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A Sega Saturn loader for Ghidra

License: Apache License 2.0

CSS 3.46% HTML 1.15% Java 95.40%

sega-saturn ghidra sh-2 sh-1 superh reverse-engineering

ghidra-segasaturn-loader's Introduction

Ghidra Sega Saturn Loader

A (WIP) Ghidra loader for the Sega Saturn. Currently supports:

ISO disc images
Mednafen Save States (MC)
Yabause Save States (YSS)

Grab from Releases or build from source.

Screenshots

Loader screenshot

Disassembly View w/Decompiler

How to Use

Sega Saturn ISOs

Select any Sega Saturn ISO file
At the "Container file detected" prompt, select "Single file"
The loader will create functions for main, initial program (the code that runs during the Sega logo), and security_check
Pros: Easy to use, useful for debugging game initialization, works great on Saturn homewbrew
Cons: Doesn't load any file after the first file on disc

Mednafen Save States (MC)

gunzip the Mednafen save state
Select the unzipped file in Ghidra
The loader will load backup cart memory, high work RAM, and low work RAM to the correct places
The loader will add labels for SH-2s PC, PR, and R15 registers

Yabause Save States (YSS)

Select any Yabause Save State (YSS)
The loader will load backup cart memory, high work RAM, and low work RAM to the correct places
The loader will add labels for SH-2s PC, PR, and R15 registers

Applying Sega Saturn Library Signatures

After loading in Ghidra, open "Script Manager" and execute ApplySig.py
Select the signature file to apply

Issues

Code quality needs serious improvement and refactoring
Memory map doesn't handle mirrored regions
Adding the onchip register region (0xffffffe00-0xffffffff) to the memory map made decompilation worse. So it's disabled.
It would be useful to label some globals to assist reversing
Mednafen memory cart data doesn't match Yabause's.

Building

gradle -PGHIDRA_INSTALL_DIR=<Absolute path to Ghidra>
The output zip file will be created within /dist

Installation

Ghidra 9.1 added SH-1/SH-2 support.
Copy the zip file to <Ghidra install directory>/Extensions/Ghidra.
Start Ghidra and use the "Install Extensions" dialog to finish the installation. (File -> Install Extensions...).
(Optional but recommended) Install the ApplySig script so you can use Sega Saturn library signatures. Copy to a ghidra_scripts directory.
(Optional but recommended) Download CyberWarriorX's Sega Saturn library signatures

Credits/References

Yabause - Sega Saturn emulator used to sanity check loader
cyberwarriorx/yssloader - YSS loader for IDA Pro
Sega Saturn SH-2 Memory Map
ISO 9660 Documentation
ApplySig - python script to load IDA Pro library signatures into Ghidra.
Sega Saturn Library Signatures - CyberWarriorX's Sega Saturn library signatures
Thank you to @mumbel, @loudinthecloud, and the Ghidra team for helping get the SuperH plugin merged to Ghidra
Thank you to @TrekkiesUnite118 for Java help and code review advice
Thank you to @CyberWarriorX for tons of amazing open source Saturn utilities

ghidra-segasaturn-loader's People

Contributors

Stargazers

Watchers

Forkers

resonancellc h0r1z0n 00mjk jollyrogerxp

ghidra-segasaturn-loader's Issues

Add Support for Bin/Cue

Similar to ISO, be able to load from Bin/Cue file.

VDP2 Registers are Named Incorrectly

When labelling the VDP2 registers the names of the SCU registers are used by mistake. The correct names can be found here: https://github.com/ijacquez/libyaul/blob/develop/libyaul/scu/bus/b/vdp/vdp2/map.h

"Too many sections big!!" error when loading Mednafen save state

Here is a Mednafen save state for Dungeons & Dragons Collection, Disc 1. It fails to load with this error:

----- Loading /C:/Games/Mednafen/mcs/Dungeons & Dragons Collection (Japan) (Disc 1) (Tower of Doom).458e98aeae4d21ae821a665722d2e5b9.mc0 -----
Too many sections big!!
java.io.IOException: Too many sections big!!
	at segasaturnloader.SegaSaturnLoader.mssMakeSectionMap(SegaSaturnLoader.java:1325)
	at segasaturnloader.SegaSaturnLoader.loadMednafenSaveState(SegaSaturnLoader.java:1689)
	at segasaturnloader.SegaSaturnLoader.load(SegaSaturnLoader.java:128)
	at ghidra.app.util.opinion.AbstractLibrarySupportLoader.doLoad(AbstractLibrarySupportLoader.java:724)
	at ghidra.app.util.opinion.AbstractLibrarySupportLoader.loadProgram(AbstractLibrarySupportLoader.java:98)
	at ghidra.app.util.opinion.AbstractProgramLoader.load(AbstractProgramLoader.java:126)
	at ghidra.plugin.importer.ImporterUtilities.importSingleFile(ImporterUtilities.java:368)
	at ghidra.plugin.importer.ImporterDialog.lambda$okCallback$7(ImporterDialog.java:351)
	at ghidra.util.task.TaskBuilder$TaskBuilderTask.run(TaskBuilder.java:306)
	at ghidra.util.task.Task.monitoredRun(Task.java:134)
	at ghidra.util.task.TaskRunner.lambda$startTaskThread$0(TaskRunner.java:106)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
	at java.base/java.lang.Thread.run(Thread.java:833)

Failed to parse MSS sections!
java.io.IOException: Failed to parse MSS sections!
	at segasaturnloader.SegaSaturnLoader.loadMednafenSaveState(SegaSaturnLoader.java:1692)
	at segasaturnloader.SegaSaturnLoader.load(SegaSaturnLoader.java:128)
	at ghidra.app.util.opinion.AbstractLibrarySupportLoader.doLoad(AbstractLibrarySupportLoader.java:724)
	at ghidra.app.util.opinion.AbstractLibrarySupportLoader.loadProgram(AbstractLibrarySupportLoader.java:98)
	at ghidra.app.util.opinion.AbstractProgramLoader.load(AbstractProgramLoader.java:126)
	at ghidra.plugin.importer.ImporterUtilities.importSingleFile(ImporterUtilities.java:368)
	at ghidra.plugin.importer.ImporterDialog.lambda$okCallback$7(ImporterDialog.java:351)
	at ghidra.util.task.TaskBuilder$TaskBuilderTask.run(TaskBuilder.java:306)
	at ghidra.util.task.Task.monitoredRun(Task.java:134)
	at ghidra.util.task.TaskRunner.lambda$startTaskThread$0(TaskRunner.java:106)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
	at java.base/java.lang.Thread.run(Thread.java:833)

Presumably this has something to do with the game's support for the 4MB RAM cartridge. I tried disabling the emulation of that, but got the same error.

Is there anything else I can do to work around this?

Thanks for reading, and for making this loader - I use it all the time!

Memory Map Doesn't Handle Mirrored Regions

Research into how to support mirrored memory regions. Currently the loader is simply over-defining a memory region.

Implement Sega Saturn Library Signatures

CyberWarriorX previously created Sega Saturn library signatures for use with IDA. Research into how to do that for Ghidra.

Memory Map: Add On-Chip Registers

Add support for on-chip registers. According to https://wiki.yabause.org/index.php5?title=SH-2CPU there in the region 0xFFFFFE00-0xFFFFFFFF.

CD_Base is Incorrect

//
// CD registers taken from: https://wiki.yabause.org/index.php5?title=CDBlock
//

final int CD_BASE = 0x20100000;

CD_BASE should be 0x25890000 according to the Yabause link referenced in the code. Credit user @Ced2911