what is the different between usrp_prims_libusb0 and usrp_prims_libusb1?
what case are they used?
They refer to version specific code for libusb (v0.1 or v1.0). Most of
the code is made common between versions, but the remaining parts are
in those files. Which file is compiled is determined by configure and
will depend on your system setup.
Thomas