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131 lines
3.5 KiB
C++
131 lines
3.5 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 Type {
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High, Low, Zero
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} type;
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Time length;
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Pulse(Type type, Time length) : type(type), length(length) {}
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Pulse() {}
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};
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/*!
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If at the start of the tape returns the first stored pulse. Otherwise advances past
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the last-returned pulse and returns the next.
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@returns the pulse that begins at the current cursor position.
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*/
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Pulse get_next_pulse();
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/// Returns the tape to the beginning.
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void reset();
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/// @returns @c true if the tape has progressed beyond all recorded content; @c false otherwise.
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virtual bool is_at_end() = 0;
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/// @returns the amount of time preceeding the most recently-returned pulse.
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virtual Time get_current_time() { return current_time_; }
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/// Advances or reverses the tape to the last time before or at @c time from which a pulse starts.
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virtual void seek(Time &time);
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private:
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Time current_time_, next_time_;
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virtual Pulse virtual_get_next_pulse() = 0;
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virtual void virtual_reset() = 0;
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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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std::shared_ptr<Storage::Tape::Tape> get_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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A specific subclass of the tape player for machines that sample such as to report only either a
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high or a low current input level.
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Such machines can use @c get_input() to get the current level of the input.
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They can also provide a delegate to be notified upon any change in the input level.
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*/
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class BinaryTapePlayer: public TapePlayer {
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public:
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BinaryTapePlayer(unsigned int input_clock_rate);
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void set_motor_control(bool enabled);
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void set_tape_output(bool set);
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bool get_input();
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void run_for_cycles(int number_of_cycles);
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class Delegate {
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public:
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virtual void tape_did_change_input(BinaryTapePlayer *tape_player) = 0;
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};
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void set_delegate(Delegate *delegate);
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protected:
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Delegate *delegate_;
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virtual void process_input_pulse(Storage::Tape::Tape::Pulse pulse);
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bool input_level_;
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bool motor_is_running_;
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};
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}
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}
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#endif /* Tape_hpp */
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