From 1ee452ff5f39a8c70b91fae4c1b7b9fdc9961250 Mon Sep 17 00:00:00 2001
From: Tnze <cjd001113@outlook.com>
Date: Thu, 19 May 2022 16:28:04 +0800
Subject: [PATCH] nbt supports encode int8 as TagByte and []int8 as
 TagByteArray

---
 nbt/encode.go      | 17 ++++++++++++++---
 nbt/encode_test.go | 14 ++++++++++++++
 2 files changed, 28 insertions(+), 3 deletions(-)

diff --git a/nbt/encode.go b/nbt/encode.go
index c230335..18e65a7 100644
--- a/nbt/encode.go
+++ b/nbt/encode.go
@@ -10,6 +10,7 @@ import (
 	"reflect"
 	"strconv"
 	"strings"
+	"unsafe"
 )
 
 // Marshal is the shortcut of NewEncoder().Encode() with empty tag name.
@@ -62,7 +63,13 @@ func (e *Encoder) writeValue(val reflect.Value, tagType byte) error {
 	default:
 		return errors.New("unsupported type 0x" + strconv.FormatUint(uint64(tagType), 16))
 	case TagByte:
-		_, err := e.w.Write([]byte{byte(val.Uint())})
+		var err error
+		switch val.Kind() {
+		case reflect.Int8:
+			_, err = e.w.Write([]byte{byte(val.Int())})
+		case reflect.Uint8:
+			_, err = e.w.Write([]byte{byte(val.Uint())})
+		}
 		return err
 	case TagShort:
 		return e.writeInt16(int16(val.Int()))
@@ -81,7 +88,11 @@ func (e *Encoder) writeValue(val reflect.Value, tagType byte) error {
 		}
 
 		if tagType == TagByteArray {
-			_, err := e.w.Write(val.Bytes())
+			_, err := e.w.Write(*(*[]byte)((unsafe.Pointer)(&reflect.SliceHeader{
+				Data: val.Pointer(),
+				Len:  val.Len(),
+				Cap:  val.Cap(),
+			})))
 			return err
 		} else {
 			for i := 0; i < n; i++ {
@@ -264,7 +275,7 @@ func getTagType(v reflect.Value) (byte, reflect.Value) {
 
 func getTagTypeByType(vk reflect.Type) byte {
 	switch vk.Kind() {
-	case reflect.Uint8:
+	case reflect.Int8, reflect.Uint8:
 		return TagByte
 	case reflect.Int16, reflect.Uint16:
 		return TagShort
diff --git a/nbt/encode_test.go b/nbt/encode_test.go
index fd488b8..96d882e 100644
--- a/nbt/encode_test.go
+++ b/nbt/encode_test.go
@@ -41,6 +41,20 @@ func TestEncoder_Encode_intArray(t *testing.T) {
 	}
 }
 
+func TestENcoder_encodeInt8(t *testing.T) {
+	// Test marshal pure Int array
+	v := []int8{0, -10, 3}
+	out := []byte{
+		TagByteArray, 0x00, 0x00, 0, 0, 0, 3,
+		0x00, 0xf6, 0x03,
+	}
+	if data, err := Marshal(v); err != nil {
+		t.Error(err)
+	} else if !bytes.Equal(data, out) {
+		t.Errorf("output binary not right: get % 02x, want % 02x ", data, out)
+	}
+}
+
 func TestEncoder_Encode_floatArray(t *testing.T) {
 	// Test marshal pure Int array
 	v := []float32{0.3, -100, float32(math.NaN())}