Simon Tatham's quasi-blog

Aperiodic Tilings V: the Refinable Frontier

2025-09-02T00:00:00+00:00

A sequel to my previous posts on finite-state transducers for aperiodic tilings: if you have a tiling you can’t build a transducer for, here’s an algorithm to turn it into one you can.

Brute-forcing Langley’s geometry problem with field extensions

2025-07-18T00:00:00+00:00

An application of algebraic extensions of the rationals: cheating (arguably) at elementary geometry puzzles.

In which I have Opinions about parsing and grammars

2025-06-05T00:00:00+00:00

A collection of semi-connected rants about context-free grammars, parser generators, and the ways in which they aren’t quite as useful as I’d like them to be.

Policy of transience

2025-05-09T00:00:00+00:00

A description of some of my personal computing habits, focusing on avoiding things ‘just turning out’ to last for ever in a disorganised manner.

Iconography of the PuTTY tools

2025-03-12T00:00:00+00:00

A PuTTY user asked about the history of its logo and icon collection. I discuss the design intentions and technical aspects.

Git without a forge

2025-03-05T00:00:00+00:00

My personal projects are in Git, but not on a ‘forge’ style website. I talk about why, and how to interact with them.

XOR

2025-02-14T00:00:00+00:00

An introduction to the boolean and bitwise XOR operators, their uses, and some advanced topics they lead in to.

Post-quantum public-key encryption: what’s it all about?

2025-01-02T00:00:00+00:00

An explanation of some post-quantum public-key cryptosystems, simplified to the level of pop-science.

Separation of concerns in a bug tracker

2024-11-01T00:00:00+00:00

A design thought about how bug trackers could use a more accurate data representation to make queries easier.

Possibly all the ways to get loop-finding in graphs wrong

2024-09-09T00:00:00+00:00

The history of all the mistakes I've made trying to detect loops in graphs while writing my puzzle collection.

Code review antipatterns

2024-08-21T00:00:00+00:00

A taxonomy of frustrating code review behaviours, and some thoughts about them.

Symbiosisware

2024-08-06T00:00:00+00:00

A definition and discussion of my term “symbiosisware”, describing software consciously designed for only yourself to use.

Beyond “Beyond the wall”

2024-07-16T00:00:00+00:00

A sequel to last month's post on finite-state transducers for aperiodic tilings.

Beyond the wall: working with aperiodic tilings using finite-state transducers

2024-06-10T00:00:00+00:00

A sequel to last year's two posts on combinatorial coordinates, this time applying regular-language theory to them.

Writing commit messages

2024-05-19T00:00:00+00:00

(Yet another) guide to writing commit messages in version control, with a focus on what facts and rationale are good things to include.

I hate bubblesort

2023-12-06T00:00:00+00:00

A short opinion: bubblesort is an awful sorting algorithm and I wish people would stop teaching it.

Stop helping!

2023-09-02T00:00:00+00:00

A short opinion: command-line tools shouldn’t print long help text as well as an error message.

Philosophy of coroutines

2023-09-01T00:00:00+00:00

Some thoughts about coroutines in general, why I like them so much, and ways of using them and thinking about them.

Writing custom C++20 coroutine systems

2023-08-06T00:00:00+00:00

A detailed introduction to the C++20 coroutine system, written in the course of teaching myself about it.

Workarounds for C11 _Generic

2023-07-29T00:00:00+00:00

A description of the big design limitation of C11's _Generic feature, and various workarounds, mostly involving using more instances of _Generic to patch up the original one.

How to read error messages

2023-07-06T00:00:00+00:00

An article about getting the most out of error messages, particularly OS and network errors. Adapted from a talk I gave to colleagues last year.

Combinatorial coordinates for the aperiodic Spectre tiling

2023-06-16T00:00:00+00:00

A description of the algorithms for generating the Spectre tiling in my puzzle game Loopy.

Two algorithms for randomly generating aperiodic tilings

2023-04-10T00:00:00+00:00

A description of the algorithms for generating Penrose and Hat tilings in my puzzle game Loopy.

Implementing OpenSSH certificate support in PuTTY

2022-12-03T00:00:00+00:00

A retrospective of the development of the headline new feature in PuTTY 0.78: OpenSSH-style certificates on host and user keys.

History of PuTTY's development

2020-03-24T00:00:00+00:00

An overview of PuTTY's development from its genesis in 1996 to the state of affairs in 2020. Written in response to an email query.

Writing a soluble-grid generator for Mines

2019-08-26T00:00:00+00:00

A description of the technique for generating guaranteed-soluble Minesweeper grids in my puzzle game Mines. Written in response to an email query.

Writing a solver for Net

2019-03-27T00:00:00+00:00

A description of the automated solver in my puzzle game Net. Written in response to an email query.

Porting PuTTY to Windows on Arm

2019-03-05T00:00:00+00:00

What I had to do to make PuTTY compile for Windows on Arm as well as on x86, plus a deep dive into the NEON-accelerated cryptography.