Microsoft.Scripting.Utils.MathUtils.GetBitCount C# (CSharp) Method

        public static int GetBitCount(this BigInt self) {
            if (self.IsZero) {
                return 1;
            }
            byte[] bytes = BigInt.Abs(self).ToByteArray();

            int index = bytes.Length;
            while (bytes[--index] == 0) ;

            int count = index * 8;
            for (int hiByte = bytes[index]; hiByte > 0; hiByte >>= 1) {
                count++;
            }
            return count;
        }