 = value2 << -bitoffset;
-				value = value | value2;
-			}
-			
-			value = value & (0xFFFFFFFFFFFFFFFFL >>> -bitsPerBlock);
 			
+			long value = MCAMath.getValueFromLongStream(blocks, blockIndex, bitsPerBlock);
 			if (value >= palette.length) {
 				Logger.global.noFloodWarning("palettewarning", "Got palette value " + value + " but palette has size of " + palette.length + " (Future occasions of this error will not be logged)");
 				return BlockState.MISSING;
@@ -231,24 +219,11 @@ public LightData getLightData(Vector3i pos) {
 			int blockHalfByteIndex = blockByteIndex >> 1; // blockByteIndex / 2 
 			boolean largeHalf = (blockByteIndex & 0x1) != 0; // (blockByteIndex % 2) == 0
 
-			int blockLight = this.blockLight.length > 0 ? getByteHalf(this.blockLight[blockHalfByteIndex], largeHalf) : 0;
+			int blockLight = this.blockLight.length > 0 ? MCAMath.getByteHalf(this.blockLight[blockHalfByteIndex], largeHalf) : 0;
-			int skyLight = this.skyLight.length > 0 ? getByteHalf(this.skyLight[blockHalfByteIndex], largeHalf) : 0;
+			int skyLight = this.skyLight.length > 0 ? MCAMath.getByteHalf(this.skyLight[blockHalfByteIndex], largeHalf) : 0;
 			
 			return new LightData(skyLight, blockLight);
 		}
-		
-		/**
-		 * Extracts the 4 bits of the left (largeHalf = <code>true</code>) or the right (largeHalf = <code>false</code>) side of the byte stored in <code>value</code>.<br> 
-		 * The value is treated as an unsigned byte.
-		 */
-		private int getByteHalf(int value, boolean largeHalf) {
-			value = value & 0xFF;
-			if (largeHalf) {
-				value = value >> 4;
-			}
-			value = value & 0xF;
-			return value;
-		}
 	}
 	
 }

BlueMapCore/src/main/java/de/bluecolored/bluemap/core/mca/ChunkAnvil116.java

@@ -145,7 +145,6 @@ private class Section {
 		private BlockState[] palette;
 
 		private int bitsPerBlock;
-		private int blocksPerLong;
 		
 		@SuppressWarnings("unchecked")
 		public Section(CompoundTag sectionData) {
@@ -189,7 +188,6 @@ public Section(CompoundTag sectionData) {
 
 			this.bitsPerBlock = 32 - Integer.numberOfLeadingZeros(palette.length - 1);
 			if (this.bitsPerBlock < 4) this.bitsPerBlock = 4;
-			this.blocksPerLong = 64 / bitsPerBlock;
 		}
 		
 		public int getSectionY() {
@@ -203,13 +201,8 @@ public BlockState getBlockState(Vector3i pos) {
 			int y = pos.getY() & 0xF;
 			int z = pos.getZ() & 0xF;
 			int blockIndex = y * 256 + z * 16 + x;
-			int longIndex = blockIndex / blocksPerLong;
-			int bitIndex = (blockIndex % blocksPerLong) * bitsPerBlock;
-			
-			long value = blocks[longIndex] >>> bitIndex;
 
-			value = value & (0xFFFFFFFFFFFFFFFFL >>> -bitsPerBlock);
+			long value = MCAMath.getValueFromLongArray(blocks, blockIndex, bitsPerBlock);
-			
 			if (value >= palette.length) {
 				Logger.global.noFloodWarning("palettewarning", "Got palette value " + value + " but palette has size of " + palette.length + "! (Future occasions of this error will not be logged)");
 				return BlockState.MISSING;
@@ -228,24 +221,11 @@ public LightData getLightData(Vector3i pos) {
 			int blockHalfByteIndex = blockByteIndex >> 1; // blockByteIndex / 2 
 			boolean largeHalf = (blockByteIndex & 0x1) != 0; // (blockByteIndex % 2) == 0
 
-			int blockLight = this.blockLight.length > 0 ? getByteHalf(this.blockLight[blockHalfByteIndex], largeHalf) : 0;
+			int blockLight = this.blockLight.length > 0 ? MCAMath.getByteHalf(this.blockLight[blockHalfByteIndex], largeHalf) : 0;
-			int skyLight = this.skyLight.length > 0 ? getByteHalf(this.skyLight[blockHalfByteIndex], largeHalf) : 0;
+			int skyLight = this.skyLight.length > 0 ? MCAMath.getByteHalf(this.skyLight[blockHalfByteIndex], largeHalf) : 0;
 			
 			return new LightData(skyLight, blockLight);
 		}
-		
-		/**
-		 * Extracts the 4 bits of the left (largeHalf = <code>true</code>) or the right (largeHalf = <code>false</code>) side of the byte stored in <code>value</code>.<br> 
-		 * The value is treated as an unsigned byte.
-		 */
-		private int getByteHalf(int value, boolean largeHalf) {
-			value = value & 0xFF;
-			if (largeHalf) {
-				value = value >> 4;
-			}
-			value = value & 0xF;
-			return value;
-		}
 	}
 	
 }

BlueMapCore/src/main/java/de/bluecolored/bluemap/core/mca/MCAMath.java

@@ -0,0 +1,74 @@
+/*
+ * This file is part of BlueMap, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) Blue (Lukas Rieger) <https://bluecolored.de>
+ * Copyright (c) contributors
+ *
+ * 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.
+ */
+package de.bluecolored.bluemap.core.mca;
+
+public class MCAMath {
+
+	/**
+	 * Having a long array where each long contains as many values as fit in it without overflowing, returning the "valueIndex"-th value when each value has "bitsPerValue" bits.
+	 */
+	public static long getValueFromLongArray(long[] data, int valueIndex, int bitsPerValue) {
+		int valuesPerLong = 64 / bitsPerValue;
+		int longIndex = valueIndex / valuesPerLong;
+		int bitIndex = (valueIndex % valuesPerLong) * bitsPerValue;
+		
+		long value = data[longIndex] >>> bitIndex;
+
+		return value & (0xFFFFFFFFFFFFFFFFL >>> -bitsPerValue);
+	}
+	
+	/**
+	 * Treating the long array "data" as a continuous stream of bits, returning the "valueIndex"-th value when each value has "bitsPerValue" bits.
+	 */
+	public static long getValueFromLongStream(long[] data, int valueIndex, int bitsPerValue) {
+		int bitIndex = valueIndex * bitsPerValue;
+		int firstLong = bitIndex >> 6; // index / 64
+		int bitoffset = bitIndex & 0x3F; // Math.floorMod(index, 64)
+		
+		long value = data[firstLong] >>> bitoffset;
+		
+		if (bitoffset > 0 && firstLong + 1 < data.length) {
+			long value2 = data[firstLong + 1];
+			value2 = value2 << -bitoffset;
+			value = value | value2;
+		}
+		
+		return value & (0xFFFFFFFFFFFFFFFFL >>> -bitsPerValue);
+	}
+	
+	/**
+	 * Extracts the 4 bits of the left (largeHalf = <code>true</code>) or the right (largeHalf = <code>false</code>) side of the byte stored in <code>value</code>.<br> 
+	 * The value is treated as an unsigned byte.
+	 */
+	public static int getByteHalf(int value, boolean largeHalf) {
+		value = value & 0xFF;
+		if (largeHalf) {
+			value = value >> 4;
+		}
+		value = value & 0xF;
+		return value;
+	}
+	
+}