sign_extend64(9)

💖 NAME 💖

okay so welcome to the Kernel API Manual entry for sign_extend64(9), bestie! This is the little kernel helper that will sign extend a 64-bit value using specified bit as sign-bit. It’s giving “tiny function, big bit energy” fr fr. 🎀

🦋 SYNOPSIS 🦋

__s64 sign_extend64 (__u64 value , int index );

💅 ARGUMENTS 💅

• value — value to sign extend. This is the value you’re handing over, no cap. 💖
• index — 0 based bit index (0<=index<64) to sign bit. So yes, it’s zero-based, and the range is literally 0<=index<64 — iykyk. 🌸

👀 SEE ALSO 👀

• Kernel file ./tools/include/linux/bitops.h — bestie, go peek at the bitops file if you want the whole vibe. 🦋
• rol32(9) — another bit-twiddling icon, periodt. 👑

xoxo, that’s the whole page, bestie! Source/version: ./tools/include/linux, date: October 2026, so now you know the lore. 💅✨