combine multi byte fields into one field

datarequest.go

@@ -0,0 +1,78 @@
+package artnet
+
+import (
+	"encoding/binary"
+	"errors"
+	"slices"
+)
+
+type DataRequest uint16
+
+const (
+	DrPoll         = 0x0000
+	DrUrlProduct   = 0x0001
+	DrUrlUserGuide = 0x0002
+	DrUrlSupport   = 0x0003
+	DrUrlPersUdr   = 0x0004
+	DrUrlPersGdtf  = 0x0005
+)
+
+type ArtDataRequest struct {
+	ID        [8]uint8
+	OpCode    uint16
+	ProtVerHi uint8
+	ProtVerLo uint8
+	EstaMan   uint16
+	Oem       uint16
+	Request   uint16
+	spare     [22]byte
+}
+
+func (ap *ArtDataRequest) GetOpCode() uint16 {
+	return ap.OpCode
+}
+
+func (ap *ArtDataRequest) GetProtVer() uint16 {
+	return uint16(ap.ProtVerHi)<<8 + uint16(ap.ProtVerLo)
+}
+
+func (ap *ArtDataRequest) GetID() [8]uint8 {
+	return ap.ID
+}
+
+func (ap *ArtDataRequest) UnmarshalBinary(data []byte) error {
+
+	if len(data) < 40 {
+		return errors.New("ArtDataRequest packet must be at least 40 bytes long")
+	}
+
+	copy(ap.ID[:], data[0:8])
+
+	if !slices.Equal(ArtNetID[:], ap.ID[:]) {
+		return errors.New("ID does not match Art-Net ID")
+	}
+
+	ap.OpCode = binary.LittleEndian.Uint16(data[8:10])
+	ap.ProtVerHi = data[10]
+	ap.ProtVerLo = data[11]
+
+	offset := 12
+	ap.EstaMan = binary.LittleEndian.Uint16(data[offset : offset+2])
+	ap.Oem = binary.LittleEndian.Uint16(data[offset+2 : offset+4])
+	ap.Request = binary.LittleEndian.Uint16(data[offset+4 : offset+6])
+	copy(ap.spare[:], data[offset+6:offset+28])
+	return nil
+}
+
+func (ap *ArtDataRequest) MarshalBinary() ([]byte, error) {
+	data := make([]byte, 8+32)
+	copy(data[0:8], ap.ID[:])
+	binary.LittleEndian.PutUint16(data[8:10], ap.OpCode)
+	data[10] = ap.ProtVerHi
+	data[11] = ap.ProtVerLo
+	binary.LittleEndian.PutUint16(data[12:14], ap.EstaMan)
+	binary.LittleEndian.PutUint16(data[14:16], ap.Oem)
+	binary.LittleEndian.PutUint16(data[16:18], ap.Request)
+	copy(data[18:40], ap.spare[:])
+	return data, nil
+}