retroforth/library/c-get-ext.retro

~~~
:keys:UP    (:-n) #-300 ;
:keys:DOWN  (:-n) #-301 ;
:keys:RIGHT (:-n) #-302 ;
:keys:LEFT  (:-n) #-303 ;

:c:get/ext (:-c)
  c:get dup #27 eq?
  [ drop c:get drop c:get #235 + n:negate ] if ;
~~~