byuu says:
Added VDP sprite rendering. Can't get any games far enough in to see if
it actually works. So in other words, it doesn't work at all and is 100%
completely broken.
Also added 68K exceptions and interrupts. So far only the VDP interrupt
is present. It definitely seems to be firing in commercial games, so
that's promising. But the implementation is almost certainly completely
wrong. There is fuck all of nothing for documentation on how interrupts
actually work. I had to find out the interrupt vector numbers from
reading the comments from the Sonic the Hedgehog disassembly. I have
literally no fucking clue what I0-I2 (3-bit integer priority value in
the status register) is supposed to do. I know that Vblank=6, Hblank=4,
Ext(gamepad)=2. I know that at reset, SR.I=7. I don't know if I'm
supposed to block interrupts when I is >, >=, <, <= to the interrupt
level. I don't know what level CPU exceptions are supposed to be.
Also implemented VDP regular DMA. No idea if it works correctly since
none of the commercial games run far enough to use it. So again, it's
horribly broken for usre.
Also improved VDP fill mode. But I don't understand how it takes
byte-lengths when the bus is 16-bit. The transfer times indicate it's
actually transferring at the same speed as the 68K->VDP copy, strongly
suggesting it's actually doing 16-bit transfers at a time. In which case,
what happens when you set an odd transfer length?
Also, both DMA modes can now target VRAM, VSRAM, CRAM. Supposedly there's
all kinds of weird shit going on when you target VSRAM, CRAM with VDP
fill/copy modes, but whatever. Get to that later.
Also implemented a very lazy preliminary wait mechanism to to stall out
a processor while another processor exerts control over the bus. This
one's going to be a major work in progress. For one, it totally breaks
the model I use to do save states with libco. For another, I don't
know if a 68K->VDP DMA instantly locks the CPU, or if it the CPU could
actually keep running if it was executing out of RAM when it started
the DMA transfer from ROM (eg it's a bus busy stall, not a hard chip
stall.) That'll greatly change how I handle the waiting.
Also, the OSS driver now supports Audio::Latency. Sound should be
even lower latency now. On FreeBSD when set to 0ms, it's absolutely
incredible. Cannot detect latency whatsoever. The Mario jump sound seems
to happen at the very instant I hear my cherry blue keyswitch activate.
byuu describes the changes since v067:
This release officially introduces the accuracy and performance cores,
alongside the previously-existing compatibility core. The accuracy core
allows the most accurate SNES emulation ever seen, with every last
processor running at the lowest possible clock synchronization level.
The performance core allows slower computers the chance to finally use
bsnes. It is capable of attaining 60fps in standard games even on an
entry-level Intel Atom processor, commonly found in netbooks.
The accuracy core is absolutely not meant for casual gaming at all. It
is meant solely for getting as close to 100% perfection as possible, no
matter the cost to speed. It should only be used for testing,
development or debugging.
The compatibility core is identical to bsnes v067 and earlier, but is
now roughly 10% faster. This is the default and recommended core for
casual gaming.
The performance core contains an entirely new S-CPU core, with
range-tested IRQs; and uses blargg's heavily-optimized S-DSP core
directly. Although there are very minor accuracy tradeoffs to increase
speed, I am confident that the performance core is still more accurate
and compatible than any other SNES emulator. The S-CPU, S-SMP, S-DSP,
SuperFX and SA-1 processors are all clock-based, just as in the accuracy
and compatibility cores; and as always, there are zero game-specific
hacks. Its compatibility is still well above 99%, running even the most
challenging games flawlessly.
If you have held off from using bsnes in the past due to its system
requirements, please give the performance core a try. I think you will
be impressed. I'm also not finished: I believe performance can be
increased even further.
I would also strongly suggest Windows Vista and Windows 7 users to take
advantage of the new XAudio2 driver by OV2. Not only does it give you
a performance boost, it also lowers latency and provides better sound by
way of skipping an API emulation layer.
Changelog:
- Split core into three profiles: accuracy, compatibility and
performance
- Accuracy core now takes advantage of variable-bitlength integers (eg
uint24_t)
- Performance core uses a new S-CPU core, written from scratch for speed
- Performance core uses blargg's snes_dsp library for S-DSP emulation
- Binaries are now compiled using GCC 4.5
- Added a workaround in the SA-1 core for a bug in GCC 4.5+
- The clock-based S-PPU renderer has greatly improved OAM emulation;
fixing Winter Gold and Megalomania rendering issues
- Corrected pseudo-hires color math in the clock-based S-PPU renderer;
fixing Super Buster Bros backgrounds
- Fixed a clamping bug in the Cx4 16-bit triangle operation [Jonas
Quinn]; fixing Mega Man X2 "gained weapon" star background effect
- Updated video renderer to properly handle mixed-resolution screens
with interlace enabled; fixing Air Strike Patrol level briefing screen
- Added mightymo's 2010-08-19 cheat code pack
- Windows port: added XAudio2 output support [OV2]
- Source: major code restructuring; virtual base classes for processor
- cores removed, build system heavily modified, etc.
Tim Allen