/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */

/*

 * Copyright (c) 2006 INRIA

 * Copyright (c) 2005 Mathieu Lacage

 * All rights reserved.

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation;

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

 *

 * Author: Mathieu Lacage <mathieu.lacage@sophia.inria.fr>

 *

 * This code started as a c++ translation of a java-based code written in 2005

 * to implement a heap sort. Which explains the Copyright Mathieu Lacage at the

 * top of this file.

 *

 * What is smart about this code ?

 *  - it does not use the index 0 in the array to avoid having to convert

 *    C-style array indexes (which start at zero) and heap-style indexes

 *    (which start at 1). This is why _all_ indexes start at 1, and that

 *    the index of the root is 1.

 *  - It uses a slightly non-standard while loop for top-down heapify

 *    to move one if statement out of the loop.

 */

#include "scheduler-heap.h"

#include "event-impl.h"

#include <cassert>

#define noTRACE_HEAP 1

#ifdef TRACE_HEAP

#include <iostream>

# define TRACE(x) \

std::cout << "HEAP TRACE " << x << std::endl;

#else /* TRACE_HEAP */

# define TRACE(format,...)

#endif /* TRACE_HEAP */

namespace ns3 {

SchedulerHeap::SchedulerHeap ()

{

  // we purposedly waste an item at the start of

  // the array to make sure the indexes in the

  // array start at one.

  Scheduler::EventKey emptyKey = {0,0};

  m_heap.push_back (std::make_pair (static_cast<EventImpl *>(0), emptyKey));

}

SchedulerHeap::~SchedulerHeap ()

{}

uint32_t 

SchedulerHeap::Parent (uint32_t id) const

{

  return id / 2;

}

uint32_t 

SchedulerHeap::Sibling (uint32_t id) const

{

  return id + 1;

}

uint32_t 

SchedulerHeap::LeftChild (uint32_t id) const

{

  return id * 2;

}

uint32_t 

SchedulerHeap::RightChild (uint32_t id) const

{

  return id * 2 + 1;

}

uint32_t

SchedulerHeap::Root (void) const

{

  return 1;

}

bool

SchedulerHeap::IsRoot (uint32_t id) const

{

  return (id == Root ())?true:false;

}

uint32_t

SchedulerHeap::Last (void) const

{

  return m_heap.size () - 1;

}

bool

SchedulerHeap::IsBottom (uint32_t id) const

{

  return (id >= m_heap.size ())?true:false;

}

void

SchedulerHeap::Exch (uint32_t a, uint32_t b) 

{

  assert (b < m_heap.size () && a < m_heap.size ());

  TRACE ("Exch " << a << ", " << b);

  std::pair<EventImpl*, Scheduler::EventKey> tmp (m_heap[a]);

  m_heap[a] = m_heap[b];

  m_heap[b] = tmp;

}

bool

{

}

uint32_t 

{

  return IsLess (a,b)?a:b;

}

bool

SchedulerHeap::RealIsEmpty (void) const

{

  return (m_heap.size () == 1)?true:false;

}

void

SchedulerHeap::BottomUp (void)

{

  uint32_t index = Last ();

  while (!IsRoot (index) && 

         IsLess (index, Parent (index))) 

    { 

      Exch(index, Parent (index)); 

      index = Parent (index); 

    }

}

void

SchedulerHeap::TopDown (void)

{

  uint32_t index = Root ();

  uint32_t right = RightChild (index);

  while (!IsBottom (right)) 

    {

      uint32_t left = LeftChild (index);

      uint32_t tmp = Smallest (left, right);

      if (IsLess (index, tmp)) 

        {

          return;

        }

      Exch (index, tmp);

      index = tmp;

      right = RightChild (index);

    }

  if (IsBottom (index)) 

    {

      return;

    }

  assert (!IsBottom (index));

  uint32_t left = LeftChild (index);

  if (IsBottom (left)) 

    {

      return;

    }

  if (IsLess (index, left)) 

    {

      return;

    }

  Exch (index, left);

}

EventId

SchedulerHeap::RealInsert (EventImpl *event, Scheduler::EventKey key)

{

  m_heap.push_back (std::make_pair (event, key));

  BottomUp ();

  return EventId (event, key.m_ns, key.m_uid);

}

EventImpl *

SchedulerHeap::RealPeekNext (void) const

{

  return m_heap[Root ()].first;

}

Scheduler::EventKey

SchedulerHeap::RealPeekNextKey (void) const

{

  return m_heap[Root ()].second;

}

void     

SchedulerHeap::RealRemoveNext (void)

{

  Exch (Root (), Last ());

  m_heap.pop_back ();

  TopDown ();

}

EventImpl *

SchedulerHeap::RealRemove (EventId id, Scheduler::EventKey *key)

{

  uint32_t top;

  uint32_t bottom;

  bottom = 1;

  top = Last ();

  key->m_ns = id.GetNs ();

  key->m_uid = id.GetUid ();

  while (top != bottom)

    {

      uint32_t i = bottom + (top - bottom) / 2;

        {

          top = i;

        }

      else

        {

          bottom = i;

        }

    }

  assert (top == bottom);

  assert (m_heap[top].second.m_uid == id.GetUid ());

  EventImpl *retval = m_heap[top].first;

  Exch (top, Last ());

  m_heap.pop_back ();

  TopDown ();

  return retval;

}

bool 

SchedulerHeap::RealIsValid (EventId id)

{

  return true;

}

}; // namespace ns3

#ifdef RUN_SELF_TESTS

#include "ns3/test.h"

namespace ns3 {

class SchedulerHeapTest : public Test 

{

public:

  SchedulerHeapTest ();

  virtual ~SchedulerHeapTest ();

  virtual bool RunTests (void);

};

SchedulerHeapTest::SchedulerHeapTest ()

  : Test ("SchedulerHeap")

{}

SchedulerHeapTest::~SchedulerHeapTest ()

{}

bool 

SchedulerHeapTest::RunTests (void)

{

  bool ok = true;

  return ok;

}

static SchedulerHeapTest g_schedulerHeapTest;

}; // namespace ns3

#endif /* RUN_SELF_TESTS */