block = (bytes[i++] & 0xff) << 16 | (bytes[i++] & 0xff) << 8 | bytes[i++] & 0xff;
            buffer.append(ALPHABET.charAt(block >>> 18));
            buffer.append(ALPHABET.charAt(block >>> 12 & 0x3f));
            buffer.append(ALPHABET.charAt(block >>> 6 & 0x3f));
            buffer.append(ALPHABET.charAt(block & 0x3f));
        }
        if (remainder == 0) {
            return buffer.toString();
        }