[ECOS] Framebuffer update on synthetic target

Bart Veer bartv@ecoscentric.com
Wed Dec 17 17:40:00 GMT 2008

>>>>> "Martin" == Martin Hansen <farhansen@gmail.com> writes:

    Martin> HI
    Martin> I have made a small game for test of the framebuffer
    Martin> device, The game itself appears to work.

    Martin> But the synthetic framebuffer has a problem. First i
    Martin> thought my program freeze, but some diag_printf's denied
    Martin> that. The problem is that after a short time the
    Martin> framebuffer window on not updated anymore.

This is almost certainly because you are not calling cyg_fb_sync() or
CYG_FB_SYNCH(). The synthetic target framebuffer is a double buffered
display so the target-side data does not get sent to the actual
display until you synch. This is not quite true during startup for the
synthetic target: some nasty things need to happen as windows get
mapped etc. But once everything is up and running, framebuffer updates
will not be visible until you synch.

You may want to look at, and try running, the example program in the
synthetic framebuffer's misc subdirectory.


Bart Veer                                   eCos Configuration Architect
eCosCentric Limited    The eCos experts      http://www.ecoscentric.com/
Barnwell House, Barnwell Drive, Cambridge, UK.      Tel: +44 1223 245571
Registered in England and Wales: Reg No 4422071.

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