1 Bits Per Pixel Screen Mode
Anyone wondered why the 1bpp screen mode does not work? The answer is simple: GP32 BIOS GpGraphicModeSet() call does it wrong and the Samsung data sheet tells incorrect information. That is indeed a good start.
The trick in order to get the 1bpp mode set up correctly is to poke some "not that obvious" values into LCDSADDR3 register. 240 pixels requires 15 half words (15 * 2 * 8 = 240). One might think that LCDSADDR3.OFFSIZE=0 and LCDSADDR3.PAGEWIDTH=15 would produce a 240 pixels high screen without offscreen area. Well no.. The screen starts wandering around. In order to get a stable screen you need to define LCDSADDR3.OFFSIZE=1 and LCDSADDR3.PAGEWIDTH=14. Weird but works. There is one slight side effect though. 16 last pixels along the 240 pixels line get mirrored from the first 16 pixels of the previous line. This effectively cuts out total 32 pixels worth of usable display area along the raster line.
