Re: Blitter speed tests (was: smart blitter usage for scrolling)

On Fri, 2007-05-11 at 04:24 +0800, Antonino A. Daplas wrote:

On Thu, 2007-05-10 at 18:48 +0200, Krzysztof Helt wrote:

quoted

Hi,

If you do, it might even be wise to change the default from
SCROLL_REDRAW to SCROLL_MOVE...?

Come to think of it we'll probably just let the driver choose the scroll
method.

SCROLL_MOVE is faster at lower bit depths because the bitmap preparation
for the putcs method slows down SCROLL_REDRAW.  But as the bit depth
goes up, the amount of data moved by bmove goes up but at a higher rate
than the data moved by putcs. Thus SCROLL_MOVE loses its edge at 16-32
bpp. At what point these lines intersect we really don't know as it
depends on the hardware and the driver's imageblit/copyarea
implementation.

Tony


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