/*
 * DrawLine2.c
 * the fixed version
 */
 
extern void Plot(int x, int y);  /* plots a pixel on the screen */

/*
 * this function draws a line on the screen between (x0,y0) and (x1,y1).
 */
void DrawLine2(int x0, int y0, int x1, int y1) {
    Plot(x0, y0);
    Plot(x1, y1);
    DrawLine2_Helper(x0, y0, x1, y1);
}

void DrawLine2_Helper(int x0, int y0, int x1, int y1) {
    int xmid, ymid;

    xmid = (x0 + x1) / 2;
    ymid = (y0 + y1) / 2;
    
    if((x0 == xmid && y0 == ymid) ||
       (x1 == xmid && y1 == ymid)) return;

    Plot(xmid, ymid);

    DrawLine2(x0, y0, xmid, ymid);
    DrawLine2(xmid, ymid, x1, y1);
}