Hacking [Q]Super Trim VC roms

[ETNWIND]

Card2romtrimtool does not limit how much you can trim. the default size is game size + 16mb save data size, but you can change the parameter to lower value.
But keep in mind that VC roms aren't like normal 3ds card2 roms, they don't have a fixed save size. Their save data is randomly distributed throughout the writable area, could be anywhere from few KB to 100+MB, and may continue to grow each time you save you game. Which mean the more you trim, the higher risk of corrupting save data. My suggestion is do not to trim VC roms.

 

[Mikecrowfone]

Card2romtrimtool does not limit how much you can trim. the default size is game size + 16mb save data size, but you can change the parameter to lower value.
But keep in mind that VC roms aren't like normal 3ds card2 roms, they don't have a fixed save size. Their save data is randomly distributed throughout the writable area, could be anywhere from few KB to 100+MB, and may continue to grow each time you save you game. Which mean the more you trim, the higher risk of corrupting save data. My suggestion is do not to trim VC roms.

The reason I'm trying to trim is because I find a 128mb 3ds file excessive for a 1mb gbc rom.

Also, I have managed to create my own custom GBC VC rom and it runs fine untrimmed. Afterwards, I trimmed the rom using 3dsexplorer. Opened the rom in a hex editor, changed the pointer (by default the pointed pointed to the end of the rom, but I added 1 to the value anyway. I then proceeded to add about 5mb worth of 00s to the end of the rom. When I launched this trimmed and hex edited rom on my 3ds, it says save corrupt, resetting data and it just gets stuck there.

 

[ETNWIND]

The reason I'm trying to trim is because I find a 128mb 3ds file excessive for a 1mb gbc rom.

Also, I have managed to create my own custom GBC VC rom and it runs fine untrimmed. Afterwards, I trimmed the rom using 3dsexplorer. Opened the rom in a hex editor, changed the pointer (by default the pointed pointed to the end of the rom, but I added 1 to the value anyway. I then proceeded to add about 5mb worth of 00s to the end of the rom. When I launched this trimmed and hex edited rom on my 3ds, it says save corrupt, resetting data and it just gets stuck there.

That's what I meant the more you trim, the higher risk of corrupting save data. Because VC roms don't have fixed save data size.

 

[Mikecrowfone]

That's what I meant the more you trim, the higher risk of corrupting save data. Because VC roms don't have fixed save data size.

But....

why don't you check the decrypted exheader to find the save size?

with the exception of the first few vc roms, they all have the save offset after the last ncch file.

edit:

Spoiler: spoiler alert

they all have a save size of 1M

 

[kyogre123]

The reason I'm trying to trim is because I find a 128mb 3ds file excessive for a 1mb gbc rom.

Also, I have managed to create my own custom GBC VC rom and it runs fine untrimmed. Afterwards, I trimmed the rom using 3dsexplorer. Opened the rom in a hex editor, changed the pointer (by default the pointed pointed to the end of the rom, but I added 1 to the value anyway. I then proceeded to add about 5mb worth of 00s to the end of the rom. When I launched this trimmed and hex edited rom on my 3ds, it says save corrupt, resetting data and it just gets stuck there.

´For custom VC, just do this:

TitleInfo:
UniqueId : 0x00000 <-- always customise this part

CardInfo:
MediaType : Card1 # Card1 / Card2
CardDevice : NorFlash # NorFlash / None

SystemControlInfo:
SaveDataSize: 512KB
RemasterVersion: 0
StackSize: 0x100000
There you go. It should work with most GBC games.

 

[ETNWIND]

But....

No, they don't. I did a lot of tests when I wrote the Card2TrimTool, the save size of VC roms are completely random.

 

[Mikecrowfone]

´For custom VC, just do this:

TitleInfo:
UniqueId : 0x00000 <-- always customise this part

CardInfo:
MediaType : Card1 # Card1 / Card2
CardDevice : NorFlash # NorFlash / None

SystemControlInfo:
SaveDataSize: 512KB
RemasterVersion: 0
StackSize: 0x100000
There you go. It should work with most GBC games.

So this in essence builds the GBC VC as a card1 hence making it possible to just simply trim the rom?

 

[ETNWIND]

Converting them to card1 rom is another way to trim them, but may not work for some games.

 

[kyogre123]

So this in essence builds the GBC VC as a card1 hence making it possible to just simply trim the rom?

Yes, but I think it won't work for all games (for example: Pokemon).

 

[Snailface]

So this in essence builds the GBC VC as a card1 hence making it possible to just simply trim the rom?

That's even a worse idea than trimming card2 roms.

You guys just keep randomly turning knobs and dials hoping something will work -- programming just doesn't work like that.

 

[Mikecrowfone]

That's even a worse idea than trimming card2 roms.

You guys just keep randomly turning knobs and dials hoping something will work -- programming just doesn't work like that.

Quite right. It does not work for Pokemon TCG.

So far the only reliable trimming for VC is via Card2TrimTool using 64mb parameter. Meh. I guess the smallest GBC VC file size is still current ~64mb

 

[ETNWIND]

Quite right. It does not work for Pokemon TCG.

So far the only reliable trimming for VC is via Card2TrimTool using 64mb parameter. Meh. I guess the smallest GBC VC file size is still current ~64mb

It's random. Could be smaller or bigger than 64MB. Even if you trim it to 64mb, it might work for some time, but there is no guarantee you save will not corrupt in the future.