Simplify the usage of the register16_t union.

Signed-off-by: Adrian Conlon <Adrian.conlon@gmail.com>

Intel8080/inc/Intel8080.h

@@ -47,9 +47,9 @@ namespace EightBit {
 		InputOutput& m_ports;
 
 		register16_t af;
-		register16_t bc = { { 0xff, 0xff } };
-		register16_t de = { { 0xff, 0xff } };
-		register16_t hl = { { 0xff, 0xff } };
+		register16_t bc = 0xffff;
+		register16_t de = 0xffff;
+		register16_t hl = 0xffff;
 
 		uint8_t R(int r) {
 			switch (r) {

Intel8080/src/Intel8080.cpp

@@ -12,10 +12,9 @@ EightBit::register16_t& EightBit::Intel8080::AF() {
 }
 
 EightBit::register16_t EightBit::Intel8080::AF() const {
-	register16_t returned;
-	returned.low = (af.low | Bit1) & ~(Bit5 | Bit3);
-	returned.high = af.high;
-	return returned;
+	const auto low = (af.low | Bit1) & ~(Bit5 | Bit3);
+	const auto high = af.high;
+	return register16_t(low, high);
 }
 
 EightBit::register16_t EightBit::Intel8080::BC() const {
@@ -142,8 +141,7 @@ void EightBit::Intel8080::add(register16_t value) {
 
 void EightBit::Intel8080::add(uint8_t value, int carry) {
 
-	register16_t result;
-	result.word = A() + value + carry;
+	const register16_t result = A() + value + carry;
 
 	adjustAuxiliaryCarryAdd(F(), A(), value, result.word);
 
@@ -159,8 +157,7 @@ void EightBit::Intel8080::adc(uint8_t value) {
 
 void EightBit::Intel8080::subtract(uint8_t& operand, uint8_t value, int carry) {
 
-	register16_t result;
-	result.word = operand - value - carry;
+	const register16_t result = operand - value - carry;
 
 	adjustAuxiliaryCarrySub(F(), operand, value, result.word);
 

Intel8080/test/Configuration.h

@@ -29,9 +29,9 @@ public:
 	}
 
 	EightBit::register16_t getStartAddress() const {
-		EightBit::register16_t returned;
-		returned.word = 0x100;
-		return returned;
+		//EightBit::register16_t returned;
+		//returned.word = 0x100;
+		return 0x100;
 	}
 
 private:

LR35902/inc/IoRegisters.h

@@ -172,7 +172,7 @@ namespace EightBit {
 			int m_timerCounter = 0;
 			int m_timerRate = 0;
 
-			register16_t m_dmaAddress = { 0, 0 };
+			register16_t m_dmaAddress;
 			bool m_dmaTransferActive = false;
 
 			bool m_scanP15 = false;

LR35902/inc/LR35902.h

@@ -36,10 +36,9 @@ namespace EightBit {
 			}
 
 			register16_t AF() const final {
-				register16_t returned;
-				returned.low = higherNibble(af.low);
-				returned.high = af.high;
-				return returned;
+				const auto low = higherNibble(af.low);
+				const auto high = af.high;
+				return register16_t(low, high);
 			}
 
 			virtual register16_t BC() const final { return bc; }
@@ -59,10 +58,10 @@ namespace EightBit {
 		private:
 			Bus& m_bus;
 
-			register16_t af = { { 0xff, 0xff } };
-			register16_t bc = { { 0xff, 0xff } };
-			register16_t de = { { 0xff, 0xff } };
-			register16_t hl = { { 0xff, 0xff } };
+			register16_t af = 0xffff;
+			register16_t bc = 0xffff;
+			register16_t de = 0xffff;
+			register16_t hl = 0xffff;
 
 			bool m_ime = false;
 			bool m_stopped = false;

LR35902/src/LR35902.cpp

@@ -120,8 +120,7 @@ void EightBit::GameBoy::LR35902::add(uint8_t& f, register16_t& operand, register
 
 void EightBit::GameBoy::LR35902::add(uint8_t& f, uint8_t& operand, uint8_t value, int carry) {
 
-	register16_t result;
-	result.word = operand + value + carry;
+	const register16_t result = operand + value + carry;
 
 	adjustHalfCarryAdd(f, operand, value, result.low);
 
@@ -138,8 +137,7 @@ void EightBit::GameBoy::LR35902::adc(uint8_t& f, uint8_t& operand, uint8_t value
 
 void EightBit::GameBoy::LR35902::subtract(uint8_t& f, uint8_t& operand, uint8_t value, int carry) {
 
-	register16_t result;
-	result.word = operand - value - carry;
+	const register16_t result = operand - value - carry;
 
 	adjustHalfCarrySub(f, operand, value, result.low);
 

M6502/inc/mos6502.h

@@ -336,6 +336,6 @@ namespace EightBit {
 
 		PinLevel m_soLine = Low;
 
-		register16_t m_intermediate = { { 0, 0 } };
+		register16_t m_intermediate;
 	};
 }

M6502/src/mos6502.cpp

@@ -51,11 +51,10 @@ void EightBit::MOS6502::reset() {
 }
 
 EightBit::register16_t EightBit::MOS6502::getWordPaged(uint8_t page, uint8_t offset) {
-	EightBit::register16_t returned;
-	returned.low = getBytePaged(page, offset);
+	const auto low = getBytePaged(page, offset);
 	++BUS().ADDRESS().low;
-	returned.high = BUS().read();
-	return returned;
+	const auto high = BUS().read();
+	return register16_t(low, high);
 }
 
 uint8_t EightBit::MOS6502::getBytePaged(uint8_t page, uint8_t offset) {
@@ -442,8 +441,7 @@ uint8_t EightBit::MOS6502::SUB_d(const uint8_t operand, const uint8_t data, cons
 }
 
 void EightBit::MOS6502::CMP(uint8_t first, uint8_t second) {
-	register16_t result;
-	result.word = first - second;
+	const register16_t result = first - second;
 	adjustNZ(result.low);
 	clearFlag(P(), CF, result.high);
 }

Z80/inc/Z80.h

@@ -114,8 +114,8 @@ namespace EightBit {
 		std::array<register16_t, 2> m_accumulatorFlags;
 		int m_accumulatorFlagsSet = 0;
 
-		register16_t m_ix = { { 0xff, 0xff } };
-		register16_t m_iy = { { 0xff, 0xff } };
+		register16_t m_ix = 0xffff;
+		register16_t m_iy = 0xffff;
 
 		refresh_t m_refresh = 0x7f;
 
@@ -421,7 +421,7 @@ namespace EightBit {
 		void ccf();
 		void cpl();
 
-		void xhtl(register16_t& operand);
+		void xhtl();
 
 		void blockCompare();
 

Z80/src/Z80.cpp

@@ -255,8 +255,7 @@ void EightBit::Z80::add(const register16_t value) {
 
 void EightBit::Z80::add(const uint8_t value, const int carry) {
 
-	register16_t result;
-	result.word = A() + value + carry;
+	const register16_t result = A() + value + carry;
 
 	adjustHalfCarryAdd(F(), A(), value, result.low);
 	adjustOverflowAdd(F(), A(), value, result.low);
@@ -274,8 +273,7 @@ void EightBit::Z80::adc(const uint8_t value) {
 
 void EightBit::Z80::subtract(uint8_t& operand, const uint8_t value, const int carry) {
 
-	register16_t result;
-	result.word = operand - value - carry;
+	const register16_t result = operand - value - carry;
 
 	adjustHalfCarrySub(F(), operand, value, result.low);
 	adjustOverflowSub(F(), operand, value, result.low);
@@ -463,14 +461,14 @@ void EightBit::Z80::ccf() {
 	adjustXY<Z80>(F(), A());
 }
 
-void EightBit::Z80::xhtl(register16_t& operand) {
+void EightBit::Z80::xhtl() {
 	MEMPTR().low = BUS().read(SP());
-	BUS().write(operand.low);
-	operand.low = MEMPTR().low;
+	BUS().write(HL2().low);
+	HL2().low = MEMPTR().low;
 	++BUS().ADDRESS().word;
 	MEMPTR().high = BUS().read();
-	BUS().write(operand.high);
-	operand.high = MEMPTR().high;
+	BUS().write(HL2().high);
+	HL2().high = MEMPTR().high;
 }
 
 void EightBit::Z80::blockCompare() {
@@ -1420,7 +1418,7 @@ void EightBit::Z80::executeOther(const int x, const int y, const int z, const in
 				addCycles(11);
 				break;
 			case 4:	// EX (SP),HL
-				xhtl(HL2());
+				xhtl();
 				addCycles(19);
 				break;
 			case 5:	// EX DE,HL

Z80/test/Configuration.h

@@ -29,9 +29,9 @@ public:
 	}
 
 	EightBit::register16_t getStartAddress() const {
-		EightBit::register16_t returned;
-		returned.word = 0x100;
-		return returned;
+		//EightBit::register16_t returned;
+		//returned.word = 0x100;
+		return 0x100;
 	}
 
 private:

inc/Bus.h

@@ -30,13 +30,17 @@ namespace EightBit {
 		uint16_t peekWord(uint16_t address) const;
 
 		uint8_t read();
-		uint8_t read(uint16_t offset);
-		uint8_t read(register16_t address);
+		template<class T> uint8_t read(const T address) {
+			ADDRESS() = address;
+			return read();
+		}
 
 		void write();
 		void write(uint8_t value);
-		void write(uint16_t offset, uint8_t value);
-		void write(register16_t address, uint8_t value);
+		template<class T> void write(const T offset, const uint8_t value) {
+			ADDRESS() = offset;
+			write(value);
+		}
 
 	protected:
 		virtual uint8_t& reference(uint16_t address) = 0;
@@ -47,6 +51,6 @@ namespace EightBit {
 
 	private:
 		uint8_t m_data = 0xff;
-		register16_t m_address{ { 0xff, 0xff } };
+		register16_t m_address = 0xffff;
 	};
 }

inc/IntelProcessor.h

@@ -183,7 +183,7 @@ namespace EightBit {
 
 	private:
 		std::array<opcode_decoded_t, 0x100> m_decodedOpcodes;
-		register16_t m_sp = { { 0xff, 0xff } };
-		register16_t m_memptr = { { 0, 0 } };
+		register16_t m_sp = 0xffff;
+		register16_t m_memptr;
 	};
 }

inc/Processor.h

@@ -124,10 +124,9 @@ namespace EightBit {
 		}
 
 		register16_t fetchWord() {
-			register16_t returned;
-			returned.low = fetchByte();
-			returned.high = fetchByte();
-			return returned;
+			const auto low = fetchByte();
+			const auto high = fetchByte();
+			return register16_t(low, high);
 		}
 
 		virtual void push(uint8_t value) = 0;
@@ -139,10 +138,9 @@ namespace EightBit {
 		}
 
 		register16_t popWord() {
-			register16_t returned;
-			returned.low = pop();
-			returned.high = pop();
-			return returned;
+			const auto low = pop();
+			const auto high = pop();
+			return register16_t(low, high);
 		}
 
 		void jump(const register16_t destination) {
@@ -166,7 +164,7 @@ namespace EightBit {
 	private:
 		Bus& m_bus;
 		int m_cycles = 0;
-		register16_t m_pc = { { 0, 0 } };
+		register16_t m_pc;
 
 		PinLevel m_intLine = Low;
 		PinLevel m_nmiLine = Low;

inc/Register.h

@@ -18,7 +18,7 @@
 #endif
 
 namespace EightBit {
-	typedef union {
+	union register16_t {
 		struct {
 #ifdef HOST_LITTLE_ENDIAN
 			uint8_t low;
@@ -30,5 +30,8 @@ namespace EightBit {
 #endif
 		};
 		uint16_t word;
-	} register16_t;
+		register16_t() : word(0) {}
+		register16_t(uint16_t w) : word(w) {}
+		register16_t(uint8_t l, uint8_t h) : low(l),  high(h) {}
+	} ;
 }

src/Bus.cpp

@@ -18,10 +18,9 @@ void EightBit::Bus::poke(const uint16_t address, const uint8_t value) {
 }
 
 uint16_t EightBit::Bus::peekWord(const uint16_t address) const {
-	register16_t returned;
-	returned.low = peek(address);
-	returned.high = peek(address + 1);
-	return returned.word;
+	const auto low = peek(address);
+	const auto high = peek(address + 1);
+	return register16_t(low, high).word;
 }
 
 uint8_t EightBit::Bus::read() {
@@ -31,16 +30,6 @@ uint8_t EightBit::Bus::read() {
 	return DATA();
 }
 
-uint8_t EightBit::Bus::read(const uint16_t offset) {
-	ADDRESS().word = offset;
-	return read();
-}
-
-uint8_t EightBit::Bus::read(const register16_t address) {
-	ADDRESS() = address;
-	return read();
-}
-
 void EightBit::Bus::write() {
 	WritingByte.fire(EventArgs::empty());
 	reference() = DATA();
@@ -52,16 +41,6 @@ void EightBit::Bus::write(const uint8_t value) {
 	write();
 }
 
-void EightBit::Bus::write(const uint16_t offset, const uint8_t value) {
-	ADDRESS().word = offset;
-	write(value);
-}
-
-void EightBit::Bus::write(const register16_t address, const uint8_t value) {
-	ADDRESS() = address;
-	write(value);
-}
-
 uint8_t EightBit::Bus::reference() const {
 	return reference(ADDRESS().word);
 }

src/IntelProcessor.cpp

@@ -21,10 +21,11 @@ uint8_t EightBit::IntelProcessor::pop() {
 }
 
 EightBit::register16_t EightBit::IntelProcessor::getWord() {
-	register16_t returned;
-	returned.low = BUS().read(MEMPTR().word++);
-	returned.high = BUS().read(++BUS().ADDRESS().word);
-	return returned;
+	BUS().ADDRESS().word = MEMPTR().word++;
+	const auto low = BUS().read();
+	++BUS().ADDRESS().word;
+	const auto high = BUS().read();
+	return register16_t(low, high);
 }
 
 void EightBit::IntelProcessor::setWord(const register16_t value) {