Question 1

How do I create a symbol file for mgbdis?

Accepted Answer

You can generate a .sym file by using the Beaten Dying Moon emulator, which tracks executed instructions during gameplay to define code blocks. Place the .sym file in the same directory as the ROM with the same name and .sym extension for mgbdis to use it.

Question 2

Is mgbdis better than radare2 for Game Boy ROMs?

Accepted Answer

mgbdis excels in outputting RGBDS-compatible assembly for reassembly and modding, with built-in graphics extraction. In contrast, radare2 is a general-purpose reverse engineering tool with more features but may not produce directly reassemblable code, making mgbdis better for homebrew development.

Question 3

How to extract sprite images from a Game Boy ROM using mgbdis?

Accepted Answer

Define image blocks in the .sym file using the .image magic label with parameters like width (e.g., w128) and palette (e.g., pE4). After running mgbdis, PNG files will be output in the /gfx directory, and the makefile can rebuild them into tile data.

Question 4

Why does mgbdis output data bytes for STOP instructions?

Accepted Answer

RGBDS automatically adds a NOP after STOP instructions, so mgbdis outputs STOP as a data byte if the original ROM lacks a following NOP. This ensures accurate reassembly but may require manual review to avoid disassembly errors in code blocks.

Question 5

Can mgbdis handle Game Boy Advance ROMs?

Accepted Answer

No, mgbdis is specifically designed for the Game Boy and Game Boy Color with the SM83 CPU architecture. For GBA ROMs, you would need a different disassembler compatible with ARM, such as Ghidra or specialized tools for that platform.

Question 6

How to improve mgbdis speed on large ROMs?

Accepted Answer

The README notes performance issues on large ROMs, and there are no built-in optimizations. To mitigate this, consider splitting the ROM into smaller sections, using a faster machine, or relying on symbol files to reduce disassembly scope, but speed remains a limitation.

mgbdis

What is mgbdis?

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