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timer.cpp

/* ScummVM - Scumm Interpreter
 * Copyright (C) 2002-2004 The ScummVM project
 *
 * This program 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 2
 * of the License, or (at your option) any later version.
 *
 * 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.
 *
 * $Header: /cvsroot/scummvm/scummvm/common/timer.cpp,v 1.30 2004/09/28 20:19:25 fingolfin Exp $
 */

#ifndef __MORPHOS__

#include "stdafx.h"
#include "common/scummsys.h"
#include "common/timer.h"
#include "common/util.h"

Timer *g_timer = NULL;

Timer::Timer(OSystem *system) :
      _system(system),
      _mutex(0),
      _timerHandler(0),
      _lastTime(0) {

      _mutex = _system->createMutex();

      g_timer = this;

      for (int i = 0; i < MAX_TIMERS; i++) {
            _timerSlots[i].procedure = NULL;
            _timerSlots[i].interval = 0;
            _timerSlots[i].counter = 0;
      }

      _thisTime = _system->getMillis();

      // Set the timer last, after everything has been initialised
      _system->setTimerCallback(&timer_handler, 10);

}

Timer::~Timer() {
      // Remove the timer callback. 
      // Note: backends *must* gurantee that after this method call returns,
      // the handler is not in use anymore; else race condtions could occurs.
      _system->setTimerCallback(0, 0);

      {
            Common::StackLock lock(_mutex);
            for (int i = 0; i < MAX_TIMERS; i++) {
                  _timerSlots[i].procedure = NULL;
                  _timerSlots[i].interval = 0;
                  _timerSlots[i].counter = 0;
            }
      }

      _system->deleteMutex(_mutex);
}

int Timer::timer_handler(int t) {
      if (g_timer)
            return g_timer->handler(t);
      return 0;
}

int Timer::handler(int t) {
      Common::StackLock lock(_mutex);
      uint32 interval, l;

      _lastTime = _thisTime;
      _thisTime = _system->getMillis();
      interval = 1000 * (_thisTime - _lastTime);

      for (l = 0; l < MAX_TIMERS; l++) {
            if (_timerSlots[l].procedure && _timerSlots[l].interval > 0) {
                  _timerSlots[l].counter -= interval;
                  while (_timerSlots[l].counter <= 0) {
                        // A small paranoia check which catches the case where
                        // a timer removes itself (which it never should do).
                        assert(_timerSlots[l].procedure && _timerSlots[l].interval > 0);
                        _timerSlots[l].counter += _timerSlots[l].interval;
                        _timerSlots[l].procedure(_timerSlots[l].refCon);
                  }
            }
      }

      return t;
}

bool Timer::installTimerProc(TimerProc procedure, int32 interval, void *refCon) {
      assert(interval > 0);
      Common::StackLock lock(_mutex);

      for (int l = 0; l < MAX_TIMERS; l++) {
            if (!_timerSlots[l].procedure) {
                  _timerSlots[l].procedure = procedure;
                  _timerSlots[l].interval = interval;
                  _timerSlots[l].counter = interval;
                  _timerSlots[l].refCon = refCon;
                  return true;
            }
      }

      warning("Couldn't find free timer slot!");
      return false;
}

void Timer::removeTimerProc(TimerProc procedure) {
      Common::StackLock lock(_mutex);

      for (int l = 0; l < MAX_TIMERS; l++) {
            if (_timerSlots[l].procedure == procedure) {
                  _timerSlots[l].procedure = 0;
                  _timerSlots[l].interval = 0;
                  _timerSlots[l].counter = 1;   // Work around a problem when a timer proc removes itself
                  _timerSlots[l].refCon = 0;
            }
      }
}

#endif

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