Improve the flexibility of the BUS mapping/read/write architecture.

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

src/Processor.cpp

@@ -25,6 +25,29 @@ void EightBit::Processor::handleIRQ() {
 	raise(IRQ());
 }
 
+void EightBit::Processor::busWrite(const register16_t address, const uint8_t data) {
+	BUS().ADDRESS() = address;
+	busWrite(data);
+}
+
+void EightBit::Processor::busWrite(const uint8_t data) {
+	BUS().DATA() = data;
+	busWrite();
+}
+
+void EightBit::Processor::busWrite() {
+	BUS().write();
+}
+
+uint8_t EightBit::Processor::busRead(const register16_t address) {
+	BUS().ADDRESS() = address;
+	return busRead();
+}
+
+uint8_t EightBit::Processor::busRead() {
+	return BUS().read();
+}
+
 int EightBit::Processor::run(const int limit) {
 	int current = 0;
 	while (LIKELY(powered() && (current < limit)))
@@ -32,6 +55,11 @@ int EightBit::Processor::run(const int limit) {
 	return current;
 }
 
+int EightBit::Processor::execute(const uint8_t value) {
+	opcode() = value;
+	return execute();
+}
+
 // http://graphics.stanford.edu/~seander/bithacks.html#FixedSignExtend
 int8_t EightBit::Processor::signExtend(const int b, uint8_t x) {
 	const uint8_t m = 1 << (b - 1); // mask can be pre-computed if b is fixed