@jimin's comment on 'Instead of spending years decompiling games for emulation now you can "recompile" them in less than 10 mins to play natively :marseyshook:'

!chuds !nonchuds emulationGODS :marseyembrace:

https://github.com/Mr-Wiseguy/Zelda64Recomp

Zelda 64: Recompiled is a project that uses N64: Recompiled to statically recompile Majora's Mask (and soon Ocarina of Time) into a native port with many new features and enhancements. This project uses RT64 as the rendering engine to provide some of these enhancements.

https://github.com/Mr-Wiseguy/N64Recomp

N64: Recompiled is a tool to statically recompile N64 binaries into C code that can be compiled for any platform. This can be used for ports or cowtools as well as for simulating behaviors significantly faster than interpreters or dynamic recompilation can. More widely, it can be used in any context where you want to run some part of an N64 binary in a standalone environment.

This is not the first project that uses static recompilation on game console binaries. A well known example is jamulator, which targets NES binaries. Additionally, this is not even the first project to apply static recompilation to N64-related projects: the IDO static recompilation recompiles the SGI IRIX IDO compiler on modern systems to faciliate matching decompilation of N64 games. This project works similarly to the IDO static recomp project in some ways, and that project was my main inspiration for making this.

The recompiler works by accepting a list of symbols and metadata alongside the binary with the goal of splitting the input binary into functions that are each individually recompiled into a C function, named according to the metadata.

Instructions are processed one-by-one and corresponding C code is emitted as each one gets processed. This translation is very literal in order to keep complexity low. For example, the instruction addiu $r4, $r4, 0x20, which adds 0x20 to the 32-bit value in the low bytes of register $r4 and stores the sign extended 64-bit result in $r4, gets recompiled into ctx->r4 = ADD32(ctx->r4, 0X20); The jal (jump-and-link) instruction is recompiled directly into a function call, and j or b instructions (unconditional jumps and branches) that can be identified as tail-call optimizations are also recompiled into function calls as well. Branch delay slots are handled by duplicating instructions as necessary. There are other specific behaviors for certain instructions, such as the recompiler attempting to turn a jr instruction into a switch-case statement if it can tell that it's being used with a jump table. The recompiler has mostly been tested on binaries built with old MIPS compilers (e.g. mips gcc 2.7.2 and IDO) as well as modern clang targeting mips. Modern mips gcc may trip up the recompiler due to certain optimizations it can do, but those cases can probably be avoided by setting specific compilation flags.

Every output function created by the recompiler is currently emitted into its own file. An option may be provided in the future to group functions together into output files, which should help improve build times of the recompiler output by reducing file I/O in the build process.

Recompiler output can be compiled with any C compiler (tested with msvc, gcc and clang). The output is expected to be used with a runtime that can provide the necessary functionality and macro implementations to run it.

An example of most of the required macro implementations can be found in the Zelda 64: Recompiled project here, with the project also containing accompanying code for implementing the rest of the required runtime.