/**
 * [字符串轉換為(2,8,16進制)ASCII碼]
 * @param string $str   [待處理字符串]
 * @param boolean $encode [字符串轉換為ASCII|ASCII轉換為字符串]
 * @param string $intType [2,8,16進制標示]
 * @return string byte_str [處理結果]
 * @author alexander
 */
function strtoascii($str, $encode=true, $intType="2"){
  if($encode == true){
    $byte_array = str_split($str);
    foreach($byte_array as &$value){
      $value = ord($value);
      switch ($intType) {
        case 16:
          $value = sprintf("%02x", $value);
          break;
        case 8:
          $value = sprintf("%03o", $value);
          break;
        default:
          $value = sprintf("%08b", $value);
          break;
      }
    }
    unset($value);
    $byte_str = implode('', $byte_array);
  }
  else{
    $chunk_size = $intType == 16 ? 2 : ($intType == 8 ? 3 : 8);
    $byte_array = chunk_split($str, $chunk_size);
    $byte_array = array_filter(explode("\r\n", $byte_array));
    foreach($byte_array as &$value){
      $fun_name = $intType == 16 ? 'hexdec' : ($intType == 8 ? 'octdec' : 'bindec');
      $value = $fun_name($value);
      $value = chr($value);
    }
    unset($value);
    $byte_str = implode('', $byte_array);
  }
  return $byte_str;
}