[GCN] Animal Crossing: Checksum help

[DsPet]

A little history:
A long time ago there was some interest in backporting the core AC:WW editor features to the AC:GC game.
Someone actually made progress, but AFAIK never released a program to the public.

The problem: getting AC:GC gamesaves to a PC (and back again) was a pain with the GameCube hardware.
This is much easier today with WiiBrew (and/or USB Gecko). But it is still a pain ;->

The .GCI file is exactly 467,008 bytes (0x72040 bytes)
They look like they contain 3 copies of data, each 0x26000 bytes long (after the 0x40 byte header)
First copy? starts at 0x00040, next copy at 0x26040, last copy at 0x4C040. The first copy has something weird about it.

NOTE: in AC:WW there are 2 copies of gamesave data. In AC:CF/Wii there is only one copy/version. The extra copies made sense because the gamesave data was on a cartridge that a user could easily unplug during save.

I'll see if I can dig up some old notes on the format (very minimal). If interested, you may have to do a lot of trial-and-error to figure out item codes and terrain codes.