func checkSum(msg []byte) uint16 {
	sum := 0
	for n := 1; n < len(msg)-1; n += 2 {
		sum += int(msg[n])*256 + int(msg[n+1])
	}
	sum = (sum >> 16) + (sum & 0xffff)
	sum += (sum >> 16)
	var answer uint16 = uint16(^sum)
	return answer
}

func checkSum(data []byte) uint16 {
	var (
		sum    uint32
		length = len(data)
		index  int
	)
	for length > 1 {
		sum += uint32(data[index])<<8 + uint32(data[index+1])
		index += 2
		length -= 2
	}
	if length > 0 {
		sum += uint32(data[index])
	}
	sum += sum >> 16
	return uint16(^sum)
}

func (m *MusicManager) Find(name string) *MusicEntry {
    if len(m.musics) == 0 {
        return nil
    }

    for _, m := range m.musics {
        if m.Name == name {
            return &m
        }
    }
    return nil
}