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94 lines
2.2 KiB
C++
94 lines
2.2 KiB
C++
//
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// SerialPort.cpp
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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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#include "SerialBus.hpp"
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using namespace Commodore::Serial;
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const char *::Commodore::Serial::StringForLine(Line line)
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{
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switch(line)
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{
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case ServiceRequest: return "Service request";
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case Attention: return "Attention";
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case Clock: return "Clock";
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case Data: return "Data";
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case Reset: return "Reset";
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}
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}
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void ::Commodore::Serial::AttachPortAndBus(std::shared_ptr<Port> port, std::shared_ptr<Bus> bus)
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{
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port->set_serial_bus(bus);
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bus->add_port(port);
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}
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void Bus::add_port(std::shared_ptr<Port> port)
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{
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_ports.push_back(port);
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for(int line = (int)ServiceRequest; line <= (int)Reset; line++)
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{
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// the addition of a new device may change the line output...
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set_line_output_did_change((Line)line);
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// ... but the new device will need to be told the current state regardless
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port->set_input((Line)line, _line_levels[line]);
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}
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}
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void Bus::set_line_output_did_change(Line line)
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{
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// i.e. I believe these lines to be open collector
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LineLevel new_line_level = High;
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for(std::weak_ptr<Port> port : _ports)
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{
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std::shared_ptr<Port> locked_port = port.lock();
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if(locked_port)
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{
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new_line_level = (LineLevel)((bool)new_line_level & (bool)locked_port->get_output(line));
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}
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}
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// post an update only if one occurred
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if(new_line_level != _line_levels[line])
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{
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_line_levels[line] = new_line_level;
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for(std::weak_ptr<Port> port : _ports)
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{
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std::shared_ptr<Port> locked_port = port.lock();
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if(locked_port)
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{
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locked_port->set_input(line, new_line_level);
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}
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}
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}
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}
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#pragma mark - The debug port
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void DebugPort::set_input(Line line, LineLevel value)
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{
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_input_levels[line] = value;
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printf("[Bus] %s is %s\n", StringForLine(line), value ? "high" : "low");
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if(!_incoming_count)
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{
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_incoming_count = (!_input_levels[Line::Clock] && !_input_levels[Line::Data]) ? 8 : 0;
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}
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else
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{
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if(line == Line::Clock && value)
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{
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_incoming_byte = (_incoming_byte >> 1) | (_input_levels[Line::Data] ? 0x80 : 0x00);
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}
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_incoming_count--;
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if(_incoming_count == 0) printf("[Bus] Observed %02x\n", _incoming_byte);
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}
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}
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