From 033ba75376f8cda99cd35cf7ef55b7555f5cdab7 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Wed, 11 Oct 2023 11:15:59 -0400
Subject: [PATCH] Standardise repetitive sign/zero/parity sets.

---
 .../Implementation/PerformImplementation.hpp  | 74 ++++++++-----------
 InstructionSets/x86/Status.hpp                | 57 ++++++++------
 2 files changed, 67 insertions(+), 64 deletions(-)

diff --git a/InstructionSets/x86/Implementation/PerformImplementation.hpp b/InstructionSets/x86/Implementation/PerformImplementation.hpp
index 59be6a9a3..8b06a4444 100644
--- a/InstructionSets/x86/Implementation/PerformImplementation.hpp
+++ b/InstructionSets/x86/Implementation/PerformImplementation.hpp
@@ -198,8 +198,7 @@ inline void aad(CPU::RegisterPair16 &ax, uint8_t imm, Status &status) {
 	*/
 	ax.halves.low = ax.halves.low + (ax.halves.high * imm);
 	ax.halves.high = 0;
-	status.sign = ax.halves.low & 0x80;
-	status.parity = status.zero = ax.halves.low;
+	status.set_from<uint8_t, Flag::Zero, Flag::Sign, Flag::ParityOdd>(ax.halves.low);
 }
 
 template <typename FlowControllerT>
@@ -223,8 +222,7 @@ inline void aam(CPU::RegisterPair16 &ax, uint8_t imm, Status &status, FlowContro
 
 	ax.halves.high = ax.halves.low / imm;
 	ax.halves.low = ax.halves.low % imm;
-	status.sign = ax.halves.low & 0x80;
-	status.parity = status.zero = ax.halves.low;
+	status.set_from<uint8_t, Flag::Zero, Flag::Sign, Flag::ParityOdd>(ax.halves.low);
 }
 
 inline void aas(CPU::RegisterPair16 &ax, Status &status) {
@@ -303,8 +301,7 @@ inline void daa(uint8_t &al, Status &status) {
 		status.carry = 0;
 	}
 
-	status.sign = al & 0x80;
-	status.zero = status.parity = al;
+	status.set_from<uint8_t, Flag::Zero, Flag::Sign, Flag::ParityOdd>(al);
 }
 
 inline void das(uint8_t &al, Status &status) {
@@ -355,8 +352,7 @@ inline void das(uint8_t &al, Status &status) {
 		status.carry = 0;
 	}
 
-	status.sign = al & 0x80;
-	status.zero = status.parity = al;
+	status.set_from<uint8_t, Flag::Zero, Flag::Sign, Flag::ParityOdd>(al);
 }
 
 template <bool with_carry, typename IntT>
@@ -371,10 +367,10 @@ void add(IntT &destination, IntT source, Status &status) {
 
 	status.carry = Numeric::carried_out<true, Numeric::bit_size<IntT>() - 1>(destination, source, result);
 	status.auxiliary_carry = Numeric::carried_in<4>(destination, source, result);
-	status.sign = result & Numeric::top_bit<IntT>();
-	status.zero = status.parity = result;
 	status.overflow = Numeric::overflow<true, IntT>(destination, source, result);
 
+	status.set_from<IntT, Flag::Zero, Flag::Sign, Flag::ParityOdd>(result);
+
 	destination = result;
 }
 
@@ -390,10 +386,10 @@ void sub(IntT &destination, IntT source, Status &status) {
 
 	status.carry = Numeric::carried_out<false, Numeric::bit_size<IntT>() - 1>(destination, source, result);
 	status.auxiliary_carry = Numeric::carried_in<4>(destination, source, result);
-	status.sign = result & Numeric::top_bit<IntT>();
-	status.zero = status.parity = result;
 	status.overflow = Numeric::overflow<false, IntT>(destination, source, result);
 
+	status.set_from<IntT, Flag::Zero, Flag::Sign, Flag::ParityOdd>(result);
+
 	if constexpr (write_back) {
 		destination = result;
 	}
@@ -419,10 +415,8 @@ void test(IntT &destination, IntT source, Status &status) {
 	*/
 	const IntT result = destination & source;
 
-	status.sign = result & Numeric::top_bit<IntT>();
-	status.zero = result;
 	status.carry = status.overflow = 0;
-	status.parity = result;
+	status.set_from<IntT, Flag::Zero, Flag::Sign, Flag::ParityOdd>(result);
 }
 
 template <typename IntT>
@@ -617,9 +611,8 @@ void inc(IntT &destination, Status &status) {
 	++destination;
 
 	status.overflow = destination == Numeric::top_bit<IntT>();
-	status.sign = destination & Numeric::top_bit<IntT>();
-	status.zero = status.parity = destination;
 	status.auxiliary_carry = ((destination - 1) ^ destination) & 0x10;
+	status.set_from<IntT, Flag::Zero, Flag::Sign, Flag::ParityOdd>(destination);
 }
 
 template <typename IntT, typename RegistersT, typename FlowControllerT>
@@ -654,8 +647,7 @@ void dec(IntT &destination, Status &status) {
 
 	--destination;
 
-	status.sign = destination & Numeric::top_bit<IntT>();
-	status.zero = status.parity = destination;
+	status.set_from<IntT, Flag::Zero, Flag::Sign, Flag::ParityOdd>(destination);
 	status.auxiliary_carry = ((destination + 1) ^ destination) & 0x10;
 }
 
@@ -672,8 +664,7 @@ void and_(IntT &destination, IntT source, Status &status) {
 
 	status.overflow = 0;
 	status.carry = 0;
-	status.sign = destination & Numeric::top_bit<IntT>();
-	status.zero = status.parity = destination;
+	status.set_from<IntT, Flag::Zero, Flag::Sign, Flag::ParityOdd>(destination);
 }
 
 template <typename IntT>
@@ -689,8 +680,7 @@ void or_(IntT &destination, IntT source, Status &status) {
 
 	status.overflow = 0;
 	status.carry = 0;
-	status.sign = destination & Numeric::top_bit<IntT>();
-	status.zero = status.parity = destination;
+	status.set_from<IntT, Flag::Zero, Flag::Sign, Flag::ParityOdd>(destination);
 }
 
 template <typename IntT>
@@ -706,8 +696,7 @@ void xor_(IntT &destination, IntT source, Status &status) {
 
 	status.overflow = 0;
 	status.carry = 0;
-	status.sign = destination & Numeric::top_bit<IntT>();
-	status.zero = status.parity = destination;
+	status.set_from<IntT, Flag::Zero, Flag::Sign, Flag::ParityOdd>(destination);
 }
 
 template <typename IntT>
@@ -729,8 +718,7 @@ void neg(IntT &destination, Status &status) {
 
 	status.carry = destination;
 	status.overflow = destination == Numeric::top_bit<IntT>();
-	status.sign = destination & Numeric::top_bit<IntT>();
-	status.zero = status.parity = destination;
+	status.set_from<IntT, Flag::Zero, Flag::Sign, Flag::ParityOdd>(destination);
 }
 
 template <typename IntT>
@@ -958,112 +946,112 @@ template <
 
 		case Operation::JO:
 			Primitive::jump(
-				status.condition<Status::Condition::Overflow>(),
+				status.condition<Condition::Overflow>(),
 				instruction.displacement(),
 				registers,
 				flow_controller);
 		return;
 		case Operation::JNO:
 			Primitive::jump(
-				!status.condition<Status::Condition::Overflow>(),
+				!status.condition<Condition::Overflow>(),
 				instruction.displacement(),
 				registers,
 				flow_controller);
 		return;
 		case Operation::JB:
 			Primitive::jump(
-				status.condition<Status::Condition::Below>(),
+				status.condition<Condition::Below>(),
 				instruction.displacement(),
 				registers,
 				flow_controller);
 		return;
 		case Operation::JNB:
 			Primitive::jump(
-				!status.condition<Status::Condition::Below>(),
+				!status.condition<Condition::Below>(),
 				instruction.displacement(),
 				registers,
 				flow_controller);
 		return;
 		case Operation::JZ:
 			Primitive::jump(
-				status.condition<Status::Condition::Zero>(),
+				status.condition<Condition::Zero>(),
 				instruction.displacement(),
 				registers,
 				flow_controller);
 		return;
 		case Operation::JNZ:
 			Primitive::jump(
-				!status.condition<Status::Condition::Zero>(),
+				!status.condition<Condition::Zero>(),
 				instruction.displacement(),
 				registers,
 				flow_controller);
 		return;
 		case Operation::JBE:
 			Primitive::jump(
-				status.condition<Status::Condition::BelowOrEqual>(),
+				status.condition<Condition::BelowOrEqual>(),
 				instruction.displacement(),
 				registers,
 				flow_controller);
 		return;
 		case Operation::JNBE:
 			Primitive::jump(
-				!status.condition<Status::Condition::BelowOrEqual>(),
+				!status.condition<Condition::BelowOrEqual>(),
 				instruction.displacement(),
 				registers,
 				flow_controller);
 		return;
 		case Operation::JS:
 			Primitive::jump(
-				status.condition<Status::Condition::Sign>(),
+				status.condition<Condition::Sign>(),
 				instruction.displacement(),
 				registers,
 				flow_controller);
 		return;
 		case Operation::JNS:
 			Primitive::jump(
-				!status.condition<Status::Condition::Sign>(),
+				!status.condition<Condition::Sign>(),
 				instruction.displacement(),
 				registers,
 				flow_controller);
 		return;
 		case Operation::JP:
 			Primitive::jump(
-				!status.condition<Status::Condition::ParityOdd>(),
+				!status.condition<Condition::ParityOdd>(),
 				instruction.displacement(),
 				registers,
 				flow_controller);
 		return;
 		case Operation::JNP:
 			Primitive::jump(
-				status.condition<Status::Condition::ParityOdd>(),
+				status.condition<Condition::ParityOdd>(),
 				instruction.displacement(),
 				registers,
 				flow_controller);
 		return;
 		case Operation::JL:
 			Primitive::jump(
-				status.condition<Status::Condition::Less>(),
+				status.condition<Condition::Less>(),
 				instruction.displacement(),
 				registers,
 				flow_controller);
 		return;
 		case Operation::JNL:
 			Primitive::jump(
-				!status.condition<Status::Condition::Less>(),
+				!status.condition<Condition::Less>(),
 				instruction.displacement(),
 				registers,
 				flow_controller);
 		return;
 		case Operation::JLE:
 			Primitive::jump(
-				status.condition<Status::Condition::LessOrEqual>(),
+				status.condition<Condition::LessOrEqual>(),
 				instruction.displacement(),
 				registers,
 				flow_controller);
 		return;
 		case Operation::JNLE:
 			Primitive::jump(
-				!status.condition<Status::Condition::LessOrEqual>(),
+				!status.condition<Condition::LessOrEqual>(),
 				instruction.displacement(),
 				registers,
 				flow_controller);
diff --git a/InstructionSets/x86/Status.hpp b/InstructionSets/x86/Status.hpp
index a678f1603..20907c181 100644
--- a/InstructionSets/x86/Status.hpp
+++ b/InstructionSets/x86/Status.hpp
@@ -9,6 +9,7 @@
 #ifndef InstructionSets_x86_Status_hpp
 #define InstructionSets_x86_Status_hpp
 
+#include "../../Numeric/Carry.hpp"
 
 namespace InstructionSet::x86 {
 
@@ -53,6 +54,29 @@ static constexpr uint32_t VirtualMode		= 1 << 17;
 
 }
 
+enum class Flag {
+	Carry,
+	AuxiliaryCarry,
+	Sign,
+	Overflow,
+	Trap,
+	Interrupt,
+	Direction,
+	Zero,
+	ParityOdd
+};
+
+enum class Condition {
+	Overflow,
+	Below,
+	Zero,
+	BelowOrEqual,
+	Sign,
+	ParityOdd,
+	Less,
+	LessOrEqual
+};
+
 struct Status {
 	// Non-zero => set; zero => unset.
 	uint32_t carry;
@@ -70,17 +94,6 @@ struct Status {
 	uint32_t parity;
 
 	// Flag getters.
-	enum class Flag {
-		Carry,
-		AuxiliaryCarry,
-		Sign,
-		Overflow,
-		Trap,
-		Interrupt,
-		Direction,
-		Zero,
-		ParityOdd
-	};
 	template <Flag flag> bool flag() {
 		switch(flag) {
 			case Flag::Carry:			return carry;
@@ -96,16 +109,6 @@ struct Status {
 	}
 
 	// Condition evaluation.
-	enum class Condition {
-		Overflow,
-		Below,
-		Zero,
-		BelowOrEqual,
-		Sign,
-		ParityOdd,
-		Less,
-		LessOrEqual
-	};
 	template <Condition test> bool condition() {
 		switch(test) {
 			case Condition::Overflow:		return flag<Flag::Overflow>();
@@ -119,6 +122,18 @@ struct Status {
 		}
 	}
 
+	// Convenience setters.
+	template <typename IntT, Flag... flags> void set_from(IntT value) {
+		for(const auto flag: {flags...}) {
+			switch(flag) {
+				default: break;
+				case Flag::Zero:		zero = value;								break;
+				case Flag::Sign:		sign = value & Numeric::top_bit<IntT>();	break;
+				case Flag::ParityOdd:	parity = value;								break;
+			}
+		}
+	}
+
 	template <typename IntT> IntT carry_bit() const { return carry ? 1 : 0; }
 	bool not_parity_bit() const {
 		// x86 parity always considers the lowest 8-bits only.