Re: Decrement And Branch

On Tue, 13 Aug 2024 09:00:25 -0000 (UTC), I wrote:

However, the good old VAX (in
its usual kitchen-sink fashion) had a whole set of variations, including
one that decremented down to -1 instead of zero. And the Motorola 68000
family only had the decrement down to -1 version.

VAX example of how to use SOBGEQ instead of SOBGTR:

        movl    «loop count», Rn
        br      bottom_of_loop
top_of_loop:
        .... body of loop ...
bottom_of_loop:
        sobgeq  Rn, top_of_loop

Like I said, I wondered why this sort of thing wasn’t more common ...