SpritesMind.Net

Thanks Eke - the annoying thing is all this stuff should have worked, but I think I messed with the timing while the bad test code was still in place. Now I've removed that code some timing or other is probably happening a few cycles too early. Ah well, at least I have things to test, now :)

What ...

Wrote a big reply, lost it, bah. Forgive me if I simplify.

I think mid-line changes are more important than most people realize.
I do agree with you, however...
you have to choose a single fixed point in time to commit every change to the VDP. This is fundamentally inaccurate.
...for most ...

It breaks everything: branch prediction, pipelining, out-of-order execution, L1 cache, etc. Very bad stuff.
Yeah, but there are a lot of things that should also break everything, but they don't, because Intel thought about it and worked around it. This isn't one of them, and they specifically ...

The overhead is not in the instructions themselves, but hidden in the processor architecture's model to execute instructions out of order and as fast as possible.
Yes indeed, specifically, it really does not like you changing the stack pointer like that. I forget the exact reason but it's ...

My VDP core is not scanline driven. It is capable of responding to changes mid-line
Mine does to, to a certain extent. Rather, changes to certain registers etc. happen on the correct line, this is not true of Gens. Changes to certain registers happen immediately. There is no doubt a few registers ...

I play most of my CDs without strict timing in PicoDrive. I can't think of the ONE that requires strict timing off the top of my head, but out of about a dozen, there was ONE that needed it.
... probably code based on Gens, I would imagine. In which case the timing is *way* more accurate than the ...

Err, what games run lock-stepped?
Without looking I can't tell you. But some of them do.

It's rather uncommon to find CD/32X games that require strict timing.
I certainly would not agree with that.

In any case, it actually doesn't matter if no games do this, since the whole point is to emulate ...

run opcodes in parallel when the results don't interfere with each other
As I said before, for both of the consoles we're talking about, this is going to happen very, very rarely. The thing will be lockstepped almost all the time. Any extra processing you do to make this work is just overhead and ...

This is all basic stuff. Trouble is the CPUs are required to be in lockstep all the time, which makes it much, much faster to do on one CPU.

Sure, multithreading is "the future" but there's other things than CPUs you can stick in other threads.

Sur devster :
yea, any cartridge can be bigger than 32mbits, but only through external bankswitching. a game rom can also allocate itself to $000000-$7FFFFF, but i never seen any carts that do this, nor do i think it'll work on genesis systems released after the model 2.

any read/write to $A13000 ...

You won't have access to rom on the cart at same speed as internal SDRAM whatever you do. The ROM is 16 bits and very slow when you compare it to the SH2 memory capabilities.
Yep. It's also much slower than the SDRAM anyway, so even if it were 32 bits, it'd still be slower.

Besides, I'm fairly ...

2) Use assembly. Can it be that C is too slow for this?
I don't think so. Well, I guess it depends on what CPU you're trying to run it on. On anything less than five years old, C should be fast enough. Sure you can do 68K faster but SH2 doesn't even have any flags, so most of the benefits of going ...

AamirM wrote:And then there is my PC-Engine emulator which desparately needs an update (a complete rewrite in fact) and I wish to work on it more than anything.

DO IT!

(I've always wanted to do that, but I promised the MagicEngine author, years ago, that I wouldn't)

Yeah, the driver could well have an effect, it's probably the driver that decides when to do the real update.

There is probably a vista specific function you can call to request that it does an update, which might fix it. Note I say 'request that it does', not 'force it to do', because that's ...

@King of Chaos:
Just so you know, I have started working on D3D9 support but it'll delay the release quite a bit. But I guess it'll be worth it.

Nope.

The Vista desktop is running under D3D. Any app running under D3D is essentially 'emulated' by the desktop. To your code everything looks the ...