* data that was read or written so far. The method should be designed so that
* can be called with the current checksum, and the buf and len fields pointing
* to the new block of data to add to the checksum computation. */
* data that was read or written so far. The method should be designed so that
* can be called with the current checksum, and the buf and len fields pointing
* to the new block of data to add to the checksum computation. */