mul_u64_add_u64_div_u64(9)

📦 version 7.3.1, in nixpkgs unstable

💅 NAME 💅

mul_u64_add_u64_div_u64 — unsigned 64bit multiply, add, and divide. bestie it does exactly what it says on the tin, no cap 🫶

it's a kernel API manual entry, so you already know this is math64.h girlie territory ✨

✨ SYNOPSIS ✨

u64 mul_u64_add_u64_div_u64 (u64 a , u64 b , u64 c , u64 d );

🎀 ARGUMENTS 🎀

  • a — first unsigned 64bit multiplicand. one half of the main character duo 💖
  • b — second unsigned 64bit multiplicand. the other half, they ate fr 🔥
  • c — unsigned 64bit addend. the little sprinkle on top after the multiply 🌸
  • d — unsigned 64bit divisor. the one doing the dividing, lowkey carrying the whole operation 😭

🦋 DESCRIPTION 🦋

okay so picture this: you multiply two 64bit values together to generate a 128bit product, then you add a third value, and then you divide by a fourth. that's the whole vibe, it's giving math chain-reaction energy 💫

the Generic code divides by 0 if d is zero and returns ~0 on overflow. yes really, that's the documented behaviour, not me being dramatic 🙈

Architecture specific code may trap on zero or overflow — so different arches can be like "nope" and trap instead. it's giving "depends on your arch bestie, check before you ship" 💀

👑 RETURN 👑

(a * b + c) / d

literally just the formula, periodt ✨

🌈 SEE ALSO 🌈

Kernel file ./include/linux/math64.h, plus the whole math64 friend group:

iykyk: this page lives in ./include/linux, dated October 2026, and it's filed under the Kernel API Manual — mul_u64_add_u64_div_u64(9) forever and always 💜 ok that's the whole page bestie, go forth and multiply (then add, then divide) 🧚🍓
📦 where this page comes from