This software allows a standard PC soundcard to be used as a shortwave data "modem". The whole processing is done on the main processor CPU.
The HF software is split into two parts. The hfkernel handles the HF protocols, but has no user interface. It provides a UNIX domain socket (so it can be easily switched to INET domain sockets in the future, when the need arises to separate the terminal software from the kernel) to communicate with terminal programs, mailboxes or other software that wants a HF circuit.