Thought I'd need this

- Consolidate common logic from transfer list and scatter list into
  MemoryBuffer

src/main/java/com/jozufozu/flywheel/backend/engine/indirect/ScatterList.java

@@ -2,12 +2,12 @@ package com.jozufozu.flywheel.backend.engine.indirect;
 
 import org.lwjgl.system.MemoryUtil;
 
-import com.jozufozu.flywheel.lib.memory.MemoryBlock;
+import com.jozufozu.flywheel.backend.util.MemoryBuffer;
 
 public class ScatterList {
 	public static final long STRIDE = Integer.BYTES * 2;
 	public final long maxBytesPerScatter;
-	private MemoryBlock block;
+	private final MemoryBuffer block = new MemoryBuffer(STRIDE);
 	private int length;
 	private long usedBytes;
 
@@ -46,9 +46,9 @@ public class ScatterList {
 	}
 
 	public void push(long sizeBytes, long srcOffsetBytes, long dstOffsetBytes) {
-		reallocIfNeeded(length);
+		block.reallocIfNeeded(length);
 
-		long ptr = block.ptr() + length * STRIDE;
+		long ptr = block.ptrForIndex(length);
 		MemoryUtil.memPutInt(ptr, packSizeAndSrcOffset(sizeBytes, srcOffsetBytes));
 		MemoryUtil.memPutInt(ptr + Integer.BYTES, (int) (dstOffsetBytes >> 2));
 
@@ -78,21 +78,7 @@ public class ScatterList {
 	}
 
 	public void delete() {
-		if (block != null) {
+		block.delete();
-			block.free();
-		}
-	}
-
-	private void reallocIfNeeded(int index) {
-		if (block == null) {
-			block = MemoryBlock.malloc(neededCapacityForIndex(index + 8));
-		} else if (block.size() < neededCapacityForIndex(index)) {
-			block = block.realloc(neededCapacityForIndex(index + 8));
-		}
-	}
-
-	private static long neededCapacityForIndex(int index) {
-		return (index + 1) * STRIDE;
 	}
 
 	private static int packSizeAndSrcOffset(long sizeBytes, long srcOffsetBytes) {

src/main/java/com/jozufozu/flywheel/backend/engine/indirect/TransferList.java

@@ -2,11 +2,11 @@ package com.jozufozu.flywheel.backend.engine.indirect;
 
 import org.lwjgl.system.MemoryUtil;
 
-import com.jozufozu.flywheel.lib.memory.MemoryBlock;
+import com.jozufozu.flywheel.backend.util.MemoryBuffer;
 
 public class TransferList {
 	private static final long STRIDE = Long.BYTES * 4;
-	private MemoryBlock block;
+	private final MemoryBuffer block = new MemoryBuffer(STRIDE);
 	private int length;
 
 	/**
@@ -24,7 +24,7 @@ public class TransferList {
 			return;
 		}
 
-		reallocIfNeeded(length);
+		block.reallocIfNeeded(length);
 
 		vbo(length, vbo);
 		srcOffset(length, srcOffset);
@@ -56,25 +56,23 @@ public class TransferList {
 	}
 
 	public int vbo(int index) {
-		return MemoryUtil.memGetInt(ptrForIndex(index));
+		return MemoryUtil.memGetInt(block.ptrForIndex(index));
 	}
 
 	public long srcOffset(int index) {
-		return MemoryUtil.memGetLong(ptrForIndex(index) + Long.BYTES);
+		return MemoryUtil.memGetLong(block.ptrForIndex(index) + Long.BYTES);
 	}
 
 	public long dstOffset(int index) {
-		return MemoryUtil.memGetLong(ptrForIndex(index) + Long.BYTES * 2);
+		return MemoryUtil.memGetLong(block.ptrForIndex(index) + Long.BYTES * 2);
 	}
 
 	public long size(int index) {
-		return MemoryUtil.memGetLong(ptrForIndex(index) + Long.BYTES * 3);
+		return MemoryUtil.memGetLong(block.ptrForIndex(index) + Long.BYTES * 3);
 	}
 
 	public void delete() {
-		if (block != null) {
+		block.delete();
-			block.free();
-		}
 	}
 
 	private boolean continuesLast(int vbo, long srcOffset, long dstOffset) {
@@ -87,38 +85,18 @@ public class TransferList {
 	}
 
 	private void vbo(int index, int vbo) {
-		MemoryUtil.memPutInt(ptrForIndex(index), vbo);
+		MemoryUtil.memPutInt(block.ptrForIndex(index), vbo);
 	}
 
 	private void srcOffset(int index, long srcOffset) {
-		MemoryUtil.memPutLong(ptrForIndex(index) + Long.BYTES, srcOffset);
+		MemoryUtil.memPutLong(block.ptrForIndex(index) + Long.BYTES, srcOffset);
 	}
 
 	private void dstOffset(int index, long dstOffset) {
-		MemoryUtil.memPutLong(ptrForIndex(index) + Long.BYTES * 2, dstOffset);
+		MemoryUtil.memPutLong(block.ptrForIndex(index) + Long.BYTES * 2, dstOffset);
 	}
 
 	private void size(int index, long size) {
-		MemoryUtil.memPutLong(ptrForIndex(index) + Long.BYTES * 3, size);
+		MemoryUtil.memPutLong(block.ptrForIndex(index) + Long.BYTES * 3, size);
-	}
-
-	private void reallocIfNeeded(int index) {
-		if (block == null) {
-			block = MemoryBlock.malloc(neededCapacityForIndex(index + 8));
-		} else if (block.size() < neededCapacityForIndex(index)) {
-			block = block.realloc(neededCapacityForIndex(index + 8));
-		}
-	}
-
-	private long ptrForIndex(int index) {
-		return block.ptr() + bytePosForIndex(index);
-	}
-
-	private static long bytePosForIndex(int index) {
-		return index * STRIDE;
-	}
-
-	private static long neededCapacityForIndex(int index) {
-		return (index + 1) * STRIDE;
 	}
 }

src/main/java/com/jozufozu/flywheel/backend/util/MemoryBuffer.java

@@ -0,0 +1,50 @@
+package com.jozufozu.flywheel.backend.util;
+
+import org.jetbrains.annotations.Nullable;
+
+import com.jozufozu.flywheel.lib.memory.MemoryBlock;
+
+public class MemoryBuffer {
+	private final long stride;
+
+	@Nullable
+	private MemoryBlock block;
+
+	public MemoryBuffer(long stride) {
+		this.stride = stride;
+	}
+
+	public boolean reallocIfNeeded(int index) {
+		if (block == null) {
+			block = MemoryBlock.malloc(neededCapacityForIndex(index + 8));
+			return true;
+		} else if (block.size() < neededCapacityForIndex(index)) {
+			block = block.realloc(neededCapacityForIndex(index + 8));
+			return true;
+		}
+
+		return false;
+	}
+
+	public long ptr() {
+		return block.ptr();
+	}
+
+	public long ptrForIndex(int index) {
+		return block.ptr() + bytePosForIndex(index);
+	}
+
+	public long bytePosForIndex(int index) {
+		return index * stride;
+	}
+
+	public long neededCapacityForIndex(int index) {
+		return (index + 1) * stride;
+	}
+
+	public void delete() {
+		if (block != null) {
+			block.free();
+		}
+	}
+}