Fastest implementation of log2(int) and log2(float)

Question

The question is

Are there any other (and/or faster) implementations of a basic 2log?

Applications

The log2(int) and

Answer 1

    static byte FloorLog2(UInt16 value)
    {
        for (byte i = 0; i < 15; ++i)
        {
            if ((value >>= 1) < 1)
            {
                return i;
            }
        }
        return 15;
    }