NewTOAPIA.Net.Udt.CACKWindow.acknowledge C# (CSharp) Method

        int acknowledge(Int32 seq, Int32 ack)
        {
            if (m_iHead >= m_iTail)
            {
                // Head has not exceeded the physical boundary of the window

                for (int i = m_iTail, n = m_iHead; i < n; ++i)
                    // looking for indentical ACK Seq. No.
                    if (seq == m_piACKSeqNo[i])
                    {
                        // return the Data ACK it carried
                        ack = m_piACK[i];

                        // calculate RTT
                        int rtt = (int)(CClock.getTime() - m_pTimeStamp[i]);
                        if (i + 1 == m_iHead)
                        {
                            m_iTail = m_iHead = 0;
                            m_piACKSeqNo[0] = -1;
                        }
                        else
                            m_iTail = (i + 1) % m_iSize;

                        return rtt;
                    }

                // Bad input, the ACK node has been overwritten
                return -1;
            }

            // Head has exceeded the physical window boundary, so it is behind tail
            for (int j = m_iTail, n = m_iHead + m_iSize; j < n; ++j)
                // looking for indentical ACK seq. no.
                if (seq == m_piACKSeqNo[j % m_iSize])
                {
                    // return Data ACK
                    j %= m_iSize;
                    ack = m_piACK[j];

                    // calculate RTT
                    int rtt = (int)(CClock.getTime() - m_pTimeStamp[j]);
                    if (j == m_iHead)
                    {
                        m_iTail = m_iHead = 0;
                        m_piACKSeqNo[0] = -1;
                    }
                    else
                        m_iTail = (j + 1) % m_iSize;

                    return rtt;
                }

            // bad input, the ACK node has been overwritten
            return -1;
        }
    }