From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: NONPLAYT <76615486+NONPLAYT@users.noreply.github.com>
Date: Tue, 16 May 2023 18:45:29 +0300
Subject: [PATCH] Optimize Varints

Original license: GPLv3
Original project: https://github.com/PaperMC/Velocity
Paper pull request: https://github.com/PaperMC/Paper/pull/8418

diff --git a/src/main/java/gq/bxteam/divinemc/configuration/DivineConfig.java b/src/main/java/gq/bxteam/divinemc/configuration/DivineConfig.java
index 2744315c62f99b48cb689dd90fdfffac405b1bcc..cc0b3089ecc246abf7a4465055a63152ad0db0c3 100644
--- a/src/main/java/gq/bxteam/divinemc/configuration/DivineConfig.java
+++ b/src/main/java/gq/bxteam/divinemc/configuration/DivineConfig.java
@@ -162,4 +162,9 @@ public class DivineConfig {
     private static void allowAnyUsername() {
         allowAnyUsername = getBoolean("settings.player.allow-any-username", allowAnyUsername);
     }
+
+    public static boolean doOptimizeVarints = true;
+    private static void doOptimizeVarints() {
+        doOptimizeVarints = getBoolean("settings.optimization.optimize-varints", doOptimizeVarints);
+    }
 }
\ No newline at end of file
diff --git a/src/main/java/net/minecraft/network/FriendlyByteBuf.java b/src/main/java/net/minecraft/network/FriendlyByteBuf.java
index 1f4b64a5f812376c499c98cb4be62469bd0b7dbe..413a35e84c8006b5ef2919e769a5a28bbd794758 100644
--- a/src/main/java/net/minecraft/network/FriendlyByteBuf.java
+++ b/src/main/java/net/minecraft/network/FriendlyByteBuf.java
@@ -13,6 +13,7 @@ import com.mojang.serialization.Codec;
 import com.mojang.serialization.DataResult;
 import com.mojang.serialization.DynamicOps;
 import com.mojang.serialization.JsonOps;
+import gq.bxteam.divinemc.configuration.DivineConfig;
 import io.netty.buffer.ByteBuf;
 import io.netty.buffer.ByteBufAllocator;
 import io.netty.buffer.ByteBufInputStream;
@@ -104,7 +105,22 @@ public class FriendlyByteBuf extends ByteBuf {
         this.source = parent;
     }
 
+    // DivineMC start - Optimize varints
+    private static final int[] VARINT_EXACT_BYTE_LENGTHS = new int[33];
+    static {
+        for (int i = 0; i <= 32; ++i) {
+            VARINT_EXACT_BYTE_LENGTHS[i] = (int) Math.ceil((31d - (i - 1)) / 7d);
+        }
+        VARINT_EXACT_BYTE_LENGTHS[32] = 1; // Special case for the number 0.
+    }
+    // DivineMC end
+
     public static int getVarIntSize(int value) {
+        // DivineMC start - Optimize varints
+        if (DivineConfig.doOptimizeVarints) {
+            return VARINT_EXACT_BYTE_LENGTHS[Integer.numberOfLeadingZeros(value)];
+        }
+        // DivineMC end
         for (int j = 1; j < 5; ++j) {
             if ((value & -1 << j * 7) == 0) {
                 return j;
@@ -615,6 +631,23 @@ public class FriendlyByteBuf extends ByteBuf {
     }
 
     public FriendlyByteBuf writeVarInt(int value) {
+        // DivineMC start - Optimize varints
+        if (DivineConfig.doOptimizeVarints) {
+            if ((value & (0xFFFFFFFF << 7)) == 0) {
+                writeByte(value);
+            } else if ((value & (0xFFFFFFFF << 14)) == 0) {
+                int w = (value & 0x7F | 0x80) << 8 | (value >>> 7);
+                writeShort(w);
+            } else {
+                while ((value & -128) != 0) {
+                    this.writeByte(value & 127 | 128);
+                    value >>>= 7;
+                }
+                this.writeByte(value);
+            }
+            return this;
+        }
+        // DivineMC end
         while ((value & -128) != 0) {
             this.writeByte(value & 127 | 128);
             value >>>= 7;