Introduces 'non-exclusive' emulator-space keyboards.

i.e. sets of keys that don't amount to an entire keyboard in the modern sense. Experimentally used by the Master System for its reset key.

Analyser/Dynamic/MultiMachine/Implementation/MultiKeyboardMachine.cpp

@@ -35,9 +35,13 @@ void MultiKeyboardMachine::type_string(const std::string &string) {
 	}
 }
 
-void MultiKeyboardMachine::keyboard_did_change_key(Inputs::Keyboard *keyboard, Inputs::Keyboard::Key key, bool is_pressed) {
-	for(const auto &machine: machines_) {
-		uint16_t mapped_key = machine->get_keyboard_mapper()->mapped_key_for_key(key);
-		if(mapped_key != KeyNotMapped) machine->set_key_state(mapped_key, is_pressed);
-	}
+Inputs::Keyboard &MultiKeyboardMachine::get_keyboard() {
+	return keyboard_;
 }
+
+//void MultiKeyboardMachine::keyboard_did_change_key(Inputs::Keyboard *keyboard, Inputs::Keyboard::Key key, bool is_pressed) {
+//	for(const auto &machine: machines_) {
+//		uint16_t mapped_key = machine->get_keyboard_mapper()->mapped_key_for_key(key);
+//		if(mapped_key != KeyNotMapped) machine->set_key_state(mapped_key, is_pressed);
+//	}
+//}

Analyser/Dynamic/MultiMachine/Implementation/MultiKeyboardMachine.hpp

@@ -32,10 +32,11 @@ class MultiKeyboardMachine: public KeyboardMachine::Machine {
 		void clear_all_keys() override;
 		void set_key_state(uint16_t key, bool is_pressed) override;
 		void type_string(const std::string &) override;
-		void keyboard_did_change_key(Inputs::Keyboard *keyboard, Inputs::Keyboard::Key key, bool is_pressed) override;
+		Inputs::Keyboard &get_keyboard() override;
 
 	private:
 		std::vector<::KeyboardMachine::Machine *> machines_;
+		Inputs::Keyboard keyboard_;
 };
 
 }

Components/9918/9918.cpp

@@ -702,6 +702,23 @@ HalfCycles TMS9918::get_time_until_interrupt() {
 	return half_cycles_before_internal_cycles(std::min(local_cycles_until_line_interrupt, time_until_frame_interrupt));
 }
 
+HalfCycles TMS9918::get_time_until_line(int line) {
+	if(line < 0) line += mode_timing_.total_lines;
+
+	int cycles_to_next_interrupt_threshold = mode_timing_.line_interrupt_position - write_pointer_.column;
+	int line_of_next_interrupt_threshold = write_pointer_.row;
+	if(cycles_to_next_interrupt_threshold <= 0) {
+		cycles_to_next_interrupt_threshold += 342;
+		++line_of_next_interrupt_threshold;
+	}
+
+	if(line_of_next_interrupt_threshold > line) {
+		line += mode_timing_.total_lines;
+	}
+
+	return half_cycles_before_internal_cycles(cycles_to_next_interrupt_threshold + (line - line_of_next_interrupt_threshold)*342);
+}
+
 bool TMS9918::get_interrupt_line() {
 	return ((status_ & StatusInterrupt) && generate_interrupts_) || (enable_line_interrupts_ && line_interrupt_pending_);
 }

Components/9918/9918.hpp

@@ -74,6 +74,16 @@ class TMS9918: public Base {
 		*/
 		HalfCycles get_time_until_interrupt();
 
+		/*!
+			Returns the amount of time until the nominated line interrupt position is
+			reached on line @c line. If no line interrupt position is defined for
+			this VDP, returns the time until the 'beginning' of that line, whatever
+			that may mean.
+
+			@line is relative to the first pixel line of the display and may be negative.
+		*/
+		HalfCycles get_time_until_line(int line);
+
 		/*!
 			@returns @c true if the interrupt line is currently active; @c false otherwise.
 		*/

Inputs/Keyboard.cpp

@@ -10,7 +10,13 @@
 
 using namespace Inputs;
 
-Keyboard::Keyboard() {}
+Keyboard::Keyboard() {
+	for(int k = 0; k < int(Key::Help); ++k) {
+		observed_keys_.insert(Key(k));
+	}
+}
+
+Keyboard::Keyboard(const std::set<Key> &observed_keys) : observed_keys_(observed_keys), is_exclusive_(false) {}
 
 void Keyboard::set_key_pressed(Key key, char value, bool is_pressed) {
 	std::size_t key_offset = static_cast<std::size_t>(key);
@@ -36,3 +42,11 @@ bool Keyboard::get_key_state(Key key) {
 	if(key_offset >= key_states_.size()) return false;
 	return key_states_[key_offset];
 }
+
+const std::set<Keyboard::Key> &Keyboard::observed_keys() {
+	return observed_keys_;
+}
+
+bool Keyboard::is_exclusive() {
+	return is_exclusive_;
+}

Inputs/Keyboard.hpp

@@ -10,6 +10,7 @@
 #define Keyboard_hpp
 
 #include <vector>
+#include <set>
 
 namespace Inputs {
 
@@ -20,8 +21,6 @@ namespace Inputs {
 */
 class Keyboard {
 	public:
-		Keyboard();
-
 		enum class Key {
 			Escape, F1, F2, F3, F4, F5, F6, F7, F8, F9, F10, F11, F12, PrintScreen, ScrollLock, Pause,
 			BackTick, k1, k2, k3, k4, k5, k6, k7, k8, k9, k0, Hyphen, Equals, BackSpace,
@@ -39,10 +38,26 @@ class Keyboard {
 			Help
 		};
 
+		/// Constructs a Keyboard that declares itself to observe all keys.
+		Keyboard();
+
+		/// Constructs a Keyboard that declares itself to observe only members of @c observed_keys.
+		Keyboard(const std::set<Key> &observed_keys);
+
 		// Host interface.
 		virtual void set_key_pressed(Key key, char value, bool is_pressed);
 		virtual void reset_all_keys();
 
+		/// @returns a set of all Keys that this keyboard responds to.
+		virtual const std::set<Key> &observed_keys();
+
+		/*
+			@returns @c true if this keyboard, on its original machine, looked
+			like a complete keyboard — i.e. if a user would expect this keyboard
+			to be the only thing a real keyboard maps to.
+		*/
+		virtual bool is_exclusive();
+
 		// Delegate interface.
 		struct Delegate {
 			virtual void keyboard_did_change_key(Keyboard *keyboard, Key key, bool is_pressed) = 0;
@@ -52,8 +67,10 @@ class Keyboard {
 		bool get_key_state(Key key);
 
 	private:
+		std::set<Key> observed_keys_;
 		std::vector<bool> key_states_;
 		Delegate *delegate_ = nullptr;
+		bool is_exclusive_ = true;
 };
 
 }

Machines/AmstradCPC/AmstradCPC.cpp

@@ -757,7 +757,7 @@ class i8255PortHandler : public Intel::i8255::PortHandler {
 template <bool has_fdc> class ConcreteMachine:
 	public CRTMachine::Machine,
 	public MediaTarget::Machine,
-	public KeyboardMachine::Machine,
+	public KeyboardMachine::MappedMachine,
 	public Utility::TypeRecipient,
 	public CPU::Z80::BusHandler,
 	public ClockingHint::Observer,

Machines/AmstradCPC/Keyboard.cpp

@@ -75,9 +75,9 @@ uint16_t KeyboardMapper::mapped_key_for_key(Inputs::Keyboard::Key key) {
 }
 
 uint16_t *CharacterMapper::sequence_for_character(char character) {
-#define KEYS(...)	{__VA_ARGS__, KeyboardMachine::Machine::KeyEndSequence}
-#define SHIFT(...)	{KeyShift, __VA_ARGS__, KeyboardMachine::Machine::KeyEndSequence}
-#define X			{KeyboardMachine::Machine::KeyNotMapped}
+#define KEYS(...)	{__VA_ARGS__, KeyboardMachine::MappedMachine::KeyEndSequence}
+#define SHIFT(...)	{KeyShift, __VA_ARGS__, KeyboardMachine::MappedMachine::KeyEndSequence}
+#define X			{KeyboardMachine::MappedMachine::KeyNotMapped}
 	static KeySequence key_sequences[] = {
 		/* NUL */	X,							/* SOH */	X,
 		/* STX */	X,							/* ETX */	X,

Machines/AmstradCPC/Keyboard.hpp

@@ -33,7 +33,7 @@ enum Key: uint16_t {
 #undef Line
 };
 
-struct KeyboardMapper: public KeyboardMachine::Machine::KeyboardMapper {
+struct KeyboardMapper: public KeyboardMachine::MappedMachine::KeyboardMapper {
 	uint16_t mapped_key_for_key(Inputs::Keyboard::Key key);
 };
 

Machines/AppleII/AppleII.cpp

@@ -40,7 +40,7 @@ namespace {
 template <Analyser::Static::AppleII::Target::Model model> class ConcreteMachine:
 	public CRTMachine::Machine,
 	public MediaTarget::Machine,
-	public KeyboardMachine::Machine,
+	public KeyboardMachine::MappedMachine,
 	public CPU::MOS6502::BusHandler,
 	public Inputs::Keyboard,
 	public AppleII::Machine,

Machines/Commodore/Vic-20/Keyboard.cpp

@@ -68,13 +68,13 @@ uint16_t KeyboardMapper::mapped_key_for_key(Inputs::Keyboard::Key key) {
 		BIND(F7, KeyF7);
 	}
 #undef BIND
-	return KeyboardMachine::Machine::KeyNotMapped;
+	return KeyboardMachine::MappedMachine::KeyNotMapped;
 }
 
 uint16_t *CharacterMapper::sequence_for_character(char character) {
-#define KEYS(...)	{__VA_ARGS__, KeyboardMachine::Machine::KeyEndSequence}
-#define SHIFT(...)	{KeyLShift, __VA_ARGS__, KeyboardMachine::Machine::KeyEndSequence}
-#define X			{KeyboardMachine::Machine::KeyNotMapped}
+#define KEYS(...)	{__VA_ARGS__, KeyboardMachine::MappedMachine::KeyEndSequence}
+#define SHIFT(...)	{KeyLShift, __VA_ARGS__, KeyboardMachine::MappedMachine::KeyEndSequence}
+#define X			{KeyboardMachine::MappedMachine::KeyNotMapped}
 	static KeySequence key_sequences[] = {
 		/* NUL */	X,							/* SOH */	X,
 		/* STX */	X,							/* ETX */	X,

Machines/Commodore/Vic-20/Keyboard.hpp

@@ -38,7 +38,7 @@ enum Key: uint16_t {
 #undef key
 };
 
-struct KeyboardMapper: public KeyboardMachine::Machine::KeyboardMapper {
+struct KeyboardMapper: public KeyboardMachine::MappedMachine::KeyboardMapper {
 	uint16_t mapped_key_for_key(Inputs::Keyboard::Key key);
 };
 

Machines/Commodore/Vic-20/Vic20.cpp

@@ -281,7 +281,7 @@ class Joystick: public Inputs::ConcreteJoystick {
 class ConcreteMachine:
 	public CRTMachine::Machine,
 	public MediaTarget::Machine,
-	public KeyboardMachine::Machine,
+	public KeyboardMachine::MappedMachine,
 	public JoystickMachine::Machine,
 	public Configurable::Device,
 	public CPU::MOS6502::BusHandler,

Machines/Electron/Electron.cpp

@@ -42,7 +42,7 @@ class ConcreteMachine:
 	public Machine,
 	public CRTMachine::Machine,
 	public MediaTarget::Machine,
-	public KeyboardMachine::Machine,
+	public KeyboardMachine::MappedMachine,
 	public Configurable::Device,
 	public CPU::MOS6502::BusHandler,
 	public Tape::Delegate,

Machines/Electron/Keyboard.cpp

@@ -56,10 +56,10 @@ uint16_t KeyboardMapper::mapped_key_for_key(Inputs::Keyboard::Key key) {
 }
 
 uint16_t *CharacterMapper::sequence_for_character(char character) {
-#define KEYS(...)	{__VA_ARGS__, KeyboardMachine::Machine::KeyEndSequence}
-#define SHIFT(...)	{KeyShift, __VA_ARGS__, KeyboardMachine::Machine::KeyEndSequence}
-#define CTRL(...)	{KeyControl, __VA_ARGS__, KeyboardMachine::Machine::KeyEndSequence}
-#define X			{KeyboardMachine::Machine::KeyNotMapped}
+#define KEYS(...)	{__VA_ARGS__, KeyboardMachine::MappedMachine::KeyEndSequence}
+#define SHIFT(...)	{KeyShift, __VA_ARGS__, KeyboardMachine::MappedMachine::KeyEndSequence}
+#define CTRL(...)	{KeyControl, __VA_ARGS__, KeyboardMachine::MappedMachine::KeyEndSequence}
+#define X			{KeyboardMachine::MappedMachine::KeyNotMapped}
 	static KeySequence key_sequences[] = {
 		/* NUL */	X,							/* SOH */	X,
 		/* STX */	X,							/* ETX */	X,

Machines/Electron/Keyboard.hpp

@@ -33,7 +33,7 @@ enum Key: uint16_t {
 	KeyBreak		= 0xfffd,
 };
 
-struct KeyboardMapper: public KeyboardMachine::Machine::KeyboardMapper {
+struct KeyboardMapper: public KeyboardMachine::MappedMachine::KeyboardMapper {
 	uint16_t mapped_key_for_key(Inputs::Keyboard::Key key);
 };
 

Machines/KeyboardMachine.cpp

@@ -10,27 +10,27 @@
 
 using namespace KeyboardMachine;
 
-Machine::Machine() {
+MappedMachine::MappedMachine() {
 	keyboard_.set_delegate(this);
 }
 
-void Machine::keyboard_did_change_key(Inputs::Keyboard *keyboard, Inputs::Keyboard::Key key, bool is_pressed) {
+void MappedMachine::keyboard_did_change_key(Inputs::Keyboard *keyboard, Inputs::Keyboard::Key key, bool is_pressed) {
 	uint16_t mapped_key = get_keyboard_mapper()->mapped_key_for_key(key);
 	if(mapped_key != KeyNotMapped) set_key_state(mapped_key, is_pressed);
 }
 
-void Machine::reset_all_keys(Inputs::Keyboard *keyboard) {
+void MappedMachine::reset_all_keys(Inputs::Keyboard *keyboard) {
 	// TODO: unify naming.
 	clear_all_keys();
 }
 
-Inputs::Keyboard &Machine::get_keyboard() {
+Inputs::Keyboard &MappedMachine::get_keyboard() {
 	return keyboard_;
 }
 
 void Machine::type_string(const std::string &) {
 }
 
-Machine::KeyboardMapper *Machine::get_keyboard_mapper() {
+MappedMachine::KeyboardMapper *MappedMachine::get_keyboard_mapper() {
 	return nullptr;
 }

Machines/KeyboardMachine.hpp

@@ -33,13 +33,10 @@ struct KeyActions {
 };
 
 /*!
-	Describes the full functionality of being an emulated machine with a keyboard: not just being
-	able to receive key actions, but being able to vend a generic keyboard and a keyboard mapper.
+	Describes an emulated machine which exposes a keyboard and accepts a typed string.
 */
-class Machine: public Inputs::Keyboard::Delegate, public KeyActions {
+class Machine: public KeyActions {
 	public:
-		Machine();
-
 		/*!
 			Causes the machine to attempt to type the supplied string.
 
@@ -50,7 +47,16 @@ class Machine: public Inputs::Keyboard::Delegate, public KeyActions {
 		/*!
 			Provides a destination for keyboard input.
 		*/
-		virtual Inputs::Keyboard &get_keyboard();
+		virtual Inputs::Keyboard &get_keyboard() = 0;
+};
+
+/*!
+	Provides a base class for machines that want to provide a keyboard mapper,
+	allowing automatic mapping from keyboard inputs to KeyActions.
+*/
+class MappedMachine: public Inputs::Keyboard::Delegate, public Machine {
+	public:
+		MappedMachine();
 
 		/*!
 			A keyboard mapper attempts to provide a physical mapping between host keys and emulated keys.
@@ -76,6 +82,12 @@ class Machine: public Inputs::Keyboard::Delegate, public KeyActions {
 		*/
 		virtual KeyboardMapper *get_keyboard_mapper();
 
+		/*!
+			Provides a keyboard that obtains this machine's keyboard mapper, maps
+			the key and supplies it via the KeyActions.
+		*/
+		virtual Inputs::Keyboard &get_keyboard() override;
+
 	private:
 		void keyboard_did_change_key(Inputs::Keyboard *keyboard, Inputs::Keyboard::Key key, bool is_pressed) override;
 		void reset_all_keys(Inputs::Keyboard *keyboard) override;

Machines/MSX/Keyboard.cpp

@@ -57,5 +57,5 @@ uint16_t MSX::KeyboardMapper::mapped_key_for_key(Inputs::Keyboard::Key key) {
 		default: break;
 	}
 #undef BIND
-	return KeyboardMachine::Machine::KeyNotMapped;
+	return KeyboardMachine::MappedMachine::KeyNotMapped;
 }

Machines/MSX/Keyboard.hpp

@@ -33,7 +33,7 @@ enum Key: uint16_t {
 #undef Line
 };
 
-struct KeyboardMapper: public KeyboardMachine::Machine::KeyboardMapper {
+struct KeyboardMapper: public KeyboardMachine::MappedMachine::KeyboardMapper {
 	uint16_t mapped_key_for_key(Inputs::Keyboard::Key key);
 };
 

Machines/MSX/MSX.cpp

@@ -139,7 +139,7 @@ class ConcreteMachine:
 	public CPU::Z80::BusHandler,
 	public CRTMachine::Machine,
 	public MediaTarget::Machine,
-	public KeyboardMachine::Machine,
+	public KeyboardMachine::MappedMachine,
 	public Configurable::Device,
 	public JoystickMachine::Machine,
 	public MemoryMap,

Machines/MasterSystem/MasterSystem.cpp

@@ -15,6 +15,7 @@
 
 #include "../CRTMachine.hpp"
 #include "../JoystickMachine.hpp"
+#include "../KeyboardMachine.hpp"
 
 #include "../../ClockReceiver/ForceInline.hpp"
 
@@ -81,6 +82,8 @@ class ConcreteMachine:
 	public Machine,
 	public CPU::Z80::BusHandler,
 	public CRTMachine::Machine,
+	public KeyboardMachine::Machine,
+	public Inputs::Keyboard::Delegate,
 	public Configurable::Device,
 	public JoystickMachine::Machine {
 
@@ -94,7 +97,8 @@ class ConcreteMachine:
 				(target.model == Target::Model::SG1000) ? TI::SN76489::Personality::SN76489 : TI::SN76489::Personality::SMS,
 				audio_queue_,
 				sn76489_divider),
-			speaker_(sn76489_) {
+			speaker_(sn76489_),
+			keyboard_({Inputs::Keyboard::Key::Enter, Inputs::Keyboard::Key::Escape}) {
 			// Pick the clock rate based on the region.
 			const double clock_rate = target.region == Target::Region::Europe ? 3546893.0 : 3579540.0;
 			speaker_.set_input_rate(static_cast<float>(clock_rate / sn76489_divider));
@@ -146,6 +150,8 @@ class ConcreteMachine:
 
 			// Apple a relatively low low-pass filter. More guidance needed here.
 			speaker_.set_high_frequency_cutoff(8000);
+
+			keyboard_.set_delegate(this);
 		}
 
 		~ConcreteMachine() {
@@ -164,6 +170,8 @@ class ConcreteMachine:
 				(region_ == Target::Region::Europe) ?
 					TI::TMS::TVStandard::PAL : TI::TMS::TVStandard::NTSC);
 			get_crt()->set_video_signal(Outputs::CRT::VideoSignal::Composite);
+
+			time_until_debounce_ = vdp_->get_time_until_line(-1);
 		}
 
 		void close_output() override {
@@ -213,7 +221,7 @@ class ConcreteMachine:
 						}
 
 						if(write_pointers_[address >> 10]) write_pointers_[address >> 10][address & 1023] = *cycle.value;
-						else LOG("Ignored write to ROM");
+//						else LOG("Ignored write to ROM");
 					break;
 
 					case CPU::Z80::PartialMachineCycle::Input:
@@ -320,6 +328,15 @@ class ConcreteMachine:
 				}
 			}
 
+			// The pause button is debounced and takes effect only one line before pixels
+			// begin; time_until_debounce_ keeps track of the time until then.
+			time_until_debounce_ -= cycle.length;
+			if(time_until_debounce_ <= HalfCycles(0)) {
+				z80_.set_non_maskable_interrupt_line(pause_is_pressed_);
+				update_video();
+				time_until_debounce_ = vdp_->get_time_until_line(-1);
+			}
+
 			return HalfCycles(0);
 		}
 
@@ -333,6 +350,23 @@ class ConcreteMachine:
 			return joysticks_;
 		}
 
+		// MARK: - Keyboard (i.e. the pause and reset buttons).
+		Inputs::Keyboard &get_keyboard() override {
+			return keyboard_;
+		}
+
+		void keyboard_did_change_key(Inputs::Keyboard *, Inputs::Keyboard::Key key, bool is_pressed) override {
+			if(key == Inputs::Keyboard::Key::Enter) {
+				pause_is_pressed_ = is_pressed;
+			} else if(key == Inputs::Keyboard::Key::Escape) {
+				reset_is_pressed_ = is_pressed;
+			}
+		}
+
+
+		void reset_all_keys(Inputs::Keyboard *) override {
+		}
+
 		// MARK: - Configuration options.
 		std::vector<std::unique_ptr<Configurable::Option>> get_options() override {
 			return Sega::MasterSystem::get_options();
@@ -388,10 +422,13 @@ class ConcreteMachine:
 		Outputs::Speaker::LowpassSpeaker<TI::SN76489> speaker_;
 
 		std::vector<std::unique_ptr<Inputs::Joystick>> joysticks_;
+		Inputs::Keyboard keyboard_;
+		bool reset_is_pressed_ = false, pause_is_pressed_ = false;
 
 		HalfCycles time_since_vdp_update_;
 		HalfCycles time_since_sn76489_update_;
 		HalfCycles time_until_interrupt_;
+		HalfCycles time_until_debounce_;
 
 		uint8_t ram_[8*1024];
 		uint8_t bios_[8*1024];

Machines/Oric/Keyboard.cpp

@@ -48,13 +48,13 @@ uint16_t KeyboardMapper::mapped_key_for_key(Inputs::Keyboard::Key key) {
 	}
 #undef BIND
 
-	return KeyboardMachine::Machine::KeyNotMapped;
+	return KeyboardMachine::MappedMachine::KeyNotMapped;
 }
 
 uint16_t *CharacterMapper::sequence_for_character(char character) {
-#define KEYS(...)	{__VA_ARGS__, KeyboardMachine::Machine::KeyEndSequence}
-#define SHIFT(...)	{KeyLeftShift, __VA_ARGS__, KeyboardMachine::Machine::KeyEndSequence}
-#define X			{KeyboardMachine::Machine::KeyNotMapped}
+#define KEYS(...)	{__VA_ARGS__, KeyboardMachine::MappedMachine::KeyEndSequence}
+#define SHIFT(...)	{KeyLeftShift, __VA_ARGS__, KeyboardMachine::MappedMachine::KeyEndSequence}
+#define X			{KeyboardMachine::MappedMachine::KeyNotMapped}
 	static KeySequence key_sequences[] = {
 		/* NUL */	X,							/* SOH */	X,
 		/* STX */	X,							/* ETX */	X,

Machines/Oric/Keyboard.hpp

@@ -35,7 +35,7 @@ enum Key: uint16_t {
 	KeyNMI			= 0xfffd,
 };
 
-struct KeyboardMapper: public KeyboardMachine::Machine::KeyboardMapper {
+struct KeyboardMapper: public KeyboardMachine::MappedMachine::KeyboardMapper {
 	uint16_t mapped_key_for_key(Inputs::Keyboard::Key key);
 };
 

Machines/Oric/Oric.cpp

@@ -194,7 +194,7 @@ class VIAPortHandler: public MOS::MOS6522::IRQDelegatePortHandler {
 template <Analyser::Static::Oric::Target::DiskInterface disk_interface> class ConcreteMachine:
 	public CRTMachine::Machine,
 	public MediaTarget::Machine,
-	public KeyboardMachine::Machine,
+	public KeyboardMachine::MappedMachine,
 	public Configurable::Device,
 	public CPU::MOS6502::BusHandler,
 	public MOS::MOS6522::IRQDelegatePortHandler::Delegate,

Machines/Utility/Typer.cpp

@@ -43,14 +43,14 @@ void Typer::run_for(const HalfCycles duration) {
 bool Typer::try_type_next_character() {
 	uint16_t *sequence = character_mapper_->sequence_for_character(string_[string_pointer_]);
 
-	if(!sequence || sequence[0] == KeyboardMachine::Machine::KeyNotMapped) {
+	if(!sequence || sequence[0] == KeyboardMachine::MappedMachine::KeyNotMapped) {
 		return false;
 	}
 
 	if(!phase_) delegate_->clear_all_keys();
 	else {
 		delegate_->set_key_state(sequence[phase_ - 1], true);
-		return sequence[phase_] != KeyboardMachine::Machine::KeyEndSequence;
+		return sequence[phase_] != KeyboardMachine::MappedMachine::KeyEndSequence;
 	}
 
 	return true;
@@ -75,6 +75,6 @@ bool Typer::type_next_character() {
 uint16_t *CharacterMapper::table_lookup_sequence_for_character(KeySequence *sequences, std::size_t length, char character) {
 	std::size_t ucharacter = static_cast<std::size_t>((unsigned char)character);
 	if(ucharacter > (length / sizeof(KeySequence))) return nullptr;
-	if(sequences[ucharacter][0] == KeyboardMachine::Machine::KeyNotMapped) return nullptr;
+	if(sequences[ucharacter][0] == KeyboardMachine::MappedMachine::KeyNotMapped) return nullptr;
 	return sequences[ucharacter];
 }

Machines/ZX8081/Keyboard.cpp

@@ -30,15 +30,15 @@ uint16_t KeyboardMapper::mapped_key_for_key(Inputs::Keyboard::Key key) {
 		BIND(Space, KeySpace);
 	}
 #undef BIND
-	return KeyboardMachine::Machine::KeyNotMapped;
+	return KeyboardMachine::MappedMachine::KeyNotMapped;
 }
 
 CharacterMapper::CharacterMapper(bool is_zx81) : is_zx81_(is_zx81) {}
 
 uint16_t *CharacterMapper::sequence_for_character(char character) {
-#define KEYS(...)	{__VA_ARGS__, KeyboardMachine::Machine::KeyEndSequence}
-#define SHIFT(...)	{KeyShift, __VA_ARGS__, KeyboardMachine::Machine::KeyEndSequence}
-#define X			{KeyboardMachine::Machine::KeyNotMapped}
+#define KEYS(...)	{__VA_ARGS__, KeyboardMachine::MappedMachine::KeyEndSequence}
+#define SHIFT(...)	{KeyShift, __VA_ARGS__, KeyboardMachine::MappedMachine::KeyEndSequence}
+#define X			{KeyboardMachine::MappedMachine::KeyNotMapped}
 	static KeySequence zx81_key_sequences[] = {
 		/* NUL */	X,							/* SOH */	X,
 		/* STX */	X,							/* ETX */	X,

Machines/ZX8081/Keyboard.hpp

@@ -25,7 +25,7 @@ enum Key: uint16_t {
 	KeySpace	= 0x0700 | 0x01,	KeyDot	= 0x0700 | 0x02,	KeyM = 0x0700 | 0x04,	KeyN = 0x0700 | 0x08,	KeyB = 0x0700 | 0x10,
 };
 
-struct KeyboardMapper: public KeyboardMachine::Machine::KeyboardMapper {
+struct KeyboardMapper: public KeyboardMachine::MappedMachine::KeyboardMapper {
 	uint16_t mapped_key_for_key(Inputs::Keyboard::Key key);
 };
 

Machines/ZX8081/ZX8081.cpp

@@ -60,7 +60,7 @@ std::vector<std::unique_ptr<Configurable::Option>> get_options() {
 template<bool is_zx81> class ConcreteMachine:
 	public CRTMachine::Machine,
 	public MediaTarget::Machine,
-	public KeyboardMachine::Machine,
+	public KeyboardMachine::MappedMachine,
 	public Configurable::Device,
 	public Utility::TypeRecipient,
 	public CPU::Z80::BusHandler,

OSBindings/Mac/Clock Signal/Documents/MachineDocument.swift

@@ -301,7 +301,7 @@ class MachineDocument:
 		if let menuItem = item as? NSMenuItem {
 			switch item.action {
 				case #selector(self.useKeyboardAsKeyboard):
-					if machine == nil || !machine.hasKeyboard {
+					if machine == nil || !machine.hasExclusiveKeyboard {
 						menuItem.state = .off
 						return false
 					}

OSBindings/Mac/Clock Signal/Machine/CSMachine.h

@@ -76,7 +76,7 @@ typedef NS_ENUM(NSInteger, CSMachineKeyboardInputMode) {
 - (bool)supportsVideoSignal:(CSMachineVideoSignal)videoSignal;
 
 // Input control.
-@property (nonatomic, readonly) BOOL hasKeyboard;
+@property (nonatomic, readonly) BOOL hasExclusiveKeyboard;
 @property (nonatomic, readonly) BOOL hasJoystick;
 @property (nonatomic, assign) CSMachineKeyboardInputMode inputMode;
 @property (nonatomic, nullable) CSJoystickManager *joystickManager;

OSBindings/Mac/Clock Signal/Machine/CSMachine.mm

@@ -91,7 +91,9 @@ struct ActivityObserver: public Activity::Observer {
 		_machine.reset(Machine::MachineForTargets(_analyser.targets, CSROMFetcher(), error));
 		if(!_machine) return nil;
 
-		_inputMode = _machine->keyboard_machine() ? CSMachineKeyboardInputModeKeyboard : CSMachineKeyboardInputModeJoystick;
+		_inputMode =
+			(_machine->keyboard_machine() && _machine->keyboard_machine()->get_keyboard().is_exclusive())
+				? CSMachineKeyboardInputModeKeyboard : CSMachineKeyboardInputModeJoystick;
 
 		_leds = [[NSMutableArray alloc] init];
 		Activity::Source *const activity_source = _machine->activity_source();
@@ -301,26 +303,11 @@ struct ActivityObserver: public Activity::Observer {
 
 - (void)setKey:(uint16_t)key characters:(NSString *)characters isPressed:(BOOL)isPressed {
 	auto keyboard_machine = _machine->keyboard_machine();
-	if(self.inputMode == CSMachineKeyboardInputModeKeyboard && keyboard_machine) {
-		// Don't pass anything on if this is not new information.
-		if(_depressedKeys[key] == !!isPressed) return;
-		_depressedKeys[key] = !!isPressed;
-
-		// Pick an ASCII code, if any.
-		char pressedKey = '\0';
-		if(characters.length) {
-			unichar firstCharacter = [characters characterAtIndex:0];
-			if(firstCharacter < 128) {
-				pressedKey = (char)firstCharacter;
-			}
-		}
-
-		@synchronized(self) {
-			Inputs::Keyboard &keyboard = keyboard_machine->get_keyboard();
-
+	if(keyboard_machine && (self.inputMode == CSMachineKeyboardInputModeKeyboard || !keyboard_machine->get_keyboard().is_exclusive())) {
+		Inputs::Keyboard::Key mapped_key = Inputs::Keyboard::Key::Help;	// Make an innocuous default guess.
+#define BIND(source, dest) case source: mapped_key = Inputs::Keyboard::Key::dest; break;
 		// Connect the Carbon-era Mac keyboard scancodes to Clock Signal's 'universal' enumeration in order
 		// to pass into the platform-neutral realm.
-#define BIND(source, dest) case source: keyboard.set_key_pressed(Inputs::Keyboard::Key::dest, pressedKey, isPressed);	break
 		switch(key) {
 			BIND(VK_ANSI_0, k0);	BIND(VK_ANSI_1, k1);	BIND(VK_ANSI_2, k2);	BIND(VK_ANSI_3, k3);	BIND(VK_ANSI_4, k4);
 			BIND(VK_ANSI_5, k5);	BIND(VK_ANSI_6, k6);	BIND(VK_ANSI_7, k7);	BIND(VK_ANSI_8, k8);	BIND(VK_ANSI_9, k9);
@@ -373,9 +360,29 @@ struct ActivityObserver: public Activity::Observer {
 			BIND(VK_DownArrow, Down); 		BIND(VK_UpArrow, Up);
 		}
 #undef BIND
+
+		Inputs::Keyboard &keyboard = keyboard_machine->get_keyboard();
+
+		if(keyboard.observed_keys().find(mapped_key) != keyboard.observed_keys().end()) {
+			// Don't pass anything on if this is not new information.
+			if(_depressedKeys[key] == !!isPressed) return;
+			_depressedKeys[key] = !!isPressed;
+
+			// Pick an ASCII code, if any.
+			char pressedKey = '\0';
+			if(characters.length) {
+				unichar firstCharacter = [characters characterAtIndex:0];
+				if(firstCharacter < 128) {
+					pressedKey = (char)firstCharacter;
+				}
+			}
+
+			@synchronized(self) {
+				keyboard.set_key_pressed(mapped_key, pressedKey, isPressed);
 			}
 			return;
 		}
+	}
 
 	auto joystick_machine = _machine->joystick_machine();
 	if(self.inputMode == CSMachineKeyboardInputModeJoystick && joystick_machine) {
@@ -536,8 +543,8 @@ struct ActivityObserver: public Activity::Observer {
 	return !!_machine->joystick_machine();
 }
 
-- (BOOL)hasKeyboard {
-	return !!_machine->keyboard_machine();
+- (BOOL)hasExclusiveKeyboard {
+	return !!_machine->keyboard_machine() && _machine->keyboard_machine()->get_keyboard().is_exclusive();
 }
 
 #pragma mark - Activity observation

OSBindings/Mac/Clock SignalTests/MasterSystemVDPTests.mm

@@ -116,7 +116,7 @@
 	NSAssert(vdp.get_interrupt_line(), @"Interrupt line wasn't set when promised");
 }
 
-- (void)testPrediction {
+- (void)testInterruptPrediction {
 	TI::TMS::TMS9918 vdp(TI::TMS::Personality::SMSVDP);
 
 	for(int c = 0; c < 256; ++c) {
@@ -134,7 +134,7 @@
 			vdp.set_register(1, 0x8a);
 
 			// Now run through an entire frame...
-			int half_cycles = 262*224*2;
+			int half_cycles = 262*228*2;
 			int last_time_until_interrupt = vdp.get_time_until_interrupt().as_int();
 			while(half_cycles--) {
 				// Validate that an interrupt happened if one was expected, and clear anything that's present.
@@ -157,4 +157,20 @@
 	}
 }
 
+- (void)testTimeUntilLine {
+	TI::TMS::TMS9918 vdp(TI::TMS::Personality::SMSVDP);
+
+	int time_until_line = vdp.get_time_until_line(-1).as_int();
+	for(int c = 0; c < 262*228*5; ++c) {
+		vdp.run_for(HalfCycles(1));
+
+		const int time_remaining_until_line = vdp.get_time_until_line(-1).as_int();
+		--time_until_line;
+		if(time_until_line) {
+			NSAssert(time_remaining_until_line == time_until_line, @"Discontinuity found in distance-to-line prediction; expected %d but got %d", time_until_line, time_remaining_until_line);
+		}
+		time_until_line = time_remaining_until_line;
+	}
+}
+
 @end

OSBindings/SDL/main.cpp

@@ -610,7 +610,7 @@ int main(int argc, char *argv[]) {
 				case SDL_KEYDOWN:
 					// Syphon off the key-press if it's control+shift+V (paste).
 					if(event.key.keysym.sym == SDLK_v && (SDL_GetModState()&KMOD_CTRL) && (SDL_GetModState()&KMOD_SHIFT)) {
-						KeyboardMachine::Machine *keyboard_machine = machine->keyboard_machine();
+						const auto keyboard_machine = machine->keyboard_machine();
 						if(keyboard_machine) {
 							keyboard_machine->type_string(SDL_GetClipboardText());
 							break;
@@ -686,7 +686,7 @@ int main(int argc, char *argv[]) {
 						SDL_ShowCursor((fullscreen_mode&SDL_WINDOW_FULLSCREEN_DESKTOP) ? SDL_DISABLE : SDL_ENABLE);
 
 						// Announce a potential discontinuity in keyboard input.
-						auto keyboard_machine = machine->keyboard_machine();
+						const auto keyboard_machine = machine->keyboard_machine();
 						if(keyboard_machine) {
 							keyboard_machine->get_keyboard().reset_all_keys();
 						}
@@ -695,11 +695,12 @@ int main(int argc, char *argv[]) {
 
 					const bool is_pressed = event.type == SDL_KEYDOWN;
 
-					KeyboardMachine::Machine *const keyboard_machine = machine->keyboard_machine();
+					const auto keyboard_machine = machine->keyboard_machine();
 					if(keyboard_machine) {
 						Inputs::Keyboard::Key key = Inputs::Keyboard::Key::Space;
 						if(!KeyboardKeyForSDLScancode(event.key.keysym.scancode, key)) break;
 
+						if(keyboard_machine->get_keyboard().observed_keys().find(key) != keyboard_machine->get_keyboard().observed_keys().end()) {
 							char key_value = '\0';
 							const char *key_name = SDL_GetKeyName(event.key.keysym.sym);
 							if(key_name[0] >= 0) key_value = key_name[0];
@@ -707,6 +708,7 @@ int main(int argc, char *argv[]) {
 							keyboard_machine->get_keyboard().set_key_pressed(key, key_value, is_pressed);
 							break;
 						}
+					}
 
 					JoystickMachine::Machine *const joystick_machine = machine->joystick_machine();
 					if(joystick_machine) {