From c78c1211599080c03c341676a27da4641e9dbde4 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Mon, 18 Jan 2021 20:16:01 -0500
Subject: [PATCH] Succeeds at executing a single instruction.

---
 InstructionSets/CachingExecutor.hpp |  4 ----
 InstructionSets/M50740/Executor.cpp | 20 +++++++++++++++++---
 InstructionSets/M50740/Executor.hpp |  3 +++
 3 files changed, 20 insertions(+), 7 deletions(-)

diff --git a/InstructionSets/CachingExecutor.hpp b/InstructionSets/CachingExecutor.hpp
index 469ebbf82..1c57b7393 100644
--- a/InstructionSets/CachingExecutor.hpp
+++ b/InstructionSets/CachingExecutor.hpp
@@ -95,10 +95,6 @@ template <
 		// indexed by array position, which is a lot more compact than a generic pointer.
 		std::array<Performer, max_performer_count> performers_;
 
-		// TODO: should I include a program counter at all? Are there platforms
-		// for which the expense of retaining opcode length doesn't buy any benefit?
-		ProgramCounterType program_counter_;
-
 
 		/*!
 			Moves the current point of execution to @c address, updating necessary performer caches
diff --git a/InstructionSets/M50740/Executor.cpp b/InstructionSets/M50740/Executor.cpp
index a3067f14a..7e487506e 100644
--- a/InstructionSets/M50740/Executor.cpp
+++ b/InstructionSets/M50740/Executor.cpp
@@ -10,6 +10,7 @@
 
 #include <algorithm>
 #include <cassert>
+#include <cstring>
 
 using namespace InstructionSet::M50740;
 
@@ -144,7 +145,20 @@ template <Operation operation, AddressingMode addressing_mode> void Executor::pe
 }
 
 template <Operation operation> void Executor::perform(uint8_t *operand [[maybe_unused]]) {
-//	switch(operation) {
-//		default: assert(false);
-//	}
+	switch(operation) {
+		case Operation::LDA:	a_ = *operand;	break;	// TODO: flags (for all three here).
+		case Operation::LDX:	x_ = *operand;	break;
+		case Operation::LDY:	y_ = *operand;	break;
+
+		case Operation::STA:	*operand = a_;	break;
+		case Operation::STX:	*operand = x_;	break;
+		case Operation::STY:	*operand = y_;	break;
+
+		default: assert(false);
+	}
+}
+
+void Executor::set_program_counter(uint16_t address) {
+	program_counter_ = address;
+	CachingExecutor::set_program_counter(address);
 }
diff --git a/InstructionSets/M50740/Executor.hpp b/InstructionSets/M50740/Executor.hpp
index 16273d1bd..81f0f3f21 100644
--- a/InstructionSets/M50740/Executor.hpp
+++ b/InstructionSets/M50740/Executor.hpp
@@ -100,6 +100,8 @@ class Executor: public CachingExecutor {
 		*/
 		template <Operation operation, AddressingMode addressing_mode> void perform();
 
+		void set_program_counter(uint16_t address);
+
 	private:
 		// MARK: - Instruction set state.
 
@@ -107,6 +109,7 @@ class Executor: public CachingExecutor {
 		uint8_t memory_[0x2000];
 
 		// Registers.
+		uint16_t program_counter_;
 		uint8_t a_, x_, y_;
 };