You need to create this struct. The comments should guide you in making the need code. I am giving the last part of the code.

<'

struct packet_s {

//control the error creation

// the address field of the packet

// the length field of the packet


// the payload field of the packet
// it's size is controlled be the length field

// set the address to respond to address errors

// the parity field

// set the parity to respond to parity errors

// set a variable with the true parity value.

// compute the parity

// define the env unit
unit env_u {
// attach the clock of the due to an e event
event clock is rise('clock') @sim;
};

// create an instance of env under sys and set direct it
// to the verilog entity
extend sys {
env: env_u is instance;
keep env.hdl_path() == "top";
};

'>