function smap(cx,cy,cw,ch,sx,sy,sw,sh,flipx,flipy,layers)

 -- negative screen sizes
 if(sw<0)flipx=not flipx sx+=sw
 if(sh<0)flipy=not flipy sy+=sh
 sw,sh=abs(sw),abs(sh)

 -- delta
 local dx,dy=cw/sw,ch/sh

 -- apply flip
 if flipx then
  cx+=cw
  dx=-dx
 end
 if flipy then
  cy+=ch
  dy=-dy
 end

 -- clip
 if(sx<0)cx-=sx*dx sx=0
 if(sy<0)cy-=sy*dy sy=0
 if(sw>128)sw=128
 if(sh>128)sh=128

 -- render with tlines
 -- pick direction that results
 -- in fewest tline calls
 if sh<sw then
  -- horizontal lines
  for y=sy,sy+sh-1 do
   tline(sx,y,sx+sw-1,y,cx,cy,dx,0,layers)
   cy+=dy
  end
 else
  -- vertical lines
  for x=sx,sx+sw-1 do
   tline(x,sy,x,sy+sh-1,cx,cy,0,dy,layers)
   cx+=dx
  end	
 end
end