sotn-decomp

Most decomp projects (that I know of) are Ship of Theseus style projects where the minimum unit is a function, give or take alignment requirements and quirks of the compiler. On the MIPS side, tools like Splat and SPIM can help identify function and even source file boundaries, generate inline ASM C files[0], and write linker scripts to build a matching binary. You can then go through and replace the ASM functions one at a time until you just have C left. 0 - for example: https://github.com/Xeeynamo/sotn-decomp/blob/master/src/boss...

I gave a talk at Game On Expo about decompiling Castlevania: Symphony of the Night (https://github.com/xeeynamo/sotn-decomp ) earlier this year and talked a little bit about exactly this. Almost everyone who works on loves the game. After that, motivation varies: some want to see ports, some want to mod, some want to learn everything they can, some want to preserve. Along with those I also like the challenge (not unlike sudoku). Doing it long enough requires learning compiler history and theory, understanding business and engineering pressures of making the game, and occasionally reveals why parts of the game work the way they do. I stream working on SotN and am happy to answer any questions in chat if you’re interested in learning more - https://m.twitch.tv/madeupofwires/home

While we're here I'll give a shoutout to the Castlevania: Symphony of the Night decomp which is coming along pretty well too (still lots to do) https://github.com/Xeeynamo/sotn-decomp

We use a tool named dirt-patcher[0], which was written for the project. It lets you write arbitrary bytes at specified offsets[1]. As far as we know at this time, they’re just uninitialized bytes that would have been padding for alignment or other reasons anyway. Maybe if we move to an official build tool chain we’ll find they are deterministic, but for now, we believe they are garbage that happened to make it into the final binary. 0 - https://github.com/Xeeynamo/sotn-decomp/blob/master/tools/di... 1 - https://github.com/Xeeynamo/sotn-decomp/blob/master/config/d...

This is awesome! I've been doing some PSX decompiling and there are lots of similar things there as well. Interestingly, something like `memmove` is linked in using an SDK library[0], but `strcpy` is a function provided by the BIOS. Later version of the SDK could patch that out for a library version, but as late as 1997 it hadn't been. 0 - https://github.com/Xeeynamo/sotn-decomp/blob/master/src/main...