bluefile.py 文件源码

def pack_header(hdr, structured=0):
    """
    Returns the header in the form of a string.

    Pack the given BLUE header dictionary to its binary format for
    storage on disk.  All keywords, main and extended, are packed
    and updated in the hdr dict that is passed in.

    If you intend on writing this header out to disk, do not forget to
    write out the extended header as well.  It should be written at
    512*hdr['ext_start'] bytes offset from the beginning of the file
    and the extended header itself should be padded out to a multiple
    of 512 bytes.

    If there is an extended header present, setting the optional
    <structured> argument to true (default is false) will cause any
    Python dictionaries, lists, and tuples to be packed with their
    structures intact.  See the doc string for pack_keywords() for
    more details.
    """
    # Leave the user's copy alone
    hdr = hdr.copy()

    # Pack the main header keywords
    pack_main_header_keywords(hdr)

    # We have to pack the adjunct part explicitly because it is a union
    endian = _rep_tran[hdr['head_rep']]
    # Recalculate class from current type (user may have changed)
    file_class = int(hdr['type'] / 1000)
    hdr['adjunct'] = _pack_blue_struct(hdr, _bluestructs['T%dADJUNCT' %
                                                         file_class], endian)

    # Pack the extended header if present
    if hdr.has_key('ext_header'):
        pack_ext_header(hdr, structured=structured)

    return _pack_blue_struct(hdr, _bluestructs['HEADER'], endian)