/DigimonWorldDisassembly

Primary LanguageC++

Digimon World PC Disassembly

This repository hosts a reconstructed code base for the Korean‑exclusive PC port of Digimon World. It contains a Visual Studio solution (digi_analysis.sln) and C++ sources that mirror the behaviour of the original digi.exe executable as much as possible. Only a handful of small functions have been reimplemented so far, but the foundation is in place for more ambitious reverse‑engineering efforts.

Project layout

The digi_analysis/ directory contains the core of the reconstruction. It includes:

  • main.cpp – A Win32 entry point demonstrating the rebuilt functions and extracted string data. It calls into the reconstructed table lookup functions and shows a sample of the decoded strings via a Windows message box.

  • functions.cpp – Hand‑reconstructed implementations of a few simple routines located near the start of the original executable (addresses 0x401000–0x401050). In this updated version two of those routines (func_401000 and func_401020) are implemented using inline x86 assembly to more closely match the original code. The other wrappers remain ordinary C++.

  • digi_table.h / digi_table.cpp – A 4 KiB lookup table used by the above routines. In the real project this table contains precomputed sine values extracted from the game. To keep this example lightweight the table is initialised to all zeros; replace it with the full dataset when accuracy is important.

  • strings.h / strings.cpp – A collection of wide strings extracted from the game binary along with the count of entries. Because the PC port uses a mixture of Korean and high‑ASCII characters, the strings are stored as UTF‑16 constants. Only a small subset of the original strings is included here for demonstration purposes.

  • functions.h – Declarations for the reconstructed functions.

  • hooks.cpp / hooks.h – Infrastructure for installing runtime hooks into the original digi.exe. Hooks allow you to redirect calls from the original code to your reconstructed C++ implementations. This version uses MinHook instead of manually writing relative jumps; MinHook simplifies creation and management of multiple hooks and preserves original function pointers so you can call into the game as needed.

  • third_party/minhook/ – A vendored copy of the MinHook library. Only the source and header files are included; you will need to compile them into your DLL project as appropriate. See hooks.cpp for an example of how to initialise and use MinHook.

  • sub_004A1F8A.cpp / sub_004A1F8A.asm – A stub implementation and disassembly listing for the routine at address 0x004A1F8A in the original game. The C++ stub simply emits a debug message so that you can verify the hook is firing. Replace the body of this function as you reverse‑engineer the real behaviour.

  • digi_analysis.sln / digi_analysis.vcxproj – Visual Studio solution and project files configured for building a Win32 DLL. The project targets a DLL so that hooks can be injected into the running game. If you prefer to build an application instead, you can switch the project type back to an EXE and adjust the entry points accordingly.

Building

To build the code on Windows:

  1. Install Visual Studio 2022 (Community edition is fine) with the Desktop development with C++ workload.
  2. Open digi_analysis.sln and allow Visual Studio to restore any missing packages or upgrade the solution if prompted.
  3. Ensure the platform is set to Win32 and the configuration is either Debug or Release.
  4. Build the solution (Build → Build Solution). The resulting DLL should compile without errors. When run via an injector, it will patch the specified addresses in the game and demonstrate the reconstructed functions and a sample of the extracted strings.

If you are working on a non‑Windows host, it is possible to build the code with MinGW or cross‑compile using a toolchain like x86_64‑w64‑mingw32, provided you supply Windows headers. Note however that the current entry points use Win32 functions to demonstrate functionality.

Hooking the original executable

As you disassemble more of digi.exe, it becomes useful to test your reconstructed functions in the context of the original game. The hooks.cpp and hooks.h files show how to use MinHook to create detours. MinHook offers a clean API for creating, enabling and disabling hooks, and it can automatically preserve the original function pointers so you can call back into the game when necessary. The stub sub_004A1F8A.cpp shows how to implement a detour for a new function: log or inspect arguments, then invoke the original behaviour through the saved pointer.