Unsupported mappers for all LibRetro-based NES emulator

[barbudreadmon]

@xuancong First time i see a nes game Mesen can't run, are you sure that rom isn't corrupt ?

edit : actually, i can see the code for this mapper in Mesen, so i'm pretty sure this rom is simply corrupt

[mitu]

@barbudreadmon said in Unsupported mappers for all NES emulator:

actually, i can see the code for this mapper in Mesen,..

..which references the implementation from Nestopia :).

pretty sure this rom is simply corrupt

or maybe not headered ?

[barbudreadmon]

@mitu said in Unsupported mappers for all NES emulator:

..which references the implementation from Nestopia :).

That's kinda surprising from Mesen's author to copy the implementation without testing it at all, but it might indeed be the case.

The rom is properly headered :

[libretro INFO] File CRC32: 0xB4597478
[libretro INFO] PRG CRC32: 0x746E2815
[libretro INFO] PRG+CHR CRC32: 0xBE1713C7
[libretro INFO] [iNes] Mapper: 252 Sub:0
[libretro INFO] [iNes] PRG ROM: 256 KB
[libretro INFO] [iNes] CHR ROM: 128 KB
[libretro INFO] [iNes] Mirroring: Vertical
[libretro INFO] [iNes] Battery: Yes

[xuancong]

The ROM is 100% not corrupted. As a proof, download the SMYNES emulator here to open the ROM:
removed
Since it is in Chinese, you just need to double-click mapper252.nes in the ROM list.
It can be run in Linux using wine:
LC_ALL=zh_CN.UTF-8 wine SMYNESC.EXE

This is just an example showing the incompleteness of the existing NES emulators. I am pretty sure there are more ROMs that cannot be played due to incomplete mapper set.

[mitu]

@xuancong You've not provided any info about your setup or answered the questions asked.
Also, I told you not to post links to ROMs - please don't do it again.

[xuancong]

@mitu Sorry, here is the link without the ROM, https://gofile.io/d/8SyJ9b
I have tested it on RetroPie on both PC and Raspberry Pi 4, tried every NES emulator core, none works.
Neither does it work on Batocera, Lakka, Recalbox, etc. because they all use the same set of NES emulator cores.

[mitu]

@xuancong said in Unsupported mappers for all LibRetro-based NES emulator:

I have tested it on RetroPie on both PC and Raspberry Pi 4, tried every NES emulator core, none works.

You're really not providing any meaningful information. Which emulators have you tried ? Don't say 'every core', just list every emulator you've tried.

What's the name of the game you're trying to run ?

Just because that ROM works in an emulator, doesn't mean it's correct, some emulators support hacked roms that are not correctly dumped or modified and are not compatible with the majority of the - standard - emulators.

[xuancong]

@mitu I said already, "every emulator" means if you can find an emulator (not my SMYNES) that can run it successfully, then you can ignore this post and the problem gets solved.

[mitu]

@xuancong as you wish. Without any actionable info, we can't help you here.

[xuancong]

@mitu Sorry, I still do not quite understand what do you mean by "which emulator"?
It is an NES rom, so obviously it is NES emulator.
Or are you referring to the emulator selector which pops up when I click on the ROM (as show below)?

As I said, all the above 4 emulators cannot load this ROM.

[barbudreadmon]

@xuancong said in Unsupported mappers for all LibRetro-based NES emulator:

The ROM is 100% not corrupted. As a proof, download the SMYNES emulator here to open the ROM:

That's no proof at all, some emulators have been using workarounds to allow broken dumps to be playable for decades, and there is no way to know what's happening internally in your closed-source non-free emulator.

Are there other games using that mapper ?
Are there other emulators running this rom ? You mention bizhawk supported mapper list but did you actually test this rom in bizhawk ? Nestopia and Mesen supposedly also support this mapper, but none of them actually run your rom properly.

Edit : i found a reference to this mapper and game (chinese port of "Sangokushi - Chuugen no Hasha" ?), but it says the crc should be 8b7ee49b, while yours is b4597478, so yet again i think your rom might be corrupt.

[mitu]

@xuancong said in Unsupported mappers for all LibRetro-based NES emulator:

@mitu Sorry, I still do not quite understand what do you mean by "which emulator"?

Which emulator : I tried lr-nestopia, lr-fceumm, etc. . - this is what I expected. RetroPie has several emulators and you may have not used every one.
For instance your listing doesn't include lr-mesen (as @barbudreadmon mentioned earlier) which is only available for PI3 and up Pi models, but since you didn't even mention what platform you're trying (as asked in https://retropie.org.uk/forum/topic/3/read-this-first), I'm not sure you've tried every emulator.

As @barbudreadmon said, the mapper you mention (252) is supported by several NES emulators present in RetroPie, but your ROM may not be correct.

The game seems similar to San Guo Zhi (Ch), which is using the 252 mapper and works (at least with Mesen and Nestopia):

[libretro INFO] Loading rom: San Guo Zhi (Ch) [b2].nes
[libretro INFO] File CRC32: 0xDC8838E9
[libretro INFO] PRG CRC32: 0xD03B3051
[libretro INFO] PRG+CHR CRC32: 0xD6C65F56
[libretro INFO] [iNes] Mapper: 252 Sub:0
[libretro INFO] [iNes] PRG ROM: 256 KB
[libretro INFO] [iNes] CHR ROM: 128 KB
[libretro INFO] [iNes] Mirroring: Vertical
[libretro INFO] [iNes] Battery: Yes
[libretro INFO] [DB] Game not found in database
[libretro INFO] [Game loaded (NTSC)] San Guo Zhi (Ch) [b2]

Screenshots also look similar, but I don't think know if it's the same

I think @barbudreadmon is right, you have an incorrect ROM.

[barbudreadmon]

@mitu said in Unsupported mappers for all LibRetro-based NES emulator:

The game seems similar to San Guo Zhi (Ch), which is using the 252 mapper and works (at least with Mesen and Nestopia):

Thanks for confirming. I got my hand on that other rom using mapper 252 and i can confirm it works properly on my side.