Half-year ago I did a small text about writing chess engines in C# and performance issues related to it, where I presented a few interesting methods of optimizing the engine. Today, I want to extend it a bit by new elements, some of them related to the lastly released .NET 5 - they aren’t game-changers, but can nicely improve some parts of code.

Just a quick announcement - I’ve made a new bitboard viewer, as a backup for the amazing bitboard calculator made by gekomad which supports my chess development since the beginning. I hope it will be helpful for some of you!

Link: https://tearth.dev/bitboard-viewer/ (with source code available here)

For the last months, I was focused on developing Cosette chess engine, toying with a very wide spectrum of algorithms and language optimizations. The second one was especially interesting because of .NET 5 release, which brings a few interesting speed improvements (I will try to write something about them in the context of the engine soon). In this article, I will show an interesting behavior of inlining intrinsic function in some specific case which led to the dropping of performance in the chess engine.

Last month was quite busy - I’ve started a new project called Cosette, which is a brand new chess engine written in C# for .NET Core platform. It’s not my first project of this kind (a few years ago I made Proxima b 2.0 (C#), together with even older Proxima b (C++)), so using the gained experience I can finally write a few words about performance tips and tricks, especially in C# language.

Swapping values is probably one of the simplest algorithms which can be imagined - we learn about it when starting our programming story. There are two popular ways to accomplish this: using a temporary variable and XORing (with some restrictions). In the newest C# versions there is also a third way, about which you can read in this article.

Random class is one of the most used parts of the .NET library, which contains a few methods to generate pseudo-random numbers. They are extremely simple to use, but even with this, there are still some traps waiting for a programmer. In this article, I will focus on differences in implementation of this class between .NET Framework and .NET Core, especially seed generation which sometimes leads to interesting bugs.