byuu says:
Changelog:
- SMS: emulated the generic Sega memory mapper (none of the more
limited forms of it yet)
- (missing ROM shift, ROM write enable emulation -- no commercial
games use either, though)
- SMS: bus I/O returns 0xff instead of 0x00 so games don't think every
key is being pressed at once
- (this is a hack until I implement proper controller pad reading)
- SMS: very limited protection against reading/writing past the end of
ROM/RAM (todo: should mirror)
- SMS: VDP background HSCROLL subtracts, rather than adds, to the
offset (unlike VSCROLL)
- SMS: VDP VSCROLL is 9-bit, modulates voffset+vscroll to 224 in
192-line mode (32x28 tilemap)
- SMS: VDP tiledata for backgrounds and sprites use `7-(x&7)` rather
than `(x&7)`
- SMS: fix output color to be 6-bit rather than 5-bit
- SMS: left clip uses register `#7`, not palette color `#7`
- (todo: do we want `color[reg7]` or `color[16 + reg7]`?)
- SMS: refined handling of 0xcb, 0xed prefixes in the Z80 core and its
disassembler
- SMS: emulated (0xfd, 0xdd) 0xcb opcodes 0x00-0x0f (still missing
0x10-0xff)
- SMS: fixed 0xcb 0b-----110 opcodes to use direct HL and never allow
(IX,IY)+d
- SMS: fixed major logic bug in (IX,IY)+d displacement
- (was using `read(x)` instead of `operand()` for the displacement
byte fetch before)
- icarus: fake there always being 32KiB of RAM in all SMS cartridges
for the time being
- (not sure how to detect this stuff yet; although I've read it's
not even really possible `>_>`)
TODO: remove processor/z80/dissassembler.cpp code block at line 396 (as it's unnecessary.)
Lots of commercial games are starting to show trashed graphical output now.
byuu says:
Changelog:
- Makefile: added $(windres), -lpthread to Windows port
- GBA: WAITCNT.prefetch is not writable (should fix Donkey Kong: King
of Swing) \[endrift\]
- SMS: fixed hcounter shift value \[hex\_usr\]
- SMS: emulated interrupts (reset button isn't hooked up anywhere, not
sure where to put it yet)
This WIP actually took a really long time because the documentation on
SMS interrupts was all over the place. I'm hoping I've emulated them
correctly, but I honestly have no idea. It's based off my best
understanding from four or five different sources. So it's probably
quite buggy.
However, a few interrupts fire in Sonic the Hedgehog, so that's
something to start with. Now I just have to hope I've gotten some games
far enough in that I can start seeing some data in the VDP VRAM. I need
that before I can start emulating graphics mode 4 to get some actual
screen output.
Or I can just say to hell with it and use a "Hello World" test ROM.
That'd probably be smarter.
byuu says:
Changelog:
- SMS: extended bus mapping of in/out ports: now decoding them fully
inside ms/bus
- SMS: moved Z80 disassembly code from processor/z80 to ms/cpu
(cosmetic)
- SMS: hooked up non-functional silent PSG sample generation, so I can
cap the framerate at 60fps
- SMS: hooked up the VDP main loop: 684 clocks/scanline, 262
scanlines/frame (no PAL support yet)
- SMS: emulated the VDP Vcounter and Hcounter polling ... hopefully
it's right, as it's very bizarre
- SMS: emulated VDP in/out ports (data read, data write, status read,
control write, register write)
- SMS: decoding and caching all VDP register flags (variable names
will probably change)
- nall: \#undef IN on Windows port (prevent compilation warning on
processor/z80)
Watching Sonic the Hedgehog, I can definitely see some VDP register
writes going through, which is a good sign.
Probably the big thing that's needed before I can get enough into the
VDP to start showing graphics is interrupt support. And interrupts are
never fun to figure out :/
What really sucks on this front is I'm flying blind on the Z80 CPU core.
Without a working VDP, I can't run any Z80 test ROMs to look for CPU
bugs. And the CPU is certainly too buggy still to run said test ROM
anyway. I can't find any SMS emulators with trace logging from reset.
Such logs vastly accelerate tracking down CPU logic bugs, so without
them, it's going to take a lot longer.
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.
byuu says:
Changelog:
- 68K: MOVEQ is 8-bit signed
- 68K: disassembler was print EOR for OR instructions
- 68K: address/program-counter indexed mode had the signed-word/long
bit backward
- 68K: ADDQ/SUBQ #n,aN always works in long mode; regardless of size
- 68K→VDP DMA needs to use `mode.bit(0)<<22|dmaSource`; increment by
one instead of two
- Z80: added registers and initial two instructions
- MS: hooked up enough to load and start running games
- Sonic the Hedgehog can execute exactly one instruction... whoo.
Tim Allen