t.Errorf("r.Len(): got %d, want %d", got, want)
	}
}

var UnreadRuneErrorTests = []struct {
	name string
	f    func(*Reader)
}{
	{"Read", func(r *Reader) { r.Read([]byte{0}) }},
	{"ReadByte", func(r *Reader) { r.ReadByte() }},
	{"UnreadRune", func(r *Reader) { r.UnreadRune() }},
	{"Seek", func(r *Reader) { r.Seek(0, io.SeekCurrent) }},
	{"WriteTo", func(r *Reader) { r.WriteTo(&Buffer{}) }},
}

    // Read the command.
    val version = fromSource.readByte() and 0xff
    if (version != VERSION_5) throw ProtocolException("unexpected version: $version")

    val command = fromSource.readByte() and 0xff

    val reserved = fromSource.readByte() and 0xff
    if (reserved != 0) throw ProtocolException("unexpected reserved: $reserved")

    val addressType = fromSource.readByte() and 0xff
    val toAddress =

  var commaFound = false
  loop@ while (!exhausted()) {
    when (this[0]) {
      ','.code.toByte() -> {
        // Consume ','.
        readByte()
        commaFound = true
      }

      ' '.code.toByte(), '\t'.code.toByte() -> {
        readByte()
        // Consume space or tab.
      }

      else -> break@loop
    }
  }
  return commaFound
}

  fun writeObjectIdentifier(s: String) {
    val utf8 = Buffer().writeUtf8(s)
    val v1 = utf8.readDecimalLong()
    require(utf8.readByte() == '.'.code.toByte())
    val v2 = utf8.readDecimalLong()
    writeVariableLengthLong(v1 * 40 + v2)

    while (!utf8.exhausted()) {
      require(utf8.readByte() == '.'.code.toByte())
      val vN = utf8.readDecimalLong()
      writeVariableLengthLong(vN)
    }
  }

			return n, nil
		}
		cr.offset = 0
		buf = buf[n:]
	}
	// mustRead reads from input and compares against provided slice.
	mustRead := func(b ...byte) error {
		for _, want := range b {
			got, err := cr.reader.ReadByte()
			if err == io.EOF {
				return io.ErrUnexpectedEOF
			}
			if got != want {
				if cr.debug {
					fmt.Printf("mustread: want: %q got: %q\n", string(want), string(got))
				}
				return errMalformedEncoding

    // 0 - 63 bytes
    var length = source.readByte().toInt()

    if (length < 0) {
      // compressed name pointer, first two bits are 1
      // drop second byte of compression offset
      source.skip(1)
    } else {
      while (length > 0) {
        // skip each part of the domain name
        source.skip(length.toLong())
        length = source.readByte().toInt()
      }
    }
  }

	n = copy(b, r.s[off:])
	if n < len(b) {
		err = io.EOF
	}
	return
}

// ReadByte implements the [io.ByteReader] interface.
func (r *Reader) ReadByte() (byte, error) {
	r.prevRune = -1
	if r.i >= int64(len(r.s)) {
		return 0, io.EOF
	}
	b := r.s[r.i]
	r.i++
	return b, nil
}

// UnreadByte complements [Reader.ReadByte] in implementing the [io.ByteScanner] interface.
func (r *Reader) UnreadByte() error {

    val sourceCodePoint1 =
      when (select(optionsDot)) {
        DELIMITER_DOT -> {
          if (readByte() != '.'.code.toByte()) throw IOException("expected '..'")
          readHexadecimalUnsignedLong()
        }

        else -> sourceCodePoint0
      }

    skipWhitespace()
    if (readByte() != ';'.code.toByte()) throw IOException("expected ';'")

    // "valid" or "mapped"
    skipWhitespace()

    }


    public char readChar () throws IOException {
        align(2);
        return this.dis.readChar();
    }


    public byte readByte () throws IOException {
        return this.dis.readByte();
    }


    public short readShort () throws IOException {
        align(2);
        return Short.reverseBytes(this.dis.readShort());
    }

    in.readFully(b);
    assertEquals(-100, b[0]);
    assertEquals(100, b[1]);
    assertEquals(true, in.readBoolean());
    assertEquals(false, in.readBoolean());
    assertEquals(100, in.readByte());
    assertEquals(-100, in.readByte());
    assertEquals(200, in.readUnsignedByte());
    assertEquals('\u6100', in.readChar());
    assertEquals(-12150, in.readShort());
    assertEquals(20675, in.readUnsignedShort());