From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: astei <andrew@steinborn.me>
Date: Sat, 1 Oct 2022 09:56:47 +0200
Subject: [PATCH] PaperPR: 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/net/minecraft/network/FriendlyByteBuf.java b/src/main/java/net/minecraft/network/FriendlyByteBuf.java
index 9938bb90bef84cf784f9a1ceb02a1a45aa8b48a1..f5080a3716a65a7175b043c41f1e002322ecbf70 100644
--- a/src/main/java/net/minecraft/network/FriendlyByteBuf.java
+++ b/src/main/java/net/minecraft/network/FriendlyByteBuf.java
@@ -103,6 +103,18 @@ public class FriendlyByteBuf extends ByteBuf {
     }
 
     public static int getVarIntSize(int value) {
+    //Paper start - Optimize VarInts
+        return VARINT_EXACT_BYTE_LENGTHS[Integer.numberOfLeadingZeros(value)]; // Paper - 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.
+    }
+    public static int getVarIntSize_(int value) {
+    //Paper end - Optimize VarInts
         for (int j = 1; j < 5; ++j) {
             if ((value & -1 << j * 7) == 0) {
                 return j;
@@ -613,6 +625,21 @@ public class FriendlyByteBuf extends ByteBuf {
     }
 
     public FriendlyByteBuf writeVarInt(int value) {
+    // Paper start - Optimize VarInts
+        // Peel the one and two byte count cases explicitly as they are the most common VarInt sizes
+        // that the proxy will write, to improve inlining.
+        if ((value & (0xFFFFFFFF << 7)) == 0) {
+            writeByte(value);
+        } else if ((value & (0xFFFFFFFF << 14)) == 0) {
+            int w = (value & 0x7F | 0x80) << 8 | (value >>> 7);
+            writeShort(w);
+        } else {
+            writeVarInt_(value);
+        }
+        return this;
+    }
+    public FriendlyByteBuf writeVarInt_(int value) {
+    // Paper end - Optimize VarInts
         while ((value & -128) != 0) {
             this.writeByte(value & 127 | 128);
             value >>>= 7;