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76 lines
1.9 KiB
C++
76 lines
1.9 KiB
C++
//
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// Tape.hpp
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// Clock Signal
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//
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// Created by Thomas Harte on 18/01/2016.
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// Copyright © 2016 Thomas Harte. All rights reserved.
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//
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#ifndef Tape_hpp
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#define Tape_hpp
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#include <memory>
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#include "../TimedEventLoop.hpp"
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namespace Storage {
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namespace Tape {
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/*!
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Models a tape as a sequence of pulses, each pulse being of arbitrary length and described
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by their relationship with zero:
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- high pulses exit from zero upward before returning to it;
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- low pulses exit from zero downward before returning to it;
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- zero pulses run along zero.
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Subclasses should implement at least @c get_next_pulse and @c reset to provide a serial feeding
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of pulses and the ability to return to the start of the feed. They may also implement @c seek if
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a better implementation than a linear search from the @c reset time can be implemented.
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*/
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class Tape {
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public:
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struct Pulse {
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enum {
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High, Low, Zero
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} type;
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Time length;
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};
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virtual Pulse get_next_pulse() = 0;
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virtual void reset() = 0;
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virtual void seek(Time seek_time); // TODO
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};
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/*!
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Provides a helper for: (i) retaining a reference to a tape; and (ii) running the tape at a certain
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input clock rate.
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Will call @c process_input_pulse instantaneously upon reaching *the end* of a pulse. Therefore a subclass
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can decode pulses into data within process_input_pulse, using the supplied pulse's @c length and @c type.
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*/
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class TapePlayer: public TimedEventLoop {
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public:
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TapePlayer(unsigned int input_clock_rate);
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void set_tape(std::shared_ptr<Storage::Tape::Tape> tape);
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bool has_tape();
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void run_for_cycles(int number_of_cycles);
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void run_for_input_pulse();
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protected:
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virtual void process_next_event();
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virtual void process_input_pulse(Tape::Pulse pulse) = 0;
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private:
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inline void get_next_pulse();
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std::shared_ptr<Storage::Tape::Tape> _tape;
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Tape::Pulse _current_pulse;
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};
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}
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}
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#endif /* Tape_hpp */
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