val flags = buf.readShort().toInt() and 0xffff
    require(flags shr 15 != 0) { "not a response" }

    val responseCode = flags and 0xf

    if (responseCode == NXDOMAIN) {
      throw UnknownHostException("$hostname: NXDOMAIN")
    } else if (responseCode == SERVFAIL) {
      throw UnknownHostException("$hostname: SERVFAIL")
    }

    val questionCount = buf.readShort().toInt() and 0xffff

      cp >>>= 4;
      dest[4] = upperHexDigits[0x8 | (cp & 0x3)];
      cp >>>= 2;
      dest[2] = upperHexDigits[cp];
      return dest;
    } else if (cp <= 0x10ffff) {
      char[] dest = new char[12];
      // Four byte UTF-8 characters [cp >= 0xffff && cp <= 0x10ffff]
      // Start with "%F-%--%--%--" and fill in the blanks
      dest[0] = '%';
      dest[1] = 'F';
      dest[3] = '%';
      dest[6] = '%';

      }
    }

    // Test that 0xFFFE and 0xFFFF are replaced with 0xFFFD
    assertEscaping(xmlEscaper, "\uFFFD", '\uFFFE');
    assertEscaping(xmlEscaper, "\uFFFD", '\uFFFF');

    assertEquals(
        "0xFFFE is forbidden and should be replaced during escaping",
        "[\uFFFD]",
        xmlEscaper.escape("[\ufffe]"));
    assertEquals(
        "0xFFFF is forbidden and should be replaced during escaping",

   * element content or {@link #xmlAttributeEscaper} in attribute values.
   *
   * <p>This escaper substitutes {@code 0xFFFD} for non-whitespace control characters and the
   * character values {@code 0xFFFE} and {@code 0xFFFF} which are not permitted in XML. For more
   * detail see section <a href="http://www.w3.org/TR/2008/REC-xml-20081126/#charsets">2.2</a> of
   * the XML specification.
   *

      checkArgument(
          (port >= 0) && (port <= 0xffff), "port '%s' is out of range (0 <= port <= 0xffff)", port);
      checkArgument(
          (flags >= 0) && (flags <= 0xffff),
          "flags '%s' is out of range (0 <= flags <= 0xffff)",
          flags);

      this.server = MoreObjects.firstNonNull(server, ANY4);

          TWO_BYTE_ROUNDTRIPPABLE_CHARACTERS;

  // 2048
  private static final long THREE_BYTE_SURROGATES = 2 * 1024;

  // 61,440 [chars 0x0800 to 0xFFFF, minus surrogates]
  private static final long THREE_BYTE_ROUNDTRIPPABLE_CHARACTERS =
      0xFFFF - 0x0800 + 1 - THREE_BYTE_SURROGATES;

  // 2,650,112
  private static final long EXPECTED_THREE_BYTE_ROUNDTRIPPABLE_COUNT =
      // All one byte characters

    }
    return tmp;
  }

  @Benchmark
  int binomial(int reps) {
    int tmp = 0;
    for (int i = 0; i < reps; i++) {
      int j = i & 0xffff;
      tmp += BigIntegerMath.binomial(factorials[j], binomials[j]).intValue();
    }
    return tmp;
  }

  }

  public void testBuilderInitialStateNoneUnsafe() {
    // No characters are unsafe by default (safeMin == 0, safeMax == 0xFFFF).
    Escaper escaper = Escapers.builder().setUnsafeReplacement("X").build();
    assertThat(escaper.escape("\0\uFFFF")).isEqualTo("\0\uFFFF");
  }

  public void testBuilderRetainsState() {
    // Setting a safe range and unsafe replacement works as expected.

    }
    return tmp;
  }

  @Benchmark
  int binomial(int reps) {
    int tmp = 0;
    for (int i = 0; i < reps; i++) {
      int j = i & 0xffff;
      tmp += BigIntegerMath.binomial(factorials[j], binomials[j]).intValue();
    }
    return tmp;
  }

      checkArgument(
          (port >= 0) && (port <= 0xffff), "port '%s' is out of range (0 <= port <= 0xffff)", port);
      checkArgument(
          (flags >= 0) && (flags <= 0xffff),
          "flags '%s' is out of range (0 <= flags <= 0xffff)",
          flags);

      this.server = MoreObjects.firstNonNull(server, ANY4);