GBA Multiplayer Core Update (Patreon)

The splitscreen core got some updates: 

- saves for both players, so all coop games work as they should

- horizontal splitscreen

But the biggest change is likely that it now has it's own name: GBA2P

This is required, because the savefiles of Singleplayer GBA and Multiplayer GBA are very restricted compatible: you can use a singleplayer savefile for multiplayer, but you cannot load both multiplayer savegames into singleplayer, only player 1 will be available.

Also it's a preperation for the seperate code repository that will hold this "new" core. 

What changes for you?

The biggest impact is for sure, that the core will try to load BIOS and games from a GBA2P folder, which you will not have.

I recommend 2 solutions: either create a new GBA2P folder and place BIOS + Multiplayer games only there or create a symlink to your original GBA folder.

I apologize for this to be not the most convenient way to do it, butIi hope it's accepable, as it's only 1 time effort and the change was required.

Overall it's hopefully still one of the most convenient ways to play GBA multiplayer.

So I hope you enjoy the update.

Code will follow probably tomorrow in a new repository.

Have fun!