does a modulo-13 mean from 0 to 12 or from 0 to 13?
so if 0-12, the state diagram would be 0000-->0001-->0010-->0011-->......-->1100-->0000, am i correct?

 

so if 0-12, the state diagram would be 0000-->0001-->0010-->0011-->......-->1100-->0000, am i correct?

Yes.