Function prev_pot

include/floor/constexpr/const_math.hpp:1118–1132

   //! returns the nearest (less or equal) power of two value of num (only numerical downwards)
   template <typename int_type> requires(ext::is_integral_v<int_type>)
   constexpr int_type prev_pot(const int_type num) {
	   if (num <= 1) {
		   return num;
	   }
	   
	   int_type tmp = 1;
	   for (size_t i = 0; i < (sizeof(int_type) * 8u); ++i) {
		   auto next = tmp << 1;
		   if (next > num) {
			   return tmp;
		   }
		   tmp = next;
	   }
	   return 0;
   }
	
	//! computes the width of an integer value (e.g. 7 = 1, 42 = 2, 987654 = 6)
	template <typename int_type> requires(ext::is_integral_v<int_type>)