GenesisPlus DC DL's + Discussion

DcSteve · Post by **DcSteve** » Fri Nov 12, 2004 2:37 pm

mek is currently rewriting the sound code and a release with src will be made very soon.

Storminator16 · Post by **Storminator16** » Sat Nov 13, 2004 3:09 pm

cristfc · Post by **cristfc** » Wed Nov 24, 2004 2:14 pm

Ill go to gownload... I am anxious for see it...

DcSteve · Post by **DcSteve** » Mon Nov 29, 2004 8:35 pm

Hey BA- mek wants you to know that he thinks that stef's c68k still has bugs in it. "the 68k- stef's core- does not perform the given clock cycles.
the paramater given to "exec" function in any cpu core.
in this case: m68k_exec". Anyway, BA, I have an important pm for you.

InternetAddict · Post by **InternetAddict** » Tue Nov 30, 2004 1:25 am

I have just two questions 1st, will your next official release be in december?
2nd Will you fix bugs that caused Punisher sprites to be invisible? Shinobi 3 annoying sound that starts when your score hits over limit. Scooby Doo mystery make that work would be nice it goes to black screen after you pick the level. uhh what else? lol oh yeah sonic 2 2 player mode the graphics are all fucked up. Can anyone think of anything else?

Stef.D · Post by **Stef.D** » Tue Nov 30, 2004 1:52 am

DcSteve wrote:Hey BA- mek wants you to know that he thinks that stef's c68k still has bugs in it. "the 68k- stef's core- does not perform the given clock cycles.
the paramater given to "exec" function in any cpu core.
in this case: m68k_exec". Anyway, BA, I have an important pm for you.

I also think C68K has still some bugs

I did few tests only with it on Genesis Plus.
About the cycle counting stuff, what do you mean ? I compared C68K versus Musashi and i saw that my cycles counting is very different. But i compared with 68000 documents i got here and musashi seems to be wrong here almost time.

InternetAddict · Post by **InternetAddict** » Tue Nov 30, 2004 1:57 am

I just remembered another game, Virtua Fighter 2 it goes straight to a draw.

BlackAura · Post by **BlackAura** » Tue Nov 30, 2004 2:59 am

I have just two questions 1st, will your next official release be in december?

Maybe.

2nd Will you fix bugs that caused Punisher sprites to be invisible?

Never heard of it, never played it. Since I'm rewriting most of the rendering code (again), it might start working. It might not.

Shinobi 3 annoying sound that starts when your score hits over limit.

I've never noticed that one either. Shinobi 3 sounds absolutely fine here.

sonic 2 2 player mode the graphics are all fudge up

I know. That will not be fixed any time soon. As far as I know, Sonic 2 is the only major game that uses that video mode, and I just haven't bothered trying to get it working. I won't even try until everything else works.

Can anyone think of anything else?

I can probably list a lot more problems than you can.

castisos · Post by **castisos** » Tue Nov 30, 2004 2:59 pm

Hey BlackAura i was wondering if your current state of the emulator is better then the SSP? because i know the only thing wrong with that emu is the sound...

Thanks

DcSteve · Post by **DcSteve** » Tue Nov 30, 2004 3:44 pm

in some ways it is(sound quality), in others it isnt (if gfx currpotion is more than SSP still).

Post by **Quzar** » Tue Nov 30, 2004 3:59 pm

it's legal.

InternetAddict · Post by **InternetAddict** » Tue Nov 30, 2004 4:03 pm

SSP is far from perfect even in the gfx department, and that sound is just horrid.

BlackAura · Post by **BlackAura** » Wed Dec 01, 2004 1:02 am

Sound is much, much, much better than the SSP. The graphics emulation of SSP was good enough to run the games that came with it, although GP/DC can't yet run all of those games without some glitches. Before I do another release, it should be able to handle all of the games that came with the SSP as well as the SSP does, probably better.

DcSteve · Post by **DcSteve** » Thu Dec 02, 2004 1:01 am

hey BA, perhaps there is something useful you can take from this???

http://gcemu.dcemu.co.uk/genesisplus.shtml

BlackAura · Post by **BlackAura** » Thu Dec 02, 2004 2:39 am

hey BA, perhaps there is something useful you can take from this???

No, nothing. The Gamecube-specific code is useless on a Dreamcast. The only thing they have over the standard Genesis Plus is Game Genie support, but I already have that working - it just needs to be connected to the menu. You also don't need to enter a master code on most games.

On the plus side, the code I'm working with has swappable CPU emulators, both controllers work, it can automatically detect the type of controller you're using, it uses the sound emulation code from Gens which sounds far better, especially at lower sample rates, and there are probably a few other things I've changed too.

law56ker · Post by **law56ker** » Thu Dec 02, 2004 8:54 am

cool ba, i appreciate your hard work, this is really exciting project for me. I got a question, i think the answer is no but is there anyway any kind of savestate or saving will be possible?

DcSteve · Post by **DcSteve** » Thu Dec 02, 2004 9:34 am

State Saving is not built into genesis plus. Ba has mentioned already that others have done there own code to have saves state working in other versions of genesis plus. He said he'll look into SS's when hes satisfied with the more important things first.

Ba- at lower sample rates, does looping and skipping still occur with the new code?

BlackAura · Post by **BlackAura** » Thu Dec 02, 2004 10:07 pm

He said he'll look into SS's when hes satisfied with the more important things first.

Indeed I will.

By the way, if anyone's wondering why I included Game Genie support, while that's not an essential feature, the answer is that it's very easy to do. Once you have a function to decode the Game Genie code (I just used the one from Gens), all you need to do is modify the ROM, which is really easy. It took virtually no time at all to add it, and I was even able to eliminate the need for a master code in most games.

Ba- at lower sample rates, does looping and skipping still occur with the new code?

Yep. I haven't rewritten the sound output code yet. The sound generating code should almost be good enough to handle it, but it still needs a few minor modifications.

I also need to make sure that the sound code will be able to deal with frameskipping - if I add auto frameskipping, I should be able to get around the problems caused by the emulator running at something like 95% full speed. That makes the sound output / generating code a little more complex, because you need to deal with two (or more) frames at once...

If it's not running at 100% full speed, you'll get some minor pitch bending with digital samples (voices), but at least it'll work.

DcSteve · Post by **DcSteve** » Thu Dec 02, 2004 10:30 pm

very interesting, also i have a lot of info about the current status of FAME. Mek has seen it working in genesis plus dc, and he reports that it actually runs slower than m68k. So my question- are you relying on the release of this cpu for these gp coding expectations?

BlackAura · Post by **BlackAura** » Thu Dec 02, 2004 11:30 pm

Mek has seen it working in genesis plus dc, and he reports that it actually runs slower than m68k.

Chances are it's not set up correctly. Still, C68k is fast enough.

So my question- are you relying on the release of this cpu for these gp coding expectations?

I'm not. That's what the frameskipping thing is for.

The emulator itself is more than fast enough to run at full speed. However, when displaying a frame, the Dreamcast's hardware requires that we wait around for it to be ready for us to start sending data. That means that, at the end of each frame, we need to wait until the graphics hardware is ready. In practice, that means that each frame lasts a multiple of 1/60th of a second.

That wouldn't be a problem, but occasionally a frame takes just over 1/60th of a second. The result is that the frame ends up taking 2/60th of a second, and is sitting around for almost an entire frame doing nothing. With the frameskipping, we can detect that a frame has taken too long, and then not draw a frame and get on with emulating the next frame instead. Hopefully, the next frame will take less that 1/60th of a second, so we'll still be running at full speed (with occasional frameskipping as required), but most importantly the sound system will still be properly synchronised.

The catch is that might throw out the timing of the next frame. This is where it becomes kinda complex, because we're replying on the video hardware to regulate speed and to synchronize everything. The only real solution is to make the emulator run at 100% full speed all the time. It's also less of a problem if we're using software rendering instead of hardware rendering, but software rendering is currently too slow to be used unless the hardware rendering makes the game unplayable.

Really, I don't think we need a faster M68k emulator. What we need is a faster Z80 emulator, because the Z80 is really eating most of the free CPU time. If we could get the Z80 running faster, we wouldn't have any problems with slower framerates at all.

If you underclock the Z80 slightly, and completely ignore the DAC emulation, it runs absolutely perfectly. That will only work if the game does not use the DAC. If a game does use the DAC, underclocking is simply impossible because it changes the pitch of the generated sound (listen to the "Sega!" intro on Sonic 1 with the Sega Smash Pack or GP/DC with an underclocked Z80 to see what that sounds like).

I think I'm going to have the Z80 automatically underclocked at the moment for games that don't use the DAC. That should be enough to get them up to completely full speed. For games that do use the DAC, we'll have to put up with some minor frameskipping until we get a faster Z80 emulator.

Unfortunately, I don't think a faster Z80 emulator is possible without using SH-4 assembly, which means it'll take quite a while to build one. The existing one already uses just about every trick it can to make it run faster, and C68k only uses one or two more.

GenesisPlus DC DL's + Discussion

Hmmm