Full Speed PSX/GBA Emulator a possibility nOW?

[wraggster]

Is a full speed Playstation or GBA emulator a possibility now.

With the advances made in sh4asm by some of the great coders in the scene, i just wonder if a sh4 asm core for either emulator would deliver a full speed GBA or PSX emulator?

[quzar]

if someone were to find an appropriate way to use the arm chip in the DC, we could have full speed gba using that (before anyone says the bus is too slow, think about its speed not relative to the rest of the DC, but to that of a gba.)

as for playstation, i think it could go up to around 20fps without using asm which, with frameskip would be playable (barely?).

There have been no sh4asm advances made, and we have yet to see anything benefitting for sh4 recently (the dsnes core was old AND it could be argued that SFC was better without it, since it got faster without sound than it can at all with the new core), and FAME has yet to be added into anything, so we dont even know if it works.

I think a dynarec core for PSX might make a large difference, but that could simply be the musings of a madman.

[Mental2k]

would an ASM GBA emu be any smaller than the equivilant C/++ one?(or what ever they're currently wriiten in)? hence would we be able to use larger roms?

[quzar]

would an ASM GBA emu be any smaller than the equivilant C/++ one?(or what ever they're currently wriiten in)? hence would we be able to use larger roms?
possibly.but not inheritly. I believe that some 16mb roms might load by trimming them. Id guess that there is somewhere between 12 and 10 mb free.

[Mental2k]

thats actuaaly quite alot, considerin most, erm... freeware roms, arent that size.

[quzar]

The only problems i forsee is that without large speedups, the most playable games will be rpgs, and those also tend to be the largest games. Unlike prior cart systems, i actually see legally obtained roms being common, as many flashcarts work from a dock system that can also be used to read games.

[GPF]

yeah right now it runs about 4-7 fps according to the pvr stats function, but I don't know how much the stats function slows down the emulation sending each fps output, across the coders cable.

I only know a little x86 assembly so I don't even know where to start.

I have checked out the gpadv emulator which uses the arm processor natively on the gp32, but don't have the slightest idea on how to even use the arm processor on the dreamcast, regardless of the impact of sound on the bus anyway.

Troy

[BlackAura]

(before anyone says the bus is too slow, think about its speed not relative to the rest of the DC, but to that of a gba.)

The ARM in the DC is not suitable. Two reasons:

1 - No Thumb mode (so most GBA games just plain won't run on it)
2 - It's too slow.

Since the ARM shares main memory with the sound hardware, and has no cache, there are serious bus contention issues which slow the effective speed of the CPU down. It's really slow anyway. In practice, it's probably much slower than the GBA's CPU, even if you don't have to worry about bus contention. And the SH-4->Sound bus is too damned slow to transfer the required graphics data fast enough anyway.

That said, with a suitable written dynamic binary translator, I see no reason that the DC couldn't emulate an ARM-7 well above the speed of the one in the GBA. It just requires someone to actually do it...

[Christuserloeser]

[...]we have yet to see anything benefitting for sh4 recently (the dsnes core was old AND it could be argued that SFC was better without it, since it got faster without sound than it can at all with the new core), and FAME has yet to be added into anything, so we dont even know if it works.

Scherzo tweaked the C core in SFCv1 to disable generating the sound in general while the dsnes asm core couldn't, as Scherzo doesn't know SH4 ASM. Muting sound in SFCv2 disables the sound from beeing actually rendered, but still is generated.

[quzar]

Scherzo tweaked the C core in SFCv1 to disable generating the sound in general while the dsnes asm core couldn't, as Scherzo doesn't know SH4 ASM. *Muting sound in SFCv2 disables the sound from beeing actually rendered, but still is generated.


Its not because he doesnt know how to turn off the sound in the core, its because you cant. The core does not function properly if you disable sound generation.

[Christuserloeser]

Oops. You're correct! I remember that he mentioned that.