On Wednesday 16 March 2005 09:56, Raphael Jacquot wrote:
> Daniel Phillips wrote:
> > I agree completely, for position.  Cursor position and cursor
> > enable should be r/w PIO registers.  But cursor definition...
> > that's not as obvious.  Well, I guess Timothy is right, the
> > simplest way to program the cursor is to control every aspect
> > through PIO.
>
> shouldn't the cursor be defined by a <dimension>*<dimension> RGBA
> bitmap, using the alpha to blend it on top of the frame buffer ?

It will be, but the cursor pix/bitmap will be loaded via pio instead of 
via DMA.  At minimum it will be one-bit indirect color and one-bit 
alpha, on a 32x32 grid, which is a minimal hardware cursor.

Here is how I imagine it will work: there are 64 words of bitmap to load 
and 6 bytes of rgb.  That can all be done with one register, there just 
needs to be a way to tell the card a new cursor upload is about to 
start.  There are 16+16 bits of cursor position, another 32 bit 
register.  There is a control/status register with an enable bit and a 
"load cursor bit".  So a total of three PIO registers for the cursor 
interface.

Regards,

Daniel
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