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118 lines
2.6 KiB
C++
118 lines
2.6 KiB
C++
//
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// IWM.hpp
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// Clock Signal
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//
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// Created by Thomas Harte on 05/05/2019.
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// Copyright © 2019 Thomas Harte. All rights reserved.
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//
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#ifndef IWM_hpp
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#define IWM_hpp
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#include "../../ClockReceiver/ClockReceiver.hpp"
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#include "../../ClockReceiver/ClockingHintSource.hpp"
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#include "../../Storage/Disk/Drive.hpp"
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#include <cstdint>
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namespace Apple {
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/*!
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Defines the drive interface used by the IWM, derived from the external pinout as
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per e.g. https://old.pinouts.ru/HD/MacExtDrive_pinout.shtml
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These are subclassed of Storage::Disk::Drive, so accept any disk the emulator supports,
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and provide the usual read/write interface for on-disk data.
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*/
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struct IWMDrive: public Storage::Disk::Drive {
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IWMDrive(int input_clock_rate, int number_of_heads) : Storage::Disk::Drive(input_clock_rate, number_of_heads) {}
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enum Line: int {
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CA0 = 1 << 0,
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CA1 = 1 << 1,
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CA2 = 1 << 2,
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LSTRB = 1 << 3,
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SEL = 1 << 4,
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};
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virtual void set_enabled(bool) = 0;
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virtual void set_control_lines(int) = 0;
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virtual bool read() = 0;
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};
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class IWM:
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public Storage::Disk::Drive::EventDelegate,
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public ClockingHint::Observer {
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public:
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IWM(int clock_rate);
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/// Sets the current external value of the data bus.
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void write(int address, uint8_t value);
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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 IWM.
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*/
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uint8_t read(int address);
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/*!
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Sets the current input of the IWM's SEL line.
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*/
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void set_select(bool enabled);
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/// Advances the controller by @c cycles.
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void run_for(const Cycles cycles);
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/// Connects a drive to the IWM.
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void set_drive(int slot, IWMDrive *drive);
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private:
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// Storage::Disk::Drive::EventDelegate.
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void process_event(const Storage::Disk::Drive::Event &event) override;
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const int clock_rate_;
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uint8_t data_register_ = 0;
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uint8_t mode_ = 0;
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bool read_write_ready_ = true;
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bool write_overran_ = false;
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int state_ = 0;
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int active_drive_ = 0;
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IWMDrive *drives_[2] = {nullptr, nullptr};
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bool drive_is_rotating_[2] = {false, false};
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void set_component_prefers_clocking(ClockingHint::Source *component, ClockingHint::Preference clocking) override;
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Cycles cycles_until_disable_;
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uint8_t write_handshake_ = 0x80;
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void access(int address);
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uint8_t shift_register_ = 0;
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uint8_t next_output_ = 0;
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int output_bits_remaining_ = 0;
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void propose_shift(uint8_t bit);
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Cycles cycles_since_shift_;
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Cycles bit_length_ = Cycles(16);
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void push_drive_state();
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enum class ShiftMode {
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Reading,
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Writing,
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CheckingWriteProtect
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} shift_mode_;
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uint8_t sense();
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void select_shift_mode();
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};
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}
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#endif /* IWM_hpp */
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