better item ID saving in nbt

src/main/java/com/falsepattern/endlessids/mixin/mixins/common/blockitem/vanilla/ItemStackMixin.java

@@ -1,5 +1,7 @@
 package com.falsepattern.endlessids.mixin.mixins.common.blockitem.vanilla;
 
+import com.falsepattern.endlessids.constants.VanillaConstants;
+import com.falsepattern.endlessids.util.DataUtil;
 import org.spongepowered.asm.mixin.Mixin;
 import org.spongepowered.asm.mixin.Overwrite;
 import org.spongepowered.asm.mixin.Shadow;
@@ -29,7 +31,7 @@ public abstract class ItemStackMixin {
      */
     @Overwrite
     public NBTTagCompound writeToNBT(NBTTagCompound nbt) {
-        nbt.setInteger("id", Item.getIdFromItem(this.field_151002_e));
+        DataUtil.writeIDToNBT(nbt, Item.getIdFromItem(this.field_151002_e));
         nbt.setByte("Count", (byte) this.stackSize);
         nbt.setShort("Damage", (short) this.itemDamage);
 
@@ -46,7 +48,7 @@ public abstract class ItemStackMixin {
      */
     @Overwrite
     public void readFromNBT(NBTTagCompound nbt) {
-        func_150996_a(Item.getItemById(nbt.getInteger("id")));
+        func_150996_a(Item.getItemById(DataUtil.readIDFromNBT(nbt)));
         this.stackSize = nbt.getByte("Count");
         this.itemDamage = nbt.getShort("Damage");
 

src/main/java/com/falsepattern/endlessids/util/DataUtil.java

@@ -1,10 +1,17 @@
 package com.falsepattern.endlessids.util;
 
+import com.falsepattern.endlessids.constants.VanillaConstants;
+
+import net.minecraft.nbt.NBTTagCompound;
 import net.minecraft.world.chunk.NibbleArray;
 
+import net.minecraftforge.common.util.Constants;
+
 import java.util.Arrays;
 
 import static com.falsepattern.endlessids.constants.ExtendedConstants.blocksPerSubChunk;
+import static net.minecraftforge.common.util.Constants.NBT.TAG_INT;
+import static net.minecraftforge.common.util.Constants.NBT.TAG_SHORT;
 
 public class DataUtil {
     public static byte[] ensureSubChunkByteArray(byte[] arr) {
@@ -14,4 +21,28 @@ public class DataUtil {
     public static NibbleArray ensureSubChunkNibbleArray(byte[] data) {
         return data == null ? null : new NibbleArray(data.length == (blocksPerSubChunk >>> 1) ? data : Arrays.copyOf(data, (blocksPerSubChunk >>> 1)), 4);
     }
+
+    public static int readIDFromNBT(NBTTagCompound nbt) {
+        if (nbt.hasKey("idExt", TAG_INT))
+            return nbt.getInteger("idExt");
+        else if (nbt.hasKey("id", TAG_INT))
+            return nbt.getInteger("id");
+        else if (nbt.hasKey("id", TAG_SHORT))
+            return nbt.getShort("id");
+        else
+            return 0;
+    }
+
+    public static void writeIDToNBT(NBTTagCompound nbt, int id) {
+        if (id > VanillaConstants.maxItemID) {
+            nbt.setShort("id", (short)0);
+            nbt.setInteger("idExt", id);
+        } else {
+            nbt.setShort("id", (short) id);
+        }
+    }
+
+    public static boolean nbtHasID(NBTTagCompound nbt) {
+        return nbt.hasKey("id", TAG_INT) || nbt.hasKey("idExt", TAG_INT) || nbt.hasKey("id", TAG_SHORT);
+    }
 }