First taste of how sprites are managed in this game. Expressing the
current and previous position in terms of the VRAM page is kind of
quirky, but not as bad as expected.
What *is* bad, however, is that the most natural next function is
undecompilable thanks to an inconsistent `LEAVE` instruction in its
epilog 🙄 And `codegen.hpp` has almost none of the instructions we
would need to hide the SI and DI registers from the compiler, and I'm
*really* not in the mood for another such mess anyway. I'd really like
to try patching these mistakes in a separate build step instead, but
unfortunately I'm out of research money as well. So let's go for
something else next.
Part of P0237, funded by Yanga.
nmlgc