#include "int64x64.h"

#include <stdint.h>

#include <iostream>

#include <sstream>

#include "assert.h"

namespace ns3 {

static uint8_t MostSignificantDigit (uint64_t value)

{

  uint8_t n = 0;

  do

    {

      n++;

      value /= 10;

    } while (value != 0);

  return n;

}

static uint64_t PowerOfTen (uint8_t n)

{

  uint64_t retval = 1;

  while (n > 0)

    {

      retval *= 10;

      n--;

    }

  return retval;

}

std::ostream &operator << (std::ostream &os, const int64x64_t &value)

{

  int64_t hi = value.GetHigh ();

  os << ((hi<0) ? "-" : "+") << ((hi<0) ? -hi : hi) << ".";

  uint64_t low = value.GetLow ();

  uint8_t msd = MostSignificantDigit (~((uint64_t)0));

  do

    {

      msd--;

      uint64_t pow = PowerOfTen (msd);

      uint8_t digit = low / pow;

      NS_ASSERT (digit < 10);

      os << (uint16_t) digit;

      low -= digit * pow;

    } while (msd > 0 && low > 0);

  return os;

}

static uint64_t ReadDigits (std::string str)

{

  const char *buf = str.c_str ();

  uint64_t retval = 0;

  while (*buf != 0)

    {

      retval *= 10;

      retval += *buf - 0x30;

      buf++;

    }

  return retval;

}

std::istream &operator >> (std::istream &is, int64x64_t &value)

{

  std::string str;

  is >> str;

  bool negative;

  // skip heading spaces

  std::string::size_type cur;

  cur = str.find_first_not_of (" ");

  std::string::size_type next;

  // first, remove the sign.

  next = str.find ("-", cur);

  if (next != std::string::npos)

    {

      negative = true;

      next++;

    }

  else

    {

      next = str.find ("+", cur);

      if (next != std::string::npos)

        {

          next++;

        }

      else

        {

          next = cur;

        }

      negative = false;

    }

  cur = next;

  int64_t hi;

  uint64_t lo;

  next = str.find (".", cur);

  if (next != std::string::npos)

    {

      hi = ReadDigits (str.substr (cur, next-cur));

      lo = ReadDigits (str.substr (next+1, str.size ()-(next+1)));

    }

  else

    {

      hi = ReadDigits (str.substr (cur, str.size ()-cur));

      lo = 0;

    }

  hi = negative ? -hi : hi;

  value = int64x64_t (hi, lo);

  return is;

}

} // namespace ns3