unit 286 Copy 
.386

assume ds:@code,cs:@code
NoJumps 

Procedure Far CopyArea x, y, w, h, S, T
   Store ds 

   imul si,y,320 
   add  si,x
   mov  di,si 
   mov  ds,S
   mov  es,T
   mov  ax,w
   mov  bx,ax
   shr  bx,2
   sub  ax,320 
   mov  dx,h 
   cld 

   $Do 
      mov  cx,bx
      rep  movsd 
      test al,10b
      $If <>0
         movsw
      $EndIf
      test al,1
      $If <>0
         movsb
      $EndIf       
  
      sub  si,ax 
      sub  di,ax 
   
      dec  dx 
   $EndDo =0
   
   Restore 
EndProc