.NET

Bit Manipulation Instructions (BMI) is an interesting extension for the x86-64 architecture, introduced by Intel in Haswell processors (early 2010s). Its main purpose is, as the name suggests, increasing the speed of the most common bit operations by replacing manual calculation with dedicated instructions (which means hardware support). This article will focus on the performance of three example instructions: BLSI (reads the lowest bit), BLSR (resets the lowest bit) and TZCNT (counts the number of trailing non-set bits).

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.

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.