sub c_out {
 my $_=shift;
 my $final=shift;
 if(defined($c_out_store)) {
  print F2 pack('H*',sprintf('%03x%03x',$_,$c_out_store));
  undef $c_out_store;
 } elsif($final) {
  print F2 pack('H*',sprintf('%03x%03x',0,$_));
 } else {
  $c_out_store=$_;
 }
}

##</code><code>##

 while($usedouble || !eof($file_in)) {
  if($usedouble) {
   $new_code=$double; $usedouble=0;
  } else {
   $r=read($file_in, $double, 3); ($double)=unpack(N,"\000$double");
   $new_code=$double & 0xfff; $double >>= 12; $usedouble=1;
  }
  # etc
 }