M68K for DC

[quzar]

yes, i dont understand why there has been a major flock recently towards sh-4 asm as being a holy grail that will magically make everything work. yes it will speed things up, is it worth it compared to fixing the real bottlenecks first. probably not.

[wraggster]

Stef, with the core you have now, would a faster genesis emu bemade with it as it stands?

[Christuserloeser]

[quote author=obelisk link=board=dcemu;num=1083323639;start=135#137 date=05/31/04 at 22:16:00]will / could this 68k stuff help out TG16 emulation on the DreamCast?[/quote]

Not at all.
PCEngine uses a NES/SNES similar CPU type, knowledge about SHx and the DreamSNES CPU core code could help porting an C emu to DC with a SHx PCE CPU core.

Until then DreamEngine is the best choice for playin PCE games on DC

http://www.gamer.uk.com/gamefaqs/tg16+duo.faq

Specs
Manufacturer NEC
Year 1988
CPU HuC6280 - 7.19509 Mhz
RAM 64 Kbytes
Sound 6 cn.
Video 360 x 256 (H)
Colores/Colours 512
Sprites 64
Card (8 Mbits)

[Christuserloeser]

[quote author=quzar link=board=dcemu;num=1083323639;start=135#140 date=05/31/04 at 22:43:02]yes, i dont understand why there has been a major flock recently towards sh-4 asm as being a holy grail that will magically make everything work. yes it will speed things up, is it worth it compared to fixing the real bottlenecks first. probably not.[/quote]
Hm. If someone's able to program in SHx most speed issues with DC will be fixed. The current situation is stucked. There isn't any room for improvements atm. Read blackaura's interview here at DCEmu.co.uk - he says it. Nothing to do, everything done, no big improvements... Not his wording though but reflects the scene very good.

As I can't code at all I cannot say very much about facts, so everything's just *theoretical*:

Using SHx it should be possible to get the following systems emulated using the DC with 44khz sound, bilinear filtering, full speed:

SNES
Genesis (with the new C68K that will be possible without SHx)
Genesis + SegaCD
NeoGeo(CD)
GBA
PSX (hi res)
N64 (lo res)
Saturn (using SH2 directly for the main CPUs, SHx for the VDPs and other units)
Amiga 500 (I know some don't agree with that :P)


Chris

[quzar]

it is possible to do that with good C coding, not with spiffy effects but fullspeed emulation yes. just requires better code =\

[Christuserloeser]

Now that would be a lot of code optimizing ;D
And afterwards someone comes up with some good SHx ASM code and it's three times faster

But I guess til someone coded a SHx ASM core for the M68K it will take a year :P

I guess that won't be possible without Stef's help anyway! We'll see a serious speed up for NeoCD and GenesisPlusDC if Stef's C68K is implemented!

[vipor231]

im wondering if it would be possible to emulate a sega saturn on the dreamcast.that would be nice playing those games and not having to pull the saturn out all the time

[Christuserloeser]

Would be nice! But I guess that won't happen til 2006 ;D

[Ian_micheal]

Well when i compiles your source code you released i get bascly the same undefines as before.


Im thinking 1 it works for you. 2 im using my make not yours as i use cygwin.

I dont know whats up i understand most of how it works it just will not compile for me

[Stef]

yes, i dont understand why there has been a major flock recently towards sh-4 asm as being a holy grail that will magically make everything work. yes it will speed things up, is it worth it compared to fixing the real bottlenecks first. probably not.

I agree, we should first focus on bottlenecks.
Now we will be able to switch to C68K on Genesis Plus, frame skip should be a lot more efficient... if it's the case, that mean VDP render code is still really slow and need to be optimised.

Stef, with the core you have now, would a faster genesis emu bemade with it as it stands?

Yes and no, without frame skip, speed improvement isn't impressive because video code is still really slow... i didn't tested with frame skip, but i think games can now run near full speed with frame skip 1 or 2 with correct 68000 speed (understand by that, no underclocking)

But I guess til someone coded a SHx ASM core for the M68K it will take a year Â*

Depend about how many free time we have, it taken me many time for C68K (about 6 months) because i'm really busy with my job...

I guess that won't be possible without Stef's help anyway! We'll see a serious speed up for NeoCD and GenesisPlusDC if Stef's C68K is implemented!

Actually C68K won't be sufficient alone in Genesis Plus DC, we also need to speed up video render part.

I never tested NeoCD since i don't have NeoGeo CD games :-/ but i follow with many interest development of NeoCD, speed is almost improved in each version, i guess C68K can bring a big speed improvement since 68000 is clocked at 12 Mhz on NeoGeo...
I should have a look in the source to see if we can easily implement C68K as i done in Genesis Plus

im wondering if it would be possible to emulate a sega saturn on the dreamcast

No, i don't think it would be ever possible... Saturn is far more complex than a PSX, many CPU are working together, VDPs are very complex, specially VDP2 which have strong 2D capabilities ! It's definitly impossible to get a correct Saturn emulator on DC...

Well when i compiles your Â*source code you released i get bascly the same undefines as before.


Im thinking 1 it works for you. 2 im using my make not yours as i use cygwin.

I dont know whats up i understand most of how it works it just will not compile for me

Can you give me your error log ?
If it's the same than last time (i.e: M68K_xxx undefined ...), it means your cpu68k.c file isn't linked correctly in your makefile...
and you can comment m68k_disassemble call, not needed in the DC version