swap -
;
+: invert-region-cs ( addr len cellsize -- )
+ >r over swap r@ rshift r> swap 1 hv-logical-memop drop
+;
+
+: invert-region ( addr len -- )
+ 2dup or 7 and CASE
+ 0 OF 3 invert-region-cs ENDOF
+ 4 OF 2 invert-region-cs ENDOF
+ 3 and
+ 2 OF 1 invert-region-cs ENDOF
+ dup OF 0 invert-region-cs ENDOF
+ ENDCASE
+;