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CLK/Machines/Commodore/SerialBus.cpp

94 lines
2.2 KiB
C++

//
// SerialPort.cpp
// Clock Signal
//
// Created by Thomas Harte on 05/07/2016.
// Copyright © 2016 Thomas Harte. All rights reserved.
//
#include "SerialBus.hpp"
using namespace Commodore::Serial;
const char *::Commodore::Serial::StringForLine(Line line)
{
switch(line)
{
case ServiceRequest: return "Service request";
case Attention: return "Attention";
case Clock: return "Clock";
case Data: return "Data";
case Reset: return "Reset";
}
}
void ::Commodore::Serial::AttachPortAndBus(std::shared_ptr<Port> port, std::shared_ptr<Bus> bus)
{
port->set_serial_bus(bus);
bus->add_port(port);
}
void Bus::add_port(std::shared_ptr<Port> port)
{
_ports.push_back(port);
for(int line = (int)ServiceRequest; line <= (int)Reset; line++)
{
// the addition of a new device may change the line output...
set_line_output_did_change((Line)line);
// ... but the new device will need to be told the current state regardless
port->set_input((Line)line, _line_levels[line]);
}
}
void Bus::set_line_output_did_change(Line line)
{
// i.e. I believe these lines to be open collector
LineLevel new_line_level = High;
for(std::weak_ptr<Port> port : _ports)
{
std::shared_ptr<Port> locked_port = port.lock();
if(locked_port)
{
new_line_level = (LineLevel)((bool)new_line_level & (bool)locked_port->get_output(line));
}
}
// post an update only if one occurred
if(new_line_level != _line_levels[line])
{
_line_levels[line] = new_line_level;
for(std::weak_ptr<Port> port : _ports)
{
std::shared_ptr<Port> locked_port = port.lock();
if(locked_port)
{
locked_port->set_input(line, new_line_level);
}
}
}
}
#pragma mark - The debug port
void DebugPort::set_input(Line line, LineLevel value)
{
_input_levels[line] = value;
printf("[Bus] %s is %s\n", StringForLine(line), value ? "high" : "low");
if(!_incoming_count)
{
_incoming_count = (!_input_levels[Line::Clock] && !_input_levels[Line::Data]) ? 8 : 0;
}
else
{
if(line == Line::Clock && value)
{
_incoming_byte = (_incoming_byte >> 1) | (_input_levels[Line::Data] ? 0x80 : 0x00);
}
_incoming_count--;
if(_incoming_count == 0) printf("[Bus] Observed %02x\n", _incoming_byte);
}
}