Skimming through this thread, all of the examples presented have used only the constants HIGH and LOW as the values being written using digitalWriteFast. This does correspond with the Reference documentation for digitalWrite as well as many of the example sketches but there are some examples (eg, BlinkWithoutDelay) and likely much existing code that use variables instead. In fact, digitalWrite currently maps any non-zero value into a write of '1'. I would like to see that behavior maintained. How will the new "fast" routines handle these cases?