■ Blog Posts (2)

Let's see Paul Allen's SIMD CSV parser

📅 📁 programming
Paul Allen's card

Look at the subtle nibble extraction. The tasteful lookup tables of it. Oh my god, it even has vqtbl1q_u8 and vmull_p64.


A year ago I wrote a CSV parser that is able to parse 64 characters at a time. It’s purely for research and hand waves over crucial steps for a production parser like validation. But the core algorithm uses SIMD and bitwise operations to classify and filter structural characters in bulk, and these are the techniques I’ll be talking about today.

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rust simd csv file formats

My memory isn't getting worse, it's just using exponential decay

📅 📁 programming

I’ve been working on a WASM interpreter from scratch. The unique feature is that it’s completely snapshotable, down to the instruction level. At any point during execution, you can call snapshot() and it will write out the entire execution state into a list of bytes, capturing everything up to that exact instruction. You can restore it later and execution picks up right where it left off.

Here’s a demo running Conway’s Game of Life. You snapshot the simulation mid-tick, fork it into a new process, and watch both diverge from the same state:

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rust data structures debuggers interpreters wasm