This is the famous Two Plus Two hand evaluator for 5-to-7-card poker hands, created by Ray Wotton with help from many others in a giant thread the Two plus Two poker forums and popularized by an old coding the wheel blog post.
It’s basically an elaborate caching system for an ealier evaluator by Cactus Kev and Paul Senzee.
This fork (https://github.com/tangentstorm/TwoPlusTwoHandEvaluator) was extracted from the XPokerEval distribution (which contains a bunch of hand evaluators compiled by the coding the wheel guy).
I added a Makefile and made some minor changes to to improve readability and allow compilation on non-windows platforms (it works on freebsd, anyway).
My own main contribution is rankhand.pas, a small example program made with free pascal that shows how to use the HandRanks.dat file that generate_table.cpp creates.
With all the people who had touched the c and c++ code, I found it difficult to decipher exactly how the cards and hands were represented (Wotton’s code uses a completely different coding system than the one in poker.h).
The pascal program is my own, and available for use under the extremely liberal zlib license. I wrote the pascal program from scratch and it has no dependencies on or relation to any of the C/C++ code. The only requirement is the generated database file.
Wotton’s code contains the self-contradictory statement “My code is GPL, use it as you like”. The Cactus Kev / Paul Senzee code has a copyright but no license.