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. */

// write out Xi RET gcm_ghash_p8_4x: LVSL (R8)(R0), T0 // 0x0001..0e0f MOVD $0x70, R8 LXVD2X (HTBL)(R9), VH2 MOVD $0x80, R9 VSPLTISB $8, T1 // 0x0808..0808 MOVD $0x90, R10 LXVD2X (HTBL)(R8), VH3L // load H^3 MOVD $0xa0, R8 LXVD2X (HTBL)(R9), VH3 MOVD $0xb0, R9 LXVD2X (HTBL)(R10), VH3H MOVD $0xc0, R10 LXVD2X (HTBL)(R8), VH4L // load H^4 MOVD $0x10, R8 LXVD2X (HTBL)(R9), VH4 MOVD $0x20, R9 LXVD2X (HTBL)(R10), VH4H MOVD $0x30, R10 VSLDOI $8, ZERO, T1, T2 // 0x0000..0808 VADDUBM T0, T2, HIPERM // 0x0001..1617...

     * @param i
     *            the number to convert
     */
    public static void appendHex(final StringBuilder buf, final byte i) {
        buf.append(Character.forDigit((i & 0xf0) >> 4, 16));
        buf.append(Character.forDigit(i & 0x0f, 16));
    }

    /**
     * Appends the hexadecimal string representation of a number to the given StringBuilder.
     *
     * @param buf

	LDAXRB (R19), R16                          // 70fe5f08
	LDAXRH (R5), R8                            // a8fc5f48
	//TODO LDNP 0xcc(RSP), ZR, R12             // ecff5928
	//TODO LDNP 0x40(R28), R9, R5              // 852744a8
	//TODO LDPSW -0xd0(R2), R0, R12            // 4c00e668
	//TODO LDPSW 0x5c(R4), R8, R5              // 85a0cb69
	//TODO LDPSW 0x6c(R12), R2, R27            // 9b894d69

		0x07, 0x00, 0x00, 0x00, 0x07, 0x00, 0x00, 0x00,
		0x50, 0x4b, 0x01, 0x02, 0x14, 0x03, 0x14, 0x00,
		0x08, 0x00, 0x00, 0x00, 0x6b, 0xb4, 0xba, 0x46,
		0x1d, 0x88, 0x77, 0xb0, 0x07, 0x00, 0x00, 0x00,
		0x07, 0x00, 0x00, 0x00, 0x03, 0x00, 0x18, 0x00,
		0x20, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
		0xa0, 0x81, 0x00, 0x00, 0x00, 0x00, 0xca, 0x64,
		0x55, 0x75, 0x78, 0x0b, 0x00, 0x50, 0x4b, 0x05,

          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

	for _, c := range s {
		if c >= 0x80 || c == 0x00 {
			return false
		}
	}
	return true
}

// toASCII converts the input to an ASCII C-style string.
// This is a best effort conversion, so invalid characters are dropped.
func toASCII(s string) string {
	if isASCII(s) {
		return s
	}
	b := make([]byte, 0, len(s))
	for _, c := range s {
		if c < 0x80 && c != 0x00 {
			b = append(b, byte(c))
		}
	}

  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(

  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",