You misunderstood. The CAS term isn't related to threads in aappleby's comment. aappleby is saying the following: He wrote a game engine, it renders transpare

You misunderstood. The CAS term isn't related to threads in aappleby's comment. aappleby is saying the following: He wrote a game engine, it renders transparent items using the painter's algorithm, which requires the items to be sorted in Z. He has a routine that iterates over all items to render them, and bubble-sorts the items in-place while iterating over the items (all in the same thread). The "compare and swap" in this case is the innermost functionality of bubblesort. I assume the author is https://github.com/aappleby https://github.com/aappleby but I don't see any obvious candidate for this code. Maybe this? https://github.com/aappleby/metroboy https://github.com/aappleby/metroboy but I can't see why a gate-level emulator woudl need to render transparent items using painter's algorithm.