sectionIndexBuffer.writeByte((section and 0x3f80) shr 7)

    // Section index.
    sectionIndexBuffer.writeByte((sectionOffset and 0x3f80) shr 7)
    sectionIndexBuffer.writeByte(sectionOffset and 0x7f)

    // Ranges.
    for (range in sectionMappedRanges) {
      rangesBuffer.writeByte(range.rangeStart)

      when (range) {
        is MappedRange.Constant -> {
          rangesBuffer.writeByte(range.b1)

 * 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

  }

  public void testEncodedLength_validStrings2() {
    HashMap<Integer, Integer> utf8Lengths = new HashMap<>();
    utf8Lengths.put(0x00, 1);
    utf8Lengths.put(0x7f, 1);
    utf8Lengths.put(0x80, 2);
    utf8Lengths.put(0x7ff, 2);
    utf8Lengths.put(0x800, 3);
    utf8Lengths.put(MIN_SUPPLEMENTARY_CODE_POINT - 1, 3);
    utf8Lengths.put(MIN_SUPPLEMENTARY_CODE_POINT, 4);
    utf8Lengths.put(MAX_CODE_POINT, 4);

  val sourceCodePoint1: Int,
  val type: Int,
  val mappedTo: ByteString,
) {
  val section: Int
    get() = sourceCodePoint0 and 0x1fff80

  val rangeStart: Int
    get() = sourceCodePoint0 and 0x7f

  val hasSingleSourceCodePoint: Boolean
    get() = sourceCodePoint0 == sourceCodePoint1

  val spansSections: Boolean
    get() = (sourceCodePoint0 and 0x1fff80) != (sourceCodePoint1 and 0x1fff80)

        val codepointDelta = (b1 and 0xF shl 14) or (b2 shl 7) or b3
        sink.writeUtf8CodePoint(codePoint - codepointDelta)
      }

      in 80..95 -> {
        // Mapped inline as codePoint delta to add
        val b2 = ranges[rangesIndex + 2].code
        val b3 = ranges[rangesIndex + 3].code

        val codepointDelta = (b1 and 0xF shl 14) or (b2 shl 7) or b3

      encodings[0x1c] = encoding // File Separator
      encodings[0x1d] = encoding // Group Separator
      encodings[0x1e] = encoding // Record Separator
      encodings[0x1f] = encoding // Unit Separator
      encodings[0x7f] = encoding // Delete
    }

  fun nonAscii(encoding: Encoding) =
    apply {
      encodings[UNICODE_2] = encoding
      encodings[UNICODE_3] = encoding
      encodings[UNICODE_4] = encoding

  /**
   * 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
		}

		0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff, 0xff,
		0xff, 0xff, 0xff, 0x31, 0x00, 0x00, 0x00, 0x00,
		0x00, 0x00, 0x00, 0x3a, 0x00, 0x00, 0x00, 0x00,
		0x00, 0x00, 0x00, 0x50, 0x4b, 0x06, 0x07, 0x00,
		0x00, 0x00, 0x00, 0x6b, 0x00, 0x00, 0x00, 0x00,
		0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x50,
		0x4b, 0x05, 0x06, 0x00, 0x00, 0x00, 0x00, 0xff,
		0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,

        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) {