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134 lines
3.7 KiB
C++
134 lines
3.7 KiB
C++
//
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// DiskController.hpp
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// Clock Signal
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//
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// Created by Thomas Harte on 14/07/2016.
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// Copyright 2016 Thomas Harte. All rights reserved.
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//
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#ifndef Storage_Disk_Controller_hpp
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#define Storage_Disk_Controller_hpp
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#include "../Drive.hpp"
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#include "../DPLL/DigitalPhaseLockedLoop.hpp"
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#include "../Track/PCMSegment.hpp"
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#include "../../../ClockReceiver/ClockReceiver.hpp"
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#include "../../../ClockReceiver/ClockingHintSource.hpp"
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namespace Storage {
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namespace Disk {
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/*!
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Provides the shell for emulating a disk controller: something that is connected to a disk drive and uses a
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phase locked loop ('PLL') to decode a bit stream from the surface of the disk.
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Partly abstract; it is expected that subclasses will provide methods to deal with receiving a newly-recognised
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bit from the PLL and with crossing the index hole.
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TODO: communication of head size and permissible stepping extents, appropriate simulation of gain.
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*/
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class Controller:
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public DigitalPhaseLockedLoop::Delegate,
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public Drive::EventDelegate,
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public ClockingHint::Source,
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public ClockingHint::Observer {
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protected:
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/*!
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Constructs a @c Controller that will be run at @c clock_rate.
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*/
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Controller(Cycles clock_rate);
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/*!
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Communicates to the PLL the expected length of a bit as a fraction of a second.
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*/
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void set_expected_bit_length(Time bit_length);
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/*!
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Advances the drive by @c number_of_cycles cycles.
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*/
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void run_for(const Cycles cycles);
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/*!
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Sets the current drive. This drive is the one the PLL listens to.
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*/
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void set_drive(std::shared_ptr<Drive> drive);
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/*!
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Should be implemented by subclasses; communicates each bit that the PLL recognises.
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*/
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virtual void process_input_bit(int value) = 0;
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/*!
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Should be implemented by subclasses; communicates that the index hole has been reached.
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*/
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virtual void process_index_hole() = 0;
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/*!
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Should be implemented by subclasses if they implement writing; communicates that
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all bits supplied to write_bit have now been written.
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*/
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virtual void process_write_completed() override;
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/*!
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Puts the controller and the drive returned by get_drive() into write mode, supplying to
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the drive the current bit length.
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While the controller is in write mode it disconnects the PLL. So subclasses will not
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receive any calls to @c process_input_bit.
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@param clamp_to_index_hole If @c true then writing will automatically be truncated by
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the index hole. Writing will continue over the index hole otherwise.
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*/
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void begin_writing(bool clamp_to_index_hole);
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/*!
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Puts the drive returned by get_drive() out of write mode, and marks the controller
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as no longer being in write mode.
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*/
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void end_writing();
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/*!
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@returns @c true if the controller is in reading mode; @c false otherwise.
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*/
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bool is_reading();
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/*!
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Returns the connected drive or, if none is connected, an invented one. No guarantees are
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made about the lifetime or the exclusivity of the invented drive.
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*/
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Drive &get_drive();
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/*!
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As per ClockingHint::Source.
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*/
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ClockingHint::Preference preferred_clocking() override;
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private:
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Time bit_length_;
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int clock_rate_multiplier_ = 1;
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int clock_rate_ = 1;
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bool is_reading_ = true;
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std::shared_ptr<DigitalPhaseLockedLoop> pll_;
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std::shared_ptr<Drive> drive_;
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std::shared_ptr<Drive> empty_drive_;
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// ClockingHint::Observer.
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void set_component_prefers_clocking(ClockingHint::Source *component, ClockingHint::Preference clocking) override;
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// for Drive::EventDelegate
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void process_event(const Track::Event &event) override;
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void advance(const Cycles cycles) override ;
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// to satisfy DigitalPhaseLockedLoop::Delegate
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void digital_phase_locked_loop_output_bit(int value) override;
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};
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}
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}
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#endif /* DiskDrive_hpp */
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