These projects are really neat. Last week, I was able to build (and play) the Xbox 360 release of Sonic Unleashed on a couple of ARM SBCs using Sonic Unleashed Recomp.
Significant progress made on Xbox 360 recompilation
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Re: Significant progress made on Xbox 360 recompilation
#12Crazy that it has taken so long. I understand these are small teams trudging off in the dark but you could have imagined there would have been more eyes on this and hands tinkering in the time when the Xbox 360 was being sold than today. Right at that same time in history the iPhone was getting cracked basically every iOS release, sometimes by teenagers. Seems like there were a ton of hackers around back then.
Most people just want emulation which was solved a while ago. Recompilation is mostly for modders which is a very small community.
Re: Significant progress made on Xbox 360 recompilation
#13What is Xbox 360 recompilation?
You take an Xbox game designed to run on an Xbox 360, a 64 bit PowerPC system and decompile its binaries back into source code. You now have the ability to modify the game as well as port it to other systems and architectures such as Windows on X86_64 or Linux on ARM64.
It's more nuanced than that; the approach you're describing is usually called "decompilation."
The difference is how far one goes in hoisting the "source code;" in this "recompliation" approach the source code, while C++, is basically an IR (intermediate representation) between the original game's assembly and a host platform, and the hardware itself is emulated (for example, the original architecture's CPU registers are represented as variables in the host architecture's memory). The machine code is translated to C++ using a custom tool.
In a "decompilation" approach the game logic is converted (using a decompiler, like IDA or Ghidra's) back into something which resembles the original source code to the game itself, and the source code is usually hand analyzed, marked up, rewritten, and then ported across platforms. The product is something that attempts to resemble the original game's source code.
Of course, they lie on a continuum and both approaches can be mixed, but, while they both involve C++ in the middle, the process is starkly different. Recompilation is much more copyright-friendly, because in many implementations only the modifications are distributed and the original binary is translated by the end user (who owns the software/a license to it), whereas decompilation produces an artifact (source code) which is a derivative work encumbered by the original software's license and generally should not be distributed.
Re: Significant progress made on Xbox 360 recompilation
#14Earlier quoted context omitted.
You take an Xbox game designed to run on an Xbox 360, a 64 bit PowerPC system and decompile its binaries back into source code. You now have the ability to modify the game as well as port it to other systems and architectures such as Windows on X86_64 or Linux on ARM64.
Seeing this [1], I thought it was something related to taking assembly instructions in the original code, emitting C statements that match the instruction, and then compiling that C code. [1] https://github.com/N64Recomp/N64Recomp
Your idea is much more accurate; see my sibling comment. It's basically using C or C++ as an intermediate representation for machine code, rather than trying to recreate the game's higher-order logic/structure or source code.
Re: Significant progress made on Xbox 360 recompilation
#15The blog post reminds me of similar efforts with Shockwave. There's people building decompilers, and runtimes, and if you join enough Discords, you will notice the people in them are cross-contaminating between communities if you will, they share insights with one another, in their efforts towards specific goals. They're hyper focused on making one game or another come back. There's Habbo Hotel, and Coke Studios, as…
I have a lot of respect for little communities where people gather to work obsessively over a goal like this. It's fun to see projects like this that would never see this much effort applied if not for the passion of a few dedicated people.
Many of the smartest people I've known got their starts in little communities like these: Obsessively learning new things that would normally be beyond their academic or career level because they need to know something advanced to move their passion project forward.
Re: Significant progress made on Xbox 360 recompilation
#16Hey, that's my newsletter -- thanks for sharing! :D
Some exciting stuff has already happened in the week since I wrote the interview. Here's Viva Pinata: Trouble in Paradise: https://www.youtube.com/watch?v=Kih42KlocII
Re: Significant progress made on Xbox 360 recompilation
#17Years ago I was searching for why emulators don't recompile to native bytecode and it seemed like the consensus at the time was that JIT etc was faster. I can't find it now, but IIRC I remember replies from maintainers saying it was a bad idea.
What changed since then, since this seems to be a trend? Is this more for more modern systems that have more static code?
Re: Significant progress made on Xbox 360 recompilation
#18Earlier quoted context omitted.
You take an Xbox game designed to run on an Xbox 360, a 64 bit PowerPC system and decompile its binaries back into source code. You now have the ability to modify the game as well as port it to other systems and architectures such as Windows on X86_64 or Linux on ARM64.
It's more nuanced than that; the approach you're describing is usually called "decompilation." The difference is how far one goes in hoisting the "source code;" in this "recompliation" approach the source code, while C++, is basically an IR (intermediate representation) between the original game's assembly and a host platform, and the hardware itself is emulated (for example, the original architecture's CPU registers…
> In a "decompilation" approach the game logic is converted (using a decompiler, like IDA or Ghidra's) back into something which resembles the original source code to the game itself, and the source code is usually hand analyzed, marked up, rewritten, and then ported across platforms
There definitely is a lot of scope to apply LLMs here
Re: Significant progress made on Xbox 360 recompilation
#19Years ago I was searching for why emulators don't recompile to native bytecode and it seemed like the consensus at the time was that JIT etc was faster. I can't find it now, but IIRC I remember replies from maintainers saying it was a bad idea. What changed since then, since this seems to be a trend? Is this more for more modern systems that have more static code?
It's a combination of things. The floodgates were opened when the N64 recompiler popped up a couple (?) of years back. Really got interest going.
I also think tooling got better, and with the advent of AI engineering it made all of this a lot more accessible.
Re: Significant progress made on Xbox 360 recompilation
#20Hey, that's my newsletter -- thanks for sharing! :D Some exciting stuff has already happened in the week since I wrote the interview. Here's Viva Pinata: Trouble in Paradise: https://www.youtube.com/watch?v=Kih42KlocII
Was playing that last night. So many great recomps lately. Ty for the newsletter