From 7296ff7cce0894b4633ddbc5fdec84362d22c30a Mon Sep 17 00:00:00 2001
From: Adrian Conlon <adrian.conlon@gmail.com>
Date: Mon, 6 Apr 2020 23:08:11 +0100
Subject: [PATCH] MC6809 tidy a few items and show a "functional" (rather than
 macro based) rmw routine.

---
 MC6809/inc/mc6809.h   | 31 +++++++++++++++++++++++++++++--
 MC6809/src/mc6809.cpp | 32 +++++++++++---------------------
 2 files changed, 40 insertions(+), 23 deletions(-)

diff --git a/MC6809/inc/mc6809.h b/MC6809/inc/mc6809.h
index 32ca432..36c977d 100644
--- a/MC6809/inc/mc6809.h
+++ b/MC6809/inc/mc6809.h
@@ -4,6 +4,7 @@
 // http://www.cpu-world.com/Arch/6809.html
 
 #include <cstdint>
+#include <functional>
 
 #include <Bus.h>
 #include <BigEndianProcessor.h>
@@ -112,6 +113,7 @@ namespace EightBit {
 		virtual uint8_t busRead() final;
 
 		virtual void call(register16_t destination) final;
+		virtual void ret() final;
 
 	private:
 		const uint8_t RESETvector = 0xfe;		// RESET vector
@@ -125,7 +127,33 @@ namespace EightBit {
 
 		void eat(int cycles = 1) {
 			for (int cycle = 0; cycle < cycles; ++cycle)
-				memoryRead(0xffff);
+				memoryRead(Mask16);
+		}
+
+		// Read/Modify/Write
+
+		// Macro version: easy to use
+		// RMW(AM_direct_byte, asl)
+		#define RMW(ACCESSOR, OPERATION) \
+		{ \
+			const auto data = ACCESSOR(); \
+			const auto address = BUS().ADDRESS(); \
+			const auto result = OPERATION(data); \
+			eat(); \
+			memoryWrite(address, result); \
+		}
+
+		typedef std::function<uint8_t(void)> accessor_t;
+		typedef std::function<uint8_t(uint8_t)> operation_t;
+
+		// C++ 11 version: looks great, but verbose to use
+		// rmw([this]() { return AM_direct_byte(); }, [this](uint8_t data) { return asl(data); });
+		void rmw(accessor_t accessor, operation_t operation) {
+			const auto data = accessor();
+			const auto address = BUS().ADDRESS();
+			const auto result = operation(data);
+			eat();
+			memoryWrite(address, result);
 		}
 
 		// Stack manipulation
@@ -363,7 +391,6 @@ namespace EightBit {
 		uint8_t rol(uint8_t operand);
 		uint8_t ror(uint8_t operand);
 		void rti();
-		void rts();
 		uint8_t sbc(uint8_t operand, uint8_t data);
 		uint8_t sub(uint8_t operand, uint8_t data, uint8_t carry = 0);
 		register16_t sub(register16_t operand, register16_t data);
diff --git a/MC6809/src/mc6809.cpp b/MC6809/src/mc6809.cpp
index 5bb6905..b0d663e 100644
--- a/MC6809/src/mc6809.cpp
+++ b/MC6809/src/mc6809.cpp
@@ -4,16 +4,6 @@
 #include <algorithm>
 #include <cassert>
 
-// Read/Modify/Write
-#define RMW(ACCESSOR, OPERATION) \
-{ \
-	const auto data = ACCESSOR(); \
-	const auto address = BUS().ADDRESS(); \
-	const auto result = OPERATION(data); \
-	eat(); \
-	memoryWrite(address, result); \
-}
-
 EightBit::mc6809::mc6809(Bus& bus)
 : BigEndianProcessor(bus) {
 	RaisedPOWER.connect([this](EventArgs) {
@@ -61,17 +51,17 @@ void EightBit::mc6809::handleHALT() {
 
 void EightBit::mc6809::handleRESET() {
 	BigEndianProcessor::handleRESET();
-	memoryRead(0xfffe);
+	memoryRead({ 0xff, RESETvector });
 	raiseNMI();
 	lowerBA();
 	raiseBS();
 	DP() = 0;
 	CC() = setBit(CC(), IF);	// Disable IRQ
 	CC() = setBit(CC(), FF);	// Disable FIRQ
-	memoryRead(0xfffe);
-	memoryRead(0xfffe);
-	memoryRead(0xfffe);
-	jump(getWordPaged(0xff, RESETvector));
+	memoryRead();
+	memoryRead();
+	memoryRead();
+	jump(getWord());
 	eat();
 }
 
@@ -142,6 +132,11 @@ void EightBit::mc6809::call(register16_t destination) {
 	jump(destination);
 }
 
+void EightBit::mc6809::ret() {
+	BigEndianProcessor::ret();
+	eat();
+}
+
 //
 
 int EightBit::mc6809::execute() {
@@ -421,7 +416,7 @@ void EightBit::mc6809::executeUnprefixed() {
 	case 0x3B:	memoryRead(); rti();									break;		// RTI (inherent)
 
 	// RTS
-	case 0x39:	memoryRead(); rts(); 									break;		// RTS (inherent)
+	case 0x39:	memoryRead(); ret(); 									break;		// RTS (inherent)
 
 	// SBC
 
@@ -1088,11 +1083,6 @@ void EightBit::mc6809::rti() {
 	eat();
 }
 
-void EightBit::mc6809::rts() {
-	ret();
-	eat();
-}
-
 void EightBit::mc6809::swi() {
 	eat();
 	saveEntireRegisterState();