Oh right so this is for the case where you say "I have given you an exactly known length of data to buzz round a million times, you don't needs to bounds check

Oh right so this is for the case where you say "I have given you an exactly known length of data to buzz round a million times, you don't needs to bounds check every time"? Like, I have a hardcoded 1024-byte buffer, my loop is hardcoded so its index increases modulo 1024, it can never run off the end any more than you can overtake your own bike chain?