From: drumc96 AT aol DOT com (DrumC96)
Newsgroups: comp.os.msdos.djgpp
Subject: Moving data from video memory to main memory?
Date: 20 Aug 1997 02:53:07 GMT
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Message-ID: <19970820025301.WAA12569@ladder02.news.aol.com>
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Organization: AOL http://www.aol.com
To: djgpp AT delorie DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp
Precedence: bulk

Hey everybody,
      I'm trying to figure this out. I wrote a blit function for svga that
is pretty fast  moving dwords at a time when possible. I made a copy
routine that is pretty much exactly the same except the bitmap destination
is edi and the source in video memory is esi (which is opposite for the
blit). I have a selector for video memory. The problem is, I can change es
in a function and have no problems, such as call movsd and having data
moved to video ram. When I change ds  to my video memory selector, I can't
use movsd to copy data to main memory from video memory without a gpf.
Please explain why and how I can get around that. If you can understand
what I just tried to explain, then you probably have an answer. Im using
nasm so please if at all possible us intel syntax.
Sincerely,    
DrumC96 AT aol DOT com