std::floor2
From cppreference.com
Defined in header <bit>


template< class T > constexpr T floor2(T x) noexcept; 
(since C++20)  
If x
is not zero, calculates the largest integral power of two that is not greater than x
. If x
is zero, returns zero.
This overload only participates in overload resolution if T
is an unsigned integer type (that is, unsigned char, unsigned short, unsigned int, unsigned long, unsigned long long, or an extended unsigned integer type).
[edit] Return value
Zero if x
is zero; otherwise, the largest integral power of two that is not greater than x
.
[edit] Example
This section is incomplete Reason: no example 