Factors out a little of the ZX81's keyboard logic.

Machines/Sinclair/ZX8081/Keyboard.cpp

@@ -192,3 +192,53 @@ const uint16_t *CharacterMapper::sequence_for_character(char character) const {
 bool CharacterMapper::needs_pause_after_key(uint16_t key) const {
 	return key != KeyShift;
 }
+
+Keyboard::Keyboard(bool is_zx81) : is_zx81_(is_zx81) {
+	clear_all_keys();
+}
+
+void Keyboard::set_key_state(uint16_t key, bool is_pressed) {
+	const auto line = key >> 8;
+
+	// Check for special cases.
+	if(line > 7) {
+		switch(key) {
+#define ShiftedKey(source, base)	\
+			case source:			\
+				set_key_state(KeyShift, is_pressed);	\
+				set_key_state(base, is_pressed);		\
+			break;
+
+			ShiftedKey(KeyDelete, Key0);
+			ShiftedKey(KeyBreak, KeySpace);
+			ShiftedKey(KeyUp, Key7);
+			ShiftedKey(KeyDown, Key6);
+			ShiftedKey(KeyLeft, Key5);
+			ShiftedKey(KeyRight, Key8);
+			ShiftedKey(KeyEdit, is_zx81_ ? Key1 : KeyEnter);
+
+#undef ShiftedKey
+		}
+	} else {
+		if(is_pressed)
+			key_states_[line] &= uint8_t(~key);
+		else
+			key_states_[line] |= uint8_t(key);
+	}
+}
+
+void Keyboard::clear_all_keys() {
+	memset(key_states_, 0xff, 8);
+}
+
+uint8_t Keyboard::read(uint16_t address) {
+	uint8_t value = 0xff;
+
+	uint16_t mask = 0x100;
+	for(int c = 0; c < 8; c++) {
+		if(!(address & mask)) value &= key_states_[c];
+		mask <<= 1;
+	}
+
+	return value;
+}

Machines/Sinclair/ZX8081/Keyboard.hpp

@@ -30,6 +30,19 @@ enum Key: uint16_t {
 	KeyBreak, KeyLeft, KeyRight, KeyUp, KeyDown, KeyEdit
 };
 
+struct Keyboard {
+	Keyboard(bool is_zx81);
+
+	void set_key_state(uint16_t key, bool is_pressed);
+	void clear_all_keys();
+
+	uint8_t read(uint16_t address);
+
+	private:
+		uint8_t key_states_[8];
+		const bool is_zx81_;
+};
+
 struct KeyboardMapper: public MachineTypes::MappedKeyboardMachine::KeyboardMapper {
 	uint16_t mapped_key_for_key(Inputs::Keyboard::Key key) const override;
 };

Machines/Sinclair/ZX8081/ZX8081.cpp

@@ -63,12 +63,12 @@ template<bool is_zx81> class ConcreteMachine:
 		ConcreteMachine(const Analyser::Static::ZX8081::Target &target, const ROMMachine::ROMFetcher &rom_fetcher) :
 			Utility::TypeRecipient<CharacterMapper>(is_zx81),
 			z80_(*this),
+			keyboard_(is_zx81),
 			tape_player_(ZX8081ClockRate),
 			ay_(GI::AY38910::Personality::AY38910, audio_queue_),
 			speaker_(ay_) {
 			set_clock_rate(ZX8081ClockRate);
 			speaker_.set_input_rate(float(ZX8081ClockRate) / 2.0f);
-			clear_all_keys();
 
 			const bool use_zx81_rom = target.is_ZX81 || target.ZX80_uses_ZX81_ROM;
 			const auto roms =
@@ -183,12 +183,7 @@ template<bool is_zx81> class ConcreteMachine:
 					if(!(address&1)) {
 						if(!nmi_is_enabled_) set_vsync(true);
 
-						uint16_t mask = 0x100;
+						value &= keyboard_.read(address);
-						for(int c = 0; c < 8; c++) {
-							if(!(address & mask)) value &= key_states_[c];
-							mask <<= 1;
-						}
-
 						value &= ~(tape_player_.get_input() ? 0x00 : 0x80);
 					}
 
@@ -339,36 +334,11 @@ template<bool is_zx81> class ConcreteMachine:
 
 		// MARK: - Keyboard
 		void set_key_state(uint16_t key, bool is_pressed) final {
-			const auto line = key >> 8;
+			keyboard_.set_key_state(key, is_pressed);
-
-			// Check for special cases.
-			if(line > 7) {
-				switch(key) {
-#define ShiftedKey(source, base)	\
-					case source:	\
-						set_key_state(KeyShift, is_pressed);	\
-						set_key_state(base, is_pressed);		\
-					break;
-
-					ShiftedKey(KeyDelete, Key0);
-					ShiftedKey(KeyBreak, KeySpace);
-					ShiftedKey(KeyUp, Key7);
-					ShiftedKey(KeyDown, Key6);
-					ShiftedKey(KeyLeft, Key5);
-					ShiftedKey(KeyRight, Key8);
-					ShiftedKey(KeyEdit, is_zx81 ? Key1 : KeyEnter);
-#undef ShiftedKey
-				}
-			} else {
-				if(is_pressed)
-					key_states_[line] &= uint8_t(~key);
-				else
-					key_states_[line] |= uint8_t(key);
-			}
 		}
 
 		void clear_all_keys() final {
-			memset(key_states_, 0xff, 8);
+			keyboard_.clear_all_keys();
 		}
 
 		// MARK: - Tape control
@@ -448,7 +418,7 @@ template<bool is_zx81> class ConcreteMachine:
 		bool vsync_ = false, hsync_ = false;
 		int line_counter_ = 0;
 
-		uint8_t key_states_[8];
+		Keyboard keyboard_;
 		ZX8081::KeyboardMapper keyboard_mapper_;
 
 		HalfClockReceiver<Storage::Tape::BinaryTapePlayer> tape_player_;