TFTP_STATE Enumeration

typedef enum {
  SM_TFTP_WAIT = 0,
  SM_TFTP_READY,
  SM_TFTP_WAIT_FOR_DATA,
  SM_TFTP_WAIT_FOR_ACK,
  SM_TFTP_DUPLICATE_ACK,
  SM_TFTP_SEND_ACK,
  SM_TFTP_SEND_LAST_ACK
} TFTP_STATE;

The TFTP state machine