I'm saying this hoping someone corrects me. It's seems to me that the G450 is not actually doing any hardware overlay? Where in the the Xserver code is the actually hardware overlay registers touched?
I'm looking at the cfbDoBitblt8To32 function. And seems to me that everything is done in software. Actually can anyone tell me the difference between cfb and fb? Where does the cfb module lie in the Xfree86 architecture?
I'm planning to make a little document explaining all of this because it seems that documentation about this is hard to find.
Luugi
Dr Andrew C Aitchison wrote:
On Fri, 25 Oct 2002, Luugi Marsan wrote:Hi,I don't understand how X11 implements overlay. I'm trying to understand the xf8_32bpp module. Is their any documentation on this? I would like to get an explanation on how this module was implemented. Is it anything like how Window does Overlay? If I want to go through the code where should I start? Seems to me that the xf86overlay.c file is a good starting point. But how is this code structured. Is there anywhere I could find something to explain the big picture of the code?There is a bit more in xaaOverl/xc/programs/Xserver/hw/xfree86/xaa/xaaInit.c xaaOverlay.c and xaaImage.c - look for overlayFlags and OVERLAY_8_32_PLANAR. How does windoes do overlays ? For the big picture I'd be guessing, but my impression is that most of the overlay code is there to persuade XAA to draw in the top byte of each pixmap, sometimes with planemasks and sometimes by using a depth 8 pixmap with 32 bit pixels (xf86overlay:512 OverlayRefreshPixmap). I'd be interested in anything you find out, since I expect I'll need to duplicate much of it for PseudoColor on DirectColor.
