Presence.cc

// Copyright 2008 Michael Marsh, University of Maryland.
//
// This file is part of pydtn.
//
// pydtn is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// pydtn 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 pydtn.  If not, see <http://www.gnu.org/licenses/>.
//
// The views and conclusions contained in the software and documentation
// are those of the authors and should not be interpreted as representing
// official policies, either expressed or implied, of the University
// of Maryland.
//
// pydtn extends and embeds the Python interpreter, which is
// Copyright 2001-2006 Python Software Foundation, All Rights Reserved,
// and is released under the PSF License Agreement.
//
// RANLUX random number generation uses the Boost library,
// Copyright 1994-2006 by various authors (details in individual files),
// which is released under the Boost Software License, Version 1.0.

#include "Presence.h"

using namespace Mobility;

void
Presence::operator=( const Presence& p )
{
   if ( &p == this ) return;
   m_time = p.m_time;
   m_position = p.m_position;
   m_duration = p.m_duration;
}

Presence
Presence::towards( const Presence& p, const Time& t ) const
{
   Time range = p.time() - (m_time+m_duration);
   Time t0 = p.time() - t;
   Time t1 = t - m_time;

   // Round-off isn't really that big a deal, because a value in
   // seconds large enough to bury the number of microseconds means
   // the microseconds don't really matter.
   double drange = 1.0*Time::MILLION*range.tv.tv_sec + range.tv.tv_usec;
   double dt0 = 1.0*Time::MILLION*t0.tv.tv_sec + t0.tv.tv_usec;
   double dt1 = 1.0*Time::MILLION*t1.tv.tv_sec + t1.tv.tv_usec;

   Position newpos = m_position*(dt0/drange) + p.position()*(dt1/drange);
   return Presence(t,newpos,Time());
}

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