M68K for DC

I have Auto frameskip on the SDL version it's running about the same speed if that helps. For me to be of any help it will need to be able to be compiled with cygwin and normal setup.


I cant get dev c++ set up to work right and i find it much harder to use.

Since i use dev C++ for my edtor and just type make there is no need for me to change.

The Z80 seems to eat massive ammounts of time. Much more than I would have thought.

I've currently got a version of GP/DC with pretty much all of the graphics code #ifdef'ed out (playing with hardware acceleration, and haven't managed to work out paletted textures yet), and it runs at around 40-50FPS (consider that to be infinite frameskip), peaking at around 55. If you underclock the Z80 to 25 cycles per scanline, the speed jumps to 65-70FPS, peaking at around 80FPS. Sound seems to do just about nothing (turning it off gets me an extra 2FPS)

Paletted textures are being a pain though. I just get a little black square where I should be getting a display of the first colour palette.

Double post

I am not sure about this but it seems that they already have ported or at least optimized the Z80 by Juergen Buchmueller (SMEG, SMSplusDC) to SH2 if I understand it correctly. SH2 basicly should be compatible to SH4:

http://smsemu.emuunlim.com/misc.htm

excyber.txt - ExCyber thoughts on optimizing Z80 emu core for Saturn's SH2s
z80sh2.txt - Just an useless comments on x86 asm optionally used in Z80 core and how it can be rewrited to sh2

PS Hey MetaFox, I didn't know that u are/were part of the Saturn emu scene


Chris

Stef, like BlackAura said, the current Z80 is having a big impact. Your C68k is much faster than mushashi by itself. Combine that with other improvements, and I think we'll see some serious speed. Also, with GCC 3.4.0, GPF has been able to compile C68k with different -O levels than other people. So I think it is quite possible that speed would improve just by that.

[quote author=GPF link=board=dcemu;num=1083323639;start=165#179 date=06/08/04 at 22:28:37]I have the complete 3.4.0 toolchain in a rar thats about 10 megs for both gcc and g++, for mingw. but my storm-studios site seems to be down right now. [/quote]

I'll try to fix this ASAP.

Good to see you (er or read you ) Will, we all missed you ;D



Chris

Just results of a quick bench :

I tried to desactive Z80, video and sound emulation to test as best i can C68K performance versus musashi on DC
Still memory functions and basic VDP/sound chip read/write which are outside but not very significant.

I overclocked the 68k core to 55 Mhz and here are the result :
musashi gives between 16-23 FPS (with an average 20 FPS) where C68K give between 43-50 FPS (with an average 46 FPS)

Well, we can see than C68K is about 2.3 time faster, if we take in account other part of emulation (as memory read/write function), i think C68K is about 3 times faster than musashi.
but that also means that 68000 emulation alone take a bit more than Â*20% of complete CPU time, not that bad but not so good too ...

wow, almost 3 times faster. that is amazing! so many things use the 68k that this will have a huge impact on them all ;D

If its 3 times faster that means all you need to do is add this to Reapers Gen + and add saving and a menu and we have a perfect Genesis emu. So pretty much all where doing is waiting for someone to compile a perfect genesis emu now...

Err, there's a little more work that needs to be done first.

Anyway, C68k could provide a good boost to NeoCD DC as well.