swapping binary

Keerthi is given an unsigned integer $M$. Her task is to swap all odd bits with even bits. For example, if the given number is $23$ (00010111), it should be converted to $43$ (00101011). Here, every even position bit is swapped with an adjacent bit on the right side, and every odd position bit is swapped with an adjacent bit on the left side. So she has to solve this problem by above logic. Give t