SDL_MOSTSIGNIFICANTBITINDEX32(3)

📦
version 3.4.18 · 9 versions
, in fedora 43, fedora 44

💅 SDL_MostSignificantBitIndex32(3)

okay bestie, pull up a chair because we're diving into SDL_bits.h — this one lives in the SDL3 FUNCTIONS section of the manual and it's genuinely so useful. no cap.

✨ NAME ✨

SDL_MostSignificantBitIndex32 — get the index of the most significant (set) bit in a 32-bit number. that's it, that's the whole job. iconic honestly. 👑

🌸 SYNOPSIS 🌸

#include <SDL3/SDL_bits.h>

SDL_FORCE_INLINE int SDL_MostSignificantBitIndex32(Uint32 x);

🦋 DESCRIPTION 🦋

so like, you've got a 32-bit number and you wanna know where the biggest set bit is chillin'. that's this. 💖

there are other ways to describe the exact same operation, and they're all saying the same thing in different fonts:

  • "count leading zeroes"
  • "log base 2"

also!! important tea 🫖: this is a forced-inline function in a header, NOT a public API function that's available inside the SDL library itself. translating that for you: the code gets embedded directly in your calling program. so the linker and the dynamic loader will not be able to find this function inside SDL itself. it's not hiding in there, bestie. it's in your binary. periodt.

🎀 FUNCTION PARAMETERS 🎀

  • x — the 32-bit value to examine. give it a number, it'll do the vibe check. 💅

🌈 RETURN VALUE 🌈

  • returns the index of the most significant bit ✨
  • or -1 if the value is 0. yeah, zero has no set bits, so there's nothing to point at. sad for it. 😭

🧚 THREAD SAFETY 🧚

it is safe to call this function from any thread. go off, multithreaded queen. 🫶

⭐ AVAILABILITY ⭐

this function is available since SDL 3.2.0. so if you're on something older... no it's not. 🙈

real talk though: since it's a forced-inline header function, don't go hunting for the symbol in libSDL3 and then get confused when it's not there. that's not a bug, that's the design. iykyk. 💜

and that's the whole page, bestie!! Simple Directmedia Layer wrote this one, this is the SDL 3.4.18 era of the docs, and if anyone asks, you read the whole thing. obsessed with you. bye!! 🎀✨💖

📦 where this page comes from