Starts pushing towards figuring out a proper infrastructure for mass storage.

Storage/MassStorage/SCSI/SCSI.cpp

@@ -0,0 +1,43 @@
+//
+//  SCSI.cpp
+//  Clock Signal
+//
+//  Created by Thomas Harte on 12/08/2019.
+//  Copyright © 2019 Thomas Harte. All rights reserved.
+//
+
+#include "SCSI.hpp"
+
+using namespace SCSI;
+
+size_t Bus::add_device() {
+	const auto slot = device_states_.size();
+	device_states_.push_back(DefaultBusState);
+	return slot;
+}
+
+void Bus::set_device_output(size_t device, BusState output) {
+	if(device_states_[device] == output) return;
+	device_states_[device] = output;
+
+	const auto previous_state = state_;
+	state_ = DefaultBusState;
+	for(auto state: device_states_) {
+		state_ |= state;
+	}
+	if(state_ == previous_state) return;
+
+	printf("SCSI bus: %08x\n", state_);
+
+	for(auto &observer: observers_) {
+		observer->scsi_bus_did_change(this, state_);
+	}
+}
+
+BusState Bus::get_state() {
+	return state_;
+}
+
+void Bus::add_observer(Observer *observer) {
+	observers_.push_back(observer);
+}