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Comment by zandorg | Hacker News Reader

I don't like to reply to my own posts, but here goes.

It's closed source just at the moment. HexRays is closed too.

It can run on Linux or MacOSX as CLisp runs on those platforms. I just haven't started work on porting to new platforms.

It decompiles 6502 as a proof of concept. It can decompile other CPUs, but not fully.

The expiration is temporary. I intend to eliminate this.

Thanks for your comments, it's great to get feedback.

Just another thing: Check out the 'Samples' page to see what it can do with different CPUs.

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> I don't like to reply to my own posts

Please do! That kind of discussion a big part of HN.

(Since this is your own work, we added "Show HN" to the title.)

I have a few technical questions, as well as a few about your intentions with the software.

How does it handle interrupt calls to the OS? It's not an issue for Windows (because it's all done through library calls, right?) But DOS int21 and Linux int80, for example?

With the x86 work, is the logic all built around protected mode? I've been using IDA to examine/document the assembly of a DOS game, so I'd be interested in the behavior if it's fed real mode code. Further (and tying in to my previous question), the game uses Borland overlays through int3f (it seeks in the binary itself and loads new sections of code into memory, while running, before jumping into the newly-retrieved code). Would that kind of thing be possible to handle automatically? IDA seems to be hard-coded to look for the offset+length tables that are used, and finds the function entry points that way.

More on the business side, you've got a way to request a quote, and the impression I get is that your aim is to run a decompilation business. Where does that leave the software itself? As a proprietary technology that lets you differentiate your business? Or is it your plan to sell the software, release binaries, release code, or some combination? My perspective is that of a hobbyist with a curiosity for reverse engineering and a (strictly non-commercial) project to apply it to, and I'm trying to figure out where this software fits into my world.

About interrupt calls... If it finds such a call, all it has to do is look at the call's input registers (assuming they are in registers) and output the call with the 'logical' contents of the registers.

The x86 code is basically 32-bit Windows. I haven't got a 16-bit compiler. However, it should work for 16-bit. The key thing is that you can write specialised modules for each CPU, and the rest (loops, variables) are standardised.

On the business side... Basically, my 6502 decompiler works the best so I thought I could sell that. And as for x86, there are issues to do with structs & arrays, that I haven't had time to figure out.

As for the decompiler software, I plan to finish the x86 and ARM decompilers and sell them for a reasonable price (say, $150 for all CPUs, not just one). As noted, arrays & structs are a problem.

As for 'release code', anyone can write a CPU module, but I need to document it first.

Thanks for your comments.

can yours be used to reverse engineering SNES games? Feed it the rom and have it split out c code?

Absolutely, although some 6502 code is more friendly than others. SNES code can be very optimised compared to C64 code.

If you make sure the binary starts at address 0, and put in the right entry point (which will be somewhere in the SNES ROM), then it should decompile it fine.

Your first step will be to use the left-hand portion of the window to disassemble the NES ROM, and then once assembly files have been created, you decompile them on the right of the window. (this is all in the documentation of course).

How close is the SNES 65C816(-ish) code to NES 6502(-ish) code supported in the demo version of the program? I understand that they're from the same family, but I'd expect some incompatible extensions in the more-advanced chip, at least.

I haven't done any work on 65C816. Just 6502 so far.

It should be possible to make a 'CPU module' for the decompiler which takes into account the features of the 65C816 (such as 16-bit registers).

How do you deal with self-modifying code? My old FORTRAN compiler generated that 8080 target

Oh, this is written in Common Lisp? Very interesting!

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