assertThat(UnsignedLongs.divide(0xfffffffffffffffeL, 0xfffffffffffffffdL)).isEqualTo(1);
    assertThat(UnsignedLongs.divide(0xfffffffffffffffdL, 0xfffffffffffffffeL)).isEqualTo(0);
    assertThat(UnsignedLongs.divide(0xfffffffffffffffeL, 65535)).isEqualTo(281479271743488L);
    assertThat(UnsignedLongs.divide(0xfffffffffffffffeL, 2)).isEqualTo(0x7fffffffffffffffL);

   * unless the user is actually calling a parse method.
   */
  private static final class ParseOverflowDetection {
    private ParseOverflowDetection() {}

    // calculated as 0xffffffffffffffff / radix
    static final long[] maxValueDivs = new long[Character.MAX_RADIX + 1];
    static final int[] maxValueMods = new int[Character.MAX_RADIX + 1];

  @Param("1234")
  int randomSeed;

  int[] xInts;
  int[] yInts;

  long[] xLongs;
  long[] yLongs;

  int[] constant;

  private static final long NONNEGATIVE_LONG_MASK = 0x7FFFFFFFFFFFFFFFL;

  @BeforeExperiment
  void setUp() {
    Random random = new Random(randomSeed);
    xInts = new int[SAMPLE_SIZE];
    yInts = new int[SAMPLE_SIZE];
    xLongs = new long[SAMPLE_SIZE];

  }

  // Test for common pitfall regarding sign extension.
  // For example: (long) data[i++] | (long) data[i++] << 8 | ...
  // If data[i] == (byte) 0x80, the first cast will sign-extend it to 0xffffffffffffff80,
  // masking the remaining seven bytes.
  // To test this, we give an input where bit 7 is not cleared. For example:
  // (1) 00 01 02 03 04 05 06 07 80
  // (2) 00 01 02 03 04 05 06 07 81

    } else if (frameLength == PAYLOAD_LONG.toLong()) {
      frameLength = source.readLong()
      if (frameLength < 0L) {
        throw ProtocolException(
          "Frame length 0x${frameLength.toHexString()} > 0x7FFFFFFFFFFFFFFF",
        )
      }
    }

    if (isControlFrame && frameLength > PAYLOAD_BYTE_MAX) {
      throw ProtocolException("Control frame must be less than ${PAYLOAD_BYTE_MAX}B.")
    }

    assertFailsWith<ProtocolException> {
      clientReader.processNextFrame()
    }.also { expected ->
      assertThat(expected.message).isEqualTo(
        "Frame length 0x8000000000000000 > 0x7FFFFFFFFFFFFFFF",
      )
    }
  }

  @Test fun serverHelloTwoChunks() {
    data.write("818537fa213d7f9f4d".decodeHex()) // Hel
    data.write("5158".decodeHex()) // lo
    serverReader.processNextFrame()

 * @author Colin Evans
 * @since 11.0
 */
@GwtCompatible
public final class UnsignedLong extends Number implements Comparable<UnsignedLong> {

  private static final long UNSIGNED_MASK = 0x7fffffffffffffffL;

  public static final UnsignedLong ZERO = new UnsignedLong(0);
  public static final UnsignedLong ONE = new UnsignedLong(1);
  public static final UnsignedLong MAX_VALUE = new UnsignedLong(-1L);