From 8176bb6f798a8fbccc266644c02a141dff99a3f6 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Fri, 6 May 2022 12:18:56 -0400
Subject: [PATCH] Expose issues with TST and TAS.

---
 InstructionSets/M68k/Executor.hpp                    |  1 +
 .../M68k/Implementation/ExecutorImplementation.hpp   | 12 ++++++++++++
 .../M68k/Implementation/PerformImplementation.hpp    |  7 ++-----
 InstructionSets/M68k/Instruction.hpp                 |  2 ++
 .../Mac/Clock SignalTests/68000ComparativeTests.mm   |  2 +-
 5 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/InstructionSets/M68k/Executor.hpp b/InstructionSets/M68k/Executor.hpp
index 38ba641dc..7ee2b779e 100644
--- a/InstructionSets/M68k/Executor.hpp
+++ b/InstructionSets/M68k/Executor.hpp
@@ -54,6 +54,7 @@ template <Model model, typename BusHandler> class Executor {
 		template <typename IntT> void movem_toM(Preinstruction instruction, uint32_t source, uint32_t dest);
 		template <typename IntT> void movem_toR(Preinstruction instruction, uint32_t source, uint32_t dest);
 		void pea(uint32_t address);
+		void tas(uint32_t address);
 
 		// TODO: ownership of this shouldn't be here.
 		struct Registers {
diff --git a/InstructionSets/M68k/Implementation/ExecutorImplementation.hpp b/InstructionSets/M68k/Implementation/ExecutorImplementation.hpp
index 727c79123..9271f7930 100644
--- a/InstructionSets/M68k/Implementation/ExecutorImplementation.hpp
+++ b/InstructionSets/M68k/Implementation/ExecutorImplementation.hpp
@@ -401,6 +401,18 @@ void Executor<model, BusHandler>::pea(uint32_t address) {
 	bus_handler_.template write<uint32_t>(sp().l, address);
 }
 
+template <Model model, typename BusHandler>
+void Executor<model, BusHandler>::tas(uint32_t address) {
+	uint8_t value = bus_handler_.template read<uint8_t>(address);
+
+	status_.overflow_flag_ = status_.carry_flag_ = 0;
+	status_.zero_result_ = value;
+	status_.negative_flag_ = value & 0x80;
+	value |= 0x80;
+
+	bus_handler_.template write<uint8_t>(address, value);
+}
+
 template <Model model, typename BusHandler>
 template <typename IntT>
 void Executor<model, BusHandler>::movep(Preinstruction instruction, uint32_t source, uint32_t dest) {
diff --git a/InstructionSets/M68k/Implementation/PerformImplementation.hpp b/InstructionSets/M68k/Implementation/PerformImplementation.hpp
index abb344b88..8494f9cfe 100644
--- a/InstructionSets/M68k/Implementation/PerformImplementation.hpp
+++ b/InstructionSets/M68k/Implementation/PerformImplementation.hpp
@@ -790,14 +790,11 @@ template <
 
 		/*
 			TAS: sets zero and negative depending on the current value of the destination,
-			and sets the high bit.
+			and sets the high bit, using a specialised atomic bus cycle.
 		*/
 
 		case Operation::TAS:
-			status.overflow_flag_ = status.carry_flag_ = 0;
-			status.zero_result_ = dest.b;
-			status.negative_flag_ = dest.b & 0x80;
-			dest.b |= 0x80;
+			flow_controller.tas(src.l);
 		break;
 
 		/*
diff --git a/InstructionSets/M68k/Instruction.hpp b/InstructionSets/M68k/Instruction.hpp
index 40a72272d..d04dc373d 100644
--- a/InstructionSets/M68k/Instruction.hpp
+++ b/InstructionSets/M68k/Instruction.hpp
@@ -275,6 +275,7 @@ template <Model model, Operation t_operation = Operation::Undefined> uint8_t ope
 		case Operation::MOVEPw:		case Operation::MOVEPl:
 		case Operation::MOVEMtoMw:	case Operation::MOVEMtoMl:
 		case Operation::MOVEMtoRw:	case Operation::MOVEMtoRl:
+		case Operation::TAS:
 			return 0;
 
 		//
@@ -286,6 +287,7 @@ template <Model model, Operation t_operation = Operation::Undefined> uint8_t ope
 		case Operation::EORItoSR:	case Operation::EORItoCCR:
 		case Operation::Bccb:		case Operation::Bccw:		case Operation::Bccl:
 		case Operation::BSRb:		case Operation::BSRw:		case Operation::BSRl:
+		case Operation::TSTb:		case Operation::TSTw:		case Operation::TSTl:
 			return FetchOp1;
 
 		//
diff --git a/OSBindings/Mac/Clock SignalTests/68000ComparativeTests.mm b/OSBindings/Mac/Clock SignalTests/68000ComparativeTests.mm
index aa727fbd1..d61b5caed 100644
--- a/OSBindings/Mac/Clock SignalTests/68000ComparativeTests.mm	
+++ b/OSBindings/Mac/Clock SignalTests/68000ComparativeTests.mm	
@@ -78,7 +78,7 @@
 
 - (void)setUp {
 	// To limit tests run to a subset of files and/or of tests, uncomment and fill in below.
-	_fileSet = [NSSet setWithArray:@[@"swap.json", @"tst.json"]];
+	_fileSet = [NSSet setWithArray:@[@"swap.json", @"tst.json", @"tas.json"]];
 //	_testSet = [NSSet setWithArray:@[@"NEGX 00c0"]];
 //	_fileSet = [NSSet setWithArray:@[@"jmp_jsr.json"]];
 //	_testSet = [NSSet setWithArray:@[@"CHK 41a8"]];