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SubjectRe: Good open source emus Reply to this message
Posted byfinaldave
Posted on04/26/04 10:40 AM

> I reckon you'd probably have to do static recompilation to get genesis working,
> especially if you want sound too.
> smf

This might be slightly controversial, but are we sure static recompilation is the solution on mobile devices? It's hard to say... I mean have a look at some of the profiling I have been doing on Cyclone running Sonic1.

Now as far as I can tell the slowdown isn't to do with the opcode fetch or anything - a 205Mhz ARM can run at about 73Mhz (one frame takes 1.7ms in the ideal case), but rather something else (yet the same opcodes crawl down to 20ms in the worst case). Maybe the RAM accesses (my best guess at the moment) are thrashing the cache in some weird way.

It affect Pocket PC, but not GP32 afaik

Now it's too early to say, but wouldn't this slowdown be true of a dynarec or a staticrec as well as an interpreter?
And in fact wouldn't this be *more* so because of the extra memory requirements for the translated rom?
Are we sure that for 68000 on ARM the bottleneck is for instruction translation? Maybe RAM access/coherence is more critical on mobile devices.

Do we actually know that recompilation would work well on devices other than the GBA with it's massive flat fast ROM cartridges? Remember the GP32 only has 8Mb, and Dynarecs on PC are typically run on machines with 128Mb or more?

You learn something old everyday...

Entire Thread
Subject  Posted byPosted On
*Good open source emus  MrJeff04/21/04 07:28 PM
.*Re: Good open source emus  finaldave04/26/04 10:29 AM
.*Re: Good open source emus  smf04/24/04 04:14 AM
...Re: Good open source emus  finaldave04/26/04 10:40 AM
...*Re: Good open source emus  smf04/30/04 03:14 AM