This is a clone of wiringPi based on 2.50 with updates to support Pi4
Original code Copyright (c) 2012-2015 Gordon Henderson
modified by Ian Binnie
Please see
for Gordon's documentation
Functionality is substantially unchanged from wiringPi 2.50 so most of the documentation would be unchanged.
This release uses code Copyright (c) 2012, Broadcom Europe Ltd included with Raspberry Pi OS (previously called Raspbian) based on Debian Buster
References to Gordon's website (with the exceptions noted above) and email have been removed.