open Printf

let iterations = 10;;

(*========================================================================================*)

let get_triple str inoff = 							(*1*)
  let bitoff = (inoff land 7)							(*2*)
  and bitind = (inoff lsr 3)							(*3*)
  in
  (if bitoff < 6 								(*4*)
  then
    ((int_of_char (str.[bitind])) lsr (5-bitoff))				(*5*)
  else
    ((int_of_char (str.[bitind])) lsl (bitoff-5)) lor  				(*6*)
    ((int_of_char (str.[bitind+1])) lsr (13-bitoff))) land 7 ;;			(*7*)
    
let put_bytetriple str index bytetriple =					(*8*)
  (str.[index] <- char_of_int ((bytetriple lsr 16) land 255) ;			(*9*)
   str.[index+1] <- char_of_int ((bytetriple lsr 8) land 255);			(*10*)
   str.[index+2] <- char_of_int (bytetriple land 255));;			(*11*)

let get_needed_bytes shifts =							(*12*)
  if shifts <3 then 0								(*13*)
  else if shifts <6 then 1							(*14*)
  else 2;;  									(*15*)  

let make_result list0 endpiece shifts = 					(*16*)
  let endpiecesize = get_needed_bytes shifts 					(*17*)
  and triplebytesize = ((List.length list0) * 3)				(*18*)
  in
  let outstr = String.create (triplebytesize + endpiecesize)			(*19*)
  in
  ((match endpiecesize with							(*20*)
    0 -> ()									(*21*)
  | 1 -> outstr.[triplebytesize] <- 						(*22*)
            char_of_int ((endpiece lsr ((shifts*3)-8)) land 255)		(*23*)
  | 2 -> (outstr.[triplebytesize] <- 						(*24*)
            char_of_int ((endpiece lsr ((shifts*3)-8)) land 255);		(*25*)
	  outstr.[triplebytesize+1] <- 						(*26*)
            char_of_int ((endpiece lsr ((shifts*3)-16)) land 255)));		(*27*)
      let rec put_list_in_string list index =					(*28*)
	match list with								(*29*)
	  bytetriple::rest -> (put_bytetriple outstr index bytetriple;		(*30*)
			       put_list_in_string rest (index-3))		(*31*)
	| [] -> outstr 	 							(*32*)
      in
 (put_list_in_string list0 (triplebytesize-3), (triplebytesize*8)+(shifts*3)));;(*33*)

let drop_0xx str len =								(*34*)
  let rec do_drop_0xx str len inoff shiftreg shifts acc =			(*35*)
    let ninoff = inoff+3 							(*36*)
    in
    if ninoff>len then								(*37*)
      make_result acc shiftreg shifts						(*38*)
    else
      let triple = get_triple str inoff 					(*39*)
      in
      if triple >= 4 								(*40*)
      then
	if shifts == 7								(*41*)
	then
	  do_drop_0xx str len ninoff 0 0 (((shiftreg lsl 3) lor triple)::acc)  	(*42*)    
	else
	  do_drop_0xx str len ninoff ((shiftreg lsl 3) lor triple) (shifts+1) acc (*43*)
      else
	do_drop_0xx str len ninoff shiftreg shifts acc 				(*44*)
  in
  do_drop_0xx str len 0 0 0 [];; 						(*45*)

(*====================================================================================*)    
let get_file fname = 
  let handle = open_in fname
  in
  let  len = (in_channel_length handle); 
  in
  let s = String.create len 
  in
  (really_input handle s 0 len;
   s);;

let rec iter n f =
  if n>1
  then
    (f(); iter (n-1) f)
  else
    f();;

let main fname =    
  let str = get_file fname
  in
  let start = Sys.time() in
  match iter iterations (function() -> drop_0xx str ((String.length str)*8)) with
    (outs,bitsize) ->
      let stop = Sys.time () in
      let time = (stop -. start) in
      let outfile = open_out (fname ^ ".ocaml") in
      (printf "%.3f" time;
       output_string outfile outs;
       flush stdout) ;; 

    
let () = 
  let w = (Array.get Sys.argv 1) in
  main w;;