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The Disk II seems lower level than that; it will read the data bus whenever it likes, it is the programmer's responsibility to keep up with that. It also reserves the right not to load the bus regardless of whether it receives a read or write access.
119 lines
2.8 KiB
C++
119 lines
2.8 KiB
C++
//
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// DiskII.hpp
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// Clock Signal
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//
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// Created by Thomas Harte on 20/04/2018.
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// Copyright 2018 Thomas Harte. All rights reserved.
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//
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#ifndef DiskII_hpp
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#define DiskII_hpp
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#include "../../ClockReceiver/ClockReceiver.hpp"
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#include "../../ClockReceiver/Sleeper.hpp"
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#include "../../Storage/Disk/Disk.hpp"
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#include "../../Storage/Disk/Drive.hpp"
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#include "../../Activity/Observer.hpp"
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#include <array>
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#include <cstdint>
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#include <vector>
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namespace Apple {
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/*!
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Provides an emulation of the Apple Disk II.
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*/
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class DiskII:
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public Storage::Disk::Drive::EventDelegate,
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public Sleeper::SleepObserver,
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public Sleeper {
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public:
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DiskII();
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/// Sets the current external value of the data bus.
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void set_data_input(uint8_t input);
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/*!
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Submits an access to address @c address.
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@returns The 8-bit value loaded to the data bus by the DiskII if any;
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@c DidNotLoad otherwise.
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*/
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int read_address(int address);
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/*!
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The value returned by @c read_address if accessing that address
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didn't cause the disk II to place anything onto the bus.
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*/
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const int DidNotLoad = -1;
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/// Advances the controller by @c cycles.
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void run_for(const Cycles cycles);
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/*!
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Supplies the image of the state machine (i.e. P6) ROM,
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which dictates how the Disk II will respond to input.
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To reduce processing costs, some assumptions are made by
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the implementation as to the content of this ROM.
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Including:
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If Q6 is set and Q7 is reset, the controller is testing
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for write protect. If and when the shift register has
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become full with the state of the write protect value,
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no further processing is required.
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*/
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void set_state_machine(const std::vector<uint8_t> &);
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/// Inserts @c disk into the drive @c drive.
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void set_disk(const std::shared_ptr<Storage::Disk::Disk> &disk, int drive);
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// As per Sleeper.
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bool is_sleeping() override;
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// The Disk II functions as a potential target for @c Activity::Sources.
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void set_activity_observer(Activity::Observer *observer);
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private:
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enum class Control {
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P0, P1, P2, P3,
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Motor,
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};
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enum class Mode {
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Read, Write
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};
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void set_control(Control control, bool on);
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void set_mode(Mode mode);
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void select_drive(int drive);
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uint8_t trigger_address(int address, uint8_t value);
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void process_event(const Storage::Disk::Track::Event &event) override;
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void set_component_is_sleeping(Sleeper *component, bool is_sleeping) override;
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uint8_t state_ = 0;
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uint8_t inputs_ = 0;
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uint8_t shift_register_ = 0;
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int stepper_mask_ = 0;
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int stepper_position_ = 0;
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bool is_write_protected();
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std::array<uint8_t, 256> state_machine_;
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Storage::Disk::Drive drives_[2];
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bool drive_is_sleeping_[2];
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bool controller_can_sleep_ = false;
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int active_drive_ = 0;
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bool motor_is_enabled_ = false;
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void set_controller_can_sleep();
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uint8_t data_input_ = 0;
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};
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}
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#endif /* DiskII_hpp */
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