Why does an 8-bit field have endianness?

Question

See the definition of TCP header in /netinet/tcp.h:

struct tcphdr
  {
    u_int16_t th_sport;         /* source port */
    u_int16_t th_dport;         /* destin         


        

Answer 1

This is compiler-dependent and non-portable. How bit fields are ordered is implementation dependent, it would be far better here to use an 8-bit field and shift/mask to obtain the subfields.