Efficient bitwise operations for counting bits or find the right|left most ones

Question

Given an unsigned int, I have to implement the following operations :

1. Count the number of bits set to 1
2. Find the index of the left-most 1 bit

Answer 1

for rightmost bit simple ans

First Method

unsigned int getFirstSetBit(int n){

return log2(n & -n) + 1; 

}

Second Method

unsigned int getFirstSetBit(int n){

return ffs(n);   

}