Hi David,
so basically you want to find out how fast you can update blocks of 64 000 pixels, starting at a VSYNC and if possible taking at most very few VSYNC periods until the update is done. Assuming ALL pixels change. > No. In fact, my copying routine is extra slow, because since mode 13h > doesn't have hardware alpha checking, I have to do it myself. Basically > I've defined my own alpha mask, and so I have to check if it's on before > drawing to the screen. You probably want to optimize that copying routine. Game programmers would at least use MMX to do the alpha checks for several pixels at the same time. In C, you can at least use logic calculations, to avoid having to do "if then" for every single pixel. If by gcc you mean DJGPP: Pointers are protected mode there, so everything is "far" in the sense that each pointer can point anywhere in your allocated memory. For Watcom, things depend on the target memory model, whether you want to use real or protected mode etc. > I suppose I could remove alpha support from my screen > copying routine and only support it between bitmaps. That can be a sensible optimization, but depends on what your requirements are, so the decision is yours. >> You mean without cutemouse, frame rate is fixed to 15 fps? That probably means that the IRQ and I/O activities of cutemouse do give your drivers or BIOS the impression that the computer is busy, keeping it from entering lower clock states to save energy. > Yeah I know about this, but I want my program to be compatible with > various video modes. Mode 13h is easy... Easy yes, but also slow. Various games used a somewhat convoluted variant with the same resolution but with pages and bits and so on, just to have several pages to flip between. The downside is that you have to switch between different hardware pages and the whole "one pixel one byte" thing is lost. So VESA would clearly be less pain. The obvious way would be to use VESA when available and fall back to MCGA mode 0x13 otherwise, even if it is slow. It is probably not worth the effort to use complex VGA modes just to have faster frame rates on ancient hardware when most computers will have VESA anyway. So mode 0x13 is okay when VESA is absent. > P.S. I did some playing with BIOS power settings and found that indeed > the BIOS can be blamed for this behavior. Even while leaving OS power > controls enabled, disabling the "idle slowdown" fixed the issue. Which settings are available for that BIOS idle slowdown? Maybe a compromise is possible which has good frame rate but still saves at least some energy :-) Regards, Eric ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Freedos-devel mailing list Freedos-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/freedos-devel
