Question

Write a program to swap odd and even bits in an integer with as few instructions as possible (e.g., bit 0 and bit 1 are swapped, bit 2 and bit 3 are swapped, and so on).

Solution

Mask odd and even bits seperately.

Code

public static int swapOddEvenBits(int x) {
    return (((x & 0xaaaaaaaa) >> 1) | ((x & 0x55555555) << 1));
}