remove constants from packet structs

timecode.go

@@ -7,29 +7,17 @@ import (
 )
 
 type ArtTimeCode struct {
-	ID        [8]uint8
-	OpCode    uint16
-	ProtVerHi uint8
-	ProtVerLo uint8
-	Filler1   uint8
-	StreamId  uint8
-	Frames    uint8
-	Seconds   uint8
-	Minutes   uint8
-	Hours     uint8
-	Type      uint8
+	filler1  uint8
+	StreamId uint8
+	Frames   uint8
+	Seconds  uint8
+	Minutes  uint8
+	Hours    uint8
+	Type     uint8
 }
 
 func (atc *ArtTimeCode) GetOpCode() uint16 {
-	return atc.OpCode
-}
-
-func (atc *ArtTimeCode) GetProtVer() uint16 {
-	return uint16(atc.ProtVerHi)<<8 + uint16(atc.ProtVerLo)
-}
-
-func (atc *ArtTimeCode) GetID() [8]uint8 {
-	return atc.ID
+	return OpTimeCode
 }
 
 func (atc *ArtTimeCode) UnmarshalBinary(data []byte) error {
@@ -37,18 +25,17 @@ func (atc *ArtTimeCode) UnmarshalBinary(data []byte) error {
 		return errors.New("ArtTimeCode packet must be at least 14 bytes long")
 	}
 
-	copy(atc.ID[:], data[0:8])
-
-	if !slices.Equal(ArtNetID[:], atc.ID[:]) {
+	if !slices.Equal(ArtNetID[:], data[0:8]) {
 		return errors.New("ID does not match Art-Net ID")
 	}
 
-	atc.OpCode = binary.LittleEndian.Uint16(data[8:10])
-	atc.ProtVerHi = data[10]
-	atc.ProtVerLo = data[11]
+	opCode := binary.LittleEndian.Uint16(data[8:10])
+	if opCode != OpTimeCode {
+		return errors.New("packet does not have the correct OpCode for an ArtTimeCode packet")
+	}
 
 	offset := 12
-	atc.Filler1 = data[offset]
+	atc.filler1 = data[offset]
 	atc.StreamId = data[offset+1]
 	atc.Frames = data[offset+2]
 	atc.Seconds = data[offset+3]
@@ -60,12 +47,12 @@ func (atc *ArtTimeCode) UnmarshalBinary(data []byte) error {
 
 func (atc *ArtTimeCode) MarshalBinary() ([]byte, error) {
 	data := make([]byte, 8+11)
-	copy(data[0:8], atc.ID[:])
-	binary.LittleEndian.PutUint16(data[8:10], atc.OpCode)
-	data[10] = atc.ProtVerHi
-	data[11] = atc.ProtVerLo
+	copy(data[0:8], ArtNetID[:])
+	binary.LittleEndian.PutUint16(data[8:10], OpTimeCode)
+	data[10] = 0
+	data[11] = 14
 	offset := 12
-	data[offset] = atc.Filler1
+	data[offset] = atc.filler1
 	data[offset+1] = atc.StreamId
 	data[offset+2] = atc.Frames
 	data[offset+3] = atc.Seconds