when {
            b == 0x80 -> {
              // 10000000
              throw IOException("index == 0")
            }

            b and 0x80 == 0x80 -> {
              // 1NNNNNNN
              val index = readInt(b, PREFIX_7_BITS)
              readIndexedHeader(index - 1)
            }

            b == 0x40 -> {
              // 01000000

  const val FLAG_END_HEADERS = 0x4 // Used for headers and continuation.
  const val FLAG_END_PUSH_PROMISE = 0x4
  const val FLAG_PADDED = 0x8 // Used for headers and data.
  const val FLAG_PRIORITY = 0x20 // Used for headers.
  const val FLAG_COMPRESSED = 0x20 // Used for data.

  /** Lookup table for valid frame types. */
  private val FRAME_NAMES =
    arrayOf(
      "DATA",
      "HEADERS",
      "PRIORITY",
      "RST_STREAM",

  public void testIsWellFormed_4BytesSamples() {
    // 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 testCollisionsDueToIncorrectSignExtension() {
    byte[] col1 = new byte[] {0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, (byte) 0x80};
    byte[] col2 = new byte[] {0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, (byte) 0x81};
    byte[] col3 = new byte[] {0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, (byte) 0xff};

    ImmutableSet<HashCode> hashCodes =
        ImmutableSet.of(

  public void testCollisionsDueToIncorrectSignExtension() {
    byte[] col1 = new byte[] {0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, (byte) 0x80};
    byte[] col2 = new byte[] {0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, (byte) 0x81};
    byte[] col3 = new byte[] {0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, (byte) 0xff};

    ImmutableSet<HashCode> hashCodes =
        ImmutableSet.of(

        new byte[] {
          0x01, (byte) 0xc0, 0x00, 0x00,
          0x00, 0x00, 0x00, 0x00,
          0x00, 0x00, 0x00, 0x00,
          0x00, 0x00, 0x00, 0x00,
          0x14, 0x00, 0x00, 0x00,
          0x00, 0x00, 0x04, 0x00,
          0x00, 0x00, 0x00, 0x14,
          0x00, 0x00, 0x00, 0x18,
          0x28, 0x00, 0x00, 0x00,
          0x00, 0x00, 0x00, 0x00,
          0x02, 0x00, 0x00, 0x00,
          0x00, 0x00, 0x00, 0x00

    assertThat(Buffer().writeUtf8("Слава Україні!").isProbablyUtf8(16L)).isTrue()
    assertThat(Buffer().writeByte(0x80).isProbablyUtf8(16L)).isTrue()
    assertThat(Buffer().writeByte(0x00).isProbablyUtf8(16L)).isFalse()
    assertThat(Buffer().writeByte(0xc0).isProbablyUtf8(16L)).isFalse()
  }

  @Test fun doesNotConsumeBuffer() {
    val buffer = Buffer()
    buffer.writeUtf8("hello ".repeat(1024))

          char c3 = input.charAt(i + 3);
          if (c0 < 0x80 && c1 < 0x80 && c2 < 0x80 && c3 < 0x80) {
            update(4, c0 | (c1 << 8) | (c2 << 16) | (c3 << 24));
            i += 4;
          } else {
            break;
          }
        }

        for (; i < utf16Length; i++) {
          char c = input.charAt(i);
          if (c < 0x80) {
            update(1, c);
          } else if (c < 0x800) {

              new byte[] {(byte) 0xcd, (byte) 0xab, (byte) 0x00, (byte) 0x00},
              0x0000abcd,
              null,
              "cdab0000"),
          new ExpectedHashCode(
              new byte[] {
                (byte) 0xef, (byte) 0xcd, (byte) 0xab, (byte) 0x00,
                (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00
              },
              0x00abcdef,
              0x0000000000abcdefL,

    assertEquals(hash32, Hashing.combineOrdered(ImmutableList.of(hash32)));
    assertEquals(
        HashCode.fromBytes(new byte[] {(byte) 0x80, 0, 0, 0}),
        Hashing.combineOrdered(ImmutableList.of(hash32, hash32)));
    assertEquals(
        HashCode.fromBytes(new byte[] {(byte) 0xa0, 0, 0, 0}),
        Hashing.combineOrdered(ImmutableList.of(hash32, hash32, hash32)));
    assertFalse(