Index: [thread] [date] [subject] [author]
  From: Thomas,Trevor <trevor.thomas@cdott.com>
  To  : 'ggi-develop@eskimo.com' <ggi-develop@eskimo.com>
  Date: Fri, 14 May 1999 17:25:33 -0400

GGi frame buffer and video memory question

hello
I am trying to display some images to the screen using the GGi frame buffers

hardware: vid card ->Mill II 8 meg (4 visible, 4 upgrade).
		   display ->	20.1 NEC AMLCD

images: 1280X1024 8bit

My problem is that I need to display these images to a accuracy of approx.
5ms for a simulation, I am using usleep() before flushing to achieve this.
I can display 3 images correctly but for > 3 it appears that the framebuffer
pointer is not starting in the right place. (image starts approx. 1/4 way
into the screen and loops back around). I think that this is doing this
because of the visible memory is only 4megs?

Any ways the questions are...

1. Is there any way to point the frame buffer pointer in the correct place?

2. I am assuming that the program is using the non visible memory to store
the images on as well as the visible (program loads all the images then
pages between them). My understanding of the layout of this card is that it
can only display from the visible portion of the video memory (could be
wrong). Does this cause any significant delays when displaying the images to
the screen?

3. Because the images are not being displayed 100% correct for >3
framebuffers does this cause any timing delays?

Please point out any technical errors that I may have made or if my
questions are not understood please tell me so.

Thank you very much

Trevor
Trevor Thomas
Computing Devices Canada
Advanced Displays Group
Phone: 613-596-7489
email: trevor.thomas@cdott.com

Index: [thread] [date] [subject] [author]