Date: Thu, 22 Sep 1994 15:04:31 +22305931 (WAUST)
From: Ron Grunwald <rgrunwal AT bluering DOT cowan DOT edu DOT au>
Subject: Re: Simple Graphics w/ DPMI?
To: Tilmann Haeberle <ctil AT zentrum DOT phys DOT chemie DOT tu-muenchen DOT de>
Cc: djgpp AT sun DOT soe DOT clarkson DOT edu



On Wed, 21 Sep 1994, Tilmann Haeberle wrote:

> Is there any simple graphics library which works under DPMI,
> especially in a DOS-Box under Windows?
> Line-Drawing would be enough for me, even point setting, if
> its fast enough.
> Using BIOS Interrupt 0x10 works, but is too slow.
> 
> Thanks to replies, 
> Tilmann Haeberle
> Inst. f. phys. Chemie I
> TU Muenchen 
> Germany
> 


I prefer writing my own graphics functions, and under DPMI they
seem to work really well for me. The fundamental piece required
for direct screen memory reads and writes under DPMI is that
you create an LDT descriptor for the screen segment. The DPMI
interface returns the Selector for the screen segment specified.

From here on you simply load a segment register with that
selector, and specify an offset in a working register. This
approach runs very well in a DOS/box running under Windows 3.1.


Hope this helps if you intend programming some graphics
yourself.


Regards, Ron.




 ********************************************************************
 | Author.............. Ron Grunwald                                | 
 | Internet............ rgrunwal AT bluering DOT cowan DOT edu DOT au              | 
 | Phone............... (09)273 8027 or (09)273 8468                |
 |------------------------------------------------------------------|
 | Department.......... Information Technology                      | 
 | Division/Faculty.... Operations and Systems Management           | 
 | Institute........... Edith Cowan University, Churchlands         | 
 | Location............ Perth, Western Australia                    |
 ********************************************************************
 "I don't have any solution but I certainly admire the problem!"