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89 lines
1.9 KiB
C++
89 lines
1.9 KiB
C++
//
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// Bus.hpp
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// Clock Signal
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//
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// Created by Thomas Harte on 10/02/2021.
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// Copyright © 2021 Thomas Harte. All rights reserved.
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//
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#ifndef Bus_hpp
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#define Bus_hpp
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#include "../../../ClockReceiver/ClockReceiver.hpp"
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#include <bitset>
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#include <cstddef>
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#include <vector>
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namespace Apple {
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namespace ADB {
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/*!
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The ADB bus models the data line of the ADB bus; it allows multiple devices to
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post their current data level, or read the current level, and also offers a tokenised
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version of all activity on the bus.
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*/
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class Bus {
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public:
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Bus(HalfCycles clock_speed);
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/*!
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Advances time; ADB is a clocked serial signal.
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*/
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void run_for(HalfCycles);
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/*!
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Adds a device to the bus, returning the index it should use
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to refer to itself in subsequent calls to set_device_output.
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*/
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size_t add_device();
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/*!
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Sets the current data line output for @c device.
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*/
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void set_device_output(size_t device, bool output);
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/*!
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@returns The current state of the ADB data line.
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*/
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bool get_state() const;
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enum class Event {
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Reset,
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Attention,
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Byte,
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ServiceRequest,
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Unrecognised
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};
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struct Observer {
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/// Reports to an observer that @c event was observed in the activity
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/// observed on this bus. If this was a byte event, that byte's value is given as @c value.
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virtual void adb_bus_did_observe_event(Bus *, Event event, uint8_t value = 0xff);
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};
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/*!
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Adds an observer.
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*/
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void add_observer(Observer *);
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private:
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HalfCycles time_in_state_;
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double half_cycles_to_microseconds_ = 1.0;
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std::vector<Observer *> observers_;
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unsigned int shift_register_ = 0;
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bool data_level_ = true;
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// ADB addressing supports at most 16 devices but that doesn't include
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// the controller. So assume a maximum of 17 connected devices.
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std::bitset<17> bus_state_{0xffffffff};
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size_t next_device_id_ = 0;
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inline void shift(unsigned int);
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};
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}
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}
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#endif /* Bus_hpp */
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