IntMath.cs


namespace GeodesicGrid
{
    internal static class IntMath
    {
        // From: http://stackoverflow.com/a/383596/303422
        public static int Pow(int x, uint pow)
        {
            int ret = 1;
            while (pow != 0)
            {
                if ((pow & 1) == 1)
                    ret *= x;
                x *= x;
                pow >>= 1;
            }
            return ret;
        }

        private static int[] MultiplyDeBruijnBitPosition = {
            0, 9, 1, 10, 13, 21, 2, 29, 11, 14, 16, 18, 22, 25, 3, 30,
            8, 12, 20, 28, 15, 17, 24, 7, 19, 27, 23, 6, 26, 5, 4, 31
        };

        public static int LogBase2(uint v)
        {
            v |= v >> 1;
            v |= v >> 2;
            v |= v >> 4;
            v |= v >> 8;
            v |= v >> 16;

            return MultiplyDeBruijnBitPosition[(v * 0x7C4ACDDU) >> 27];
        }
    }
}