interrupt.h

/*
 * This file is part of libsidplayfp, a SID player engine.
 *
 * Copyright 2011-2018 Leandro Nini <drfiemost@users.sourceforge.net>
 * Copyright 2007-2010 Antti Lankila
 * Copyright 2000 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 INTERRUPT_H
#define INTERRUPT_H
 
#include "Event.h"
#include "EventScheduler.h"
 
#include <stdint.h>
 
#include "sidcxx11.h"
 
namespace libsidplayfp
{
 
class MOS6526;
 
class InterruptSource : protected Event
{
public:
    enum
    {
        INTERRUPT_NONE         = 0,      
        INTERRUPT_UNDERFLOW_A  = 1 << 0, 
        INTERRUPT_UNDERFLOW_B  = 1 << 1, 
        INTERRUPT_ALARM        = 1 << 2, 
        INTERRUPT_SP           = 1 << 3, 
        INTERRUPT_FLAG         = 1 << 4, 
        INTERRUPT_REQUEST      = 1 << 7  
    };
 
protected:
    MOS6526 &parent;
 
    EventScheduler &eventScheduler;
 
private:
    uint8_t icr;
 
    uint8_t idr;
 
protected:
    bool interruptMasked() const { return icr & idr; }
 
    bool interruptTriggered() const { return idr & INTERRUPT_REQUEST; }
 
    void triggerInterrupt() { idr |= INTERRUPT_REQUEST; }
 
    void triggerBug() { idr &= ~INTERRUPT_UNDERFLOW_B; }
 
protected:
    InterruptSource(EventScheduler &scheduler, MOS6526 &parent) :
        Event("CIA Interrupt"),
        parent(parent),
        eventScheduler(scheduler),
        icr(0),
        idr(0)
    {}
 
public:
    virtual ~InterruptSource() {}
 
    virtual void trigger(uint8_t interruptMask) { idr |= interruptMask; }
 
    virtual uint8_t clear()
    {
        uint8_t const old = idr;
        idr = 0;
        return old;
    }
 
    virtual void reset()
    {
        icr = 0;
        idr = 0;
        eventScheduler.cancel(*this);
    }
 
    void set(uint8_t interruptMask)
    {
        if (interruptMask & 0x80)
        {
            icr |= interruptMask & ~INTERRUPT_REQUEST;
            trigger(INTERRUPT_NONE);
        }
        else
        {
            icr &= ~interruptMask;
        }
    }
};
 
}
 
#endif // INTERRUPT_H