How to map magic

gistfile1.py

if location == 'file':
    # Usually the tag index directly follows the index header. However,
    # some forms of map protection move the tag index to other locations.
    index_offset = map_header.index_offset + index_header.primary_magic - 0x40440000

    # On disk, we need to use a magic value to convert pointers into file offsets.
    # The magic value is based on the index location within the file, since this
    # always appears at the same place in memory.
    map_magic = index_header.primary_magic - index_offset

elif location == 'mem':
    # Almost always 0x40440028, unless the map has been protected in a specific way.
    index_offset = index_header.primary_magic

    # In memory, offsets are just raw pointers and require no adjustment.
    map_magic = 0