Homebrew blargSnes -- SNES emulator for the 3DS (WIP)

[cracker]

For anyone compiling themselves who want a better experience add

memset(((u16*)TopFB), 0, 400*240*2);

between

running = 1;
                           
SPC_Reset();

in main.c (currently line 814)

It clears the top screen of the logo artifacts that were distracting from the game.

 

[Arisotura]

Alternately, I could add support for loading borders from .bmp files, ala GameYob.

 

[cracker]

True. I know it might not be for me but many others would probably love it. It would be cool to tack onto the end of a game to load it Super Gameboy style -- if present -- as well.

 

[kyogre123]

Yes! I would use a plain black boarder, lol.

 

[Saxer]

Alternately, I could add support for loading borders from .bmp files, ala GameYob.

i'll love that feature

 

[Cyan]

Doesn't Wario Woods use SRAM as additional RAM rather than for saving data?

I didn't know Snes games could do that.
learning new things everyday

 

[hippy dave]

Border options would be a nice bonus feature when there's spare time. CRT TV please

 

[cracker]

I'll admit that I'm naive to the new-ish 3DS homebrew scene... How much RAM is allowed to homebrew (or commercial software for that matter)? I want to add something that might take a MB of RAM. I'm sure this will be fine but I'm just gathering info before I start. Also is it better to statically or dynamically allocate RAM -- are there any known side effects from the latter? TIA.

 

[cracker]

Border options would be a nice bonus feature when there's spare time. CRT TV please

Maybe Beavis and Butthead's TV. Actually that would be a border that I would probably enjoy.

 

[Silentsurvivor]

I didn't know Snes games could do that.
learning new things everyday

I might be wrong but I think some of the Final Fantasy games do that too

They write to the SRAM like a million times. If you're set to autowrite your flash memory won't like it. I don't know all the games that do that.

 

[cracker]

I tried finding a list of games that use SRAM as extra WRAM but the only game I could find mention of was Yoshi's Island. I'm not even sure if that is correct because it could be RAM included in the special chip.

 

[DiscostewSM]

I know when you shut-down the 3DS or close a game from the Home menu, it can do things like save data. Would it be possible to do something like this with homebrew, either through Gateway or possibly Smea's ssspwn? If there's a kind of call-back method to allow your program to do "on-close" stuff, you could do your saving to flash memory there there. Like, when you load up a game, the save data is read in and stored in a section of RAM, to which when the game makes save calls, it'll write to that, but when you close the program or shut-down the system, it'll write that SRAM to the the flash memory.

 

[bobmcjr]

Given that you have to pause the game with the touchscreen anyway to properly exit, why not save the game on pause?

 

[dubbz82]

Given that you have to pause the game with the touchscreen anyway to properly exit, why not save the game on pause?

I'd say this might be better as like an option (i.e. Save and quit)

 

[Arisotura]

CRT TV border would be doable, but I won't be the one drawing crazy borders as I have no drawing skills (blargSnes' interface probably witnesses that, heh)

However, if you want a CRT filter for the SNES video output, that's not coming anytime soon. We don't know enough about the PICA200 and I doubt it has enough support anyway (it doesn't seem to have real pixel shaders from what I've seen).


Which brings me to something else; I think I might be able to offload some rendering to the PICA200. Atleast, it's doable for color-math and master brightness I guess.


Saving on pause and all those things are coming.

 

[Arisotura]

Progress is kinda dropping because I'm entering univ, heh.


blargSnes is going to be ported to the most recent ctrulib. This implies, for one, correct framebuffer management (no more screens disappearing or turning into garbage).

I also plan on changing the renderer to use the PICA200 instead of straight writing to the framebuffer. This implies:

* hardware-assisted color math (blending) and master brightness. If my plans work, those will be emulated at literally no cost.
* possibility for flexible scaling modes (fullscreen, stretching while keeping ratio, in addition to the current 1:1 mode, and maybe more weird modes depending on games)
* possible 3D support in the future (may require special game-specific renderers though. The standard renderer will just squish all layers and sprites into two layers and blend them together, like the SNES PPU does)
* hell, let's get crazy... 3D borders?
* oh and also, proper VSync. No more tearing, and games will run at the correct speed.


Sound support will be coded in whenever I get access to a homebrew loader that gets me CSND access. Gateway users won't get sound (unless the Gateway team updates their firmware as needed). (currently this sucks because I'm also a Gateway user. blarg). Oh well, rest assured we're working on this issue. I'm kinda sidetracked between the actual blargSnes and trying to find a way to play sound.


Stay tuned!

 

[Abcdfv]

Stay tuned!

Any word on if using the GPU is feasible, or does it seem to run relatively well on just ARM11? Didn't you say you also figured out using multiple cores?

 

[hippy dave]

Sound support will be coded in whenever I get access to a homebrew loader that gets me CSND access. Gateway users won't get sound (unless the Gateway team updates their firmware as needed). (currently this sucks because I'm also a Gateway user. blarg).

I'd say that if someone figures out the sound, and that it's possible for Gateway to update for it, and the code's made available to them, then they'd likely do it. They seem open to stuff like this that their customers want, especially if the groundwork is done for them.

Anyway progress sounding interesting, keep up the great work!

 

[kyogre123]

Sound support will be coded in whenever I get access to a homebrew loader that gets me CSND access. Gateway users won't get sound (unless the Gateway team updates their firmware as needed).

What? Why is that not supported (and why it relates to sound)? I thought Gateway only blocked kernel access.

 

[Arisotura]

Using the GPU for the final effects like color math is likely feasible. Not easy, it's going to require some weird blending equation, but possible.

Implementing any more of it on the GPU is impossible. You would need pixel shaders, which the PICA200 doesn't have.

There's also the part where any PPU register can be changed mid-frame. And as I said, the PPU does color-math by first flattening the layers into two screens and then blending them together. Trying to render each layer separately could (and likely will) give wrong blending results.

PPU emulation in software is the bottleneck, but I'll do my best to optimize it.


About sound, the issue isn't figuring out how to play sound, but getting access to it. CSND is nice and easy but only few system apps have access to it. Homebrew would get access to it if we were able to specify custom, unsigned accessdescs.

Alternately, there's the DSP which we can use. But it's mostly unknown and requires providing a signed DSP binary (ie stealing a binary from a game, not quite legal).


I'd also rather not rely on the Gateway team.