In reply to son la:
Change your struct to
typedef struct {logic [0:21] single_packet; logic [3:0] header_code; logic [3:0] data_code ; } packet_s;
In reply to son la:
Change your struct to
typedef struct {logic [0:21] single_packet; logic [3:0] header_code; logic [3:0] data_code ; } packet_s;