From: reboot AT fr2 DOT flashnet DOT it (Cristiano Muzi)
Newsgroups: comp.os.msdos.djgpp
Subject: HELP: vesa 2 & linear framebuffering
Date: Tue, 08 Apr 1997 12:18:22 GMT
Organization: Flashnet
Lines: 64
Message-ID: <5id9j3$6sb@news.flashnet.it>
NNTP-Posting-Host: ppp-1.fr2.flashnet.it
To: djgpp AT delorie DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp

Hi,

I'  m very new in djgpp, protected mode programming & vbe2 linear
frame-buffering.

I'm trying to use video-mode 640x480x256 with linear addressing, using
near pointers; I'm following the instructions in djgpp tutorial by
Remus Rutgers.

Well, I set the video mode and I obtain the PhisBasePtr in the
ModeInfoBlock.

Then I convert it into a linear address in this way:

    __dpmi_meminfo mi;
    mi.size = (unsigned long)(ModeInfoBlock.XRes*ModeInfoBlock.YRes);
    mi.address = ModeInfoBlock.PhysBasePtr;
    __dpmi_physical_address_mapping(&mi);
   LinearAddress=mi.address;

And then I try to put a pixel:

 unsigned char *VideoPtr = (unsigned char *)LinearAddress;
  __djgpp_nearptr_enable();
 VideoPtr[XRes*Y+X+__djgpp_conventional_base]=C;
  __djgpp_nearptr_disable(); 

But it seems not to work :((

No pixel appears on the monitor.

(the setmode function works fine, if I set mode without linear
addressing and I write

_farpokeb (_dos_ds,0xA0000+640*y+X,c)

this works fine).

Thank you,
greetings,

PS:  Perhaps my problem is a problem of bios or videocard. A demo of
Allegro 2.2 and a test program crash my pc when they try to use linear
addressing :((

I have a dx2/66, a vlb cirrus logic 5428 and I use univbe 5.1.  Is
here my problem ??


Cristiano Muzi <reboot AT fr2 DOT flashnet DOT it>
               Fidonet Point: 2:335/610.11

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