/*_|_|   CLASS13H.CPP   PUBLIC DOMAIN   Kurt Kuzba (6/11/1997)
_|_|_|   Basic mode 13h class for C++. DOS. Not portable.
_|_|*/
#include 
class GraphicsScreen {
public:
   GraphicsScreen();
   ~GraphicsScreen();
   void PutPixel(int, int, int);
   int GetPixel(int, int);
   void Box(int, int, int, int, int);
   void Line(int, int, int, int, int);
   void Circle(int, int, int, int);
private:
   int abs(int a)   {return (a < 0) ? -a : a;}
};
GraphicsScreen::GraphicsScreen()
{
      _asm {
         mov ax, 13h
         int 10h
      }
}
GraphicsScreen::~GraphicsScreen()
{
      asm {
         mov ax, 3h
         int 10h
      }
}
void GraphicsScreen::PutPixel(int x, int y, int c)
{
   if(x  319 || y  199)   return;
   *((char*)0xA0000000L + x + (y << 8) + (y << 6)) = (char)c;
}
int GraphicsScreen::GetPixel(int x, int y)
{
   if(x  319 || y  199)   return 0;
   return *((char*)0xA0000000L + x + (y << 8) + (y << 6));
}
void GraphicsScreen::Box(int x1,int y1,int x2,int y2, int c)
{
   for(; x1 <= x2; x1++)   Line(x1, y1, x1, y2, c);
}
void GraphicsScreen::Circle(int xc, int yc, int r, int c)
{  /*_|_|   based on code in SNIPPETS -- BRESNHAM.C   */
   int x = 0, d = 2 * (1 - r), w = 2 * 320 / 200;
   while(r >= 0)
   {
     PutPixel(xc + x, yc + r, c);     PutPixel(xc + x, yc - r, c);
     PutPixel(xc - x, yc + r, c);     PutPixel(xc - x, yc - r, c);
     if(d + r > 0)   d -= (w * --r) - 1;
     if(x > d)   d += (2 * ++x) + 1;
   }
}
void GraphicsScreen::Line(int x, int y, int x2, int y2, int c)
{  /*_|_|   based on code in SNIPPETS -- BRESNHAM.C   */
   int i, steep = 0, sx, sy, dx, dy, e;
   dx = abs(x2 - x);   sx = ((x2 - x) > 0) ? 1 : -1;
   dy = abs(y2 - y);   sy = ((y2 - y) > 0) ? 1 : -1;
   if(dy > dx)
   {
     steep =  x;   x =  y;   y = steep;  /* swap  x and  y */
     steep = dx;  dx = dy;  dy = steep;  /* swap dx and dy */
     steep = sx;  sx = sy;  sy = steep;  /* swap sx and sy */
     steep = 1;
   }
   e = 2 * dy - dx;
   for(i = 0;i < dx;i++)
   {
     if(steep)   PutPixel(y, x, c);
     else  PutPixel(x, y, c);
     while(e >= 0)   {   y += sy;   e -= 2 * dx;   }
     x += sx;   e += 2 * dy;
   }
   PutPixel(x2, y2, c);
}
int main(void)
{
      GraphicsScreen *gs = new GraphicsScreen;
      int circumference;
      gs->Box(100,100,200,200,0x13);
      gs->PutPixel(150,150,0x2F);
      for(circumference = 4; circumference < 50; circumference += 5)
         gs->Circle(150, 150, circumference, 33);
      getch();
      delete gs;
      return 0;
}
> ] Let's try randomly accessing YOUR memory once...............
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