SNES ROM Loader does not detect valid ROM

[ran-j]

I was trying to to use this plugin with TENCHI MUYO! 1.1 translated to English.

The plugin is installed correctly and the SNES ROM Loader appears in Ghidra's loader list. But when I importing the ROM, Ghidra defaults to Raw Binary because the SNES loader does not auto-detect the file as a supported SNES ROM.

After checking the ROM header manually, the ROM appears to be:

File size:        0x300200 bytes
SMC header:       0x200 bytes
Actual ROM size:  0x300000 bytes / 3 MiB / 24 Mbit
Internal header:  0x101C0 in the file
Title:            TENCHI MUYO! 1.1
Map mode:         0x31
Mapping:          HiROM / FastROM
Checksum:         0xCE1A
Complement:       0x31E5
Reset vector:     0x8000

The declare ROM size byte = 0x0B that means 2 MiB. But the actual file size is 3 MiB. Since this is a translated from japanese idk if this messup the ROM size.

Checking a bit of SnesRomHeaderDetector it seens that it will reject the room if

declaredRomSize < romSize

That seens to be my case:

declaredRomSize = 0x200000
romSize         = 0x300000

But again is just a theory.

[ran-j]

Check a bit more there is also a possible issue in checksum handling for 3 MiB / 24 Mbit ROMs.

For this 24 Mbit / 3 MiB ROM, the internal checksum appears to be calculated over a 4 MiB logical image, where the trailing 1 MiB block is mirrored once.