GP2X Clever Idea For 6502 Emulators

[bitbank]

I started a blog about ARM and optimization related topics. Today I released one of my many cpu emulator optmization ideas. Have a look:

Larry's Personal & Tech Ramblings

L.B.

 

[Mudi]

I'm working (slowly) on an NES emulator... I've actually gotten the 6502 emulation all written out (and quite possibly still buggy), but it's all in C++ (no virtuals or other such to slow it down so hopefully about the same speed as C) right now... it looks like you are very good at ARM ASM and I would like to have an ASM 6502 core at some point, would you be willing to work on it with me?

I have basically none of the PPU done, that's my next big project...

EDIT: looking at your older entries, looks like you already have a pretty good multiple 6502/Z80-based system emulator out for PPC... I would also be interested in porting that (or if you wanted to port it yourself, or whatever, I'm confused), since there's a good 50/50 chance that my code will never actually work :lol:

 

[Exophase]

Nice trick. It should carry over to any pointer addition with fixed offsets, unfortunately pointer subtraction wouldn't work the same way.

 

[reaper79]

I started a blog about ARM and optimization related topics. Today I released one of my many cpu emulator optmization ideas. Have a look:

Larry's Personal & Tech Ramblings

L.B.



Nice blog! There is some interesting pearls in there.

Reap

 

[Blah]

Theres an ARM ASM 6502 emulator written for the Acorn Archimedes out there somewhere.

 

[slaanesh]

PocketNES for the GBA uses a 6502 ARM ASM engine. The source code is freely available.

 

[Mudi]

I looked at PocketNES... the source code was reasonably scary. I might try it again sometime because it would be blazing fast on the GP2X.

 

[rabidcow]

Today I released one of my many cpu emulator optmization ideas. Have a look:
Larry's Personal & Tech Ramblings



A while ago I realized you could do a similar trick for the paired registers in z80 and x86 (don't recall exactly which processor I was thinking of...): store the low register in the upper bits and the high register in the lower bits. When you need to treat it as a paired register, rotate it around to do the math. If you need them separate, just mask it off. I don't think I bothered to look to see if anyone was already doing that.

 

[Lazrhog]

Hi bitbank. Enjoyed your ramblings

I know exactly where you are coming from .... It's like us programmers are kindred spirits littered across the planet ! I still remember that buzz I got as a teenager getting split screen scrolling working in assembler for the C64 for the first time at about 3.00am, and realising it was what I wanted to do with my life