{**************************************************************

Show file with controls

Types the givien file, and expands the control characters out
into our \ctl format (\cr and \lf are excepted).

**************************************************************}

program ShowControls(source,  { file to show }
                     output); { prints to }

var c : char; { buffer }
    source: text;

procedure expand(c : char); { expand and print control sequence }

begin
   if ord(c) > 127 then c := chr(ord(c) - 128); { strip any high bit }
   if (ord(c) >= ord(' ')) and (c <> '\del') then
      write(c) { write printable character }
   else case c of { write control character }

      '\nul': write('\\nul');
      '\soh': write('\\soh');
      '\stx': write('\\stx');
      '\etx': write('\\etx');
      '\eot': write('\\eot');
      '\enq': write('\\enq');
      '\ack': write('\\ack');
      '\bel': write('\\bel');
      '\bs':  write('\\bs');
      '\ht':  write('\\ht');
      '\lf':  write('\\lf');
      '\vt':  write('\\vt');
      '\ff':  write('\\ff');
      '\cr':  write('\\cr');
      '\so':  write('\\so');
      '\si':  write('\\si');
      '\dle': write('\\dle');
      '\dc1': write('\\dc1');
      '\dc2': write('\\dc2');
      '\dc3': write('\\dc3');
      '\dc4': write('\\dc4');
      '\nak': write('\\nak');
      '\syn': write('\\syn');
      '\etb': write('\\etb');
      '\can': write('\\can');
      '\em':  write('\\em');
      '\sub': write('\\sub');
      '\esc': write('\\esc');
      '\fs':  write('\\fs');
      '\gs':  write('\\gs');
      '\rs':  write('\\rs');
      '\us':  write('\\us');
      '\del': write('\\del')

   end
end;

begin { ShowControls }

   reset(source); { open source file }
   while not eof(source) do begin

      while not eoln(source) do begin

         read(source, c); { read character }
         expand(c)        { print }

      end;
      readln(source); { next line }
      writeln

   end
end.