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*****************************************************************************/

/*****************************************************************************
written by
   Yunhong Gu, last updated 01/22/2011
*****************************************************************************/

#include <cmath>
#include "common.h"
#include "window.h"
#include <algorithm>

using namespace std;

CACKWindow::CACKWindow(int size):
m_piACKSeqNo(NULL),
m_piACK(NULL),
m_pTimeStamp(NULL),
m_iSize(size),
m_iHead(0),
m_iTail(0)
{
   m_piACKSeqNo = new int32_t[m_iSize];
   m_piACK = new int32_t[m_iSize];
   m_pTimeStamp = new uint64_t[m_iSize];

   m_piACKSeqNo[0] = -1;
}

CACKWindow::~CACKWindow()
{
   delete [] m_piACKSeqNo;
   delete [] m_piACK;
   delete [] m_pTimeStamp;
}

void CACKWindow::store(int32_t seq, int32_t ack)
{
   m_piACKSeqNo[m_iHead] = seq;
   m_piACK[m_iHead] = ack;
   m_pTimeStamp[m_iHead] = CTimer::getTime();

   m_iHead = (m_iHead + 1) % m_iSize;

   // overwrite the oldest ACK since it is not likely to be acknowledged
   if (m_iHead == m_iTail)
      m_iTail = (m_iTail + 1) % m_iSize;
}

int CACKWindow::acknowledge(int32_t seq, int32_t& 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(CTimer::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(CTimer::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;
}

////////////////////////////////////////////////////////////////////////////////

CPktTimeWindow::CPktTimeWindow(int asize, int psize):
m_iAWSize(asize),
m_piPktWindow(NULL),
m_iPktWindowPtr(0),
m_iPWSize(psize),
m_piProbeWindow(NULL),
m_iProbeWindowPtr(0),
m_iLastSentTime(0),
m_iMinPktSndInt(1000000),
m_LastArrTime(),
m_CurrArrTime(),
m_ProbeTime()
{
   m_piPktWindow = new int[m_iAWSize];
   m_piPktReplica = new int[m_iAWSize];
   m_piProbeWindow = new int[m_iPWSize];
   m_piProbeReplica = new int[m_iPWSize];

   m_LastArrTime = CTimer::getTime();

   for (int i = 0; i < m_iAWSize; ++ i)
      m_piPktWindow[i] = 1000000;

   for (int k = 0; k < m_iPWSize; ++ k)
      m_piProbeWindow[k] = 1000;
}

CPktTimeWindow::~CPktTimeWindow()
{
   delete [] m_piPktWindow;
   delete [] m_piPktReplica;
   delete [] m_piProbeWindow;
   delete [] m_piProbeReplica;
}

int CPktTimeWindow::getMinPktSndInt() const
{
   return m_iMinPktSndInt;
}

int CPktTimeWindow::getPktRcvSpeed() const
{
   // get median value, but cannot change the original value order in the window
   std::copy(m_piPktWindow, m_piPktWindow + m_iAWSize - 1, m_piPktReplica);
   std::nth_element(m_piPktReplica, m_piPktReplica + (m_iAWSize / 2), m_piPktReplica + m_iAWSize - 1);
   int median = m_piPktReplica[m_iAWSize / 2];

   int count = 0;
   int sum = 0;
   int upper = median << 3;
   int lower = median >> 3;

   // median filtering
   int* p = m_piPktWindow;
   for (int i = 0, n = m_iAWSize; i < n; ++ i)
   {
      if ((*p < upper) && (*p > lower))
      {
         ++ count;
         sum += *p;
      }
      ++ p;
   }

   // claculate speed, or return 0 if not enough valid value
   if (count > (m_iAWSize >> 1))
      return (int)ceil(1000000.0 / (sum / count));
   else
      return 0;
}

int CPktTimeWindow::getBandwidth() const
{
   // get median value, but cannot change the original value order in the window
   std::copy(m_piProbeWindow, m_piProbeWindow + m_iPWSize - 1, m_piProbeReplica);
   std::nth_element(m_piProbeReplica, m_piProbeReplica + (m_iPWSize / 2), m_piProbeReplica + m_iPWSize - 1);
   int median = m_piProbeReplica[m_iPWSize / 2];

   int count = 1;
   int sum = median;
   int upper = median << 3;
   int lower = median >> 3;

   // median filtering
   int* p = m_piProbeWindow;
   for (int i = 0, n = m_iPWSize; i < n; ++ i)
   {
      if ((*p < upper) && (*p > lower))
      {
         ++ count;
         sum += *p;
      }
      ++ p;
   }

   return (int)ceil(1000000.0 / (double(sum) / double(count)));
}

void CPktTimeWindow::onPktSent(int currtime)
{
   int interval = currtime - m_iLastSentTime;

   if ((interval < m_iMinPktSndInt) && (interval > 0))
      m_iMinPktSndInt = interval;

   m_iLastSentTime = currtime;
}

void CPktTimeWindow::onPktArrival()
{
   m_CurrArrTime = CTimer::getTime();

   // record the packet interval between the current and the last one
   *(m_piPktWindow + m_iPktWindowPtr) = int(m_CurrArrTime - m_LastArrTime);

   // the window is logically circular
   ++ m_iPktWindowPtr;
   if (m_iPktWindowPtr == m_iAWSize)
      m_iPktWindowPtr = 0;

   // remember last packet arrival time
   m_LastArrTime = m_CurrArrTime;
}

void CPktTimeWindow::probe1Arrival()
{
   m_ProbeTime = CTimer::getTime();
}

void CPktTimeWindow::probe2Arrival()
{
   m_CurrArrTime = CTimer::getTime();

   // record the probing packets interval
   *(m_piProbeWindow + m_iProbeWindowPtr) = int(m_CurrArrTime - m_ProbeTime);
   // the window is logically circular
   ++ m_iProbeWindowPtr;
   if (m_iProbeWindowPtr == m_iPWSize)
      m_iProbeWindowPtr = 0;
}