phoenix2000 wrote:open source library which is developed by professional engineers in microchip
As ric points out, you probably shouldn't assume much about the people who wrote the libraries. E.g., search for "RCIF = 0" in the serial library; that might lead you to believe it was written by someone who didn't read the data sheet. Or search for a value being assigned to PEIE; that might lead you to the same conclusion. Those are just a couple of glaring examples.
Other than things like USB/Ethernet/CAN, there isn't a peripheral on the PIC18 that is complex enough to warrant a library.