PaperMC/patches/server/0901-Optimize-VarInts.patch

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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
2023-10-29 01:58:15 +02:00
From: astei <andrew@steinborn.me>
Date: Sat, 28 Oct 2023 19:46:21 -0400
Subject: [PATCH] Optimize VarInts
https://github.com/PaperMC/Paper/pull/6957#issuecomment-985250854
diff --git a/src/main/java/net/minecraft/network/VarInt.java b/src/main/java/net/minecraft/network/VarInt.java
index 49a8ddc269d53458cfbd639b7de838c2e5765748..74ed47659d3e615c2dae7da98d5a8cf1559625bf 100644
--- a/src/main/java/net/minecraft/network/VarInt.java
+++ b/src/main/java/net/minecraft/network/VarInt.java
@@ -9,6 +9,18 @@ public class VarInt {
private static final int DATA_BITS_PER_BYTE = 7;
public static int getByteSize(int i) {
+ // Paper start - Optimize VarInts
+ return VARINT_EXACT_BYTE_LENGTHS[Integer.numberOfLeadingZeros(i)];
+ }
+ 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 getByteSizeOld(int i) {
+ // Paper end - Optimize VarInts
for (int j = 1; j < 5; j++) {
if ((i & -1 << j * 7) == 0) {
return j;
@@ -39,6 +51,21 @@ public class VarInt {
}
public static ByteBuf write(ByteBuf buf, int i) {
+ // 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 ((i & (0xFFFFFFFF << 7)) == 0) {
+ buf.writeByte(i);
+ } else if ((i & (0xFFFFFFFF << 14)) == 0) {
+ int w = (i & 0x7F | 0x80) << 8 | (i >>> 7);
+ buf.writeShort(w);
+ } else {
+ writeOld(buf, i);
+ }
+ return buf;
+ }
+ public static ByteBuf writeOld(ByteBuf buf, int i) {
+ // Paper end - Optimize VarInts
while ((i & -128) != 0) {
buf.writeByte(i & 127 | 128);
i >>>= 7;