These should all produce:
x StL x StL
-----------
c=x(StL), d=x(StL), b=0, nctl=0, pctl=x
c=x(StL), d=x(StL), b=0, nctl=x, pctl=x
c=x(StH), d=x(StH), b=1, nctl=x, pctl=x