From: Endlisnis <s257m AT unb DOT ca>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: 640 x 400
Date: Mon, 07 Sep 1998 19:14:49 -0300
Organization: NBTel Internet
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References: <01bdd031$0b208f20$0818d3d4 AT billy> <35EB2179 DOT 8A0437FF AT btinternet DOT com> <35F32B57 DOT 1A78 AT club-internet DOT fr>
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Ludvig Larsson wrote:
> BTW, I had some problem with those VESA 1.2 modes because they are Not
> always compatible with VESA 2.0 One thing that worked for me was to set
> the bit in the for the lineframe buffer(why it works, I have no idéa,
> but it does, using banks). So mode 0x100 will be 0x4100 etc.
> The best thing offcourse, to make the code work on well almost all cards
> is to scan the card for the desired graphic mode.
	As far as I know, this will work on EVERY VESA 1.2+ card.

> Ps. to plot a pixel: (in 640xNNN in 256color mode)
> bank=(x+y*640)>>16
> offset=(x+y*640)-bank<<16
> set bank to 'bank' and
> put the colorvalue at 0xA0000+offset
	That is making the assumption that bank's have a 64k granularity (which they
do not always have!  Most Cirrus Logic cards do NOT have this, they us 4k/16k
granularity).  You will have to check to see the bank-size before knowing how
much to bitshift by.
-- 
     (\/) Endlisnis (\/)
          s257m AT unb DOT ca
          Endlisnis AT GeoCities DOT com
          Endlis AT nbnet DOT nb DOT ca