new byte[] {
                (byte) 0xef, (byte) 0xcd, (byte) 0xab, (byte) 0x89,
                (byte) 0x67, (byte) 0x45, (byte) 0x23, (byte) 0x01
              },
              0x89abcdef,
              0x0123456789abcdefL,
              "efcdab8967452301"),
          new ExpectedHashCode(
              new byte[] {
                (byte) 0xef, (byte) 0xcd, (byte) 0xab, (byte) 0x89,

              new byte[] {
                (byte) 0xef, (byte) 0xcd, (byte) 0xab, (byte) 0x89,
                (byte) 0x67, (byte) 0x45, (byte) 0x23, (byte) 0x01
              },
              0x89abcdef,
              0x0123456789abcdefL,
              "efcdab8967452301"),
          new ExpectedHashCode(
              new byte[] {
                (byte) 0xef, (byte) 0xcd, (byte) 0xab, (byte) 0x89,

     * @param b the byte array to check
     * @return true if the bytes represent UTF-8 BOM, false otherwise
     */
    private boolean isUtf8BomBytes(final byte[] b) {
        return b[0] == (byte) 0xEF && b[1] == (byte) 0xBB && b[2] == (byte) 0xBF;
    }

    /**
     * Sets whether to process Google on/off comment directives.
     *
     * @param useGoogleOffOn true to enable Google on/off processing, false to disable

 * fills, it is doubled.
 */
@Suppress("NAME_SHADOWING")
object Hpack {
  private const val PREFIX_4_BITS = 0x0f
  private const val PREFIX_5_BITS = 0x1f
  private const val PREFIX_6_BITS = 0x3f
  private const val PREFIX_7_BITS = 0x7f

  private const val SETTINGS_HEADER_TABLE_SIZE = 4_096

  /**
   * The decoder has ultimate control of the maximum size of the dynamic table but we can choose

    // Valid 4 byte.
    assertWellFormed(0xF0, 0xA4, 0xAD, 0xA2);
    // Bad trailing bytes
    assertNotWellFormed(0xF0, 0xA4, 0xAD, 0x7F);
    assertNotWellFormed(0xF0, 0xA4, 0xAD, 0xC0);
    // Special cases for byte2
    assertNotWellFormed(0xF0, 0x8F, 0xAD, 0xA2);
    assertNotWellFormed(0xF4, 0x90, 0xAD, 0xA2);
  }

  /** Tests some hard-coded test cases. */
  public void testSomeSequences() {

        int chunk = (bytes[i++] & 0xFF) << 16 | (bytes[i++] & 0xFF) << 8 | (bytes[i++] & 0xFF);
        target.append(alphabet.encode(chunk >>> 18));
        target.append(alphabet.encode((chunk >>> 12) & 0x3F));
        target.append(alphabet.encode((chunk >>> 6) & 0x3F));
        target.append(alphabet.encode(chunk & 0x3F));
      }
      if (i < off + len) {

  /**
   * The largest value that fits into an unsigned byte.
   *
   * @since 13.0
   */
  public static final byte MAX_VALUE = (byte) 0xFF;

  private static final int UNSIGNED_MASK = 0xFF;

  /**
   * Returns the value of the given byte as an integer, when treated as unsigned. That is, returns
   * {@code value + 256} if {@code value} is negative; {@code value} itself otherwise.

// TODO: update when package unicode captures more of the properties.
func isSeparator(r rune) bool {
	// ASCII alphanumerics and underscore are not separators
	if r <= 0x7F {
		switch {
		case '0' <= r && r <= '9':
			return false
		case 'a' <= r && r <= 'z':
			return false
		case 'A' <= r && r <= 'Z':
			return false
		case r == '_':
			return false
		}

   * of reads and delaying a lock acquisition until the threshold is crossed or a mutation occurs.
   *
   * <p>This must be a (2^n)-1 as it is used as a mask.
   */
  static final int DRAIN_THRESHOLD = 0x3F;

  /**
   * Maximum number of entries to be drained in a single cleanup run. This applies independently to
   * the cleanup queue and both reference queues.
   */
  // TODO(fry): empirically optimize this

   * of reads and delaying a lock acquisition until the threshold is crossed or a mutation occurs.
   *
   * <p>This must be a (2^n)-1 as it is used as a mask.
   */
  static final int DRAIN_THRESHOLD = 0x3F;

  /**
   * Maximum number of entries to be drained in a single cleanup run. This applies independently to
   * the cleanup queue and both reference queues.
   */
  // TODO(fry): empirically optimize this