Import ASCII csv

I needed to use the import cyrillic file. There was a problem with the encoding, because that is the standard means to recognize the p1251 is quite difficult. Here is my solution.

// function tablefield_import_csv
  foreach ($csv as $col_id => $col) {
    //detect encoding, mb_detect_encoding not working here
    $encoding = tablefield_detect_encoding($col);
    $col = mb_convert_encoding($col, "UTF-8", $encoding);

    $form_state['input'][$field_name][$language][$delta]['tablefield']['cell_' . $row_count . '_' . $col_id] =
    $form_state['values'][$field_name][$language][$delta]['tablefield']['cell_' . $row_count . '_' . $col_id] = $col;

And function (author Chechetkin Dmitrii)

//  http://forum.dklab.ru/viewtopic.php?t=37830  (russian article)
function tablefield_detect_encoding($string, $pattern_size = 50)
{
  $list = array('cp1251', 'utf-8', 'ascii', '855', 'KOI8R', 'ISO-IR-111', 'CP866', 'KOI8U');
  $c = strlen($string);
  if ($c > $pattern_size) {
    $string = substr($string, floor(($c - $pattern_size) /2), $pattern_size);
    $c = $pattern_size;
  }

  $reg1 = '/(\xE0|\xE5|\xE8|\xEE|\xF3|\xFB|\xFD|\xFE|\xFF)/i';
  $reg2 = '/(\xE1|\xE2|\xE3|\xE4|\xE6|\xE7|\xE9|\xEA|\xEB|\xEC|\xED|\xEF|\xF0|\xF1|\xF2|\xF4|\xF5|\xF6|\xF7|\xF8|\xF9|\xFA|\xFC)/i';

  $mk = 10000;
  $enc = 'ascii';

  foreach ($list as $item){
    $sample1 = @iconv($item, 'cp1251', $string);
    $gl = @preg_match_all($reg1, $sample1, $arr);
    $sl = @preg_match_all($reg2, $sample1, $arr);

    if (!$gl || !$sl) continue;
      $k = abs(3 - ($sl / $gl));
      $k += $c - $gl - $sl;

      if ($k < $mk) {
        $enc = $item;
        $mk = $k;
      }
    }
  return $enc;
}

May be it's helps anybody. May be you know more better method?