*
* @param flen file length for which to compute the depth
* @return depth of the tree, always > 0. A depth of 1 means only a DBLOCK.
*
* @param flen file length for which to compute the depth
* @return depth of the tree, always > 0. A depth of 1 means only a DBLOCK.
* @param cls closure for reader, proc, progress and cont
* @param reader function to call to read plaintext data
* @param proc function to call on each encrypted block
* @param cls closure for reader, proc, progress and cont
* @param reader function to call to read plaintext data
* @param proc function to call on each encrypted block
* @param te the tree encoder to clean up
* @param uri set to the resulting URI (if encoding finished)
* @param emsg set to an error message (if an error occured
* @param te the tree encoder to clean up
* @param uri set to the resulting URI (if encoding finished)
* @param emsg set to an error message (if an error occured
* @param te encoding to resume
* @param data set to the resume data
* @param size set to the size of the resume data
* @param te encoding to resume
* @param data set to the resume data
* @param size set to the size of the resume data
* @param te encoding to resume
* @param data the resume data
* @param size the size of the resume data
* @param te encoding to resume
* @param data the resume data
* @param size the size of the resume data