Fix BIT instructions zero flag behavior

pineman / fpt

Gameboy emulator (yes, written in rust)

https://pineman.github.io/fpt

MIT License

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Fix BIT instructions zero flag behavior #72

Closed pineman closed 4 months ago

pineman commented 4 months ago

The rgbds entry says: which I interpreted as "only mutates the Z flag if the result is 0". But it actually always sets (or resets) the zero flag (see sameboy). This fixes the start button not doing anything in Tetris.

pineman commented 4 months ago

no idea why it breaks so many rom tests

pineman commented 4 months ago

turns out lots of rom tests were false positives since BIT wasn't working correctly, and BIT is used a lot in the mooneye roms (in macros). disabling the ones that dont run for now as we spoke