/*
     * The striding algorithm works roughly as follows: it is universally the case that
     * CRC(x ^ y) == CRC(x) ^ CRC(y).  The approach we take is to break the message as follows,
     * with each letter representing a 4-byte word: ABCDABCDABCDABCD... and to calculate
     * CRC(A000A000A000...), CRC(0B000B000B...), CRC(00C000C000C...), CRC(000D000D000D...)
     * and then to XOR them together.  The STRIDE_TABLE enables us to hash an int followed by 12

				hash.ChecksumSHA256.String(): part.ChecksumSHA256,
			}
			if wantCS[checksumType.String()] != crc {
				return oi, InvalidPart{
					PartNumber: part.PartNumber,
					ExpETag:    wantCS[checksumType.String()],
					GotETag:    crc,
				}
			}
			cs := hash.NewChecksumString(checksumType.String(), crc)
			if !cs.Valid() {
				return oi, InvalidPart{
					PartNumber: part.PartNumber,
				}
			}

	if c == nil {
		return nil
	}
	var tmp [binary.MaxVarintLen32]byte
	n := binary.PutUvarint(tmp[:], uint64(c.Type))
	crc := c.Raw
	if len(crc) != c.Type.RawByteLen() {
		return b
	}
	b = append(b, tmp[:n]...)
	b = append(b, crc...)
	if c.Type.Is(ChecksumMultipart) {
		var checksums int
		// Ensure we don't divide by 0:

	0, 0, 0, 41, // headers byte-length.
	139, 161, 157, 242, // prelude crc.
	13, ':', 'm', 'e', 's', 's', 'a', 'g', 'e', '-', 't', 'y', 'p', 'e', 7, 0, 5, 'e', 'v', 'e', 'n', 't', // headers.
	11, ':', 'e', 'v', 'e', 'n', 't', '-', 't', 'y', 'p', 'e', 7, 0, 4, 'C', 'o', 'n', 't', // headers.
	156, 134, 74, 13, // message crc.
}

// Refer genProgressHeader().
var progressHeader = []byte{

   * href="https://en.wikipedia.org/wiki/Hash_function">hash function</a>.
   *
   * @since 18.0
   */
  public static HashFunction crc32c() {
    return Crc32cHashFunction.CRC_32_C;
  }

  /**
   * Returns a hash function implementing the CRC-32 checksum algorithm (32 hash bits).
   *
   * <p>To get the {@code long} value equivalent to {@link Checksum#getValue()} for a {@code

}

// ContentCRCType returns the content checksum type.
func (r *Reader) ContentCRCType() ChecksumType {
	return r.contentHash.Type
}

// ContentCRC returns the content crc if set.
func (r *Reader) ContentCRC() map[string]string {
	if r.contentHash.Type == ChecksumNone || !r.contentHash.Valid() {
		return nil
	}
	if r.contentHash.Type.Trailing() {

				err = msgp.WrapError(err, "ModTime")
				return
			}
		case "index":
			z.Index, err = dc.ReadBytes(z.Index)
			if err != nil {
				err = msgp.WrapError(err, "Index")
				return
			}
		case "crc":
			var zb0002 uint32
			zb0002, err = dc.ReadMapHeader()
			if err != nil {
				err = msgp.WrapError(err, "Checksums")
				return
			}
			if z.Checksums == nil {

					return nil, err
				}
			case 1, 2:
				v, b, err := msgp.ReadBytesZC(b)
				if err != nil {
					return nil, err
				}
				if _, nbuf, err := msgp.ReadUint32Bytes(b); err == nil {
					// Read metadata CRC (added in v2, ignore if not found)
					b = nbuf
				}

				_, err = msgp.CopyToJSON(buf, bytes.NewReader(v))
				if err != nil {
					return nil, err
				}
				data = b
			case 3:

		t.Errorf("unexpected method and flags: %v", b[6:10])
	}

	if !bytes.Equal(b[14:26], make([]byte, 12)) { // FileHeader.{CRC32,CompressSize,UncompressedSize} all zero.
		t.Errorf("unexpected crc, compress and uncompressed size to be 0 was: %v", b[14:26])
	}

	binary.LittleEndian.PutUint32(sig[:], uint32(dataDescriptorSignature))
	if bytes.Contains(b, sig[:]) {
		t.Error("there should be no data descriptor")