(* break70.ml - Don Yang (uguu.org)

   Insert newline every 70 characters.

   09/03/04
                                                                           *)

(* Linebreak frequency *)
let break_limit = 70;;

(* Open first argument for input if available, otherwise use stdin *)
let input () =
   if Array.length Sys.argv > 1
   then open_in_bin Sys.argv.(1)
   else stdin;;

(* Open second argument for input if available, otherwise use stdout *)
let output () =
   if Array.length Sys.argv > 2
   then open_out_bin Sys.argv.(2)
   else stdout;;

(* Break every freq characters *)
let break_func freq x c =
   output_byte (fst x) c;
   if (snd x) - 1 = 0
   then (output_char (fst x) '\n'; (fst x, freq))
   else (fst x, (snd x) - 1);;

(* Process file one byte at a time *)
let rec process infile x freq =
   let (i, j) =
      try ((break_func freq x (input_byte infile)), 0)
      with End_of_file -> (x, 1) in
      if j != 0 then ()
      else process infile i freq;;


(* Program entry point *)
let infile = input() in
   let outfile = output() in
      process infile (outfile, break_limit) break_limit;
      close_out outfile;
      close_in infile;;