mirror of https://github.com/bsnes-emu/bsnes.git
7 Commits
| Author | SHA1 | Message | Date |
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Tim Allen
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04072b278b |
Update to v102r16 release.
byuu says:
Changelog:
- Emulator::Stream now allows adding low-pass and high-pass filters
dynamically
- also accepts a pass# count; each pass is a second-order biquad
butterworth IIR filter
- Emulator::Stream no longer automatically filters out >20KHz
frequencies for all streams
- FC: added 20Hz high-pass filter; 20KHz low-pass filter
- GB: removed simple 'magic constant' high-pass filter of unknown
cutoff frequency (missed this one in the last WIP)
- GB,SGB,GBC: added 20Hz high-pass filter; 20KHz low-pass filter
- MS,GG,MD/PSG: added 20Hz high-pass filter; 20KHz low-pass filter
- MD: added save state support (but it's completely broken for now;
sorry)
- MD/YM2612: fixed Voice#3 per-operator pitch support (fixes sound
effects in Streets of Rage, etc)
- PCE: added 20Hz high-pass filter; 20KHz low-pass filter
- WS,WSC: added 20Hz high-pass filter; 20KHz low-pass filter
So, the point of the low-pass filters is to remove frequencies above
human hearing. If we don't do this, then resampling will introduce
aliasing that results in sounds that are audible to the human ear. Which
basically an annoying buzzing sound. You'll definitely hear the
improvement from these in games like Mega Man 2 on the NES. Of course,
these already existed before, so this WIP won't sound better than
previous WIPs.
The high-pass filters are a little more complicated. Their main role is
to remove DC bias and help to center the audio stream. I don't
understand how they do this at all, but ... that's what everyone who
knows what they're talking about says, thus ... so be it.
I have set all of the high-pass filters to 20Hz, which is below the
limit of human hearing. Now this is where it gets really interesting ...
technically, some of these systems actually cut off a lot of range. For
instance, the GBA should technically use an 800Hz high-pass filter when
output is done through the system's speakers. But of course, if you plug
in headphones, you can hear the lower frequencies.
Now 800Hz ... you definitely can hear. At that level, nearly all of the
bass is stripped out and the audio is very tinny. Just like the real
system. But for now, I don't want to emulate the audio being crushed
that badly.
I'm sticking with 20Hz everywhere since it won't negatively affect audio
quality. In fact, you should not be able to hear any difference between
this WIP and the previous WIP. But theoretically, DC bias should mostly
be removed as a result of these new filters. It may be that we need to
raise the values on some cores in the future, but I don't want to do
that until we know for certain that we have to.
What I can say is that compared to even older WIPs than r15 ... the
removal of the simple one-pole low-pass and high-pass filters with the
newer three-pass, second-order filters should result in much better
attenuation (less distortion of audible frequencies.) Probably not
enough to be noticeable in a blind test, though.
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Tim Allen
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4c3f9b93e7 |
Update to v102r12 release.
byuu says:
Changelog:
- MD/PSG: fixed 68K bus Z80 status read address location
- MS, GG, MD/PSG: channels post-decrement their counters, not
pre-decrement [Cydrak]¹
- MD/VDP: cache screen width registers once per scanline; screen
height registers once per frame
- MD/VDP: support 256-width display mode (used in Shining Force, etc)
- MD/YM2612: implemented timers²
- MD/YM2612: implemented 8-bit PCM DAC²
- 68000: TRAP instruction should index the vector location by 32 (eg
by 128 bytes), fixes Shining Force
- nall: updated hex(), octal(), binary() functions to take uintmax
instead of template<typename T> parameter³
¹: this one makes an incredible difference. Sie noticed that lots of
games set a period of 0, which would end up being a really long period
with pre-decrement. By fixing this, noise shows up in many more games,
and sounds way better in games even where it did before. You can hear
extra sound on Lunar - Sanposuru Gakuen's title screen, the noise in
Sonic The Hedgehog (Mega Drive) sounds better, etc.
²: this also really helps sound. The timers allow PSG music to play
back at the correct speed instead of playing back way too quickly. And
the PCM DAC lets you hear a lot of drum effects, as well as the
"Sega!!" sound at the start of Sonic the Hedgehog, and the infamous,
"Rise from your grave!" line from Altered Beast.
Still, most music on the Mega Drive comes from the FM channels, so
there's still not a whole lot to listen to.
I didn't implement Cydrak's $02c test register just yet. Sie wasn't 100%
certain on how the extended DAC bit worked, so I'd like to play it a
little conservative and get sound working, then I'll go back and add a
toggle or something to enable undocumented registers, that way we can
use that to detect any potential problems they might be causing.
³: unfortunately we lose support for using hex() on nall/arithmetic
types. If I have a const Pair& version of the function, then the
compiler gets confused on whether Natural<32> should use uintmax or
const Pair&, because compilers are stupid, and you can't have explicit
arguments in overloaded functions. So even though either function would
work, it just decides to error out instead >_>
This is actually really annoying, because I want hex() to be useful for
printing out nall/crypto keys and hashes directly.
But ... this change had to be made. Negative signed integers would crash
programs, and that was taking out my 68000 disassembler.
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Tim Allen
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d76c0c7e82 |
Update to v102r08 release.
byuu says:
Changelog:
- PCE: restructured VCE, VDCs to run one scanline at a time
- PCE: bound VDCs to 1365x262 timing (in order to decouple the VDCs
from the VCE)
- PCE: the two changes above allow save states to function; also
grants a minor speed boost
- PCE: added cheat code support (uses 21-bit bus addressing; compare
byte will be useful here)
- 68K: fixed `mov *,ccr` to read two bytes instead of one [Cydrak]
- Z80: emulated /BUSREQ, /BUSACK; allows 68K to suspend the Z80
[Cydrak]
- MD: emulated the Z80 executing instructions [Cydrak]
- MD: emulated Z80 interrupts (triggered during each Vblank period)
[Cydrak]
- MD: emulated Z80 memory map [Cydrak]
- MD: added stubs for PSG, YM2612 accesses [Cydrak]
- MD: improved bus emulation [Cydrak]
The PCE core is pretty much ready to go. The only major feature missing
is FM modulation.
The Mega Drive improvements let us start to see the splash screens for
Langrisser II, Shining Force, Shining in the Darkness. I was hoping I
could get them in-game, but no such luck. My Z80 implementation is
probably flawed in some way ... now that I think about it, I believe I
missed the BusAPU::reset() check for having been granted access to the
Z80 first. But I doubt that's the problem.
Next step is to implement Cydrak's PSG core into the Master System
emulator. Once that's in, I'm going to add save states and cheat code
support to the Master System core.
Next, I'll add the PSG core into the Mega Drive. Then I'll add the
'easy' PCM part of the YM2612. Then the rest of the beastly YM2612 core.
Then finally, cap things off with save state and cheat code support.
Should be nearing a new release at that point.
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Tim Allen
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fa6cbac251 |
Update to v102r06 release.
byuu says:
Changelog:
- added higan/emulator/platform.hpp (moved out Emulator::Platform from
emulator/interface.hpp)
- moved gmake build paramter to nall/GNUmakefile; both higan and
icarus use it now
- added build=profile mode
- MD: added the region select I/O register
- MD: started to add region selection support internally (still no
external select or PAL support)
- PCE: added cycle stealing when reading/writing to the VDC or VCE;
and when using ST# instructions
- PCE: cleaned up PSG to match the behavior of Mednafen (doesn't
improve sound at all ;_;)
- note: need to remove loadWaveSample, loadWavePeriod
- HuC6280: ADC/SBC decimal mode consumes an extra cycle; does not set
V flag
- HuC6280: block transfer instructions were taking one cycle too many
- icarus: added code to strip out PC Engine ROM headers
- hiro: added options support to BrowserDialog
The last one sure ended in failure. The plan was to put a region
dropdown directly onto hiro::BrowserDialog, and I had all the code for
it working. But I forgot one important detail: the system loads
cartridges AFTER powering on, so even though I could technically change
the system region post-boot, I'd rather not do so.
So that means we have to know what region we want before we even select
a game. Shit.
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Tim Allen
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4c3f58150c |
Update to v101r15 release.
byuu says:
Changelog:
- added (poorly-named) castable<To, With> template
- Z80 debugger rewritten to make declaring instructions much simpler
- Z80 has more instructions implemented; supports displacement on
(IX), (IY) now
- added `Processor::M68K::Bus` to mirror `Processor::Z80::Bus`
- it does add a pointer indirection; so I'm not sure if I want to
do this for all of my emulator cores ...
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Tim Allen
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d91f3999cc |
Update to v101r14 release.
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.
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Tim Allen
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5df717ff2a |
Update to v101r12 release.
byuu says:
Changelog:
- new md/bus/ module for bus reads/writes
- abstracts byte/word accesses wherever possible (everything but
RAM; forces all but I/O to word, I/O to byte)
- holds the system RAM since that's technically not part of the
CPU anyway
- added md/controller and md/system/peripherals
- added emulation of gamepads
- added stub PSG audio output (silent) to cap the framerate at 60fps
with audio sync enabled
- fixed VSRAM reads for plane vertical scrolling (two bugs here: add
instead of sub; interlave plane A/B)
- mask nametable read offsets (can't exceed 8192-byte nametables
apparently)
- emulated VRAM/VSRAM/CRAM reads from VDP data port
- fixed sprite width/height size calculations
- added partial emulation of 40-tile per scanline limitation (enough
to fix Sonic's title screen)
- fixed off-by-one sprite range testing
- fixed sprite tile indexing
- Vblank happens at Y=224 with overscan disabled
- unsure what happens when you toggle it between Y=224 and Y=240
... probably bad things
- fixed reading of address register for ADDA, CMPA, SUBA
- fixed sign extension for MOVEA effect address reads
- updated MOVEM to increment the read addresses (but not writeback)
for (aN) mode
With all of that out of the way, we finally have Sonic the Hedgehog
(fully?) playable. I played to stage 1-2 and through the special stage,
at least. EDIT: yeah, we probably need HIRQs for Labyrinth Zone.
Not much else works, of course. Most games hang waiting on the Z80, and
those that don't (like Altered Beast) are still royally screwed. Tons of
features still missing; including all of the Z80/PSG/YM2612.
A note on the perihperals this time around: the Mega Drive EXT port is
basically identical to the regular controller ports. So unlike with the
Famicom and Super Famicom, I'm inheriting the exension port from the
controller class.
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