Fastest way to count number of bit transitions in an unsigned int

Question

I\'m looking for the fastest way of counting the number of bit transitions in an unsigned int.

If the int contains: 0b0000000000000000000000000000101

Answer 1

In C/C++ I would do the following:

unsigned int Transitions(unsigned int value)
{
    unsigned int result = 0;

    for (unsigned int markers = value ^ (value >> 1); markers; markers = markers >> 1)
    {
        if (markers & 0x01) result++;
    }

    return result;
}