EventScheduler.h

/*
 * This file is part of libsidplayfp, a SID player engine.
 *
 *  Copyright (C) 2011-2015 Leandro Nini
 *  Copyright (C) 2009 Antti S. Lankila
 *  Copyright (C) 2001 Simon White
 *
 *  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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 */
 
#ifndef EVENTSCHEDULER_H
#define EVENTSCHEDULER_H
 
#include "Event.h"
 
#include "sidcxx11.h"
 
 
namespace libsidplayfp
{
 
using event_phase_t = enum
{
    EVENT_CLOCK_PHI1 = 0,
    EVENT_CLOCK_PHI2 = 1
};
 
 
class EventScheduler
{
private:
    Event *firstEvent = nullptr;
 
    event_clock_t currentTime = 0;
 
private:
    void schedule(Event &event)
    {
        // find the right spot where to tuck this new event
        Event **scan = &firstEvent;
        for (;;)
        {
            if ((*scan == nullptr) || ((*scan)->triggerTime > event.triggerTime))
            {
                 event.next = *scan;
                 *scan = &event;
                 break;
             }
             scan = &((*scan)->next);
         }
    }
 
public:
    void schedule(Event &event, unsigned int cycles, event_phase_t phase)
    {
        // this strange formulation always selects the next available slot regardless of specified phase.
        event.triggerTime = currentTime + ((currentTime & 1) ^ phase) + (cycles << 1);
        schedule(event);
    }
 
    void schedule(Event &event, unsigned int cycles)
    {
        event.triggerTime = currentTime + (cycles << 1);
        schedule(event);
    }
 
    void cancel(Event &event);
 
    void reset();
 
    void clock()
    {
        Event &event = *firstEvent;
        firstEvent = firstEvent->next;
        currentTime = event.triggerTime;
        event.event();
    }
 
    bool isPending(Event &event) const;
 
    event_clock_t getTime(event_phase_t phase) const
    {
        return (currentTime + (phase ^ 1)) >> 1;
    }
 
    event_phase_t phase() const { return static_cast<event_phase_t>(currentTime & 1); }
 
    event_clock_t remaining(Event &event) const { return event.triggerTime - currentTime; }
};
 
}
 
#endif // EVENTSCHEDULER_H