Remove magic value for pre-filled var ints

src/main/java/net/minestom/server/utils/PacketUtils.java

@@ -143,7 +143,7 @@ public final class PacketUtils {
      * @param packet the packet to write into {@code buf}
      */
     public static void writePacket(@NotNull ByteBuf buf, @NotNull ServerPacket packet) {
-        Utils.writeVarIntBuf(buf, packet.getId());
+        Utils.writeVarInt(buf, packet.getId());
         writePacketPayload(buf, packet);
     }
 
@@ -173,14 +173,13 @@ public final class PacketUtils {
     public static void frameBuffer(@NotNull ByteBuf packetBuffer, @NotNull ByteBuf frameTarget) {
         final int packetSize = packetBuffer.readableBytes();
         final int headerSize = Utils.getVarIntSize(packetSize);
-
         if (headerSize > 3) {
             throw new IllegalStateException("Unable to fit " + headerSize + " into 3");
         }
 
         frameTarget.ensureWritable(packetSize + headerSize);
 
-        Utils.writeVarIntBuf(frameTarget, packetSize);
+        Utils.writeVarInt(frameTarget, packetSize);
         frameTarget.writeBytes(packetBuffer, packetBuffer.readerIndex(), packetSize);
     }
 
@@ -196,7 +195,7 @@ public final class PacketUtils {
     public static void compressBuffer(@NotNull VelocityCompressor compressor, @NotNull ByteBuf packetBuffer, @NotNull ByteBuf compressionTarget) {
         final int packetLength = packetBuffer.readableBytes();
         final boolean compression = packetLength > MinecraftServer.getCompressionThreshold();
-        Utils.writeVarIntBuf(compressionTarget, compression ? packetLength : 0);
+        Utils.writeVarInt(compressionTarget, compression ? packetLength : 0);
         if (compression) {
             compress(compressor, packetBuffer, compressionTarget);
         } else {
@@ -217,10 +216,11 @@ public final class PacketUtils {
         final int compressionThreshold = MinecraftServer.getCompressionThreshold();
 
         // Index of the var-int containing the complete packet length
-        final int packetLengthIndex = Utils.writeEmptyVarIntHeader(buffer);
+        final int packetLengthIndex = Utils.writeEmpty3BytesVarInt(buffer);
+        final int startIndex = buffer.writerIndex(); // Index where the content starts (after length)
         if (compressionThreshold > 0) {
             // Index of the uncompressed payload length
-            final int dataLengthIndex = Utils.writeEmptyVarIntHeader(buffer);
+            final int dataLengthIndex = Utils.writeEmpty3BytesVarInt(buffer);
 
             // Write packet
             final int contentIndex = buffer.writerIndex();
@@ -228,7 +228,7 @@ public final class PacketUtils {
             final int packetSize = buffer.writerIndex() - contentIndex;
 
             final int uncompressedLength = packetSize >= compressionThreshold ? packetSize : 0;
-            Utils.overrideVarIntHeader(buffer, dataLengthIndex, uncompressedLength);
+            Utils.write3BytesVarInt(buffer, dataLengthIndex, uncompressedLength);
             if (uncompressedLength > 0) {
                 // Packet large enough, compress
                 ByteBuf uncompressedCopy = buffer.copy(contentIndex, packetSize);
@@ -241,8 +241,8 @@ public final class PacketUtils {
             writePacket(buffer, serverPacket);
         }
         // Total length
-        final int totalPacketLength = buffer.writerIndex() - packetLengthIndex - Utils.VARINT_HEADER_SIZE;
+        final int totalPacketLength = buffer.writerIndex() - startIndex;
-        Utils.overrideVarIntHeader(buffer, packetLengthIndex, totalPacketLength);
+        Utils.write3BytesVarInt(buffer, packetLengthIndex, totalPacketLength);
     }
 
     /**

src/main/java/net/minestom/server/utils/Utils.java

@@ -10,11 +10,7 @@ import java.util.UUID;
 
 public final class Utils {
 
-    // Do NOT modify
-    public static final int VARINT_HEADER_SIZE = 3;
-
     private Utils() {
-
     }
 
     public static int getVarIntSize(int input) {
@@ -25,7 +21,7 @@ public final class Utils {
                 ? 4 : 5;
     }
 
-    public static void writeVarIntBuf(ByteBuf buf, int value) {
+    public static void writeVarInt(@NotNull ByteBuf buf, int value) {
         // Took from velocity
         if ((value & (0xFFFFFFFF << 7)) == 0) {
             buf.writeByte(value);
@@ -36,19 +32,14 @@ public final class Utils {
             int w = (value & 0x7F | 0x80) << 16 | ((value >>> 7) & 0x7F | 0x80) << 8 | (value >>> 14);
             buf.writeMedium(w);
         } else {
-            // Naive loop
+            int w = (value & 0x7F | 0x80) << 24 | ((value >>> 7) & 0x7F | 0x80) << 16
-            while (true) {
+                    | ((value >>> 14) & 0x7F | 0x80) << 8 | ((value >>> 21) & 0x7F | 0x80);
-                if ((value & 0xFFFFFF80) == 0) {
+            buf.writeInt(w);
-                    buf.writeByte(value);
+            buf.writeByte(value >>> 28);
-                    return;
-                }
-                buf.writeByte(value & 0x7F | 0x80);
-                value >>>= 7;
-            }
         }
     }
 
-    public static void overrideVarIntHeader(@NotNull ByteBuf buffer, int startIndex, int value) {
+    public static void write3BytesVarInt(@NotNull ByteBuf buffer, int startIndex, int value) {
         final int indexCache = buffer.writerIndex();
         buffer.writerIndex(startIndex);
         final int w = (value & 0x7F | 0x80) << 16 | ((value >>> 7) & 0x7F | 0x80) << 8 | (value >>> 14);
@@ -56,31 +47,26 @@ public final class Utils {
         buffer.writerIndex(indexCache);
     }
 
-    public static int writeEmptyVarIntHeader(@NotNull ByteBuf buffer) {
+    public static int writeEmpty3BytesVarInt(@NotNull ByteBuf buffer) {
         final int index = buffer.writerIndex();
         buffer.writeMedium(0);
         return index;
     }
 
-    public static int readVarInt(ByteBuf buffer) {
+    public static int readVarInt(ByteBuf buf) {
-        int numRead = 0;
+        int i = 0;
-        int result = 0;
+        final int maxRead = Math.min(5, buf.readableBytes());
-        byte read;
+        for (int j = 0; j < maxRead; j++) {
-        do {
+            final int k = buf.readByte();
-            read = buffer.readByte();
+            i |= (k & 0x7F) << j * 7;
-            int value = (read & 0b01111111);
+            if ((k & 0x80) != 128) {
-            result |= (value << (7 * numRead));
+                return i;
-
-            numRead++;
-            if (numRead > 5) {
-                throw new RuntimeException("VarInt is too big");
             }
-        } while ((read & 0b10000000) != 0);
+        }
-
+        throw new RuntimeException("VarInt is too big");
-        return result;
     }
 
-    public static long readVarLong(ByteBuf buffer) {
+    public static long readVarLong(@NotNull ByteBuf buffer) {
         int numRead = 0;
         long result = 0;
         byte read;
@@ -148,14 +134,14 @@ public final class Utils {
         if (bitsPerEntry < 9) {
             // Palette has to exist
             final Short2ShortLinkedOpenHashMap paletteBlockMap = section.getPaletteBlockMap();
-            writeVarIntBuf(buffer, paletteBlockMap.size());
+            writeVarInt(buffer, paletteBlockMap.size());
             for (short paletteValue : paletteBlockMap.values()) {
-                writeVarIntBuf(buffer, paletteValue);
+                writeVarInt(buffer, paletteValue);
             }
         }
 
         final long[] blocks = section.getBlocks();
-        writeVarIntBuf(buffer, blocks.length);
+        writeVarInt(buffer, blocks.length);
         for (long datum : blocks) {
             buffer.writeLong(datum);
         }

src/main/java/net/minestom/server/utils/binary/BinaryWriter.java

@@ -152,7 +152,7 @@ public class BinaryWriter extends OutputStream {
      * @param i the int to write
      */
     public void writeVarInt(int i) {
-        Utils.writeVarIntBuf(buffer, i);
+        Utils.writeVarInt(buffer, i);
     }
 
     /**