[COFF] [TUHS] Maximum Array Sizes in 16 bit C

[Dan Cross]

On Fri, Sep 20, 2024 at 8:22 PM Douglas McIlroy
<douglas.mcilroy at dartmouth.edu> wrote:
> Moved to Coff, because it's about programming style, not history.

Heh, I had deliberately removed the list in my response to you, but
it's not too embarrassing to have this redirected back to COFF. :-)

> > Perhaps I'm missing something? Clever arithmetic in the index
> > calculation aside, this is semantically different than using an actual
> > negative integer to index into an array? Moreover, if the intent is to
> > start the sequence with 0, why set `fib(0)` to 1? How is this
> > substantially different from the usual way of writing this:
>
> I said the Fibonacci example was silly. Maybe you'll be more convinced by the binomial-coefficient program below.
> [snip]

The caveat sent later notwithstanding, I agree that I was overly
fixated on the Fibonacci example in my response and this better
illustrates the motivation for the technique.

Regardless, I feel like we're somewhat speaking at cross-purposes. In
particular, this uses macros to introduce a more pleasant syntax, but
at the language level, the index into the underlying array is always
non-negative and within the array's defined bounds. This is
qualitatively and quantitatively different from using an actual
negative value in the actual indexing operation.

        - Dan C.