Not sure what you're trying to say. The point of what I wrote, and what the article says, is that `-n` is equivalent to `2^N - n`, and thus `-n % n` is equivalent to `(2^N - n) % n`.
If 2^N - n happens to be a number that's "full of 1s where there were zeros", then that's what it's supposed to be. I don't understand why you think it "won't compute the expected modulus". That's exactly what it will do.
If N is 32 and n is 5, then -n is 4294967291 and -n % n is 1. It doesn't matter whether that was calculated on a ones complement or twos complement machine.
