VOXEL demo regression

[consolethinks]

The leaked VOXEL rendering game demo doesn't work anymore on the latest version of BSNES (nor on the 2014 libretro core).
There's only a single video of it apparently running correctly on BSNES v0.55: https://www.youtube.com/watch?v=hPR-iSnaCuc

However this is how it looks like on the current version.

VOXEL.zip
Here's a rom for verification

[Screwtapello]

How does the demo run on real hardware?

[consolethinks]

According to someone who owns an SD2SNES/FXPAK, it runs just like in the video. I could ask them to record a video of it, if need be, although I don't know how accurate is the FPGA core for SuperFX

[Screwtapello]

I don't know when we'll find somebody who's able and available to investigate this, but it sounds like something we should track down eventually. Thanks for reporting it!

[consolethinks]

Here's a screenshot from a SNES (unnamed hardware clone) with an SD2SNES

[jchv]

I can confirm at least that this works using SD2SNES on a (real) Super Famicom. Unfortunately that's still not quite good enough confirmation, but it's closer.

[bsnesFan]

Near fixed this in bsnes v0.051 so I think it was known to be hardware accurate.

• corrected ROMBR and PBR SuperFX register masking; fixes Voxel demo [MooglyGuy]

Changelog: https://gitlab.com/higan/bsnes-history-kit/-/blob/master/sources/tukuyomi/misc/bsnes_changelog.txt#L5098
v0.051 source code: https://gitlab.com/higan/bsnes-history-kit/-/blob/master/sources/tukuyomi/emus/bsnes/bsnes_v051.tar.bz2

[bsnesFan]

Okay, when you compare v0.050 with v0.051, you can see two things that changed in the superfx core:

superfx -> opcodes.cpp (left: old, right: new)

superfx->mmio.cpp (left: old, right: new)

These lines are still in the newest bsnes version:

bsnes/bsnes/processor/gsu/instructions.cpp

Line 378 in 0ab0ab6

regs.rombr = regs.sr() & 0x7f;

bsnes/bsnes/sfc/coprocessor/superfx/io.cpp

Line 93 in 0ab0ab6

regs.pbr = data & 0x7f;

but the code around that changed. Unfortunately, I can't do more than that. I hope it helped.

[Max833]

You have closed the wrong issue, @Screwtapello.

[Screwtapello]

Whoops, sorry about that!

We updated the copy of SameBoy that bsnes includes, and one of the updates happened to fix SameBoy's issue 123, looks like GitHub got over-eager and marked this one closed.

[jbo-85]

What's happening here: (it's the same in ares and higan)

1. the game is 384KB, in commit a937f9b some refactoring took place, that basically masks every address in bus_read/write() by rom_mask/ram_mask, you can handle non power-of-2 sizes with "addr = Bus::mirror(addr, rom.size());"

2. after 106, icarus was basically rewritten, and some heuristics got changed, Voxel needs at least 64k expansion ram (previously 128k was used), that's hardcoded to 32k in SuperFamicom::expansionRamSize() for roms that don't set the extended header flags (i.e. Star Fox)

It's not really suprising that the heuristics don't really work for a prototype, adding an entry to the database would be sensible here