From 62fa0991eda8191824e1366a9d5da4436f86dabd Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Wed, 15 Jun 2022 12:59:03 -0400
Subject: [PATCH 1/4] Disallow copying, add some basic asserts.

---
 Processors/68000Mk2/68000Mk2.hpp                              | 2 ++
 Processors/68000Mk2/Implementation/68000Mk2Implementation.hpp | 2 ++
 Processors/68000Mk2/Implementation/68000Mk2Storage.hpp        | 2 ++
 3 files changed, 6 insertions(+)

diff --git a/Processors/68000Mk2/68000Mk2.hpp b/Processors/68000Mk2/68000Mk2.hpp
index 5defa8eac..b3f4617af 100644
--- a/Processors/68000Mk2/68000Mk2.hpp
+++ b/Processors/68000Mk2/68000Mk2.hpp
@@ -394,6 +394,8 @@ template <class BusHandler, bool dtack_is_implicit = true, bool permit_overrun =
 class Processor: private ProcessorBase {
 	public:
 		Processor(BusHandler &bus_handler) : ProcessorBase(), bus_handler_(bus_handler) {}
+		Processor(const Processor& rhs) = delete;
+		Processor& operator=(const Processor& rhs) = delete;
 
 		void run_for(HalfCycles duration);
 
diff --git a/Processors/68000Mk2/Implementation/68000Mk2Implementation.hpp b/Processors/68000Mk2/Implementation/68000Mk2Implementation.hpp
index f26df65c8..2134522b2 100644
--- a/Processors/68000Mk2/Implementation/68000Mk2Implementation.hpp
+++ b/Processors/68000Mk2/Implementation/68000Mk2Implementation.hpp
@@ -1091,6 +1091,7 @@ void Processor<BusHandler, dtack_is_implicit, permit_overrun, signal_will_perfor
 			//	(i) this operand isn't used; or
 			//	(ii) its address calculation will end up conflated with performance,
 			//		so there's no generic bus-accurate approach.
+			assert(next_operand_ >= 0 && next_operand_ < 2);
 			if(!(operand_flags_ & (1 << next_operand_))) {
 				MoveToStateDynamic(perform_state_);
 			}
@@ -1099,6 +1100,7 @@ void Processor<BusHandler, dtack_is_implicit, permit_overrun, signal_will_perfor
 
 		// As above, but for .l.
 		BeginState(FetchOperand_l):
+			assert(next_operand_ >= 0 && next_operand_ < 2);
 			if(!(operand_flags_ & (1 << next_operand_))) {
 				MoveToStateDynamic(perform_state_);
 			}
diff --git a/Processors/68000Mk2/Implementation/68000Mk2Storage.hpp b/Processors/68000Mk2/Implementation/68000Mk2Storage.hpp
index 243c0c86b..95e0a7662 100644
--- a/Processors/68000Mk2/Implementation/68000Mk2Storage.hpp
+++ b/Processors/68000Mk2/Implementation/68000Mk2Storage.hpp
@@ -22,6 +22,8 @@ struct ProcessorBase: public InstructionSet::M68k::NullFlowController {
 	ProcessorBase() {
 		read_program_announce.address = read_program.address = &program_counter_.l;
 	}
+	ProcessorBase(const ProcessorBase& rhs) = delete;
+	ProcessorBase& operator=(const ProcessorBase& rhs) = delete;
 
 	int state_ = std::numeric_limits<int>::min();
 

From 8ff09a1923cebcc76ab13cb2a570f2423cd970d9 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Wed, 15 Jun 2022 17:06:40 -0400
Subject: [PATCH 2/4] Fix `value8_high`.

---
 Processors/68000Mk2/68000Mk2.hpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Processors/68000Mk2/68000Mk2.hpp b/Processors/68000Mk2/68000Mk2.hpp
index b3f4617af..fafba7f79 100644
--- a/Processors/68000Mk2/68000Mk2.hpp
+++ b/Processors/68000Mk2/68000Mk2.hpp
@@ -233,7 +233,7 @@ struct Microcycle {
 		@c 0xff otherwise. Assumes this is a write cycle.
 	*/
 	forceinline uint8_t value8_high() const {
-		const uint8_t values[] = { uint8_t(value->w), value->b};
+		const uint8_t values[] = { uint8_t(value->w >> 8), value->b};
 		return values[operation & SelectByte];
 	}
 

From 12b058867eb7d2c4b68e54aab6104f3d8c8770f5 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Wed, 15 Jun 2022 17:06:56 -0400
Subject: [PATCH 3/4] Correct very minor typo.

---
 Processors/68000Mk2/Implementation/68000Mk2Implementation.hpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Processors/68000Mk2/Implementation/68000Mk2Implementation.hpp b/Processors/68000Mk2/Implementation/68000Mk2Implementation.hpp
index 2134522b2..9eef84cee 100644
--- a/Processors/68000Mk2/Implementation/68000Mk2Implementation.hpp
+++ b/Processors/68000Mk2/Implementation/68000Mk2Implementation.hpp
@@ -1185,7 +1185,7 @@ void Processor<BusHandler, dtack_is_implicit, permit_overrun, signal_will_perfor
 
 			Access(operand_[next_operand_].high);	// nW
 			effective_address_[1].l += 2;
-			Access(operand_[next_operand_].low);	// nW
+			Access(operand_[next_operand_].low);	// nw
 
 			Prefetch();								// np
 		MoveToStateSpecific(Decode);

From 7d00b50e13eb12e431b10ed5aeedb457666449c6 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Wed, 15 Jun 2022 21:11:31 -0400
Subject: [PATCH 4/4] Fix upper/lower_data_select; simplify value8_low.

---
 Processors/68000Mk2/68000Mk2.hpp | 17 +++++++----------
 1 file changed, 7 insertions(+), 10 deletions(-)

diff --git a/Processors/68000Mk2/68000Mk2.hpp b/Processors/68000Mk2/68000Mk2.hpp
index fafba7f79..3e43de1b8 100644
--- a/Processors/68000Mk2/68000Mk2.hpp
+++ b/Processors/68000Mk2/68000Mk2.hpp
@@ -175,17 +175,17 @@ struct Microcycle {
 	}
 
 	/*!
-		@returns non-zero if this is a byte read and 68000 LDS is asserted.
+		@returns non-zero if the 68000 LDS is asserted; zero otherwise.
 	*/
 	forceinline int lower_data_select() const {
-		return (operation & SelectByte) & ((*address & 1) << 3);
+		return ((operation & SelectByte) & (*address & 1)) | (operation & SelectWord);
 	}
 
 	/*!
-		@returns non-zero if this is a byte read and 68000 UDS is asserted.
+		@returns non-zero if the 68000 UDS is asserted; zero otherwise.
 	*/
 	forceinline int upper_data_select() const {
-		return (operation & SelectByte) & ~((*address & 1) << 3);
+		return ((operation & SelectByte) & ~(*address & 1)) | (operation & SelectWord);
 	}
 
 	/*!
@@ -229,8 +229,7 @@ struct Microcycle {
 	}
 
 	/*!
-		@returns the value currently on the high 8 lines of the data bus if any;
-		@c 0xff otherwise. Assumes this is a write cycle.
+		@returns the value currently on the high 8 lines of the data bus.
 	*/
 	forceinline uint8_t value8_high() const {
 		const uint8_t values[] = { uint8_t(value->w >> 8), value->b};
@@ -238,12 +237,10 @@ struct Microcycle {
 	}
 
 	/*!
-		@returns the value currently on the low 8 lines of the data bus if any;
-		@c 0xff otherwise. Assumes this is a write cycle.
+		@returns the value currently on the low 8 lines of the data bus.
 	*/
 	forceinline uint8_t value8_low() const {
-		const uint8_t values[] = { uint8_t(value->w), value->b};
-		return values[operation & SelectByte];
+		return value->b;
 	}
 
 	/*!