From 79b126e6bb0436d1130e7ea2a1d762012636cc44 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Fri, 10 Nov 2023 22:11:52 -0500
Subject: [PATCH] Add route for tracking segment register changes.

---
 .../Implementation/PerformImplementation.hpp  | 14 ++++++++++--
 InstructionSets/x86/Instruction.hpp           |  5 ++++-
 OSBindings/Mac/Clock SignalTests/8088Tests.mm | 22 +++++++++++++------
 3 files changed, 31 insertions(+), 10 deletions(-)

diff --git a/InstructionSets/x86/Implementation/PerformImplementation.hpp b/InstructionSets/x86/Implementation/PerformImplementation.hpp
index 1808366e4..26b42b168 100644
--- a/InstructionSets/x86/Implementation/PerformImplementation.hpp
+++ b/InstructionSets/x86/Implementation/PerformImplementation.hpp
@@ -253,7 +253,12 @@ template <
 		return;
 
 		case Operation::LEA:	Primitive::lea<IntT>(instruction, destination_w(), context);	return;
-		case Operation::MOV:	Primitive::mov<IntT>(destination_w(), source_r());				break;
+		case Operation::MOV:
+			Primitive::mov<IntT>(destination_w(), source_r());
+			if constexpr (std::is_same_v<IntT, uint16_t>) {
+				context.registers.did_update(instruction.destination.source());
+			}
+		break;
 
 		case Operation::JO:		jcc(context.flags.template condition<Condition::Overflow>());		return;
 		case Operation::JNO:	jcc(!context.flags.template condition<Condition::Overflow>());		return;
@@ -319,7 +324,12 @@ template <
 
 		case Operation::XLAT:	Primitive::xlat<AddressT>(instruction, context);		return;
 
-		case Operation::POP:	destination_w() = Primitive::pop<IntT, false>(context);	break;
+		case Operation::POP:
+			destination_w() = Primitive::pop<IntT, false>(context);
+			if constexpr (std::is_same_v<IntT, uint16_t>) {
+				context.registers.did_update(instruction.destination.source());
+			}
+		break;
 		case Operation::PUSH:
 			Primitive::push<IntT, false>(source_rmw(), context);	// PUSH SP modifies SP before pushing it;
 																	// hence PUSH is sometimes read-modify-write.
diff --git a/InstructionSets/x86/Instruction.hpp b/InstructionSets/x86/Instruction.hpp
index 589e6d330..4fc19a297 100644
--- a/InstructionSets/x86/Instruction.hpp
+++ b/InstructionSets/x86/Instruction.hpp
@@ -444,7 +444,7 @@ enum class Source: uint8_t {
 	T0 = 0, T1 = 1, T2 = 2, T3 = 3, T4 = 4, T5 = 5, T6 = 6, T7 = 7,
 	D0 = 0, D1 = 1, D2 = 2, D3 = 3, D4 = 4, D5 = 5, D6 = 6, D7 = 7,
 
-	// Selectors.
+	// Segment registers.
 	ES, CS, SS, DS, FS, GS,
 
 	/// @c None can be treated as a source that produces 0 when encountered;
@@ -473,6 +473,9 @@ enum class Source: uint8_t {
 constexpr bool is_register(Source source) {
 	return source < Source::None;
 }
+constexpr bool is_segment_register(Source source) {
+	return is_register(source) && source >= Source::ES;
+}
 
 enum class Repetition: uint8_t {
 	None, RepE, RepNE, Rep,
diff --git a/OSBindings/Mac/Clock SignalTests/8088Tests.mm b/OSBindings/Mac/Clock SignalTests/8088Tests.mm
index 0310acab2..0bd7a64c6 100644
--- a/OSBindings/Mac/Clock SignalTests/8088Tests.mm	
+++ b/OSBindings/Mac/Clock SignalTests/8088Tests.mm	
@@ -68,6 +68,7 @@ struct Registers {
 	uint16_t &di()	{	return di_;				}
 
 	uint16_t es_, cs_, ds_, ss_;
+	uint32_t es_base_, cs_base_, ds_base_, ss_base_;
 
 	uint16_t ip_;
 	uint16_t &ip()	{	return ip_;				}
@@ -77,6 +78,17 @@ struct Registers {
 	uint16_t &ds()	{	return ds_;				}
 	uint16_t &ss()	{	return ss_;				}
 
+	using Source = InstructionSet::x86::Source;
+	void did_update(Source segment) {
+		switch(segment) {
+			default: break;
+			case Source::ES:	es_base_ = es_ << 4;	break;
+			case Source::CS:	cs_base_ = cs_ << 4;	break;
+			case Source::DS:	ds_base_ = ds_ << 4;	break;
+			case Source::SS:	ss_base_ = ss_ << 4;	break;
+		}
+	}
+
 	bool operator ==(const Registers &rhs) const {
 		return
 			ax_.full == rhs.ax_.full &&
@@ -395,9 +407,9 @@ struct FailedExecution {
 	NSString *path = [NSString stringWithUTF8String:TestSuiteHome];
 	NSSet *allowList = [NSSet setWithArray:@[
 		// Current execution failures, albeit all permitted:
-		@"D4.json.gz",		// AAM
-		@"F6.7.json.gz",	// IDIV byte
-		@"F7.7.json.gz",	// IDIV word
+//		@"D4.json.gz",		// AAM
+//		@"F6.7.json.gz",	// IDIV byte
+//		@"F7.7.json.gz",	// IDIV word
 	]];
 
 	NSSet *ignoreList = nil;
@@ -694,10 +706,6 @@ struct FailedExecution {
 		failure_list = &permitted_failures;
 	}
 
-	if(failure_list == &execution_failures) {
-		printf("Fail: %d\n", int(decoded.second.operation()));
-	}
-
 	// Record a failure.
 	FailedExecution failure;
 	failure.instruction = decoded.second;