Iridion 3d - Glitches Logo and game over

[wwark]

Save states - Glitches at the game over screen
https://github.com/MiSTer-devel/GBA_MiSTer/files/4130122/Iridion.3D.USA.Europe.zip

From @M-Walrus
"I see Iridion 3D was already reported. I was just about to report it but checked here first.
Here are two places where you can see the glitchy line in Iridion 3D. First is actually right at the beginning (Developer Logo) and seems the same as the "game over" screen example. Top row of pixels in each example is shifted far to the left:
Logo: https://youtu.be/WWyJugZctRY?t=45
Game Over: https://youtu.be/WWyJugZctRY?t=1500"

Thanks.

[fleroviux]

I had the same issue in NanoBoyAdvance. The issue is that mid-frame writes to BGX/Y don't get copied into the internal registers immediately like GBATEK says. They're copied at the start of the next scanline instead.

I have a test ROM here that might help to solve the issue:
https://github.com/nba-emu/hw-test/tree/master/ppu/bgx

[wwark]

thank you @fleroviux for all those HW tests you write.
Some tests are OK with the current core.
Maybe others not OK could help to improve accuracy of the core.

[RobertPeip]

Thanks a lot for the hint!

I didn't know you have written such tests. I should take some time and look at them.