Shiroha/shiroha-server/minecraft-patches/features/0084-Some-optimizations-from-krypton.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: MrHua269 <mrhua269@gmail.com>
Date: Fri, 1 May 2026 21:51:11 +0800
Subject: [PATCH] Some optimizations from krypton

A part of krypton's mixin:

https://github.com/astei/krypton/blob/master/src/main/java/me/steinborn/krypton/mixin/shared/network/microopt/StringEncodingMixin.java and https://github.com/astei/krypton/blob/master/src/main/java/me/steinborn/krypton/mixin/shared/network/microopt/VarIntsMixin.java

Original project license: https://github.com/astei/krypton/blob/master/LICENSE

diff --git a/net/minecraft/network/Utf8String.java b/net/minecraft/network/Utf8String.java
index 8b778744a5f01943976f180ad340a1cbce7db506..56616d2b00535d691867462af09ea2dd09570159 100644
--- a/net/minecraft/network/Utf8String.java
+++ b/net/minecraft/network/Utf8String.java
@@ -33,6 +33,22 @@ public class Utf8String {
     }
 
     public static void write(final ByteBuf output, final CharSequence value, final int maxLength) {
+        // Shiroha start - Krypton optimizations
+        if (true) {
+            if (value.length() > maxLength) {
+                throw new EncoderException("String too big (was " + value.length() + " characters, max " + maxLength + ")");
+            }
+            int utf8Bytes = ByteBufUtil.utf8Bytes(value);
+            int maxBytesPermitted = ByteBufUtil.utf8MaxBytes(maxLength);
+            if (utf8Bytes > maxBytesPermitted) {
+                throw new EncoderException("String too big (was " + utf8Bytes + " bytes encoded, max " + maxBytesPermitted + ")");
+            } else {
+                VarInt.write(output, utf8Bytes);
+                output.writeCharSequence(value, StandardCharsets.UTF_8);
+            }
+            return;
+        }
+        // Shiroha end
         if (value.length() > maxLength) {
             throw new EncoderException("String too big (was " + value.length() + " characters, max " + maxLength + ")");
         }
diff --git a/net/minecraft/network/VarInt.java b/net/minecraft/network/VarInt.java
index 1428ce80e8316a24cfca7b6aafdea8588a5a790e..c62371f85c8da7e2b5c7036cf40fb11b50de4685 100644
--- a/net/minecraft/network/VarInt.java
+++ b/net/minecraft/network/VarInt.java
@@ -60,7 +60,8 @@ public class VarInt {
             int s = (value & 0x7F | 0x80) << 8 | (value >>> 7);
             output.writeShort(s);
         } else {
-            writeSlow(output, value);
+            // writeSlow(output, value); // Shiroha - Krypton optimizations
+            writeVarIntFull(output, value); // Shiroha - Krypton optimizations
         }
         return output;
     }
@@ -74,4 +75,27 @@ public class VarInt {
         output.writeByte(value);
         return output;
     }
+    // Shiroha start - Krypton optimizations
+    private static void writeVarIntFull(ByteBuf buf, int value) {
+        // See https://steinborn.me/posts/performance/how-fast-can-you-write-a-varint/
+        if ((value & (0xFFFFFFFF << 7)) == 0) {
+            buf.writeByte(value);
+        } else if ((value & (0xFFFFFFFF << 14)) == 0) {
+            int w = (value & 0x7F | 0x80) << 8 | (value >>> 7);
+            buf.writeShort(w);
+        } else if ((value & (0xFFFFFFFF << 21)) == 0) {
+            int w = (value & 0x7F | 0x80) << 16 | ((value >>> 7) & 0x7F | 0x80) << 8 | (value >>> 14);
+            buf.writeMedium(w);
+        } else if ((value & (0xFFFFFFFF << 28)) == 0) {
+            int w = (value & 0x7F | 0x80) << 24 | (((value >>> 7) & 0x7F | 0x80) << 16)
+                    | ((value >>> 14) & 0x7F | 0x80) << 8 | (value >>> 21);
+            buf.writeInt(w);
+        } else {
+            int w = (value & 0x7F | 0x80) << 24 | ((value >>> 7) & 0x7F | 0x80) << 16
+                    | ((value >>> 14) & 0x7F | 0x80) << 8 | ((value >>> 21) & 0x7F | 0x80);
+            buf.writeInt(w);
+            buf.writeByte(value >>> 28);
+        }
+    }
+    // Shiroha end
 }