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146 lines
4.1 KiB
C++
146 lines
4.1 KiB
C++
//
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// 6522.hpp
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// Clock Signal
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//
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// Created by Thomas Harte on 06/06/2016.
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// Copyright 2016 Thomas Harte. All rights reserved.
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//
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#ifndef _522_hpp
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#define _522_hpp
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#include <cstdint>
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#include <typeinfo>
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#include <cstdio>
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#include "Implementation/6522Storage.hpp"
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#include "../../ClockReceiver/ClockReceiver.hpp"
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namespace MOS {
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namespace MOS6522 {
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enum Port {
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A = 0,
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B = 1
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};
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enum Line {
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One = 0,
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Two = 1
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};
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/*!
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Provides the mechanism for just-int-time communication from a 6522; the normal use case is to compose a
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6522 and a subclass of PortHandler in order to reproduce a 6522 and its original bus wiring.
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*/
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class PortHandler {
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public:
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/// Requests the current input value of @c port from the port handler.
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uint8_t get_port_input(Port port) { return 0xff; }
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/// Sets the current output value of @c port and provides @c direction_mask, indicating which pins are marked as output.
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void set_port_output(Port port, uint8_t value, uint8_t direction_mask) {}
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/// Sets the current logical output level for line @c line on port @c port.
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void set_control_line_output(Port port, Line line, bool value) {}
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/// Sets the current logical value of the interrupt line.
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void set_interrupt_status(bool status) {}
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/// Provides a measure of time elapsed between other calls.
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void run_for(HalfCycles duration) {}
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/// Receives passed-on flush() calls from the 6522.
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void flush() {}
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};
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/*!
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Provided as an optional alternative base to @c PortHandler for port handlers; via the delegate pattern adds
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a virtual level of indirection for receiving changes to the interrupt line.
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*/
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class IRQDelegatePortHandler: public PortHandler {
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public:
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class Delegate {
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public:
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/// Indicates that the interrupt status has changed for the IRQDelegatePortHandler provided.
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virtual void mos6522_did_change_interrupt_status(void *irq_delegate) = 0;
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};
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/// Sets the delegate that will receive notification of changes in the interrupt line.
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void set_interrupt_delegate(Delegate *delegate);
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/// Overrides PortHandler::set_interrupt_status, notifying the delegate if one is set.
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void set_interrupt_status(bool new_status);
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private:
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Delegate *delegate_ = nullptr;
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};
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/*!
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Implements a template for emulation of the MOS 6522 Versatile Interface Adaptor ('VIA').
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The VIA provides:
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* two timers, each of which may trigger interrupts and one of which may repeat;
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* two digial input/output ports; and
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* a serial-to-parallel shifter.
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Consumers should derive their own curiously-recurring-template-pattern subclass,
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implementing bus communications as required.
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*/
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template <class T> class MOS6522: public MOS6522Storage {
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public:
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MOS6522(T &bus_handler) noexcept : bus_handler_(bus_handler) {}
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MOS6522(const MOS6522 &) = delete;
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/*! Sets a register value. */
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void write(int address, uint8_t value);
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/*! Gets a register value. */
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uint8_t read(int address);
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/*! @returns the bus handler. */
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T &bus_handler();
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/// Sets the input value of line @c line on port @c port.
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void set_control_line_input(Port port, Line line, bool value);
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/// Runs for a specified number of half cycles.
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void run_for(const HalfCycles half_cycles);
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/// Runs for a specified number of cycles.
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void run_for(const Cycles cycles);
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/// @returns @c true if the IRQ line is currently active; @c false otherwise.
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bool get_interrupt_line();
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/// Updates the port handler to the current time and then requests that it flush.
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void flush();
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private:
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void do_phase1();
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void do_phase2();
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void shift_in();
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void shift_out();
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T &bus_handler_;
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HalfCycles time_since_bus_handler_call_;
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void access(int address);
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uint8_t get_port_input(Port port, uint8_t output_mask, uint8_t output);
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inline void reevaluate_interrupts();
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/// Sets the current intended output value for the port and line;
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/// if this affects the visible output, it will be passed to the handler.
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void set_control_line_output(Port port, Line line, LineState value);
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void evaluate_cb2_output();
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};
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}
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}
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#include "Implementation/6522Implementation.hpp"
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#endif /* _522_hpp */
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