23 Mar 2024 As a side-quest I recently decided to write a branchless utf8 decoder utilizing the pext or "parallel extract" instruction. It's compliant with rfc-3629, meaning that it doesn't just naively decode the code-point but also checks for overlong encoding, surrogate pairs and such. Compiled with gcc -O3 -march=x86-64-v3 the entire decoder results in just about 29 instructions. That's pretty sweet, if you ask me. The full source code can be found here: utf8-pext.c. UTF8: what is it? A smal...