Re: [Qemu-devel] [PATCH] [v2] Update cocoa.m to match new DisplayState code

[Samuel Benson]

On Jan 27, 2009, at 4:47 AM, Stefano Stabellini wrote:

> As I was telling you before, the guest in 16bpp is one of the "odd"
> cases, because everything usually is converted into 32bpp.
> It only happen when both host and guest are x86 because the 16bpp
> optimization that the displaystate interface change introduced is only
> enabled when guest and host have the same endianness.

> I think the way you specify bitsPerComponent may be incorrect in the
> 16bpp case, because the format is actually 565:

It was; since OS X is an RGBA system, it also assumes everything to be  
RGBA, so when I did the
math for 16bpp, it comes out 4444. It turns out OSX not only assumes,  
but forces everything
it does into RGBA; valid bits-per-component are forced into powers of  
2. Also, according to
CoreImage mail-list, OSX does not support RGB 565;  however it does  
support XRGB 1555.

> isn't there a way to provide the full color masks like with sdl?
>
> guest_screen = SDL_CreateRGBSurfaceFrom(ds_get_data(ds),  
> ds_get_width(ds), ds_get_height(ds),
>                                             
> ds_get_bits_per_pixel(ds), ds_get_linesize(ds),
>                                            ds->surface->pf.rmask, ds- 
> >surface->pf.gmask,
>                                            ds->surface->pf.bmask, ds- 
> >surface->pf.amask);

I spent a couple hours pouring thru the documentation, and being  
unable to find a similar
function, I was forced to google. That's when I came across the above  
mentioned "answer".

Now, you stated that the 16bpp case only exists when both host and  
guest are x86; Is there a way
I can trick it into thinking its a x86 guest on a ppc host so it would  
return the upconverted
32bpp? I'm assuming it would be just a toggle of the  
QEMU_BIG_ENDIAN_FLAG on the DisplaySurface.

The only other option I can think of is passing it thru some  
CoreVector Imaging constructs to
try to convert it to XRGB and telling it to ignore the leading fake  
alpha bit.

—Sam