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SubjectRe: [Linux-fbdev-devel] Re: FBdev updates.
On  5 Mar 03 at 20:22, James Simmons wrote:
>
> > And one (or two...) generic questions: why is not pseudo_palette
> > u32* pseudo_palette, or even directly u32 pseudo_palette[17] ?
>
> pseudo_palette was originally designed to be a pointer to some kind of
> data for color register programming. For example many PPC graphics cards
> have a color register region. Now you could have that point to
> pseudo_palette. Note pseudo_palette is only visiable in fbmem.c for the
> logo drawing code. Personally I liek to see that hidden.

cfbfillrect? cfbimageblit? Both use pseudo_palette, and both convert
it to u32*.

> > And why we do not fill this pseudo_palette with
> > i * 0x01010101U for 8bpp pseudocolor and i * 0x11111111U for 4bpp
> > pseudocolor? This allowed me to remove couple of switches and tests
> > from acceleration fastpaths (and from cfb_imageblit and cfb_fillrect,
> > but I did not changed these two in my benchmarks below).
>
> ??? Does your accel engine require these kinds of values?

Yes. It is 32bit engine, and so it wants 32bit value. And even if
not, code doing

if (p->fix.visual == FB_VISUAL_TRUECOLOR ||
p->fix.visual == FB_VISUAL_DIRECTCOLOR)
fg = p->pseudo_palette[rect->color];
else
fg = rect->color;

is horrible. Two conditional jumps on each rectangle. If you'll do
always lookup through pseudo_palette, not only that you get rid of
these jumps, you can also remove calls to pixel_to_pat32 (and accompanying
tables & lookups), as you do this expansion at set_var time,
instead of at blit/clear time.
Best regards,
Petr Vandrovec
vandrove@vc.cvut.cz


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