From: csantill AT lausd DOT k12 DOT ca DOT us
Message-ID: <341CACD6.7148@lausd.k12.ca.us>
Date: Sun, 14 Sep 1997 20:37:54 -0700
MIME-Version: 1.0
To: djgpp AT delorie DOT com
Subject: Re: Problem with vitual screens in mode 0x13
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from: csantill AT lausd DOT k12 DOT ca DOT us

Your line
\\ char *video=(char *)0xA0000;
is wrong.

Try this code:
................
#include <sys/farptr.h>
#include <sys/nearptr.h>
#include <dpmi.h>
#include <go32.h>

#include <time.h>

#include <stdlib.h>

#include <string.h>
#include <stdio.h>
// The includes are from my original file - circle/box/line snipped out
// I owe a big thanx to Sinan for my receipt of some actually working
VGA
//   code. THAAAAAAAAAAAAAAAANNNNNNNNXXXXXXXXXXXXXXXXXXX!!!!!!!!!!!!! :]

enum GR_MODE{GR_INVALID=-1, GR_TEXT=0x03, GR_VGA=0x13};

enum GR_MODE Set_GR_Mode(enum GR_MODE mode)
{
  __dpmi_regs r;

  memset(&r, 0, sizeof(r));
  r.x.ax=mode;

  return(__dpmi_int(0x10,&r) ? GR_INVALID:mode);
}
//
************************************************************************
void Put_Pix_Far(int x, int y, char c)
{
  _farpokeb(_dos_ds, 0xA0000+(y<<8)+(y<<6)+x,c);
  return;
}
//
************************************************************************
void Put_Pix_Near(int x, int y, char c)
{
  char *v_m=(char *)(0xA0000+__djgpp_conventional_base);
  v_m[(y<<8)+(y<<6)+x] = c;
}
...............
You can modify fill screen to send to your char pointer but you
would just be including to ptr headers & adding size to your EXE.

It might be better to just malloc a buffer & double buffer from that
buffer to 0xA0000 using the farnspokew(it moves 4 bytes at a time).
On my P120/16MB/1MB video, I get 192 fill screens per sec w/all
optimizations turned on(-09 -m486).