store map on computer?

There is a wide range of choice for this, far too much to cover in an answer here.

I would suggest browsing this summary on the OSM wiki: Offline Routers. Only you will know what is likely to fit your software environment, technical knowledge and routing requirements. Many, if not all, of these require OSM data to be stored in a format appropriate for routing: the OSM XML format is not optimal for this purpose.