Re: [Linux-fbdev-devel] cfb_copyarea()

[Geert U. <ge...@li...>]

On Mon, 19 Aug 2002, Geert Uytterhoeven wrote:
> On Mon, 19 Aug 2002, Geert Uytterhoeven wrote:
> > In cfb_copyarea(), `tmp' must be unsigned long because it is used to store
> > unsigned long values (see patch at the end).
> > 
> > cfb_copyarea() also doesn't clear the bits to modify in the first and last
> > words of a line, e.g. it does
> > 
> > |	last = (FB_READ(src) & start_mask);
> > |
> > |	if (shift > 0) 
> > |		FB_WRITE(FB_READ(dst) | (last >> shift_right), dst);
> >                          ^^^^^^^^^^^^
> > After this read, the bits to modify must be cleared first, before the OR!
> > 
> > I'm working on a version of cfb_copyarea() that fixes this and handles _all_
> > possible values of var.bits_per_pixel (the current code assumes
> > var.bits_per_pixel is a multiple of 8). Stay tuned!
>                         ^^^^^^^^^^^^^^^
> Oops, actually 8, 16, or 32 only (and 24 after Antonino Daplas' patch). I also
> plan on relaxing the current limitation that line_size must be a multiple of
> sizeof(unsigned long).

A very first version is available in fbtest (module `fbtest' in linux-fbdev's
CVS at sourceforge.net).

More optimizations (e.g. cached first/last masks) to be released later...

Gr{oetje,eeting}s,

						Geert

P.S. Yes, I work in userspace right know ;-)
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- ge...@li...

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
							    -- Linus Torvalds