count_leading_zeros(9)

💖 count_leading_zeros(9) — NAME 💖

Hey bestie, welcome to the count_leading_zeros(9) page in the Kernel API Manual ✨ This one is literally about counting zeros, and it's giving main character energy:

count_leading_zeros — Count the number of zeros from the MSB back 🎀

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✨ SYNOPSIS ✨

int count_leading_zeros (unsigned long x );

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🎀 ARGUMENTS 🎀

• x — The value. That's it, that's the whole input, no cap 💅

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🦋 DESCRIPTION 🦋

Okay so the vibe is: count the number of leading zeros from the MSB going towards the LSB in x. Periodt 💖

The results go like this:

• If the MSB of x is set, the result is 0. Slay, no zeros to count 🔥
• If only the LSB of x is set, then the result is BITS_PER_LONG-1. Iconic edge case behavior 🎀
• If x is 0, then the result is BITS_PER_LONG. That's the full count, bestie 😭

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👑 SEE ALSO 👑

• Kernel file ./include/linux/count_zeros.h — go check it out, iykyk 🦋
• count_trailing_zeros(9) — the other zero-counting bestie, matching energy 💅

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mwah 💖 this page lives in the Kernel API Manual, source ./include/linux, dated October 2026 — bye bestie, go count those zeros ✨