Introduces the ActivityObserver protocol for LEDs, drive events, etc.

The Electron's caps lock LED is the test case.

ActivityObserver/ActivityObserver.hpp

@@ -0,0 +1,47 @@
+//
+//  Header.h
+//  Clock Signal
+//
+//  Created by Thomas Harte on 07/05/2018.
+//  Copyright © 2018 Thomas Harte. All rights reserved.
+//
+
+#ifndef Header_h
+#define Header_h
+
+#include <string>
+
+/*!
+	Provides a purely virtual base class for anybody that wants to receive notifications of
+	'activity' — any feedback from an emulated system which a user could perceive other than
+	through the machine's native audio and video outputs.
+
+	So: status LEDs, drive activity, etc. A receiver may choose to make appropriate noises
+	and/or to show or unshow status indicators.
+*/
+class ActivityObserver {
+	public:
+		/// Announces to the receiver that there is an LED of name @c name.
+		virtual void register_led(const std::string &name) = 0;
+
+		/// Announces to the receiver that there is a drive of name @c name.
+		virtual void register_drive(const std::string &name) = 0;
+
+		/// Informs the receiver of the new state of the LED with name @c name.
+		virtual void set_led_status(const std::string &name, bool lit) = 0;
+
+		enum class DriveEvent {
+			Step,
+			StepBelowZero,
+			StepBeyondMaximum
+		};
+
+		/// Informs the receiver that the named event just occurred for the drive with name @c name.
+		virtual void announce_drive_event(const std::string &name, DriveEvent event) = 0;
+
+		/// Informs the receiver of the motor-on status of the drive with name @c name.
+		virtual void set_drive_motor_status(const std::string &name, bool is_on) = 0;
+
+};
+
+#endif /* Header_h */

Analyser/Dynamic/MultiMachine/MultiMachine.cpp

@@ -22,6 +22,10 @@ MultiMachine::MultiMachine(std::vector<std::unique_ptr<DynamicMachine>> &&machin
 	crt_machine_.set_delegate(this);
 }
 
+ActivitySource::Machine *MultiMachine::activity_source() {
+	return nullptr; // TODO
+}
+
 ConfigurationTarget::Machine *MultiMachine::configuration_target() {
 	if(has_picked_) {
 		return machines_.front()->configuration_target();

Analyser/Dynamic/MultiMachine/MultiMachine.hpp

@@ -50,6 +50,7 @@ class MultiMachine: public ::Machine::DynamicMachine, public MultiCRTMachine::De
 		static bool would_collapse(const std::vector<std::unique_ptr<DynamicMachine>> &machines);
 		MultiMachine(std::vector<std::unique_ptr<DynamicMachine>> &&machines);
 
+		ActivitySource::Machine *activity_source() override;
 		ConfigurationTarget::Machine *configuration_target() override;
 		CRTMachine::Machine *crt_machine() override;
 		JoystickMachine::Machine *joystick_machine() override;

Machines/ActivitySource.hpp

@@ -0,0 +1,24 @@
+//
+//  ActivitySource.h
+//  Clock Signal
+//
+//  Created by Thomas Harte on 07/05/2018.
+//  Copyright © 2018 Thomas Harte. All rights reserved.
+//
+
+#ifndef ActivitySource_h
+#define ActivitySource_h
+
+#include "../ActivityObserver/ActivityObserver.hpp"
+
+namespace ActivitySource {
+
+class Machine {
+	public:
+		virtual void set_activity_observer(ActivityObserver *receiver) = 0;
+};
+
+}
+
+
+#endif /* ActivitySource_h */

Machines/DynamicMachine.hpp

@@ -10,6 +10,7 @@
 #define DynamicMachine_h
 
 #include "../Configurable/Configurable.hpp"
+#include "ActivitySource.hpp"
 #include "ConfigurationTarget.hpp"
 #include "CRTMachine.hpp"
 #include "JoystickMachine.hpp"
@@ -24,6 +25,8 @@ namespace Machine {
 */
 struct DynamicMachine {
 	virtual ~DynamicMachine() {}
+
+	virtual ActivitySource::Machine *activity_source() = 0;
 	virtual ConfigurationTarget::Machine *configuration_target() = 0;
 	virtual CRTMachine::Machine *crt_machine() = 0;
 	virtual JoystickMachine::Machine *joystick_machine() = 0;

Machines/Electron/Electron.cpp

@@ -8,6 +8,7 @@
 
 #include "Electron.hpp"
 
+#include "../ActivitySource.hpp"
 #include "../ConfigurationTarget.hpp"
 #include "../CRTMachine.hpp"
 #include "../KeyboardMachine.hpp"
@@ -45,7 +46,8 @@ class ConcreteMachine:
 	public Configurable::Device,
 	public CPU::MOS6502::BusHandler,
 	public Tape::Delegate,
-	public Utility::TypeRecipient {
+	public Utility::TypeRecipient,
+	public ActivitySource::Machine {
 	public:
 		ConcreteMachine() :
 			m6502_(*this),
@@ -215,12 +217,15 @@ class ConcreteMachine:
 
 							tape_.set_is_enabled((*value & 6) != 6);
 							tape_.set_is_in_input_mode((*value & 6) == 0);
-							tape_.set_is_running(((*value)&0x40) ? true : false);
+							tape_.set_is_running((*value & 0x40) ? true : false);
 
-							// TODO: caps lock LED
+							caps_led_state_ = !!(*value & 0x80);
+							if(activity_observer_)
+								activity_observer_->set_led_status(caps_led, caps_led_state_);
 						}
 
-					// deliberate fallthrough
+					// deliberate fallthrough; fe07 contains the display mode.
+
 					case 0xfe02: case 0xfe03:
 					case 0xfe08: case 0xfe09: case 0xfe0a: case 0xfe0b:
 					case 0xfe0c: case 0xfe0d: case 0xfe0e: case 0xfe0f:
@@ -322,8 +327,6 @@ class ConcreteMachine:
 										if(!ram_[0x247] && service_call == 14) {
 											tape_.set_delegate(nullptr);
 
-											// TODO: handle tape wrap around.
-
 											int cycles_left_while_plausibly_in_data = 50;
 											tape_.clear_interrupts(Interrupt::ReceiveDataFull);
 											while(!tape_.get_tape()->is_at_end()) {
@@ -477,6 +480,14 @@ class ConcreteMachine:
 			return selection_set;
 		}
 
+		void set_activity_observer(ActivityObserver *observer) override {
+			activity_observer_ = observer;
+			if(activity_observer_) {
+				activity_observer_->register_led(caps_led);
+				activity_observer_->set_led_status(caps_led, caps_led_state_);
+			}
+		}
+
 	private:
 		// MARK: - Work deferral updates.
 		inline void update_display() {
@@ -563,6 +574,11 @@ class ConcreteMachine:
 		Outputs::Speaker::LowpassSpeaker<SoundGenerator> speaker_;
 
 		bool speaker_is_enabled_ = false;
+
+		// MARK: - Caps Lock status and the activity observer.
+		const std::string caps_led = "CAPS";
+		bool caps_led_state_ = false;
+		ActivityObserver *activity_observer_ = nullptr;
 };
 
 }

Machines/Utility/TypedDynamicMachine.hpp

@@ -25,6 +25,10 @@ template<typename T> class TypedDynamicMachine: public ::Machine::DynamicMachine
 			return *this;
 		}
 
+		ActivitySource::Machine *activity_source() override {
+			return get<ActivitySource::Machine>();
+		}
+
 		ConfigurationTarget::Machine *configuration_target() override {
 			return get<ConfigurationTarget::Machine>();
 		}

OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj

@@ -697,6 +697,8 @@
 		4B055ABE1FAE98000060FFFF /* MachineForTarget.cpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.cpp; path = MachineForTarget.cpp; sourceTree = "<group>"; };
 		4B055ABF1FAE98000060FFFF /* MachineForTarget.hpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; path = MachineForTarget.hpp; sourceTree = "<group>"; };
 		4B055AF01FAE9C080060FFFF /* OpenGL.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = OpenGL.framework; path = System/Library/Frameworks/OpenGL.framework; sourceTree = SDKROOT; };
+		4B055C1E20A113B00014E5AB /* ActivityObserver.hpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.h; path = ActivityObserver.hpp; sourceTree = "<group>"; };
+		4B055C1F20A1166A0014E5AB /* ActivitySource.hpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; path = ActivitySource.hpp; sourceTree = "<group>"; };
 		4B0783591FC11D10001D12BB /* Configurable.cpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.cpp; path = Configurable.cpp; sourceTree = "<group>"; };
 		4B08A2741EE35D56008B7065 /* Z80InterruptTests.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = Z80InterruptTests.swift; sourceTree = "<group>"; };
 		4B08A2761EE39306008B7065 /* TestMachine.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = TestMachine.h; sourceTree = "<group>"; };
@@ -1496,6 +1498,15 @@
 			path = ../SDL;
 			sourceTree = "<group>";
 		};
+		4B055C1D20A113B00014E5AB /* ActivityObserver */ = {
+			isa = PBXGroup;
+			children = (
+				4B055C1E20A113B00014E5AB /* ActivityObserver.hpp */,
+			);
+			name = ActivityObserver;
+			path = ../../ActivityObserver;
+			sourceTree = "<group>";
+		};
 		4B0CCC411C62D0B3001CAC5F /* CRT */ = {
 			isa = PBXGroup;
 			children = (
@@ -2697,6 +2708,7 @@
 			isa = PBXGroup;
 			children = (
 				4BC76E6A1C98F43700E6EF73 /* Accelerate.framework */,
+				4B055C1D20A113B00014E5AB /* ActivityObserver */,
 				4B8944E2201967B4007DE474 /* Analyser */,
 				4BB73EA01B587A5100552FC2 /* Clock Signal */,
 				4BB73EB51B587A5100552FC2 /* Clock SignalTests */,
@@ -2800,6 +2812,7 @@
 			isa = PBXGroup;
 			children = (
 				4B54C0BB1F8D8E790050900F /* KeyboardMachine.cpp */,
+				4B055C1F20A1166A0014E5AB /* ActivitySource.hpp */,
 				4BA9C3CF1D8164A9002DDB61 /* ConfigurationTarget.hpp */,
 				4B046DC31CFE651500E9E45E /* CRTMachine.hpp */,
 				4BBB709C2020109C002FE009 /* DynamicMachine.hpp */,