remove constants from packet structs

sync.go

@@ -7,24 +7,12 @@ import (
 )
 
 type ArtSync struct {
-	ID        [8]uint8
-	OpCode    uint16
-	ProtVerHi uint8
-	ProtVerLo uint8
-	Aux1      uint8
-	Aux2      uint8
+	Aux1 uint8
+	Aux2 uint8
 }
 
 func (as *ArtSync) GetOpCode() uint16 {
-	return as.OpCode
-}
-
-func (as *ArtSync) GetProtVer() uint16 {
-	return uint16(as.ProtVerHi)<<8 + uint16(as.ProtVerLo)
-}
-
-func (as *ArtSync) GetID() [8]uint8 {
-	return as.ID
+	return OpSync
 }
 
 func (as *ArtSync) UnmarshalBinary(data []byte) error {
@@ -33,15 +21,14 @@ func (as *ArtSync) UnmarshalBinary(data []byte) error {
 		return errors.New("ArtSync packet must be at least 14 bytes long")
 	}
 
-	copy(as.ID[:], data[0:8])
-
-	if !slices.Equal(ArtNetID[:], as.ID[:]) {
+	if !slices.Equal(ArtNetID[:], data[0:8]) {
 		return errors.New("ID does not match Art-Net ID")
 	}
 
-	as.OpCode = binary.LittleEndian.Uint16(data[8:10])
-	as.ProtVerHi = data[10]
-	as.ProtVerLo = data[11]
+	opCode := binary.LittleEndian.Uint16(data[8:10])
+	if opCode != OpSync {
+		return errors.New("packet does not have the correct OpCode for an ArtSync packet")
+	}
 
 	offset := 12
 	as.Aux1 = data[offset]
@@ -51,10 +38,10 @@ func (as *ArtSync) UnmarshalBinary(data []byte) error {
 
 func (as *ArtSync) MarshalBinary() ([]byte, error) {
 	data := make([]byte, 8+6)
-	copy(data[0:8], as.ID[:])
-	binary.LittleEndian.PutUint16(data[8:10], as.OpCode)
-	data[10] = as.ProtVerHi
-	data[11] = as.ProtVerLo
+	copy(data[0:8], ArtNetID[:])
+	binary.LittleEndian.PutUint16(data[8:10], OpSync)
+	data[10] = 0
+	data[11] = 14
 	data[12] = as.Aux1
 	data[13] = as.Aux2
 	return data, nil