144 lines
3.4 KiB
Plaintext
144 lines
3.4 KiB
Plaintext
/*
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* This file is part of libsidplayfp, a SID player engine.
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*
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* Copyright 2011-2015 Leandro Nini <drfiemost@users.sourceforge.net>
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* Copyright 2007-2010 Antti Lankila
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* Copyright 2000 Simon White
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*/
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#ifndef INTERRUPT_H
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#define INTERRUPT_H
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#include "Event.h"
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#include "EventScheduler.h"
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#include <stdint.h>
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#include "sidcxx11.h"
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namespace libsidplayfp
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{
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class MOS6526;
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/**
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* This is the base class for the MOS6526 interrupt sources.
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*/
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class InterruptSource : protected Event
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{
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public:
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enum
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{
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INTERRUPT_NONE = 0,
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INTERRUPT_UNDERFLOW_A = 1 << 0,
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INTERRUPT_UNDERFLOW_B = 1 << 1,
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INTERRUPT_ALARM = 1 << 2,
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INTERRUPT_SP = 1 << 3,
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INTERRUPT_FLAG = 1 << 4,
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INTERRUPT_REQUEST = 1 << 7
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};
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protected:
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/// Pointer to the MOS6526 which this Interrupt belongs to.
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MOS6526 &parent;
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/// Event scheduler.
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EventScheduler &eventScheduler;
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private:
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/// Interrupt control register
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uint8_t icr;
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/// Interrupt data register
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uint8_t idr;
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protected:
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bool interruptMasked() const { return icr & idr; }
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bool interruptTriggered() const { return (idr & INTERRUPT_REQUEST) == 0; }
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void triggerInterrupt() { idr |= INTERRUPT_REQUEST; }
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protected:
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/**
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* Create a new InterruptSource.
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*
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* @param scheduler event scheduler
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* @param parent the MOS6526 which this Interrupt belongs to
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*/
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InterruptSource(EventScheduler &scheduler, MOS6526 &parent) :
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Event("CIA Interrupt"),
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parent(parent),
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eventScheduler(scheduler),
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icr(0),
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idr(0)
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{}
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public:
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/**
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* Trigger an interrupt.
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*
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* @param interruptMask Interrupt flag number
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*/
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virtual void trigger(uint8_t interruptMask) { idr |= interruptMask; }
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/**
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* Clear interrupt state.
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*
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* @return old interrupt state
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*/
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virtual uint8_t clear()
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{
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uint8_t const old = idr;
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idr = 0;
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return old;
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}
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/**
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* Clear pending interrupts, but do not signal to CPU we lost them.
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* It is assumed that all components get reset() calls in synchronous manner.
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*/
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virtual void reset()
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{
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icr = 0;
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idr = 0;
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eventScheduler.cancel(*this);
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}
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/**
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* Set interrupt control mask bits.
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*
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* @param interruptMask control mask bits
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*/
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void set(uint8_t interruptMask)
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{
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if (interruptMask & 0x80)
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{
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icr |= interruptMask & ~INTERRUPT_REQUEST;
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trigger(INTERRUPT_NONE);
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}
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else
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{
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icr &= ~interruptMask;
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}
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}
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};
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}
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#endif // INTERRUPT_H
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