Holiday plans

Happy December to all of you reading this!

At the moment, I’m taking a break from CorgiDS… by working on another emulator project called DaneBoy (named after the Great Dane). Don’t fear though; I’m not doing this merely for diversion, but rather, for practice.

The UI for CorgiDS is written using Qt. While Qt makes C++ UI development easy, it does so by making itself extremely bloated. One effect of this is that Qt does a lot of work on the main thread, which is not good for emulators and any other projects that require lots of processing time. Since I’d rather not switch UI libraries, the solution is, of course, moving emulation over to a separate thread. Assuming negligible overhead from thread synchronization once a frame, this would boost FPS by 20-100%, depending on the game.

The catch? I’m not privy to multithreading, so I’m afraid to touch the CorgiDS codebase and risk introducing nasty bugs due to my lack of knowledge. Instead, DaneBoy will bear the brunt of my learning experiences. I’ll incorporate what I’ve learned into CorgiDS once I believe I’m not going to deadlock everything.

Before I started DaneBoy, I also created a little program that automatically generates a jump table for ARMv5 instructions. Unlike the Z80 in the Game Boy, ARM CPUs aren’t easily decoded using a giant switch block. The two options are either using an ugly mess of if-statements or creating a jump table with 4096 separate elements. CorgiDS used the former for a while, but I finally got around to rewriting that behemoth of the codebase a couple of days ago. I don’t know of the existence of any similar decoding programs, but if there aren’t any, I’ll release mine along with CorgiDS. This is so that anyone else developing an emulator that uses an ARM CPU can benefit from this.

I don’t plan on doing anything noteworthy with DaneBoy, nor do I even want to release it. This is just a practice project; CorgiDS is what I’m really concerned about. Either way, it’s actually pretty fun to work on a much simpler system than the DS. 🙂

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