mirror of https://github.com/TomHarte/CLK.git
129 lines
3.0 KiB
C++
129 lines
3.0 KiB
C++
//
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// SerialPort.hpp
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// Clock Signal
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//
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// Created by Thomas Harte on 05/07/2016.
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// Copyright 2016 Thomas Harte. All rights reserved.
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//
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#pragma once
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#include <cstdint>
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#include <memory>
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#include <vector>
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namespace Commodore::Serial {
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enum Line {
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ServiceRequest = 0,
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Attention,
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Clock,
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Data,
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Reset
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};
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enum LineLevel: bool {
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High = true,
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Low = false
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};
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class Port;
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class Bus;
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/*!
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Returns a C string giving a human-readable name for the supplied line.
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*/
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const char *StringForLine(Line line);
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/*!
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Calls both of the necessary methods to (i) set @c bus as the target for @c port outputs; and
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(ii) add @c port as one of the targets to which @c bus propagates line changes.
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*/
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void AttachPortAndBus(std::shared_ptr<Port> port, std::shared_ptr<Bus> bus);
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/*!
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A serial bus is responsible for retaining a weakly-held collection of attached ports and for deciding the
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current bus levels based upon the net result of each port's output, and for communicating changes in bus
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levels to every port.
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*/
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class Bus {
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public:
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Bus() : line_levels_{High, High, High, High, High} {}
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/*!
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Adds the supplied port to the bus.
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*/
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void add_port(std::shared_ptr<Port> port);
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/*!
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Communicates to the bus that one of its attached port has changed its output level for the given line.
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The bus will therefore recalculate bus state and propagate as necessary.
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*/
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void set_line_output_did_change(Line line);
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private:
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LineLevel line_levels_[5];
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std::vector<std::weak_ptr<Port>> ports_;
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};
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/*!
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A serial port is an endpoint on a serial bus; this class provides a direct setter for current line outputs and
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expects to be subclassed in order for specific port-housing devices to deal with input.
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*/
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class Port {
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public:
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Port() : line_levels_{High, High, High, High, High} {}
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virtual ~Port() = default;
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/*!
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Sets the current level of an output line on this serial port.
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*/
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void set_output(Line line, LineLevel level) {
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if(line_levels_[line] != level) {
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line_levels_[line] = level;
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std::shared_ptr<Bus> bus = serial_bus_.lock();
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if(bus) bus->set_line_output_did_change(line);
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}
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}
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/*!
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Gets the previously set level of an output line.
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*/
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LineLevel get_output(Line line) {
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return line_levels_[line];
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}
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/*!
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Called by the bus to signal a change in any input line level. Subclasses should implement this.
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*/
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virtual void set_input(Line line, LineLevel value) = 0;
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/*!
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Sets the supplied serial bus as that to which line levels will be communicated.
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*/
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inline void set_serial_bus(std::shared_ptr<Bus> serial_bus) {
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serial_bus_ = serial_bus;
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}
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private:
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std::weak_ptr<Bus> serial_bus_;
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LineLevel line_levels_[5];
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};
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/*!
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A debugging port, which makes some attempt to log bus activity. Incomplete. TODO: complete.
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*/
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class DebugPort: public Port {
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public:
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void set_input(Line line, LineLevel value);
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DebugPort() : incoming_count_(0) {}
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private:
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uint8_t incoming_byte_;
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int incoming_count_;
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LineLevel input_levels_[5];
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};
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}
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