Right, what I meant was more "I can see that the effort required is too large for the project to currently be anything more than a proof of concept".
It's a
lot of effort to raise the speed enough while not breaking the emulated execution environment (aka game compatibility). A just-in-time compiler (JIT) needs to be made for this part, which turns the ARM code of Nintendo DS games into MIPS code for the GCW Zero to run without constantly needing to consult translation tables. Because the DS runs an ARM7 processor, which is also present in the GBA, some of the code could be taken from ReGBA... but it would need to be hooked into the new memory map of the DS, and Desmume's way of doing things.
Secondly, because the DS has two processors, an emulator must synchronise two chips, running some of the ARM7 code, then the ARM9, then the ARM7, then the ARM9, etc. Those processor switches are expensive because they must save the first processor's state, restore the second's and determine where to go after each switch.
After those are done, you then get into issues with rendering the screens; because there is a 3D renderer, the part of the emulator that deals with the GPU must be optimised. And, because the 2D graphics modes are much more plentiful and complex than on the GBA, there is much more code to select and perform the correct renderer for each graphics mode, sprite size, background tile size, rotation etc. than ReGBA. All of that makes emulation yet slower.
And then, finally, you can get into the 2-screen to 1-screen mapping, and the touchscreen emulation with no touchscreen on the GCW.
I'm not saying that this should stay a proof-of-concept forever. If gameblabla has done any work on Desmume past the version in the Original Post, you can be certain that I will appreciate it. I'm merely saying that I won't blame gameblabla if he has started to do work but finds that it's insufficient -or- he has hit roadblocks and the last public version stays a proof-of-concept. The demands placed on the GCW to emulate a Nintendo DS are simply very great; a JIT compiler takes lots of knowledge, design effort and time to make, and won't guarantee that any game runs fast enough; and if you get past those hurdles, then input and output are going to suck.
ReGBA takes 35%-55% of the GCW Zero's 1 GHz CPU to emulate a 16 MHz ARM7 processor. The Nintendo DS has a 33 MHz ARM7 and a 66 MHz ARM9. As
the Atari Jaguar ad said, Do The Math!
