CLK/Processors/65816/Implementation/65816Storage.hpp

//
//  65816Implementation.hpp
//  Clock Signal
//
//  Created by Thomas Harte on 23/09/2020.
//  Copyright © 2020 Thomas Harte. All rights reserved.
//

#ifndef WDC65816Implementation_h
#define WDC65816Implementation_h

enum MicroOp: uint8_t {
	/// Fetches a byte from the program counter to the instruction buffer and increments the program counter.
	CycleFetchIncrementPC,
	/// Fetches a byte from the program counter without incrementing it, and throws it away.
	CycleFetchPC,

	/// Fetches a byte from the data address to the data buffer.
	CycleFetchData,
	/// Fetches a byte from the data address to the data buffer and increments the data address.
	CycleFetchIncrementData,

	/// Stores a byte from the data buffer.
	CycleStoreData,
	/// Stores a byte to the data address from the data buffer and increments the data address.
	CycleStoreIncrementData,
	/// Stores a byte to the data address from the data buffer and decrements the data address.
	CycleStoreDecrementData,

	/// Pushes a single byte from the data buffer to the stack.
	CyclePush,

	/// Sets the data address by copying the final two bytes of the instruction buffer.
	OperationConstructAbsolute,
	/// Sets the data address
	OperationConstructAbsoluteIndexedIndirect,

	/// Performs whatever operation goes with this program.
	OperationPerform,

	/// Copies the current program counter to the data buffer.
	OperationCopyPCToData,

	/// Complete this set of micr-ops.
	OperationMoveToNextProgram
};

enum class AccessType {
	Read, Write
};

class ProcessorStorageConstructor;

class ProcessorStorage {
	public:
		ProcessorStorage();

		enum Operation: uint8_t {
			// These perform the named operation using the value in the data buffer;
			// they are implicitly AccessType::Read.
			ADC, AND, BIT, CMP, CPX, CPY, EOR, ORA, SBC,

			// These load the respective register from the data buffer;
			// they are implicitly AccessType::Read.
			LDA, LDX, LDY,

			// These move the respective register (or value) to the data buffer;
			// they are implicitly AccessType::Write.
			STA, STX, STY, STZ,

			/// Loads the PC with the operand from the data buffer.
			JMP,

			/// Loads the PC with the operand from the daa buffer, replacing
			/// it with the old PC.
			JSR,
		};

		struct Instruction {
			size_t program_offset;
			Operation operation;
		};
		Instruction instructions[256];

	private:
		std::vector<MicroOp> micro_ops_;

		AccessType access_type_for_operation(Operation);
		void install(void (* generator)(AccessType, bool, const std::function<void(MicroOp)>&), Operation, ProcessorStorageConstructor &);
};

#endif /* WDC65816Implementation_h */