From 1a22263c03142869d6923ed13b6233c2bd30e77c Mon Sep 17 00:00:00 2001
From: deathcap <deathcap@gmx.co.uk>
Date: Sun, 14 Feb 2016 22:21:29 -0800
Subject: [PATCH] Add optionalLengthPrefixedNbt data type, used in MC 1.7

---
 src/datatypes/minecraft.js | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/src/datatypes/minecraft.js b/src/datatypes/minecraft.js
index 6add0d2..6c2236e 100644
--- a/src/datatypes/minecraft.js
+++ b/src/datatypes/minecraft.js
@@ -5,6 +5,7 @@ module.exports = {
   'UUID': [readUUID, writeUUID, 16],
   'nbt': [readNbt, writeNbt, sizeOfNbt],
   'optionalNbt':[readOptionalNbt,writeOptionalNbt,sizeOfOptionalNbt],
+  'optionalLengthPrefixedNbt':[readOptionalLengthPrefixedNbt,writeOptionalLengthPrefixedNbt,sizeOfOptionalLengthPrefixedNbt],
   'restBuffer': [readRestBuffer, writeRestBuffer, sizeOfRestBuffer],
   'entityMetadataLoop': [readEntityMetadata, writeEntityMetadata, sizeOfEntityMetadata]
 };
@@ -54,6 +55,29 @@ function sizeOfOptionalNbt(value) {
   return nbt.proto.sizeOf(value,"nbt");
 }
 
+// Length-prefixed optional NBT, short instead of null byte: http://wiki.vg/index.php?title=Slot_Data&diff=6056&oldid=4753
+function readOptionalLengthPrefixedNbt(buffer, offset) {
+  if(buffer.readInt16BE(offset) == -1) return {size:2};
+  return nbt.proto.read(buffer,offset,"nbt");
+}
+
+function writeOptionalLengthPrefixedNbt(value, buffer, offset) {
+  if(value==undefined) {
+    buffer.writeInt16BE(-1,offset);
+    return offset+2;
+  }
+  buffer.writeInt16(sizeOfNbt(value),offset);
+  return nbt.proto.write(value,buffer,offset+2,"nbt");
+}
+
+function sizeOfOptionalLengthPrefixedNbt(value) {
+  if(value==undefined)
+    return 2;
+  return 2+nbt.proto.sizeOf(value,"nbt");
+}
+
+
+
 function readRestBuffer(buffer, offset) {
   return {
     value: buffer.slice(offset),