WHDLoad question

[Amiga1992]

This is not a problem per se...

I was wondering.. I have a few games that run through WHDLoad and have slowdowns. The slowdowns should not be there, since my machine has an accelerated processor. So why are they? They play just like in my A600.

For example, R-Type 2. When lots of stuff gets on the screen, it just slows down like my A600... Shouldn't this be "fixed" in a much faster machine?

[Codetapper]

Galahad might correct me on this but I think this is what happens!

The game on an accelerated Amiga runs the code a lot faster as you would expect. But the blitter is a lot slower in comparison to the CPU. On the A500, the blitter was very fast, but not so on accelerated Amigas.

The game therefore gets to the point where it needs to blit some data and it starts into a loop saying "are you finished yet?" OVER and OVER! Just like when somebody is watching over your shoulder, this doesn't exactly help and actually slows down the blitter as DMA time is wasted while checking that the blit operation is finished so often.

There is a BlitWait macro in WHDLoad which tests CIAA which can avoid some blitter slowdown so this should be used in cases like this where heavy blitter usage occurs. Also moving some code to fast memory can avoid the slowdown in some cases. (I believe Galahad has done this for SWOS).

And yes this is bloody annoying I agree!

[Amiga1992]

Hey, is not that it works worse than on an A500, it works about at the same speed, which surprised me!

Would it be possible to use the CPU as the blitter, like the Fblit program does?

[Codetapper]

The short answer is no.

Because the operating system is generally killed in games, the FBlit program won't work in WHDLoad installs.

Most games setup for a blit by loading the hardware registers $dff044 to $dff074 and then writing to $dff058 starts the blit. Some games use nice subroutines to do their blitter operations, so in theory if you could load the FBlit code into fast memory you could patch the game to use it.

So basically it's not possible at the moment but it's not impossible!

Every game would need special patching (but of course you might only need this on the 5% of games which go REALLY slow under WHDLoad) or perhaps some magic by the MMU commands in WHDLoad could convert the blitter operations to FBlit's format and call them.

[Amiga1992]

Originally posted by Codetapper
The short answer is no.
Because the operating system is generally killed in games, the FBlit program won't work in WHDLoad installs.

Nah, I'm not a dummy, I know this. I was asking if a similar function could be implemented in WHDLoad. Not using FBlit and Whdload . The last part of yoru reply answered me perfectly, thanks a bunch

[Galahad/FLT]

simple maths.

A500 Blitter is faster than processor
A1200 030/040/060 processor is faster than blitter

The slowdown occurs because the processor will execute more code in a routine quicker than an a5oo, and will encounter a blitwait sooner.

I'm another victim of this problem, isn't there anthing that can be done?

[Amiga1992]

I think that, as Galahad says, not. Unless the WHDLoad coders decide to include a module for blitter emulation through CPU (much in the way FBlit works).

That would make the games run smooth, I presume!

It's hard to accept this incompatibility. After all WhdLoad's purpose is to make old, incompatible, badly written games run on modern amigas.

[Amiga1992]

Hey, they RUN, but they slowdown! . It's not an incompatibility problem.

They run but sometimes they decide to walk I thought WHDLoad is for compatibility problems!

[Twistin'Ghost]

It’s the reason to still collect the disks/adf’s...

[Amiga1992]

Originally posted by Burseg
I thought WHDLoad is for compatibility problems!

Yep! As I said, the games run, are compatible with your new Amiga. But run badly

The disk/adfs wont even run on accelerated Amigas, me Twister. it's good to hve them but they are mostly useless in an expanded Amiga.