Gameboy Emulation in Javascript and HTML5

http://imrannazar.com/GameBoy-Emulation-in-JavaScript

by elblanco • 16 years ago

47 7 16 years ago

thristian2• 16 years ago

I'd like to see somebody using the tracing-compiler technique outlined by Robert O'Callahan in an emulator for a real-life hardware system:

http://weblogs.mozillazine.org/roc/archives/2010/11/implemen...

sparky• 16 years ago

Am I misunderstanding or does his "tracing" stop at the basic block level? While basic blocks are completely predictable traces through the program, they are usually very short. You can get much more benefit by finding long common traces through multiple basic blocks and compiling the whole thing as a unit, providing tests and/or fixup code in case you find you actually needed to branch somewhere else in the middle of a trace. This is what I think most compiler people would call a "tracing JIT."

thristian2• 16 years ago

Hm, that's a good point. For some reason I assumed it would trace through unconditional branches, but the post I linked to does indeed say "I terminate the trace after any branch instruction", not "any conditional branch instruction". That seems like quite a missed opportunity; I wonder why the code has that restriction.

daeken2• 16 years ago

I did this last year: http://daeken.github.com/Dyna6502Asm/

I took the awesome 6502 emulator from http://6502asm.com/ and converted it to accumulate instructions from each basic block, turn them into functions, caches them, and let the JIT do its magic. While I never benchmarked it, I'd say it got between a 5x and 20x speedup on most things. It breaks certain self-modifying code (never bothered to add cache invalidation), but overall it works well.

bryanh• 16 years ago

When I see these sorts of things, I like to imagine that in 10 years we'll be playing Doom 3 run off Javascript in a browser.

You know, march of progress and all.

corysama• 16 years ago

It'll be a lot less than 10 years. We can already play Quake2 running on JavaScript in the browser.

http://tatari.se:8080/GwtQuake.html

Gameboy Emulation in Javascript and HTML5

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