Re: [Linux-fbdev-devel] Re: FBdev updates.

[Antonino Daplas <adaplas@pol.net>]

On Thu, 2003-03-06 at 04:23, James Simmons wrote:
> 
> > >   And one (or two...) generic questions: why is not pseudo_palette
> > > u32* pseudo_palette, or even directly u32 pseudo_palette[17] ?
> > 
> > Yes, all drivers should treat the pseudo_palette as u32* anyway, so why
> > not change pseudo-palette from void* to u32*?
> 
> See other email.
> 
> > > 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).
> > 
> > I also agree for a different reason.  Cards with unconventional formats
> > (such as monochrome at 8 bpp - 0 for black , 0xff for white) will not
> > work with the current code.
> 
> Isn't that the job of setcolreg?
> 
setcolreg does that for directcolor and truecolor modes, because they're
the only ones that uses the pseudo_palette.  See all driver codes, the
pseudo_palette is never initialized if in pseudo_color.

The purpose of the pseudo_palette is to enable to write pixels to the
framebuffer without knowing the color format at all.  So, if you have
monochrome, then black is 0 and white is 1.  But for monochrome 8bpp,
black is 0 and white is 0xff. 

fbcon will send 0's and 1's, thus 0 and 1 will be written to the
framebuffer.  If the drawing functions referred to the pseudo_palette,
whatever the visual format, then 0 and 0xff will be written, as it
should be.

Tony
> 
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