vga_setmodeX - try to set Mode X-like memory organization
Try to enable Mode X-like memory organization for 256 color modes using up to
256K of memory like 320x200x256 and 640x400x256.
Modes like 320x240x256 etc. are Mode X-like by default. vga_modeinfo
lists which modes have Mode X memory layout.
A mode X like memory layout means that memory is organized in four pages
(3)) and that the top most pixel 0,1,2,3 are the first pixel
in pages 0,1,2,3. Pixels 4,5,6,7 are than the second pixels in pages 0,1,2,3.
The other, packed pixel, mode will have pixel 0,1,2,3 as pixel 0,1,2,3 in page 0
and so on. It will only use the next pages if the size of the first 64K page
is exceeded. Most SVGA 256 color modes work this way.
This is not guaranteed to work. Probably a new mode should be defined for planar
This manual page was edited by Michael Weller
<email@example.com>. The exact source of the referenced
function as well as of the original documentation is unknown.
It is very likely that both are at least to some extent are due to Harm
Occasionally this might be wrong. I hereby asked to be excused by the original
author and will happily accept any additions or corrections to this first
version of the svgalib manual.