byuu says:
Changelog:
- removed Emulator::Interface::Capabilities¹
- MS: improved the PSG emulation a bit
- MS: added cheat code support
- MS: added save state support²
- MD: emulated the PSG³
¹: there's really no point to it anymore. I intend to add cheat codes
to the GBA core, as well as both cheat codes and save states to the Mega
Drive core. I no longer intend to emulate any new systems, so these
values will always be true. Further, the GUI doesn't respond to these
values to disable those features anymore ever since the hiro rewrite, so
they're double useless.
²: right now, the Z80 core is using a pointer for HL-\>(IX,IY)
overrides. But I can't reliably serialize pointers, so I need to convert
the Z80 core to use an integer here. The save states still appear to
work fine, but there's the potential for an instruction to execute
incorrectly if you're incredibly unlucky, so this needs to be fixed as
soon as possible. Further, I still need a way to serialize
array<T, Size> objects, and I should also add nall::Boolean
serialization support.
³: I don't have a system in place to share identical sound chips. But
this chip is so incredibly simple that it's not really much trouble to
duplicate it. Further, I can strip out the stereo sound support code
from the Game Gear portion, so it's even tinier.
Note that the Mega Drive only just barely uses the PSG. Not at all in
Altered Beast, and only for a tiny part of the BGM music on Sonic 1,
plus his jump sound effect.
byuu says:
Changelog:
- rewrote the Z80 core to properly handle 0xDD (IX0 and 0xFD (IY)
prefixes
- added Processor::Z80::Bus as a new type of abstraction
- all of the instructions implemented have their proper T-cycle counts
now
- added nall/certificates for my public keys
The goal of `Processor::Z80::Bus` is to simulate the opcode fetches being
2-read + 2-wait states; operand+regular reads/writes being 3-read. For
now, this puts the cycle counts inside the CPU core. At the moment, I
can't think of any CPU core where this wouldn't be appropriate. But it's
certainly possible that such a case exists. So this may not be the
perfect solution.
The reason for having it be a subclass of Processor::Z80 instead of
virtual functions for the MasterSystem::CPU core to define is due to
naming conflicts. I wanted the core to say `in(addr)` and have it take
the four clocks. But I also wanted a version of the function that didn't
consume time when called. One way to do that would be for the core to
call `Z80::in(addr)`, which then calls the regular `in(addr)` that goes to
`MasterSystem::CPU::in(addr)`. But I don't want to put the `Z80::`
prefix on all of the opcodes. Very easy to forget it, and then end up not
consuming any time. Another is to use uglier names in the
`MasterSystem::CPU` core, like `read_`, `write_`, `in_`, `out_`, etc. But,
yuck.
So ... yeah, this is an experiment. We'll see how it goes.
byuu says:
Changelog:
- MS: added ms/bus
- Z80: implemented JP/JR/CP/DI/IM/IN instructions
- MD/VDP: added window layer emulation
- MD/controller/gamepad: fixed d2,d3 bits (Altered Beast requires
this)
The Z80 is definitely a lot nastier than the LR35902. There's a lot of
table duplication with HL→IX→IY; and two of them nest two levels deep
(eg FD CB xx xx), so the design may change as I implement more.
Tim Allen