From ac6a9ab631a8c6ab34ac489f8e2bfd8e1426535b Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Fri, 6 May 2022 12:23:04 -0400
Subject: [PATCH] Fix TAS Dn.

---
 InstructionSets/M68k/Executor.hpp             |  2 +-
 .../Implementation/ExecutorImplementation.hpp | 21 ++++++++++++-------
 .../Implementation/PerformImplementation.hpp  |  2 +-
 .../68000ComparativeTests.mm                  |  5 ++++-
 4 files changed, 20 insertions(+), 10 deletions(-)

diff --git a/InstructionSets/M68k/Executor.hpp b/InstructionSets/M68k/Executor.hpp
index 7ee2b779e..c77ddecaf 100644
--- a/InstructionSets/M68k/Executor.hpp
+++ b/InstructionSets/M68k/Executor.hpp
@@ -54,7 +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);
+		void tas(Preinstruction instruction, 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 9271f7930..96ee3ba00 100644
--- a/InstructionSets/M68k/Implementation/ExecutorImplementation.hpp
+++ b/InstructionSets/M68k/Implementation/ExecutorImplementation.hpp
@@ -402,15 +402,22 @@ void Executor<model, BusHandler>::pea(uint32_t address) {
 }
 
 template <Model model, typename BusHandler>
-void Executor<model, BusHandler>::tas(uint32_t address) {
-	uint8_t value = bus_handler_.template read<uint8_t>(address);
+void Executor<model, BusHandler>::tas(Preinstruction instruction, uint32_t address) {
+	uint8_t original_value;
+	if(instruction.mode<0>() != AddressingMode::DataRegisterDirect) {
+		uint8_t value = bus_handler_.template read<uint8_t>(address);
+		original_value = value;
+		value |= 0x80;
+		bus_handler_.template write<uint8_t>(address, value);
+	} else {
+		original_value = uint8_t(address);
+		address |= 0x80;
+		registers_[instruction.reg<0>()].b = 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);
+	status_.zero_result_ = original_value;
+	status_.negative_flag_ = original_value & 0x80;
 }
 
 template <Model model, typename BusHandler>
diff --git a/InstructionSets/M68k/Implementation/PerformImplementation.hpp b/InstructionSets/M68k/Implementation/PerformImplementation.hpp
index 8494f9cfe..b227d264f 100644
--- a/InstructionSets/M68k/Implementation/PerformImplementation.hpp
+++ b/InstructionSets/M68k/Implementation/PerformImplementation.hpp
@@ -794,7 +794,7 @@ template <
 		*/
 
 		case Operation::TAS:
-			flow_controller.tas(src.l);
+			flow_controller.tas(instruction, src.l);
 		break;
 
 		/*
diff --git a/OSBindings/Mac/Clock SignalTests/68000ComparativeTests.mm b/OSBindings/Mac/Clock SignalTests/68000ComparativeTests.mm
index d61b5caed..8064e14b3 100644
--- a/OSBindings/Mac/Clock SignalTests/68000ComparativeTests.mm	
+++ b/OSBindings/Mac/Clock SignalTests/68000ComparativeTests.mm	
@@ -49,6 +49,9 @@
 //	mulu_muls
 //	neg_not
 //	negx_clr
+//	swap
+//	tas
+//	tst
 
 // Issues to fix:
 //
@@ -78,7 +81,7 @@
 
 - (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", @"tas.json"]];
+	_fileSet = [NSSet setWithArray:@[@"rts.json", @"rtr.json"]];
 //	_testSet = [NSSet setWithArray:@[@"NEGX 00c0"]];
 //	_fileSet = [NSSet setWithArray:@[@"jmp_jsr.json"]];
 //	_testSet = [NSSet setWithArray:@[@"CHK 41a8"]];