EightBit/Intel8080/inc/Intel8080.h

#pragma once

// Auxiliary carry logic from https://github.com/begoon/i8080-core

#include <cassert>
#include <cstdint>
#include <stdexcept>

#include <Bus.h>
#include <IntelProcessor.h>
#include <EventArgs.h>
#include <Signal.h>
#include <Register.h>

namespace EightBit {
	class Intel8080 final : public IntelProcessor {
	public:
		DECLARE_PIN_OUTPUT(DBIN)		// Active high
		DECLARE_PIN_OUTPUT(WR)		// Active low

	public:
		enum StatusBits {
			SF = Bit7,
			ZF = Bit6,
			AC = Bit4,
			PF = Bit2,
			CF = Bit0,
		};

		Intel8080(Bus& bus);

		Signal<Intel8080> ExecutingInstruction;
		Signal<Intel8080> ExecutedInstruction;

		void execute() noexcept final;
		int step() noexcept final;

		[[nodiscard]] const register16_t& AF() const noexcept final;
		[[nodiscard]] auto& AF() noexcept { return IntelProcessor::AF(); }
		[[nodiscard]] const register16_t& BC() const noexcept final;
		[[nodiscard]] auto& BC() noexcept { return IntelProcessor::BC(); }
		[[nodiscard]] const register16_t& DE() const noexcept final;
		[[nodiscard]] auto& DE() noexcept { return IntelProcessor::DE(); }
		[[nodiscard]] const register16_t& HL() const noexcept final;
		[[nodiscard]] auto& HL() noexcept { return IntelProcessor::HL(); }

		[[nodiscard]] bool requestingIO() noexcept { return m_requestIO; }
		[[nodiscard]] bool requestingMemory() noexcept { return m_requestMemory; }

		[[nodiscard]] bool requestingRead() noexcept { return raised(DBIN()); }
		[[nodiscard]] bool requestingWrite() noexcept { return lowered(WR()); }

	protected:
		void handleRESET() noexcept final;
		void handleINT() noexcept final;

		void memoryWrite() noexcept final;
		uint8_t memoryRead() noexcept final;

		void busWrite() noexcept final;
		uint8_t busRead() noexcept final;

	private:
		bool m_requestIO = false;
		bool m_requestMemory = false;

		bool m_interruptEnable = false;

		register16_t af;
		register16_t bc = Mask16;
		register16_t de = Mask16;
		register16_t hl = Mask16;

		auto R(const int r) {
			switch (r) {
			case 0b000:
				return B();
			case 0b001:
				return C();
			case 0b010:
				return D();
			case 0b011:
				return E();
			case 0b100:
				return H();
			case 0b101:
				return L();
			case 0b110:
				return IntelProcessor::memoryRead(HL());
			case 0b111:
				return A();
			default:
				UNREACHABLE;
			}
		}

		void R(int r, const uint8_t value) {
			switch (r) {
			case 0b000:
				B() = value;
				break;
			case 0b001:
				C() = value;
				break;
			case 0b010:
				D() = value;
				break;
			case 0b011:
				E() = value;
				break;
			case 0b100:
				H() = value;
				break;
			case 0b101:
				L() = value;
				break;
			case 0b110:
				IntelProcessor::memoryWrite(HL(), value);
				break;
			case 0b111:
				A() = value;
				break;
			default:
				UNREACHABLE;
			}
		}

		auto& RP(const int rp) {
			switch (rp) {
			case 0b00:
				return BC();
			case 0b01:
				return DE();
			case 0b10:
				return HL();
			case 0b11:
				return SP();
			default:
				UNREACHABLE;
			}
		}

		auto& RP2(const int rp) {
			switch (rp) {
			case 0b00:
				return BC();
			case 0b01:
				return DE();
			case 0b10:
				return HL();
			case 0b11:
				return AF();
			default:
				UNREACHABLE;
			}
		}

		static void adjustAuxiliaryCarryAdd(uint8_t& f, uint8_t before, uint8_t value, int calculation) {
			f = setBit(f, AC, calculateHalfCarryAdd(before, value, calculation));
		}

		static void adjustAuxiliaryCarrySub(uint8_t& f, uint8_t before, uint8_t value, int calculation) {
			f = clearBit(f, AC, calculateHalfCarrySub(before, value, calculation));
		}

		void subtract(uint8_t& operand, uint8_t value, int carry = 0);

		void execute(int x, int y, int z, int p, int q);

		void increment(uint8_t& operand);
		void decrement(uint8_t& operand);

		void di();
		void ei();

		int returnConditionalFlag(int flag);
		int jumpConditionalFlag(int flag);
		int callConditionalFlag(int flag);

		void add(register16_t value);

		void add(uint8_t value, int carry = 0);
		void adc(uint8_t value);
		void sbb(uint8_t value);
		void andr(uint8_t value);
		void xorr(uint8_t value);
		void orr(uint8_t value);
		void compare(uint8_t value);

		void rlc();
		void rrc();
		void rl();
		void rr();

		void daa();

		void cma();
		void stc();
		void cmc();

		void xhtl(register16_t& exchange);

		void portWrite(uint8_t port);
		void portWrite();

		uint8_t portRead(uint8_t port);
		uint8_t portRead();

		void requestIO() noexcept { assert(!requestingMemory());  m_requestIO = true; }
		void releaseIO() noexcept { m_requestIO = false; }
		void requestMemory() noexcept { assert(!requestingIO()); m_requestMemory = true; }
		void releaseMemory() noexcept { m_requestMemory = false; }

		void requestRead() { raise(DBIN()); }
		void releaseRead() { lower(DBIN()); }
		void requestWrite() { lower(WR()); }
		void releaseWrite() { raise(WR()); }
	};
}