Re: Modular type. What is it and why?

[Marin David Condic <condicma@bogon.pwfl.com>]

Mike Silva wrote:
> Now with Ada I'll be able to write (assuming 'index' is the appropriate
> modular type):
> 
> case ( key ) is
>    when ARROW_DOWN =>
>       index := index + 1;
>    when ARROW_UP =>
>       index := index - 1;
> end case;
> 
> Now -that's- what I call progress!
> 

My C is pretty rusty - not having done anything serious in it in at
least 10 years - but wasn't there some kind of type/operation that
allowed for wraparound semantics? I know one of the major early bitches
about Ada(83) was that it didn't allow for unsigned integers, logical
ops on integers & wraparound math - all things considered critical for
embedded programming. (At least at that point in time) If C doesn't
support some or all of these things, then how could it be so "popular"
with the embedded crowd?

I remember enough C to recall that you did have logical operations on
integers and shift/rotate operations on integers as well. Maybe (if my
Parts-heimers would clear up a little so I could remember) the
wraparound semantics were always implemented using logical ops? Not
nearly as pretty as The Ada Way, but it would get you there...

MDC
-- 
Marin David Condic
Real Time & Embedded Systems, Propulsion Systems Analysis
United Technologies, Pratt & Whitney, Large Military Engines
M/S 731-95, P.O.B. 109600, West Palm Beach, FL, 33410-9600
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