HoldemHand.Hand.OutsMask C# (CSharp) Method

        public static ulong OutsMask(ulong player, ulong board, params ulong[] opponents)
        {
            ulong retval = 0UL;

            #if DEBUG
            if (BitCount(player) != 2) throw new ArgumentException("player must have exactly 2 cards");
            if (BitCount(board) != 3 && BitCount(board) != 4) throw new ArgumentException("board must contain 3 or 4 cards");
            #endif

            // Get original mask value
            uint playerOrigHandVal = Hand.Evaluate(player | board);

            // Look ahead one card
            foreach (ulong card in Hand.Hands(0UL, board | player, 1))
            {
                // Get new mask value
                uint playerNewHandVal = Hand.Evaluate(player | board | card);
                // Get new board value
                uint boardHandVal = Hand.Evaluate(board | card);

                // Is the new mask better than the old one?
                bool handImproved = playerNewHandVal > playerOrigHandVal;

                // This compare ensures we move up in mask type.
                bool handStrongerThanBoard = Hand.HandType(playerNewHandVal) > Hand.HandType(boardHandVal) ||
                                            (Hand.HandType(playerNewHandVal) == Hand.HandType(boardHandVal) &&
                                            Hand.TopCard(playerNewHandVal) > Hand.TopCard(boardHandVal));

                // Check against opponents cards
                bool handBeatAllOpponents = true;
                if (handImproved && handStrongerThanBoard && opponents != null && opponents.Length > 0)
                {
                    foreach (ulong opponent in opponents)
                    {
                        uint opponentHandVal = Hand.Evaluate(opponent | board | card);
                        if (opponentHandVal > playerNewHandVal)
                        {
                            handBeatAllOpponents = false;
                            break;
                        }
                    }
                }

                // If the mask improved then we have an out
                if (handImproved && handStrongerThanBoard && handBeatAllOpponents)
                {
                    // Add card to outs mask
                    retval |= card;
                }
            }

            // return outs as a mask mask
            return retval;
        }