Encog.MathUtil.LIBSVM.Cache.swap_index C# (CSharp) Method

        internal virtual void swap_index(int i, int j)
        {
            if (i == j)
                return;

            if (head[i].len > 0)
                lru_delete(head[i]);
            if (head[j].len > 0)
                lru_delete(head[j]);
            do
            {
                float[] _ = head[i].data;
                head[i].data = head[j].data;
                head[j].data = _;
            } while (false);
            do
            {
                int _ = head[i].len;
                head[i].len = head[j].len;
                head[j].len = _;
            } while (false);
            if (head[i].len > 0)
                lru_insert(head[i]);
            if (head[j].len > 0)
                lru_insert(head[j]);

            if (i > j)
                do
                {
                    int _ = i;
                    i = j;
                    j = _;
                } while (false);
            for (head_t h = lru_head.next; h != lru_head; h = h.next)
            {
                if (h.len > i)
                {
                    if (h.len > j)
                        do
                        {
                            float _ = h.data[i];
                            h.data[i] = h.data[j];
                            h.data[j] = _;
                        } while (false);
                    else
                    {
                        // give up
                        lru_delete(h);
                        size += h.len;
                        h.data = null;
                        h.len = 0;
                    }
                }
            }
        }