//------------------------------------------------------------------------------
void bresline0(int xa,int ya,int xb,int yb)
{
    int dx,dy,e,ekt,et,c,x,y;
    dx=xb-xa;
    dy=yb-ya;
    ekt=dy+dy;
    e=ekt-dx;
    et=e-dx;
    c=getcolor();
    for(x=xa,y=ya; x<=xb; x++)
    {
        putpixel(x,y,c);
        if(e<0)e+=ekt;
        else
        {
            y++;
            e+=et;
        }
    }
}
//------------------------------------------------------------------------------
void bresline1(int xa,int ya,int xb,int yb)
{
    int dx,dy,e,ekt,et,c,x,y;
    dx=xb-xa;
    dy=yb-ya;
    ekt=dx+dx;
    e=ekt-dy;
    et=e-dy;
    c=getcolor();
    for(y=ya,x=xa; y<=yb; y++)
    {
        putpixel(x,y,c);
        if(e<0)e+=ekt;
        else
        {
            x++;
            e+=et;
        }
    }
}
//------------------------------------------------------------------------------
void bresline2(int xa,int ya,int xb,int yb)
{
    int dx,dy,e,ekg,eg,c,x,y;
    dx=xb-xa;
    dy=-(yb-ya);
    ekg=dy+dy;
    e=ekg-dx;
    eg=e-dx;
    c=getcolor();
    for(x=xa,y=ya; x<=xb; x++)
    {
        putpixel(x,y,c);
        if(e<0)e+=ekg;
        else
        {
            y--;
            e+=eg;
        }
    }
}
//------------------------------------------------------------------------------
void bresline3(int xa,int ya,int xb,int yb)
{
    int dx,dy,e,ekt,et,c,x,y;
    dx=xb-xa;
    dy=-(yb-ya);
    ekt=dx+dx;
    e=ekt-dy;
    et=e-dy;
    c=getcolor();
    for(y=ya,x=xa; y>=yb; y--)
    {
        putpixel(x,y,c);
        if(e<0)e+=ekt;
        else
        {
            x++;
            e+=et;
        }
    }
}
void bresline(int xa,int ya,int xb,int yb)
{
    int i,c;
    float m;
    if(xa>xb)
    {
        hv(&xa,&xb);
        hv(&ya,&yb);
    }
    c=getcolor();
    if(xa==xb) for(i=ya; i<=yb; i++) putpixel(xa,i,c);
    if(ya==yb) for(i=xa; i<=xb; i++) putpixel(i,ya,c);
    else
    {
        m =(float)(yb-ya)/(float)(xb-xa);
        if((m>0)&&(m<1))bresline0(xa,ya,xb,yb);
        if(m>=1) bresline1(xa,ya,xb,yb);
        if(m<=-1) bresline3(xa,ya,xb,yb);
        if((m<0)&&(m>-1))bresline2(xa,ya,xb,yb);
    }
}