// Double#doubleToRawLongBits(double)} spec.
  static final long SIGNIFICAND_MASK = 0x000fffffffffffffL;

  // The mask for the exponent, according to the {@link
  // Double#doubleToRawLongBits(double)} spec.
  static final long EXPONENT_MASK = 0x7ff0000000000000L;

  // The mask for the sign, according to the {@link
  // Double#doubleToRawLongBits(double)} spec.

 * Double#doubleToRawLongBits}, which differs from both the primitive double {@code ==} operator and
 * from {@link Double#equals}, as if implemented by:
 *
 * <pre>{@code
 * static boolean bitEquals(double x, double y) {
 *   long xBits = Double.doubleToRawLongBits(x);
 *   long yBits = Double.doubleToRawLongBits(y);
 *   return xBits == yBits;
 * }
 * }</pre>
 *

  // Double#doubleToRawLongBits(double)} spec.
  static final long SIGNIFICAND_MASK = 0x000fffffffffffffL;

  // The mask for the exponent, according to the {@link
  // Double#doubleToRawLongBits(double)} spec.
  static final long EXPONENT_MASK = 0x7ff0000000000000L;

  // The mask for the sign, according to the {@link
  // Double#doubleToRawLongBits(double)} spec.

  };

  /** The notion of equality used by AtomicDouble */
  static boolean bitEquals(double x, double y) {
    return Double.doubleToRawLongBits(x) == Double.doubleToRawLongBits(y);
  }

  static void assertBitEquals(double x, double y) {
    assertEquals(Double.doubleToRawLongBits(x), Double.doubleToRawLongBits(y));
  }

  /** constructor initializes to given value */
  public void testConstructor() {
    for (double x : VALUES) {

    assertThrows(IllegalArgumentException.class, () -> DoubleUtils.ensureNonNegative(Double.NaN));
  }

  public void testOneBits() {
    assertEquals(DoubleUtils.ONE_BITS, Double.doubleToRawLongBits(1.0));
  }

  private static void failFormat(String template, Object... args) {
    fail(String.format(template, args));
  }

  };

  /** The notion of equality used by AtomicDoubleArray */
  static boolean bitEquals(double x, double y) {
    return Double.doubleToRawLongBits(x) == Double.doubleToRawLongBits(y);
  }

  static void assertBitEquals(double x, double y) {
    assertEquals(Double.doubleToRawLongBits(x), Double.doubleToRawLongBits(y));
  }

  @J2ktIncompatible
  @GwtIncompatible // NullPointerTester
  public void testNulls() {

            case HALF_EVEN:
              // roundFloorAsDouble and roundCeilingAsDouble are neighbors, so precisely
              // one of them should have an even long representation
              return ((Double.doubleToRawLongBits(roundFloorAsDouble) & 1L) == 0)
                  ? roundFloorAsDouble
                  : roundCeilingAsDouble;
            case HALF_DOWN:

            case HALF_EVEN:
              // roundFloorAsDouble and roundCeilingAsDouble are neighbors, so precisely
              // one of them should have an even long representation
              return ((Double.doubleToRawLongBits(roundFloorAsDouble) & 1L) == 0)
                  ? roundFloorAsDouble
                  : roundCeilingAsDouble;
            case HALF_DOWN:

    assertThrows(IllegalArgumentException.class, () -> DoubleUtils.ensureNonNegative(Double.NaN));
  }

  public void testOneBits() {
    assertEquals(DoubleUtils.ONE_BITS, Double.doubleToRawLongBits(1.0));
  }

  private static void failFormat(String template, Object... args) {
    fail(String.format(template, args));
  }