dmg-acid2 VS giibiiadvance

My Game Boy emulator has almost passed dmg-acid2, except that it has the "Eye displayed instead of right chin" failure mode. The README says that this signals an issue with the "window internal line counter," but I don't see where that's documented. Can someone enlighten me?

I tested it with the classic dmg-acid2 test rom and another rom called sprite_priority.gb which is part of the Mooneye Test Suite.

For everything beyond opcodes, and especially graphics, the pandocs go over almost everything you need. For testing graphics, you can use the dmg-acid2 test roms which have tests for most of the common graphics errors.

Adequate PPU emulation (passes dmg-acid2 test). This emulator uses Pixel FIFO, as opposed to common scanline renderer.

acid-dmg, this is a really nice PPU test, you can try to complete it step by step.

Does anyone know of good documentation beyond: - Pan Docs - The Cycle-Accurate Game Boy Docs - Complete Technical Reference - Nitty Gritty Gameboy Cycle Timing

For actual documentation, you probably know the pandocs, but there are a lot of more specific information in the docs linked in their references, especially the cycle-accurate GB docs, the GB complete technical reference by Gekkio. You can also check the source code of the relevant test roms, like the Blargg’s test roms for more general behaviour and the MooneyeGB test suite for more specific things.

The Cycle-Accurate GB Docs: https://github.com/AntonioND/giibiiadvance/blob/master/docs/TCAGBD.pdf