From 9538491ee908bae75d288e9c73f4e97a382d2979 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Tue, 31 Oct 2023 21:55:22 -0400
Subject: [PATCH] Fix pushes and pops.

---
 .../Implementation/PerformImplementation.hpp  | 34 ++++++++++---------
 OSBindings/Mac/Clock SignalTests/8088Tests.mm |  4 ++-
 2 files changed, 21 insertions(+), 17 deletions(-)

diff --git a/InstructionSets/x86/Implementation/PerformImplementation.hpp b/InstructionSets/x86/Implementation/PerformImplementation.hpp
index 1e77aba08..3e24922b0 100644
--- a/InstructionSets/x86/Implementation/PerformImplementation.hpp
+++ b/InstructionSets/x86/Implementation/PerformImplementation.hpp
@@ -193,18 +193,18 @@ namespace Primitive {
 
 // The below takes a reference in order properly to handle PUSH SP, which should place the value of SP after the
 // push onto the stack.
-template <typename IntT, typename MemoryT, typename RegistersT>
+template <typename IntT, bool preauthorised, typename MemoryT, typename RegistersT>
 void push(IntT &value, MemoryT &memory, RegistersT &registers) {
 	registers.sp_ -= sizeof(IntT);
-	memory.template access<IntT, AccessType::Write>(
+	memory.template access<IntT, preauthorised ? AccessType::PreAuthorised : AccessType::Write>(
 		InstructionSet::x86::Source::SS,
 		registers.sp_) = value;
 	memory.template write_back<IntT>();
 }
 
-template <typename IntT, typename MemoryT, typename RegistersT>
+template <typename IntT, bool preauthorised, typename MemoryT, typename RegistersT>
 IntT pop(MemoryT &memory, RegistersT &registers) {
-	const auto value = memory.template access<IntT, AccessType::Write>(
+	const auto value = memory.template access<IntT, preauthorised ? AccessType::PreAuthorised : AccessType::Read>(
 		InstructionSet::x86::Source::SS,
 		registers.sp_);
 	registers.sp_ += sizeof(IntT);
@@ -903,23 +903,25 @@ void jump_far(InstructionT &instruction,
 template <typename FlowControllerT, typename RegistersT, typename MemoryT>
 void iret(RegistersT &registers, FlowControllerT &flow_controller, MemoryT &memory, Status &status) {
 	// TODO: all modes other than 16-bit real mode.
-	registers.ip() = pop<uint16_t>(memory, registers);
-	registers.cs() = pop<uint16_t>(memory, registers);
-	status.set(pop<uint16_t>(memory, registers));
+	memory.preauthorise_stack(sizeof(uint16_t) * 3);
+	registers.ip() = pop<uint16_t, true>(memory, registers);
+	registers.cs() = pop<uint16_t, true>(memory, registers);
+	status.set(pop<uint16_t, true>(memory, registers));
 	flow_controller.did_iret();
 }
 
 template <typename InstructionT, typename FlowControllerT, typename RegistersT, typename MemoryT>
 void ret_near(InstructionT instruction, RegistersT &registers, FlowControllerT &flow_controller, MemoryT &memory) {
-	registers.ip() = pop<uint16_t>(memory, registers);
+	registers.ip() = pop<uint16_t, false>(memory, registers);
 	registers.sp() += instruction.operand();
 	flow_controller.did_near_ret();
 }
 
 template <typename InstructionT, typename FlowControllerT, typename RegistersT, typename MemoryT>
 void ret_far(InstructionT instruction, RegistersT &registers, FlowControllerT &flow_controller, MemoryT &memory) {
-	registers.ip() = pop<uint16_t>(memory, registers);
-	registers.cs() = pop<uint16_t>(memory, registers);
+	memory.preauthorise_stack(sizeof(uint16_t) * 2);
+	registers.ip() = pop<uint16_t, true>(memory, registers);
+	registers.cs() = pop<uint16_t, true>(memory, registers);
 	registers.sp() += instruction.operand();
 	flow_controller.did_far_ret();
 }
@@ -1368,13 +1370,13 @@ inline void shr(IntT &destination, uint8_t count, Status &status) {
 
 template <typename MemoryT, typename RegistersT>
 void popf(MemoryT &memory, RegistersT &registers, Status &status) {
-	status.set(pop<uint16_t>(memory, registers));
+	status.set(pop<uint16_t, false>(memory, registers));
 }
 
 template <typename MemoryT, typename RegistersT>
 void pushf(MemoryT &memory, RegistersT &registers, Status &status) {
 	uint16_t value = status.get();
-	push<uint16_t>(value, memory, registers);
+	push<uint16_t, false>(value, memory, registers);
 }
 
 template <typename AddressT, Repetition repetition>
@@ -1785,10 +1787,10 @@ template <
 
 		case Operation::XLAT:	Primitive::xlat<AddressT>(instruction, memory, registers);	return;
 
-		case Operation::POP:	destination_w() = Primitive::pop<IntT>(memory, registers);	break;
-		case Operation::PUSH:	Primitive::push<IntT>(source_r(), memory, registers);		break;
-		case Operation::POPF:	Primitive::popf(memory, registers, status);					break;
-		case Operation::PUSHF:	Primitive::pushf(memory, registers, status);				break;
+		case Operation::POP:	destination_w() = Primitive::pop<IntT, false>(memory, registers);	break;
+		case Operation::PUSH:	Primitive::push<IntT, false>(source_r(), memory, registers);		break;
+		case Operation::POPF:	Primitive::popf(memory, registers, status);							break;
+		case Operation::PUSHF:	Primitive::pushf(memory, registers, status);						break;
 
 		case Operation::CMPS:
 			Primitive::cmps<IntT, AddressT, Repetition::None>(instruction, eCX(), eSI(), eDI(), memory, status, flow_controller);
diff --git a/OSBindings/Mac/Clock SignalTests/8088Tests.mm b/OSBindings/Mac/Clock SignalTests/8088Tests.mm
index 440f7c29d..7abe43f10 100644
--- a/OSBindings/Mac/Clock SignalTests/8088Tests.mm	
+++ b/OSBindings/Mac/Clock SignalTests/8088Tests.mm	
@@ -25,7 +25,7 @@ namespace {
 
 // The tests themselves are not duplicated in this repository;
 // provide their real path here.
-constexpr char TestSuiteHome[] = "/Users/thomasharte/Projects/ProcessorTests/8088/v1";
+constexpr char TestSuiteHome[] = "/Users/tharte/Projects/ProcessorTests/8088/v1";
 
 using Status = InstructionSet::x86::Status;
 struct Registers {
@@ -133,6 +133,8 @@ struct Memory {
 		return physical_address << 4;
 	}
 
+	void preauthorise_stack(uint32_t) {}
+
 	// Entry point used by the flow controller so that it can mark up locations at which the flags were written,
 	// so that defined-flag-only masks can be applied while verifying RAM contents.
 	template <typename IntT, AccessType type> IntT &access(InstructionSet::x86::Source segment, uint16_t address, Tag tag) {