PSPGBA v1.2: nouvel émulateur!

[benja32]

j'avai lu un truck sur le forum de psp-gen enfaite c une histoire de compatiblité, la psp a un processeur vraiment different que la gba donc tres dur a emulé fin je ne connais pas les detaiiles

[F Destroyer]

Oui. Je crois que y'a une meme histoire avec la Saturn. Son hardware est tellement different de celui de PC, que aucun emulateur n'a été crée a jour d'aujourd'hui.

[benja32]

Just out of curiousity, exactly what is it that makes this version so much better than the other ports? I've looked over the source and I haven't seen any optimizations to the actual critical portions of the emulator.

I hate to break it to you all, but unless someone rewrites the CPU core completely a VBA port to PSP will probably not achieve full CPU emulation speed for a majority of games, and unless someone rewrites the video rendering functions a VBA port will never achieve low or no frameskip. And if the CPU isn't being emulated full speed then sound is just going to be awful no matter what (the direct sound channels, anyway).

Don't mean to sound too negative, but I've looked through VBA's source enough and it just isn't an efficient emulator. The CPU core has had some strong brute force style optimizations thrown at it, but the result is something rather huge (not cache friendly for a low cache machine like PSP) and the more important optimizations are x86 only. At the same time it misses some somewhat obvious optimizations that involve more than expanding tables. It also spends a lot of extra cycles maintaining more accuracy than it really needs to.

The renderer is much worse off, it's just very slow. It is done in a way that very literally models the GBA's video hardware and it's quite accurate but there are a lot of potential optimizations it misses (okay, some at the slight expense of accuracy), even some pretty simple ones.

Don't get me wrong, I'm not saying VBA is a bad emulator, quite the contrary, obviously it's the best GBA emulator available for desktop computers. However, the devs never really bothered making it super fast because I suppose there was never enough of a reason to, and doing so quickly becomes a serious headache. The emulator, like No$GBA, was also made with developers in mind, meaning it has to play to certain rules to provide higher accuracy than is necessary to plau most commercial ROMs.

I don't want to take anything away from ZX-81's accomplishments here but I also don't see anywhere where he gives any indication that this will get any faster. In fact, given that he says he tried almost pointless things like converting the code from .cpp to .c expecting it to actually substantially improve performance, I'd say that he doesn't have any real plans for making this faster now, or any real hope. Once again, props go to PSPUpdates for instilling false hope and expectations within their naive readers.

*puts on flame proof suit*

 

Poste de Exophase sur QJ.Net, en gros il explique que si on veux espérer atteindre le full Emulation speed, il faudrait réecrire CPU Core, ce qui sous entend qu'un portage ne sera pas suffisant. Cependant, espérons que Zx-81 nous apportera plus de précision.

[Matrix15]

donc a présent il y a deux emulateurs:

une premiere version de vba, la deuxieme (1.0.2 je crois)

 

et pspgba (ce topic donc) qui est en une seule version seulement.

 

Pour le moment pspgba est plus fluide que vba.

L'émulation gba avance a grand pas.

[Link14]

J'espère que l'émulation a 60FPS va pas tarder!