Nds Decompiler [top] Site

Decompiling a Nintendo DS (NDS) ROM is a multi-step process that involves unpacking the ROM file, identifying the target processor architecture, and using a static analysis tool to convert machine code back into human-readable C-like pseudocode. 🏗️ Step 1: Unpacking the ROM

A .nds file is a container for various binaries and assets. Before decompiling, you must extract these components.

ndstool: The industry-standard command-line tool for unpacking and repacking NDS files.

DSLazy: A popular graphical interface for ndstool that simplifies extraction to a single click. Files to look for: arm9.bin: The main code for the primary processor.

arm7.bin: Code for the secondary processor (handles audio and Wi-Fi).

overlays/: Small chunks of code loaded into memory dynamically. 🛠️ Step 2: Choosing a Decompiler

Since the NDS uses the ARMv5TE architecture, you need a tool capable of translating this specific instruction set. 1. Ghidra (Free & Open Source)

Developed by the NSA, Ghidra is the most accessible tool for hobbyists.

Pros: Free, includes a high-quality decompiler, and supports collaboration. NDS Setup: Requires setting the language to ARM:LE:32:v5t.

Essential Plugin: NTRGhidra is a specialized loader that automatically handles NDS-specific memory mapping and overlays. 2. IDA Pro (Industry Standard) The premier tool for professional reverse engineering.

Unlocking the Code: A Guide to NDS Decompilers Nintendo DS (NDS) decompilation has evolved from simple resource extraction to sophisticated reverse engineering that can recreate human-readable C code. Whether you're looking to mod a classic, fix legacy bugs, or study game logic, choosing the right tool is the first step. Essential Decompilation Tools

The "best" decompiler depends on your budget and technical goals. Most modern workflows involve a combination of the following:

Ghidra: A powerful, free, open-source suite developed by the NSA. It is highly favored by hobbyists because it includes a built-in decompiler that outputs C-like pseudocode.

IDA Pro + Hex-Rays Decompiler: Considered the industry standard for professional reverse engineering. While highly effective and feature-rich, the full version carries a significant cost, making it less accessible for casual modders.

ds-decomp: A specialized toolkit designed specifically for extracting and rebuilding DS ROMs.

NDS-Decompilation-Project-Maker: A utility that helps organize decompilation projects by generating symbol files and identifying ARM9 sections. The NDS Reverse Engineering Workflow nds decompiler

Decompiling an NDS ROM isn't a one-click process. It typically follows these stages: How to reverse engineer your favourite game

Summary

If you are looking for a "One-Click NDS Decompiler," it does not exist. The process requires:

1. Extracting the ARM9 binary.
2. Loading it into Ghidra.
3. Analyzing the Assembly/Pseudo-C code manually.

If you are interested in a specific game, search GitHub to see if a decompilation project (matching repo) already exists for it.

You're looking for information on developing a decompiler for the Nintendo DS (NDS) console. A decompiler is a tool that takes compiled machine code and converts it back into a higher-level programming language, such as C or assembly code.

Background

The Nintendo DS is a handheld game console released in 2004, which uses a dual-core ARM9 and ARM7 processor. The console's games and applications are typically developed using a combination of C, C++, and assembly languages, and are compiled into ARM machine code.

Decompiler goals

Developing an NDS decompiler would involve creating a tool that can:

1. Disassemble ARM machine code into assembly code.
2. Analyze the disassembled code to identify high-level structures, such as functions, loops, and conditional statements.
3. Reconstruct the original high-level code (e.g., C or C++) from the analyzed assembly code.

Challenges

Decompiling NDS games and applications poses several challenges:

1. Lack of debugging information: NDS games often don't contain debugging symbols or information, making it harder to identify functions, variables, and data structures.
2. Optimizations: Compilers often apply optimizations that make it difficult to reconstruct the original high-level code.
3. Proprietary formats: NDS games use proprietary file formats, which may require reverse-engineering to understand.

Existing tools and projects

There are some existing tools and projects that can help with NDS decompilation:

1. NDS disassemblers: Tools like bin3g and dsdecide can disassemble NDS firmware and games into assembly code.
2. ARM decompilers: Projects like RetDec and Miasm provide ARM decompilation capabilities.

Development steps

To develop an NDS decompiler, you could follow these steps:

1. Choose a programming language: Select a suitable language for your decompiler, such as C, C++, or Python.
2. Implement a disassembler: Use an existing disassembler or implement one from scratch to convert ARM machine code into assembly code.
3. Develop analysis and reconstruction modules: Create modules to analyze the disassembled code and reconstruct high-level structures and code.
4. Integrate with existing tools: Consider integrating your decompiler with existing tools, such as disassemblers or binary analysis frameworks.

Example use case

Suppose you want to decompile a popular NDS game like Pokémon Diamond. You could:

1. Dump the game's firmware: Use a tool like bin3g to extract the game's firmware.
2. Disassemble the firmware: Disassemble the firmware into assembly code using your chosen disassembler.
3. Analyze and reconstruct: Use your decompiler to analyze the assembly code and reconstruct the original high-level code.

Keep in mind that decompiling copyrighted materials, like games, may be subject to legal restrictions. Always ensure you have the necessary permissions or rights to work with the materials you're decompiling.

If you're interested in developing an NDS decompiler, I recommend exploring existing projects and tools, as well as researching the challenges and complexities involved in decompilation. Good luck!

Decompiling a Nintendo DS (NDS) game is a multi-step process that has become significantly more accessible with modern tools. Unlike simple "one-click" decompilers for high-level languages, NDS decompilation involves unpacking the ROM, decrypting its contents, and then using a reverse engineering suite to turn binary code back into readable C or assembly. 1. Essential Tools for Your Toolkit

To successfully decompile a DS game in 2026, you generally need a combination of these community-standard tools:

: A free, open-source reverse engineering suite developed by the NSA. It includes a powerful decompiler that can translate ARM machine code into C-like code. : A specialized Ghidra extension that allows you to load

ROM files directly into Ghidra, handling the complex memory mapping for you.

: A modern toolkit specifically designed to automate the setup of NDS decompilation projects, saving months of manual work by organizing code into translation units.

: Essential for decrypting retail DS cart images. You cannot analyze a ROM in Ghidra if it is still encrypted, as it will appear as "digital garbage".

: A versatile viewer and editor for NDS files. It is best used for extracting and converting non-code assets like images, text, and sounds. 2. The Decompilation Workflow

If you are looking to reverse engineer a specific title, the standard workflow follows these steps: AetiasHax/ds-decomp: Toolkit for decompiling DS games 3 Apr 2026 —

Part 2: The Toolchain – From Bits to C Code

No single tool performs full NDS decompilation. Instead, reverse engineers use a pipeline of tools.

2.1 Disassemblers: The First Step Before decompilation comes disassembly. Tools like Ghidra (developed by the NSA) or IDA Pro load an NDS ROM, detect the ARM/Thumb instruction sets, and produce assembly language. Ghidra, with its open-source nature, has become a cornerstone of NDS reverse engineering. It can automatically split the ARM9 and ARM7 binaries and begin the process of labeling functions. However, assembly is still far from the original source. A typical line of ARM assembly: STR R0, [R1, #0x14] might be equivalent to: gameState->score = currentScore;

2.2 Decompilers: Raising Abstraction The true decompiler (e.g., Ghidra’s built-in decompiler or the now-commercial Hex-Rays for IDA) attempts to lift assembly into a pseudo-C representation. For the NDS, this process is fraught with difficulty. The decompiler must identify function prologues and epilogues, reconstruct loops, infer data types, and recognize compiler idioms.

A successful decompilation from Ghidra for an NDS function might produce: Decompiling a Nintendo DS (NDS) ROM is a

undefined4 FUN_0203a4c8(void)
int i;
  for (i = 0; i < 4; i = i + 1) 
    FUN_0201b2e4(i);
return 0;

This is a massive improvement over raw hex, but it lacks semantic meaning. What does FUN_0201b2e4 do? What does the return value represent? The human reverse engineer must rename functions and variables, creating a Symbol Map.

2.3 The C++ Problem Most modern NDS games were written in C++, not C. Decompiling C++ is exponentially harder. Name mangling (where the compiler encodes class and namespace information into function names), virtual tables (vtables), inheritance hierarchies, and templates are nearly impossible to recover perfectly. An NDS decompiler can identify that a function is a constructor or a virtual call, but recovering the original class structure is a manual, detective process. Tools like Ghidra’s CPPAnalyzer plugin or retdec attempt to reconstruct classes, but they often produce approximations that require significant human correction.

2.4 Specialized NDS Tools Beyond general decompilers, the NDS scene has created specialized tools:

• NDSTool / mkdsmk: Unpack and repack ROMs.
• CrystalTile2: Views raw ROM data as tile graphics, aiding asset extraction.
• DeSmuME (Debugger): The open-source emulator includes a powerful debugger that allows step-by-step execution, memory watching, and breakpoints. This is crucial for dynamic analysis, where you observe code running to understand it.
• blz (GBATEK compression tools): Many NDS assets are compressed with proprietary algorithms (LZ77, Huffman, etc.). Decompression is a prerequisite to analysis.

4. Per-Game Decompilation Projects

The "Gold Standard" of NDS decompilation is creating a "Matching Build." This involves writing C code that, when compiled, produces the exact same binary as the original rom.

Community projects that have achieved this (or are close) include:

• Pokemon Diamond/Pearl: The pokeplatinum project is a famous example of a matching decompilation.
• Pokemon HeartGold/SoulSilver: Active projects exist.
• Mario Kart DS: Heavily reverse engineered.

Where to find these: These are typically hosted on GitHub. Searching for [Game Name] decompilation or [Game Name] matching usually yields results.

Conclusion: Embrace the Disassembly, Respect the Complexity

There is no NDS decompiler in the magical sense. But there is a powerful, mature ecosystem of disassemblers, pseudo-C decompilers (Ghidra, IDA), and script extraction tools. If you are willing to spend weeks learning ARM assembly and the DS’s quirky hardware registers, you can reconstruct 90% of a game’s logic.

The truth is, the Nintendo DS era sits at a perfect midpoint: recent enough that its CPUs are well-understood (ARMv5TE), but old enough that developers used optimization tricks that confuse automated decompilers. The ultimate NDS decompiler is you—the reverse engineer—using Ghidra as your magnifying glass and a hex editor as your scalpel.

So next time you see a forum post asking for "a tool to convert .nds to C source", you can reply: “There isn’t one. But here is how to start with Ghidra, a memory map, and a weekend of patience.”

Further Resources:

• GBATEK – The bible of NDS/ARM hardware.
• Ghidra NDS Loader script
• MelonDS debugger build
• #ndsdev on Libera.Chat IRC

Word count: ~1,650

Technical Overview: What is an NDS Decompiler?

An NDS decompiler is a tool (or set of tools) designed to translate machine code—binary instructions understood by the Nintendo DS hardware—back into a human-readable format, such as C or C++ source code.

This is rarely a "one-click" process. Unlike compiling (turning code into a game), decompiling is an investigative effort. The Nintendo DS presents unique challenges:

1. Dual Architecture: The NDS utilizes two processors: an ARM946E-S (main CPU for gameplay/graphics) and an ARM7TDMI (sub CPU for sound, touchscreen, and Wi-Fi). A decompiler must handle two different instruction sets simultaneously.
2. Proprietary File Systems: NDS ROMs are structured into a header, a FAT (File Allocation Table), and distinct overlays for code. A decompiler must first parse this filesystem before it can even begin to analyze the code.
3. Loss of Information: When a game is compiled, comments, variable names, and function names are stripped away. A decompiler sees function sub_02001234 rather than UpdatePlayerPosition().

Unlocking the Arm9: The Comprehensive Guide to NDS Decompilation

4. Existing Tools & Their Capabilities

| Tool | Decompilation Quality for NDS | Notes | |------|-------------------------------|-------| | Ghidra (with Sleigh ARM/Thumb) | Good – best free option | Handles Thumb mode switching if configured correctly; needs manual type restoration | | IDA Pro (Hex-Rays) | Very good (commercial) | Better at function boundary detection, but costly | | radare2 + r2dec | Fair | Requires extensive scripting for NDS specifics | | Decompiler Explorer (Dogbolt) | Not directly for NDS | Can compare Ghidra/IDA outputs for small functions | | no$gba debugger | No decompiler, but excellent dynamic analysis | Useful to verify decompiled logic | | NDSDis (custom scripts) | Limited | Old tool, mainly disassembly |

Key limitation: No tool automatically recovers NDS hardware register names (REG_DISPCNT, VRAM_BANK, etc.) or ARM7/ARM9 synchronization primitives. Extracting the ARM9 binary