From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 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;