From: Brian Reich <breich AT sunlink DOT net>
Newsgroups: comp.os.msdos.djgpp
Subject: Help! VGA programming problem in DJGPP
Date: Wed, 07 Jan 1998 22:19:31 -0800
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I am wondering why this code will not work when I try to use the plot
function. it gives me all kinds of 'segment fault' errors... Any idea???

/* Mode 13h code lovingly copied from VGA Basics Tutorial,
http://silo.csci.unt.edu/home/brackeen/vga/basics.html
Rest of program written by Brian Reich */

                //Required Libraries
#include <bios.h>
#include <iostream.h>
                // Global Macros
#define VGAMode 0x13
#define TEXTMode 0x03

                //Global Variables
typedef unsigned char byte;
byte *VideoBuffer = (byte *)0xA000000L;

                // Function which changes to desired video mode
void setVideoMode(int mode) {
        union REGS regs;
        regs.h.ah = 0x00;
        regs.h.al = mode;
        int86(0x10, &regs, &regs);
}

                // Function which draws Pixel directly to video buffer
(FAST!)
                // Taken from Tricks of the Game Programming Gurus
void plot(int x, int y, unsigned int color)
        {
        int index = (y<<8) + (y<<6) + x;
        VideoBuffer[index] = color;
        }

void main(void) {
        setVideoMode(VGAMode);
        cout <<"Nifty";
        plot(2,2,5);
//        setVideoMode(TEXTMode);
}

When it gets to plot(2, 2, 5); the program crashes. All I want to do is
plot a damn pixel! If you can help PLEASE lemme know what I am doing
wrong.

breich AT sunlink DOT net