String and multi-digit conversion functions in PHP

/**
 * [字符串转换为(2,8,16进制)ASCII码]
 * @param  string  $str     [待处理字符串]
 * @param  boolean $encode  [字符串转换为ASCII|ASCII转换为字符串]
 * @param  string  $intType [2,8,16进制标示]
 * @return string  byte_str [处理结果]
 * @author alexander
 */
function strtoascii($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;
}