Enum TxState

enum TxState {
    Idle,
    Preamble { packet: ToTransmit, left: uint<4> },
    Header { packet: ToTransmit, left: uint<5> },
    Payload { left: uint<11>, padding: uint<11> },
    Padding { left: uint<11> },
    FrameCheckSeq { left: uint<2> },
    InterpacketGap { left: uint<5> },
}