I'm trying to extract the memory/bus interface, and pass it in at
the start of each cycle instead of having the BusPort permanently
embedded, which will allow migrating to emulator-hal.
The functional way would be argument drilling; passing an extra argument
to each function in the entire execution core. The problem is that it's
messy, so a solution that is still functional is to implement all of the
execution logic on a newtype that contains a reference to the mutable
state and the owned cycle data, and at the end of the cycle, decompose
the M68kCycleGuard that holds the reference, and keep the cycle data for
debugging purposes.
The debug loop that reads a command and does something is part of the
frontend's main loop, so that it can potentially update, even though
it doesn't actually work for minifb because the command input is a
blocking call. It's also not implemented in the pixels frontend.
At some point I'll make a web frontend.
Now it's up to 99% tests passing, 15362 are still failing, but many
of those are the unimplemented IN/OUT instructions, which the Genesis
doesn't seem to use
Special thanks to raddad772 https://github.com/raddad772
Also added some fixes to the Z80 for panicking math operations, but
it still won't complete due to an unimplemented instruction
I wanted to make this a bit more modular, so it's easier in theory to
write external crates that can reuse bits, and selectively compile in
bits, such as adding new systems or new cpu implementations
