It generates two sets of files:
- WDL files (extension: .rtbw) storing win/draw/loss information for access during search.
- DTZ files (extension: .rtbz) storing distance-to-zero information for access at the root.
In addition to win/draw/loss information, the WDL files also store whether the win or loss can be enforced within 50 moves.
The tables use custom compression. Total compressed size:
Code: Select all
WDL DTZ up to 5 pieces 378 MB 561 MB up to 6 pieces 68.3 GB 81.9 GB
Probing code is included, but it requires some work to add it to an engine. As a proof of concept I have adapted the probing code to Stockfish. The probing code is fully multithreaded as well.
My engine (playing on FICS as TrojanKnight(C)) has been using these tables since a couple of months quite successfully. With the WDL tables stored on SSD, it is possible to probe the tables at all depths without much slowdown (I don't probe in qsearch).
The license for the generator is GPLv2. The probing code is released without restrictions. So anyone wanting to add support for these tables to his/her engine is free to do so.