From 096add7551e6a16e6b96d5eb7acb0a124e323716 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Fri, 16 Oct 2020 21:05:42 -0400
Subject: [PATCH] Exposes non-BusOperation bus outputs.

---
 Processors/65816/65816.hpp                     | 18 +++++++++++++++++-
 .../Implementation/65816Implementation.hpp     | 17 +++++++++++++++++
 .../65816/Implementation/65816Storage.cpp      |  2 ++
 .../65816/Implementation/65816Storage.hpp      |  4 ++++
 4 files changed, 40 insertions(+), 1 deletion(-)

diff --git a/Processors/65816/65816.hpp b/Processors/65816/65816.hpp
index 3c168ac80..503b65e44 100644
--- a/Processors/65816/65816.hpp
+++ b/Processors/65816/65816.hpp
@@ -25,6 +25,13 @@ using BusOperation = CPU::MOS6502Esque::BusOperation;
 using Register = CPU::MOS6502Esque::Register;
 using Flag = CPU::MOS6502Esque::Flag;
 
+enum ExtendedBusOutput {
+	Emulation = (1 << 0),
+	MemorySize = (1 << 1),
+	IndexSize = (1 << 2),
+	MemoryLock = (1 << 3),
+};
+
 #include "Implementation/65816Storage.hpp"
 
 class ProcessorBase: protected ProcessorStorage {
@@ -35,9 +42,18 @@ class ProcessorBase: protected ProcessorStorage {
 		inline void set_reset_line(bool);
 		inline void set_abort_line(bool);
 		inline bool get_is_resetting() const;
-		void set_value_of_register(Register r, uint16_t value);
 
+		/*!
+			Returns the current state of all lines not ordinarily pushed to the BusHandler.
+		*/
+		inline int get_extended_bus_output();
+
+		/*!
+			Provided for symmetry with the 6502; a 65816 is never jammed.
+		*/
 		inline bool is_jammed() const;
+
+		void set_value_of_register(Register r, uint16_t value);
 		uint16_t get_value_of_register(Register r) const;
 };
 
diff --git a/Processors/65816/Implementation/65816Implementation.hpp b/Processors/65816/Implementation/65816Implementation.hpp
index 10df709d6..c536ea818 100644
--- a/Processors/65816/Implementation/65816Implementation.hpp
+++ b/Processors/65816/Implementation/65816Implementation.hpp
@@ -55,6 +55,7 @@ template <typename BusHandler, bool uses_ready_line> void Processor<BusHandler,
 					instruction_buffer_.clear();
 					data_buffer_.clear();
 					last_operation_pc_ = registers_.pc;
+					memory_lock_ = false;
 				} continue;
 
 				case OperationDecode: {
@@ -176,6 +177,14 @@ template <typename BusHandler, bool uses_ready_line> void Processor<BusHandler,
 
 #undef stack_access
 
+				//
+				// Memory lock control.
+				//
+
+				case OperationSetMemoryLock:
+					memory_lock_ = true;
+				continue;
+
 				//
 				// STP and WAI.
 				//
@@ -985,3 +994,11 @@ bool ProcessorBase::is_jammed() const { return false; }
 bool ProcessorBase::get_is_resetting() const {
 	return pending_exceptions_ & (Reset | PowerOn);
 }
+
+int ProcessorBase::get_extended_bus_output() {
+	return
+		(memory_lock_ ? ExtendedBusOutput::MemoryLock : 0) |
+		(registers_.mx_flags[0] ? ExtendedBusOutput::MemorySize : 0) |
+		(registers_.mx_flags[1] ? ExtendedBusOutput::IndexSize : 0) |
+		(registers_.emulation_flag ? ExtendedBusOutput::Emulation : 0);
+}
diff --git a/Processors/65816/Implementation/65816Storage.cpp b/Processors/65816/Implementation/65816Storage.cpp
index 593801914..796a65b3f 100644
--- a/Processors/65816/Implementation/65816Storage.cpp
+++ b/Processors/65816/Implementation/65816Storage.cpp
@@ -156,6 +156,8 @@ struct CPU::WDC65816::ProcessorStorageConstructor {
 	}
 
 	static void read_modify_write(bool is8bit, const std::function<void(MicroOp)> &target) {
+		target(OperationSetMemoryLock);
+
 		if(!is8bit)	target(CycleFetchIncrementData);	// Data low.
 		target(CycleFetchData);							// Data [high].
 
diff --git a/Processors/65816/Implementation/65816Storage.hpp b/Processors/65816/Implementation/65816Storage.hpp
index 0e7eba2b9..4bc731372 100644
--- a/Processors/65816/Implementation/65816Storage.hpp
+++ b/Processors/65816/Implementation/65816Storage.hpp
@@ -149,6 +149,9 @@ enum MicroOp: uint8_t {
 	/// address register.
 	OperationPrepareException,
 
+	/// Sets the memory lock output for the rest of this instruction.
+	OperationSetMemoryLock,
+
 	/// Complete this set of micr-ops.
 	OperationMoveToNextProgram,
 
@@ -289,6 +292,7 @@ struct ProcessorStorage {
 	int selected_exceptions_ = 0;
 
 	bool ready_line_ = false;
+	bool memory_lock_ = false;
 
 	// Just to be safe.
 	static_assert(PowerOn != IRQ);