Date: Wed, 24 May 1995 21:43:16 -0400 (EDT)
From: James N Hormuzdiar <jimh AT minerva DOT cis DOT yale DOT edu>
To: djgpp AT sun DOT soe DOT clarkson DOT edu
Subject: Graphics


Hello again,

	Well, thank you all for your prompt replies.  They helped me 
through the first level of confusion anyone experiences with a new 
product.  Unfortunately, I got some more questions now.

	Before I ask though, would it be impolite to express my 
frustration in trying to find out any information myself.  (Does anyone 
else agree?)  I have found 3 faq lists, and have the docs, but it still 
seems like it takes so long to find out how to do many things.  I 
feel bad having to bother you all when I need something.  Maybe I 
just do not know how best to use the info program, but I haven't found 
anything I wanted on it.  From what I have learned, djgpp is a great 
product, and I'm glad I chose it.

	On to the main question.  I want to be able to set up a vga 
graphics mode, then write to it.  I have been reading everything I can 
find in the information I have, but still can't do it.  Some of the 
information I have is contradictory-

	1). One faq I have says one should set up the modes same as with 
real mode programming.  Another says I need a GrSetMode() function.  i do 
not even know what GrSetMode is, and it is not found using 'info libc'.  
Looking in the header file, I found that it has three inputs, 'height', 
'width', and 'mode' (I think).  But I do not know what these are for.

	2). One faq says I must write to 0xd0000000, the other says I 
must use some sort of technique to allow me to write to usual addresses.

	3). Some places I have read claim I need a graphics driver?  I 
have always avoided using them, and just wrote directly to video memory 
(for speed).  Do I need one?

	Basically, all I want to do is set up a mode and use assembly to 
write to the screen as fast as I possibly can.  What is the best way to 
do this?  Are there any examples?

	By the way- so far, I think I have set the mode correctly, but 
when I tried something like this-

	asm("
		mov    $1, %ax;
		mov    $0xd0000000, %ebx;
		mov    ax, (%ebx);
	    ")

	I just get a blank screen.

	I have not set up a graphics driver as I have none (like I said, 
I always just put locations directly in the video memory).

	Well, thank you in advance.

						-James Hormuzdiar