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Magikoopa 3DS

From GameBrew - a wiki dedicated to Video Game Homebrew.

Magikoopa
Magikoopa.jpeg
General
Author(s)RicBent
TypeUtilities
Versionunknown
LicenceMixed
Links
Download
Website
Source
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Magikoopa

Compiles custom code for 3ds games and injects it into existing code.bin files and patches the exheader Motivation for this is to create a NSMB2 hack with fully custom code. In theory this should work with all other games as well tho. Work in progress. Should be in a kinda working state now. Might still have bugs that wait to be reported :) You can find examples on how to use Magikoopa in combination with NSMB2 here: https://github.com/RicBent/Magikoopa-NSMB2-Examples/

Getting started

  • Build the project in QtCreator.
  • Run Magikoopa in the build directory.

Hooks

Hooks can be specified with hks files in a patch's working directory. The format is similar to YAML:

hook_name_1:
type: xxx
link: false
addr: 0x00430988
func: FunctionNameHere
hook_name_2:
...

There are several types of hooks. | Type | Description | | - | - | | branch | Branch to a function (overwrites the original instruction) | | softbranch | Branch to a function (preserves the original instruction) | | patch | Patch data at an offset | | symbol | Write the address of a symbol | The following parameters are common to all hook types: | Parameter | Description | | - | - | | addr | Hook address |

Branch hooks

Parameter Description
link true to make a BL instruction, false for B
func (1) Branch destination function name. This will be converted to an address using the symbol table.
dest (2) Branch destination address
link and one of func and dest are required parameters.

Soft-branch hooks

Parameter Description
func (1) Branch destination function name. This will be converted to an address using the symbol table.
dest (2) Branch destination address
opcode "pre", "post" or "ignore". Defaults to "ignore" if not specified. "pre" to branch to func/dest after the original instruction, "post" to branch before the original instruction.
One of func and dest are required parameters.

Patch hooks

Parameter Description
data (1) Data to insert (in hexadecimal)
src (2) Symbol name of data to insert
len (2) Length of data to insert
data, or both src and len, are required parameters.

Thanks to

  • Dirbaio -- Creator of the NSMBDS asm patch template which was used as a basis
  • StapleButter -- Partial coding of the Filesystem classes
  • Icons8 -- Icons (https://icons8.com/)

Magikoopa Code patcher for 3ds games

Magikoopa is a tool that compiles custom code for 3ds games and inserts it into code.bin files and also allows to insert hooks into the original code to the inserted code allowing for example replacing functions. Because of memory segmentation it is not easy to add as much code to code.bin files as we want. To allow that we insert a small loader into the padding between the executable and data section that reprotects memory to our needs to mark perviously read-write only memory as executable.

Magikoopa features a nice UI that displays anthing that can go wrong during the compiling and inserting steps. It even allows you to jump directly to issues in code/hooks my clicking on the issues displayed in the UI.

Source Code: https://github.com/RicBent/Magikoopa

I will add better explaination how to use the tool and add builds when I make a bit more progress on it. You can also find examples working with NSMB2 here: https://github.com/RicBent/Magikoopa-NSMB2-Examples (The memory offsets in the example are based on the US Gold Edition)