[Prcmaker]

100% great suggestion. I found this solution the hard way, by hand, on paper, a few weeks before learning this algorithm already existed. Reminded me that a large percentage of efficient engineering is just knowing what tools you have available off the shelf.

The algorithm I figured out was mostly equivalent, though about 3x slower than implementing Goertzel. In my use case, it was already a win hitting the product requirements, but implementing Goertzel allowed background functionality to operate better while capturing data.