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Setting Up Code Modifications

So, you're ready to dive into the code of the game? Let's get started!

In this tutorial, you will learn how to:

  • Set up the NSMB DS Code Template
  • Set up ARM GCC
  • Set up NCPatcher
  • Extract/Build your ROM

This guide will cover the "NCPatcher Standalone" method described in the code template as the steps are more synchronized between all operating systems.

Setting Up the Code Template

  1. Head over to the code template's GitHub
  2. Click on Code -> Download ZIP
  3. Now extract this zip and rename the folder to what you want to call your project (this will be referred to as your project root)

  4. Don't put any spaces in your folder name!

You have now set up the code template

Setting up ARM GCC
  1. Head to the Arm GNU Toolchain Download Page
  2. Now search (using CTRL/CMD + F) for AArch32 bare-metal target (arm-none-eabi) and download the correct installer for your operating system.
  3. Open the installer and install the toolchain.

  4. Pick a location without spaces to install the toolchain!

You have now set up ARM GCC

Setting Up NCPatcher

  1. Head over to the NCPatcher GitHub releases page
  2. Download the latest release for your operating system
  3. Extract NCPatcher

Now, NCPatcher depends on ncpatcher.json, so lets make it!

If you'd like to learn more about this file, head over to the NCPatcher GitHub!

In your project root, create the following files:

  • ncpatcher.json
    • Copy/Paste the following JSON into the file
{
"$arm_flags": "-masm-syntax-unified -mno-unaligned-access -mfloat-abi=soft -mabi=aapcs",
"$c_flags": "-Os -fomit-frame-pointer -ffast-math -fno-builtin -nostdlib -nodefaultlibs -nostartfiles -DSDK_GCC -DSDK_FINALROM",
"$cpp_flags": "-fno-rtti -fno-exceptions -std=c++20",
"$asm_flags": "-Os -x assembler-with-cpp -fomit-frame-pointer",
"$ld_flags": "-lgcc -lc -lstdc++ --use-blx",

"backup": "backup",
"filesystem": "nsmb",
"toolchain": "arm-none-eabi-",

"arm7": {},
"arm9": {
"target": "arm9.json",
"build": "build"
},

"pre-build": [],
"post-build": [],

"thread-count": 0
}

You have now set up NCPatcher

Extracting, Building, and Repackaging Your ROM

If you're on Windows
  1. Download fireflower.zip and extract it.
  2. Move nds-build.exe and nds-extract.exe out from the folder
If you're on macOS/Linux
  1. Download nds-extract.zip
  2. Download nds-build.zip
    • If these links are down, you can also find these files in our Discord
  3. Extract both ZIPs

Now, you need to build the tools.

For NDS Extract:

  1. Open a new Terminal window in the folder of the code
  2. Run this command: g++ nds-extract.cpp -o nds-extract -std=c++20

For NDS Build:

  1. Open a new Terminal window in the folder of the code
  2. Run this command: g++ nds-build.cpp -o nds-build -std=c++20

From here on, the instructions will work for all operating systems. If you are on Windows 10, you can use Command Prompt instead of Terminal

Extracting Your ROM
  1. Open a Terminal window in your project root
  2. Run this command: /path/to/nds-extract rom.nds nsmb

Replace /path/to/ with the actual file path to nds-extract. Also replace "rom" with the actual name of your .nds file

This will extract the contents of your ROM into a folder named nsmb

You have extracted your ROM

Building Your ROM

This step will compile and patch your ROM with any code files found in the source directory in your project root. The Code Template comes with a few examples included in the source directory.

  1. Open a Terminal window in your project root
  2. Run this command: /path/to/ncpatcher

Replace /path/to/ with the actual file path to ncpatcher

You have built your ROM

Repackaging Your ROM

nds-extract depends on buildrules.txt, so let's create it!

  • buildrules.txt
    • Copy/Paste the following text into the file:

rom_header NSNDY/header.bin
arm9_entry KEEP
arm9_load KEEP
arm7_entry KEEP
arm7_load KEEP
fnt nsmb/fnt.bin
file_mode ADJUST
arm9 nsmb/arm9.bin
arm7 nsmb/arm7.bin
arm9ovt nsmb/arm9ovt.bin
arm7ovt nsmb/arm7ovt.bin
icon nsmb/banner.bin
rsa_sig nsmb/rsasig.bin
data nsmb/root
ovt_repl_flag 0xFF
ov9 nsmb/overlay9
ov7 nsmb/overlay7

This step will take the files form the nsmb folder and repackage them into a .nds file

  1. Open a Terminal window in your project root
  2. Run this command: /path/to/nds-build buildrules.txt NSMB.nds

Replace /path/to/ with the actual file path to nds-build.

You have repackaged your ROM

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