Pyrrhic is a partial cleanup of the Fathom library for probing up-tp 7-man Syzygy Tablebases. Pyrrhic attempts to reduce the burden on the global namespace introduced by Fathom, as well as provide a more robust API for decoding the results of function calls. Pyrrhic is kept fairly up-to date with changes as they are made to Stockfish's implementation, or the Fathom repository itself.
Integration with Pyrrhic
To make use of Pyrrhic in your engine, you'll want to copy the contents of this repository into a directory for your engine's source. Once done, you will need to update the definitions in tbconfig.h. This file allows Pyrrhic to make use of your engine's utilities. Namely, you'll be defining macros for popcnt, lsb, and poplsb, which are all common in engines. You'll also be providing a basic interface for Bitboad attack generation for each piece type.
Compatibility with Pyrrhic
Pyrrhic has a miniature chess implementation via tbconfig.h. Each chess program picks its own conventions. Pyrrhic uses the most common Bitboard orientation, where A1 = 0, and H8 = 63. If your engine uses a different layout, you'll need to do a form of translation when crafting calls to the Pyrrhic endpoint, as well as when reading the results back.
Building Alongside Pyrrhic
The only source file that needs to be compiled is tbprobe.c. Any other .c files in the Pyrrhic project should not be explicitly compiled. The only .h file that should be included by a project is tbprobe.h. The api.h file is simply reference material, and should never be explicitly included.
Initializing Pyrrhic
tb_init(const char* path) is used to initialize the tablebases from a directory. Multiple file paths at once should be seperated by a semicolon in Windows systems, and by a colon on Unix-based systems. When finished, tb_free() is called to cleanup any remaining memory. The tablebases may be initialized once again if desired. Lastly, if the path is an empty string, or <empty>, then tb_init() will return without doing anything. tb_init() will also set TB_LARGEST, TB_NUM_WDL, TB_NUM_DTM, TB_NUM_DTZ to pass back information about what was loaded. Those variables have extern definitions, and can be referenced through tbprobe.h
Performing Tablebase Probes
Refer to the Wiki, which lays out the 4 possible Tablebase Probing functions