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

/*

 * Copyright (c) 2010 INRIA

 *

 * 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>

 */

#ifndef HIGH_PRECISION_128_H

#define HIGH_PRECISION_128_H

#include "ns3/simulator-config.h"

#include <math.h>

#include <stdint.h>

#if defined(HAVE___UINT128_T) and !defined(HAVE_UINT128_T)

typedef __uint128_t uint128_t;

typedef __int128_t int128_t;

#endif

namespace ns3 {

class HighPrecision

{

public:

  inline HighPrecision ();

  inline int64_t GetInteger (void) const;

  inline double GetDouble (void) const;

  inline void Add (HighPrecision const &o);

  inline void Sub (HighPrecision const &o);

  void Mul (HighPrecision const &o);

  void Div (HighPrecision const &o);

  void MulByInvert (const HighPrecision &o);

  static HighPrecision Invert (uint64_t v);

  inline int Compare (HighPrecision const &o) const;

  inline static HighPrecision Zero (void);

private:

  static uint128_t UmulByInvert (uint128_t a, uint128_t b);

  static uint128_t Umul (uint128_t a, uint128_t b);

  static uint128_t Divu (uint128_t a, uint128_t b);

  int128_t m_value;

};

} // namespace ns3

namespace ns3 {

HighPrecision::HighPrecision ()

  : m_value (0)

{}

HighPrecision::HighPrecision (int64_t value, bool dummy)

  : m_value (value)

{

  m_value <<= 64;

}

int64_t HighPrecision::GetInteger (void) const

{

  int128_t v = m_value >> 64;

  return v;

}

void

HighPrecision::Add (HighPrecision const &o)

{

  m_value += o.m_value;

}

void

HighPrecision::Sub (HighPrecision const &o)

{

  m_value -= o.m_value;

}

int 

HighPrecision::Compare (HighPrecision const &o) const

{

  return (m_value < o.m_value)?-1:(m_value == o.m_value)?0:1;

}

HighPrecision

HighPrecision::Zero (void)

{

  return HighPrecision ();

}

#define HP128_MAX_64 18446744073709551615.0

double 

HighPrecision::GetDouble (void) const

{

  bool is_negative = m_value < 0;

  uint128_t value = is_negative ? -m_value:m_value;

  uint64_t hi = value >> 64;

  uint64_t lo = value;

  double flo = lo;

  flo /= HP128_MAX_64;

  double retval = hi;

  retval += flo;

  retval = is_negative ? -retval : retval;

  return retval;

}

HighPrecision::HighPrecision (double value)

{

  bool is_negative = value < 0;

  value = is_negative?-value:value;

  double hi = floor (value);

  double lo = (value - hi) * HP128_MAX_64;

  m_value = (int128_t)hi;

  m_value <<= 64;

  m_value += (int128_t)lo;

  m_value = is_negative?-m_value:m_value;

}

#undef HP128_MAX_64

} // namespace ns3

#endif /* HIGH_PRECISION_128_H */