Just some questions about NullDC

1401 Views 3 Replies 4 Participants Last post by PsyMan, Oct 21, 2009

AerosolSP

Discussion Starter · Oct 20, 2009

No no, not "when is the next release out?"

What is the cpu core coded in? Is it in assembly? I'm curious, because I'm trying to get some insight into how emulators are coded.

In addition, what is the main bottleneck of emulator speed right now? Is it the cpu or graphics processing?

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xZabuzax

· #2 · Oct 20, 2009 (Edited)

AerosolSP said:
In addition, what is the main bottleneck of emulator speed right now? Is it the cpu or graphics processing?

It's the graphics processing, i can run anything at full speed on my brother crappy athlon64 3200+ at 2ghz with the highest settings on a Ati HD 4850.

In my pc Athlon64 3200+ at 2ghz with the integrated Nvidia 6100 it runs slow with the lowest settings.

Haven't tested the emulator with a very fast cpu, but i suspect it will only gain a minimal speed boost on a fast cpu with a crappy graphic card. You will get better results with a good graphic card instead.

Edit: BTW, this post is based on nullDC, other emulators will benefit from a fast cpu instead of a good graphic card (M.A.M.E, No$GBA, etc...). Not all emulators are the same.

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Squall-Leonhart

· #3 · Oct 21, 2009

the ARM ops are assembly iirc.

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PsyMan

· #4 · Oct 21, 2009

AerosolSP said:
No no, not "when is the next release out?"

What is the cpu core coded in? Is it in assembly? I'm curious, because I'm trying to get some insight into how emulators are coded.

In addition, what is the main bottleneck of emulator speed right now? Is it the cpu or graphics processing?

The recompiler is in ASM mostly with some parts of C and the interpreter is in C (if I recall correctly). I think that ASM is used on some other speed intensive parts too. The truth is that I don't really remember ATM.

The bottleneck is mostly the CPU speed/cores/(bit?) since nullDC takes advantage of 2 cores and even 64 bit instructions (not sure about the 64 bits actually) when available.

The selected plugins and their configuration can also be the bottleneck on some cases too.
For example, nullPVR puts the load on the GPU mostly so a fast video card is recommended, especially on high resolutions or when fog effects are used. As a result, when using nullPVR CPU requirements get somewhat lower but GPU requirements increase.
On the other hand the Chankast video plugin puts more load on the CPU and less on the GPU. As a result, when this plugin is used CPU requirements increase but GPU requirements decrease to a level that nullDC can run with budget cards released about 10 years ago without major GPU related slowdowns.

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