fls(9)

📦 version 7.3.1, in nixpkgs unstable

okay bestie, welcome to fls(9) from the Kernel API Manual — this is the bit-hunting page and it's lowkey iconic 🎀✨

🌸 NAME 🌸

fls — find the last (most-significant) bit set. that's the whole vibe: last bit, most-significant, set. periodt 💅

✨ SYNOPSIS ✨

int fls (unsigned int x );

yup, that's the signature, don't @ me 🫶

🎀 ARGUMENTS 🎀

  • x — the word to search. literally the word you're sending in to get searched 🔍💖

💖 DESCRIPTION 💖

okay so this is defined the same way as ffs — no cap, same definition energy.

and here's the note you need to keep in your group chat: fls(0) = 0, fls(1) = 1, and fls(0x80000000) = 32 ⭐. write those down, bestie, they're giving exam-question main character energy 😭

🦋 SEE ALSO 🦋

  • Kernel file ./include/asm-generic/bitops/builtin-fls.h — go read it if you want the source tea 🍵💜

sign-off time: source/version ./include/asm-generic/bitops, dated October 2026, manual fls(9) — mwah, go slay those bits 💋✨

📦 where this page comes from