# SDL_MostSignificantBitIndex32

Get the index of the most significant (set) bit in a 32-bit number.

## Header File

Defined in [<SDL3/SDL_bits.h>](https://github.com/libsdl-org/SDL/blob/main/include/SDL3/SDL_bits.h)

## Syntax

```c
SDL_FORCE_INLINE int SDL_MostSignificantBitIndex32(Uint32 x);
```

## Function Parameters

|                  |       |                              |
| ---------------- | ----- | ---------------------------- |
| [Uint32](Uint32) | **x** | the 32-bit value to examine. |

## Return Value

(int) Returns the index of the most significant bit, or -1 if the value is
0.

## Remarks

This operation can also be stated as "count leading zeroes" and "log base
2".

Note that this is a forced-inline function in a header, and not a public
API function available in the SDL library (which is to say, the code is
embedded in the calling program and the linker and dynamic loader will not
be able to find this function inside SDL itself).

## Thread Safety

It is safe to call this function from any thread.

## Version

This function is available since SDL 3.2.0.

----
[CategoryAPI](CategoryAPI), [CategoryAPIFunction](CategoryAPIFunction), [CategoryBits](CategoryBits)

