purplesyringa's blog
purplesyringa's blog
Alisa Sireneva
Hi! 👋 I'm Alisa Sireneva (she/her), a software developer and blogger from Moscow. I specialize in performance optimization and systems programming. I also have experience with security, compression, and decentralized systems. My primary goal as a writer is to teach the concepts I regularly apply through accessible content.
Latest Posts
I need a place to describe this algorithm, since it seems to be undocumented on the 'net, so here it is. SRC is a replacement for MTF in BWT-based compressors. According to OpenBWT, it’s the best known MTF replacement measured by...
So I was optimizing a domain-specific compressor the other day, as one does. One important problem was chunking the input string and optimally choosing the most compact encoding for each chunk (different encodings compress different...
So I was optimizing a domain-specific compressor the other day, as one does. One important problem was chunking the input string and optimally choosing the most compact encoding for each chunk (different encodings compress different...
This problem arose when I was writing a specialized data compressor. Say you want to encode a byte stream, and bytes can be encoded in different formats, e.g. optimized for ASCII, numbers, raw binary, etc. These formats prioritize better...
I blog because I want to share knowledge. That’s how I have fun. It feels rewarding to sit down and formulate your thoughts after spending a week researching a topic for a side project. Oftentimes, such topics are largely unexplored:...
Intended audience: data compression geeks. The Burrows-Wheeler transform takes a string as an input and rearranges its characters, grouping them by context. It is invertible with 𝒪(1) additional input, and together these properties give...
This is a guest post by Yuki about some tricks we use for Lua code compression in our shared ComputerCraft pet project. I’ve written about how we adapted bzip2 for this purpose earlier; this story is an installment that takes place in...
This post assumes basic familiarity with arithmetic coding. I’ve written an arithmetic coder, like, three times in my life, so the mistake I want to highlight is likely amateurish. But since I didn’t have a clue that my understanding was...
Everyone knows Wasm is a stack machine. Wikipedia says so, the official Wasm design specification says so, you get it. I thought so too. That is, until I started writing Wasm code – not compiling for Wasm, but writing the instructions by...
I needed to convert file status flags between operating systems yesterday. They are the values you pass as the second argument to open – O_NONBLOCK, O_NOATIME, O_SYNC, O_DSYNC, and so on: int open(const char *path, int flags, /* mode_t...
The appearance of Mythos – a private LLM allegedly capable of finding a multitude of 0-days – has made people concerned about being denied powerful tools. This seems to be a turning point in the mainstream discourse, and it motivated me...
In case you’re unaware, I’m not a developer. I’m actually an autistic catgirl annoyed by suboptimal use of computing power, and fixing that happens to involve programming. Crucially, it also includes discussing foundational technology...
What came to your mind when you read “hash functions” in the title? If you’re pragmatic, you probably remembered SHA-256 or MD5. Those are cryptographic hash functions, and they work fast and well for arbitrary inputs, even if they are...
This is a rant about how broken everything Web is based on is. You know, the usual. No offence intended towards framework developers, I’m glad this technology exists, but I’m sure you know this feeling. It gets too much sometimes. I’ve...