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80 lines
3.6 KiB
Markdown
80 lines
3.6 KiB
Markdown
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[← Home](../README.md) · [Reverse Engineering](README.md)
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# Ghidra Setup for Amiga 68k Binaries
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## Requirements
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| Component | Version / Notes |
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|---|---|
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| Ghidra | 10.x+ or 11.x+ recommended |
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| Processor module | M68k — included in Ghidra standard install |
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| HUNK loader & Amiga extensions | **ghidra-amiga** by BartmanAbyss |
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---
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## Step 1: Install the Amiga Extension
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Ghidra natively supports the M68000 architecture and includes a powerful decompiler for it, but it does not understand the Amiga OS executable format (HUNK) out of the box.
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1. Download the latest release of `ghidra-amiga` from: https://github.com/BartmanAbyss/ghidra-amiga
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2. Open Ghidra.
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3. Go to `File → Install Extensions...`
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4. Click the green `+` (Add extension) button.
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5. Select the downloaded `.zip` file (do not extract it).
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6. Restart Ghidra.
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This essential extension provides:
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- A complete Amiga HUNK format loader.
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- Custom chipset register definitions mapped to `$DFF000`.
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- OS library LVO (Library Vector Offset) definitions.
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- Analyzer scripts specifically for resolving Amiga binaries.
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---
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## Step 2: Importing and Analyzing
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1. Create a new project or open an existing one.
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2. Select `File → Import File...` and choose your Amiga executable or library.
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3. The format should automatically be detected as `Amiga Executable` (thanks to the extension).
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4. Double-click the imported file to open it in the CodeBrowser.
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5. When prompted to analyze, click **Yes**.
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6. Ensure the `Amiga` analyzers (provided by the extension) are enabled in the analysis options list before hitting Analyze.
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---
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## Step 3: Decompilation and M68k Specifics
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Unlike IDA Pro (which lacks Hex-Rays support for M68k), **Ghidra's built-in decompiler fully supports the Motorola 68000 family.**
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- The `ghidra-amiga` extension actively assists the decompiler by automatically annotating library calls (like `exec/AllocMem` or `dos/Open`) when it detects jumps to negative offsets on `A6`.
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- The decompiler will translate these `JSR` instructions directly into C pseudocode function calls with the correct parameters, making it vastly superior for analyzing C/C++ compiled Amiga software.
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---
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## Step 4: Custom Hardware Registers ($DFF000)
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The `ghidra-amiga` extension automatically creates memory blocks for Amiga custom chips and CIA registers.
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1. Go to `Window → Memory Map`. You will see `custom` ($DFF000), `ciaa` ($BFE001), and `ciab` ($BFD000) accurately mapped into the address space.
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2. The extension automatically defines the Amiga Custom Chip data types.
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3. When analyzing code that bangs the hardware (e.g., `move.w d0, $096(A4)`), if Ghidra knows `A4` is `$DFF000`, it will automatically format it as `custom->dmacon` in the C pseudocode!
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4. If it fails to detect the base register automatically, you can manually set the register value by highlighting the start of the function, right-clicking, and selecting `Set Register Values` (or `Ctrl-R`), then defining `A4 = 0xDFF000`.
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---
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## Step 5: Dynamic Analysis
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Ghidra is purely for **static analysis**.
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For dynamic debugging, the workflow is identical to IDA:
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1. Do your mapping and decompilation in Ghidra.
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2. Note the physical addresses and offsets.
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3. Run the binary in WinUAE and drop into the native debugger (`Shift+F12`) to set breakpoints and step through the hardware state live.
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---
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## References
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- [ghidra-amiga by BartmanAbyss](https://github.com/BartmanAbyss/ghidra-amiga) — The definitive Amiga loader and extension suite for Ghidra.
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- [Ghidra Official Website](https://ghidra-sre.org/)
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- [vscode-amiga-debug](https://github.com/BartmanAbyss/vscode-amiga-debug) — Excellent extension for source-level Amiga debugging if you are writing modern Amiga patches.
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