return 0
		}
		if inv == 0xff {
			return ^int64(x)
		}
		return int64(x)
	}

	// Normal case is base-8 (octal) format.
	return p.parseOctal(b)
}

// formatNumeric encodes x into b using base-8 (octal) encoding if possible.
// Otherwise it will attempt to use base-256 (binary) encoding.
func (f *formatter) formatNumeric(b []byte, x int64) {
	if fitsInOctal(len(b), x) {

		{"\xff\x80\x00\x00\x00\x00\x00\x00\x00", math.MinInt64, true},
		{"\xff\x7f\xff\xff\xff\xff\xff\xff\xff", 0, false},
		{"\xf5\xec\xd1\xc7\x7e\x5f\x26\x48\x81\x9f\x8f\x9b", 0, false},

		// Test base-8 (octal) encoded values.
		{"0000000\x00", 0, true},
		{" \x0000000\x00", 0, true},
		{" \x0000003\x00", 3, true},
		{"00000000227\x00", 0227, true},
		{"032033\x00 ", 032033, true},
		{"320330\x00 ", 0320330, true},

  }

  public void testDecodeLong() {
    assertThat(UnsignedLongs.decode("0xffffffffffffffff")).isEqualTo(0xffffffffffffffffL);
    assertThat(UnsignedLongs.decode("01234567")).isEqualTo(01234567); // octal
    assertThat(UnsignedLongs.decode("#1234567890abcdef")).isEqualTo(0x1234567890abcdefL);
    assertThat(UnsignedLongs.decode("987654321012345678")).isEqualTo(987654321012345678L);

			// files generated by a pre-Go1.8 toolchain. If the generated file
			// happened to have a prefix field that parses as valid
			// atime and ctime fields (e.g., when they are valid octal strings),
			// then it is impossible to distinguish between a valid GNU file
			// and an invalid pre-Go1.8 file.
			//
			// See https://golang.org/issues/12594
			// See https://golang.org/issues/21005

      value = (value * radix) + digit;
    }

    return value;
  }

  /**
   * Returns the unsigned {@code long} value represented by the given string.
   *
   * <p>Accepts a decimal, hexadecimal, or octal number given by specifying the following prefix:
   *
   * <ul>
   *   <li>{@code 0x}<i>HexDigits</i>
   *   <li>{@code 0X}<i>HexDigits</i>
   *   <li>{@code #}<i>HexDigits</i>
   *   <li>{@code 0}<i>OctalDigits</i>

    return (int) (toLong(dividend) % toLong(divisor));
  }

  /**
   * Returns the unsigned {@code int} value represented by the given string.
   *
   * <p>Accepts a decimal, hexadecimal, or octal number given by specifying the following prefix:
   *
   * <ul>
   *   <li>{@code 0x}<i>HexDigits</i>
   *   <li>{@code 0X}<i>HexDigits</i>
   *   <li>{@code #}<i>HexDigits</i>
   *   <li>{@code 0}<i>OctalDigits</i>

   * NumberFormatException} if the input string is invalid.
   *
   * <p><b>Warning:</b> please see {@link Short#decode} to understand exactly how strings are
   * parsed. For example, the string {@code "0123"} is treated as <i>octal</i> and converted to the
   * value {@code 83}.
   *
   * @since 16.0
   */
  public static Converter<String, Short> stringConverter() {
    return ShortConverter.INSTANCE;
  }

  /**

   * NumberFormatException} if the input string is invalid.
   *
   * <p><b>Warning:</b> please see {@link Short#decode} to understand exactly how strings are
   * parsed. For example, the string {@code "0123"} is treated as <i>octal</i> and converted to the
   * value {@code 83}.
   *
   * @since 16.0
   */
  public static Converter<String, Short> stringConverter() {
    return ShortConverter.INSTANCE;
  }

  /**

   * NumberFormatException} if the input string is invalid.
   *
   * <p><b>Warning:</b> please see {@link Integer#decode} to understand exactly how strings are
   * parsed. For example, the string {@code "0123"} is treated as <i>octal</i> and converted to the
   * value {@code 83}.
   *
   * @since 16.0
   */
  public static Converter<String, Integer> stringConverter() {
    return IntConverter.INSTANCE;
  }

  /**

}

func TestRoundTrip(t *testing.T) {
	data := []byte("some file contents")

	var b bytes.Buffer
	tw := NewWriter(&b)
	hdr := &Header{
		Name:       "file.txt",
		Uid:        1 << 21, // Too big for 8 octal digits
		Size:       int64(len(data)),
		ModTime:    time.Now().Round(time.Second),
		PAXRecords: map[string]string{"uid": "2097152"},
		Format:     FormatPAX,
		Typeflag:   TypeReg,
	}