Add support for 64 bit arch and python 3
Add support for 64 bit arch and python 3

Added signature to pass *data as pointer instead of int (default) which
was causing problems on 64 bit systems. Use truncating division
operator to support python 3.

drichmond/riffa,drichmond/riffa,drichmond/riffa,drichmond/riffa,drichmond/riffa,drichmond/riffa