Autocad file comparison(repost)

The task is to make a binary file comparison of AutoCad DXF, DWG files. This would entail reading elements of an AutoCad DXF, DWG and then reading the internal objects it in-memory. The reading and writing must have fidelity and not lose objects or tags. The task would be to read it in-memory and then lexically look at changes in the structure, then render it to a viewer. Then save it back to disks, highlighting the changes. The viewer must be able to do annotations, view the structure of the AutoCad (e.g., the drawing inside the file) and then allow the user to pan, zoom and look at what changed or has been changed between two files. This should be done with C#, C++, MFC.