654 lines
No EOL
14 KiB
C++
654 lines
No EOL
14 KiB
C++
#pragma once
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#include "stdafx.h"
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#include "MemoryManager.h"
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#include "Snapshotable.h"
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namespace PSFlags
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{
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enum PSFlags : uint8_t
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{
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Carry = 0x01,
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Zero = 0x02,
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Interrupt = 0x04,
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Decimal = 0x08,
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Break = 0x10,
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Reserved = 0x20,
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Overflow = 0x40,
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Negative = 0x80
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};
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}
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enum AddrMode
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{
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None, Imp, Imm, Rel,
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Zero, ZeroX, ZeroY,
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IndX, IndY, IndYW,
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Abs, AbsX, AbsXW, AbsY, AbsYW
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};
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enum class IRQSource
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{
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External = 1,
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FrameCounter = 2,
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DMC = 4,
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};
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struct State
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{
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uint16_t PC;
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uint8_t SP;
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uint8_t A;
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uint8_t X;
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uint8_t Y;
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uint8_t PS;
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};
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class CPU : public Snapshotable
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{
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private:
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const uint16_t NMIVector = 0xFFFA;
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const uint16_t ResetVector = 0xFFFC;
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const uint16_t IRQVector = 0xFFFE;
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typedef void(CPU::*Func)();
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static int32_t CycleCount;
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static int32_t RelativeCycleCount;
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static uint32_t CyclePenalty;
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Func _opTable[256];
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uint8_t _cycles[256];
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AddrMode _addrMode[256];
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AddrMode _instAddrMode;
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uint8_t _cyclesPageCrossed[256];
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bool _pageCrossed = false;
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State _state;
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MemoryManager *_memoryManager = nullptr;
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static bool NMIFlag;
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static uint32_t IRQFlag;
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bool _runNMI = false;
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bool _runIRQ = false;
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uint8_t ReadByte()
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{
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return MemoryRead(_state.PC++);
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}
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uint16_t ReadWord()
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{
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uint16_t value = MemoryReadWord(PC());
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_state.PC += 2;
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return value;
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}
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void ClearFlags(uint8_t flags)
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{
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_state.PS &= ~flags;
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}
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void SetFlags(uint8_t flags)
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{
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_state.PS |= flags;
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}
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bool CheckFlag(uint8_t flag)
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{
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return (_state.PS & flag) == flag;
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}
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void SetZeroNegativeFlags(uint8_t value)
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{
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if(value == 0) {
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SetFlags(PSFlags::Zero);
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} else if(value & 0x80) {
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SetFlags(PSFlags::Negative);
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}
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}
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bool CheckPageCrossed(uint16_t valA, int8_t valB)
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{
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_pageCrossed = ((valA + valB) & 0xFF00) != (valA & 0xFF00);
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return _pageCrossed;
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}
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bool CheckPageCrossed(uint16_t valA, uint8_t valB)
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{
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_pageCrossed = ((valA + valB) & 0xFF00) != (valA & 0xFF00);
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return _pageCrossed;
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}
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void MemoryWrite(uint16_t addr, uint8_t value)
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{
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_memoryManager->Write(addr, value);
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}
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uint8_t MemoryRead(uint16_t addr) {
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return _memoryManager->Read(addr);
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}
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uint16_t MemoryReadWord(uint16_t addr) {
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return _memoryManager->ReadWord(addr);
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}
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void SetRegister(uint8_t ®, uint8_t value) {
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ClearFlags(PSFlags::Zero | PSFlags::Negative);
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SetZeroNegativeFlags(value);
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reg = value;
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}
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void Push(uint8_t value) {
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MemoryWrite(SP() + 0x100, value);
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SetSP(SP() - 1);
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}
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void Push(uint16_t value) {
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Push((uint8_t)(value >> 8));
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Push((uint8_t)value);
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}
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uint8_t Pop() {
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SetSP(SP() + 1);
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return MemoryRead(0x100 + SP());
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}
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uint16_t PopWord() {
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uint8_t lo = Pop();
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uint8_t hi = Pop();
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return lo | hi << 8;
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}
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uint8_t A() { return _state.A; }
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void SetA(uint8_t value) { SetRegister(_state.A, value); }
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uint8_t X() { return _state.X; }
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void SetX(uint8_t value) { SetRegister(_state.X, value); }
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uint8_t Y() { return _state.Y; }
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void SetY(uint8_t value) { SetRegister(_state.Y, value); }
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uint8_t SP() { return _state.SP; }
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void SetSP(uint8_t value) { _state.SP = value; }
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uint8_t PS() { return _state.PS; }
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void SetPS(uint8_t value) { _state.PS = (value & 0xCF) | PSFlags::Reserved; }
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uint16_t PC() { return _state.PC; }
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void SetPC(uint16_t value) { _state.PC = value; }
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uint16_t GetOperandAddr()
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{
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switch(_instAddrMode) {
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case AddrMode::Abs: return GetAbsAddr();
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case AddrMode::AbsX: return GetAbsXAddr(false);
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case AddrMode::AbsXW: return GetAbsXAddr(true);
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case AddrMode::AbsY: return GetAbsYAddr(false);
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case AddrMode::AbsYW: return GetAbsYAddr(true);
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case AddrMode::Imm: return GetImmediate();
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case AddrMode::IndX: return GetIndXAddr();
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case AddrMode::IndY: return GetIndYAddr(false);
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case AddrMode::IndYW: return GetIndYAddr(true);
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case AddrMode::Zero: return GetZeroAddr();
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case AddrMode::ZeroX: return GetZeroXAddr();
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case AddrMode::ZeroY: return GetZeroYAddr();
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}
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return 0;
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}
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uint8_t GetOperand()
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{
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uint16_t addr = GetOperandAddr();
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if(_instAddrMode != AddrMode::Imm) {
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return MemoryRead(addr);
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} else {
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return (uint8_t)addr;
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}
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}
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uint8_t GetImmediate() { return ReadByte(); }
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uint8_t GetZero() { return MemoryRead(GetZeroAddr()); }
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uint8_t GetZeroAddr() { return ReadByte(); }
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uint8_t GetZeroX() { return MemoryRead(GetZeroXAddr()); }
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uint8_t GetZeroXAddr() { return ReadByte() + X(); }
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uint8_t GetZeroY() { return MemoryRead(GetZeroYAddr()); }
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uint8_t GetZeroYAddr() { return ReadByte() + Y(); }
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uint8_t GetAbs() { return MemoryRead(GetAbsAddr()); }
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uint16_t GetAbsAddr() { return ReadWord(); }
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uint8_t GetAbsX() { return MemoryRead(GetAbsXAddr(false)); }
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uint16_t GetAbsXAddr(bool dummyRead = true) {
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uint16_t baseAddr = ReadWord();
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bool pageCrossed = CheckPageCrossed(baseAddr, X());
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if(pageCrossed || dummyRead) {
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//Dummy read done by the processor (only when page is crossed for READ instructions)
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MemoryRead(baseAddr + X() - (pageCrossed ? 0x100 : 0));
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}
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return baseAddr + X();
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}
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uint8_t GetAbsY() { return MemoryRead(GetAbsYAddr(false)); }
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uint16_t GetAbsYAddr(bool dummyRead = true) {
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uint16_t baseAddr = ReadWord();
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bool pageCrossed = CheckPageCrossed(baseAddr, Y());
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if(pageCrossed || dummyRead) {
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//Dummy read done by the processor (only when page is crossed for READ instructions)
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MemoryRead(baseAddr + Y() - (pageCrossed ? 0x100 : 0));
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}
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return baseAddr + Y();
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}
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uint16_t GetInd() {
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uint16_t addr = ReadWord();
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if((addr & 0xFF) == 0xFF) {
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auto lo = MemoryRead(addr);
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auto hi = MemoryRead(addr - 0xFF);
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return (lo | hi << 8);
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} else {
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return MemoryReadWord(addr);
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}
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}
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uint8_t GetIndX() { return MemoryRead(GetIndXAddr()); }
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uint16_t GetIndXAddr() {
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uint8_t zero = ReadByte();
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//Dummy read
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MemoryRead(zero);
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zero += X();
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uint16_t addr;
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if(zero == 0xFF) {
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addr = MemoryRead(0xFF) | MemoryRead(0x00) << 8;
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} else {
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addr = MemoryReadWord(zero);
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}
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return addr;
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}
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uint8_t GetIndY() { return MemoryRead(GetIndYAddr(false)); }
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uint16_t GetIndYAddr(bool dummyRead = true) {
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uint8_t zero = ReadByte();
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uint16_t addr;
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if(zero == 0xFF) {
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addr = MemoryRead(0xFF) | MemoryRead(0x00) << 8;
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} else {
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addr = MemoryReadWord(zero);
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}
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bool pageCrossed = CheckPageCrossed(addr, Y());
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if(pageCrossed || dummyRead) {
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//Dummy read done by the processor (only when page is crossed for READ instructions)
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MemoryRead(addr + Y() - (pageCrossed ? 0x100 : 0));
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}
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return addr + Y();
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}
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void AND() { SetA(A() & GetOperand()); }
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void EOR() { SetA(A() ^ GetOperand()); }
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void ORA() { SetA(A() | GetOperand()); }
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void ADD(uint8_t value)
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{
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uint16_t result = (uint16_t)A() + (uint16_t)value + (CheckFlag(PSFlags::Carry) ? PSFlags::Carry : 0x00);
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ClearFlags(PSFlags::Carry | PSFlags::Negative | PSFlags::Overflow | PSFlags::Zero);
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SetZeroNegativeFlags((uint8_t)result);
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if(~(A() ^ value) & (A() ^ result) & 0x80) {
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SetFlags(PSFlags::Overflow);
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}
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if(result > 0xFF) {
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SetFlags(PSFlags::Carry);
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}
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SetA((uint8_t)result);
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}
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void ADC() { ADD(GetOperand()); }
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void SBC() { ADD(GetOperand() ^ 0xFF); }
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void CMP(uint8_t reg, uint8_t value)
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{
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ClearFlags(PSFlags::Carry | PSFlags::Negative | PSFlags::Zero);
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auto result = reg - value;
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if(reg >= value) {
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SetFlags(PSFlags::Carry);
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}
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if(reg == value) {
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SetFlags(PSFlags::Zero);
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}
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if((result & 0x80) == 0x80) {
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SetFlags(PSFlags::Negative);
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}
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}
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void CPA() { CMP(A(), GetOperand()); }
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void CPX() { CMP(X(), GetOperand()); }
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void CPY() { CMP(Y(), GetOperand()); }
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void INC()
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{
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uint16_t addr = GetOperandAddr();
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ClearFlags(PSFlags::Negative | PSFlags::Zero);
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uint8_t value = MemoryRead(addr);
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MemoryWrite(addr, value); //Dummy write
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value++;
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SetZeroNegativeFlags(value);
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MemoryWrite(addr, value);
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}
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void DEC()
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{
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uint16_t addr = GetOperandAddr();
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ClearFlags(PSFlags::Negative | PSFlags::Zero);
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uint8_t value = MemoryRead(addr);
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MemoryWrite(addr, value); //Dummy write
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value--;
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SetZeroNegativeFlags(value);
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MemoryWrite(addr, value);
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}
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uint8_t ASL(uint8_t value)
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{
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ClearFlags(PSFlags::Carry | PSFlags::Negative | PSFlags::Zero);
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if(value & 0x80) {
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SetFlags(PSFlags::Carry);
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}
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uint8_t result = value << 1;
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SetZeroNegativeFlags(result);
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return result;
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}
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uint8_t LSR(uint8_t value) {
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ClearFlags(PSFlags::Carry | PSFlags::Negative | PSFlags::Zero);
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if(value & 0x01) {
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SetFlags(PSFlags::Carry);
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}
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uint8_t result = value >> 1;
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SetZeroNegativeFlags(result);
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return value >> 1;
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}
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uint8_t ROL(uint8_t value) {
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bool carryFlag = CheckFlag(PSFlags::Carry);
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ClearFlags(PSFlags::Carry | PSFlags::Negative | PSFlags::Zero);
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if(value & 0x80) {
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SetFlags(PSFlags::Carry);
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}
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uint8_t result = (value << 1 | (carryFlag ? 0x01 : 0x00));
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SetZeroNegativeFlags(result);
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return result;
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}
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uint8_t ROR(uint8_t value) {
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bool carryFlag = CheckFlag(PSFlags::Carry);
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ClearFlags(PSFlags::Carry | PSFlags::Negative | PSFlags::Zero);
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if(value & 0x01) {
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SetFlags(PSFlags::Carry);
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}
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uint8_t result = (value >> 1 | (carryFlag ? 0x80 : 0x00));
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SetZeroNegativeFlags(result);
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return result;
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}
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void ASLAddr() {
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uint16_t addr = GetOperandAddr();
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uint8_t value = MemoryRead(addr);
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MemoryWrite(addr, value); //Dummy write
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MemoryWrite(addr, ASL(value));
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}
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void LSRAddr() {
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uint16_t addr = GetOperandAddr();
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uint8_t value = MemoryRead(addr);
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MemoryWrite(addr, value); //Dummy write
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MemoryWrite(addr, LSR(value));
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}
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void ROLAddr() {
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uint16_t addr = GetOperandAddr();
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uint8_t value = MemoryRead(addr);
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MemoryWrite(addr, value); //Dummy write
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MemoryWrite(addr, ROL(value));
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}
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void RORAddr() {
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uint16_t addr = GetOperandAddr();
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uint8_t value = MemoryRead(addr);
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MemoryWrite(addr, value); //Dummy write
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MemoryWrite(addr, ROR(value));
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}
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void JMP(uint16_t addr) {
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SetPC(addr);
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}
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void BranchRelative(bool branch) {
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int8_t offset = GetImmediate();
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if(branch) {
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CheckPageCrossed(PC(), offset);
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IncCycleCount(1);
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SetPC(PC() + offset);
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}
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}
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void BIT() {
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uint8_t value = GetOperand();
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ClearFlags(PSFlags::Zero | PSFlags::Overflow | PSFlags::Negative);
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if((A() & value) == 0) {
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SetFlags(PSFlags::Zero);
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}
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if(value & 0x40) {
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SetFlags(PSFlags::Overflow);
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}
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if(value & 0x80) {
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SetFlags(PSFlags::Negative);
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}
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}
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bool IsPageCrossed() {
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bool pageCrossed = _pageCrossed;
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_pageCrossed = false;
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return pageCrossed;
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}
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uint32_t GetCyclePenalty() {
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uint32_t cyclePenalty = CPU::CyclePenalty;
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CPU::CyclePenalty = 0;
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return cyclePenalty;
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}
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#pragma region OP Codes
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void LDA() { SetA(GetOperand()); }
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void LDX() { SetX(GetOperand()); }
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void LDY() { SetY(GetOperand()); }
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void STA() { MemoryWrite(GetOperandAddr(), A()); }
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void STX() { MemoryWrite(GetOperandAddr(), X()); }
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void STY() { MemoryWrite(GetOperandAddr(), Y()); }
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void TAX() { SetX(A()); }
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void TAY() { SetY(A()); }
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void TSX() { SetX(SP()); }
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void TXA() { SetA(X()); }
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void TXS() { SetSP(X()); }
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void TYA() { SetA(Y()); }
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void PHA() { Push(A()); }
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void PHP() {
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uint8_t flags = PS() | PSFlags::Break;
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Push((uint8_t)flags);
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}
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void PLA() { SetA(Pop()); }
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void PLP() { SetPS(Pop()); }
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void INX() { SetX(X() + 1); }
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void INY() { SetY(Y() + 1); }
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void DEX() { SetX(X() - 1); }
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void DEY() { SetY(Y() - 1); }
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void ASL_Acc() { SetA(ASL(A())); }
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void ASL_Memory() { ASLAddr(); }
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void LSR_Acc() { SetA(LSR(A())); }
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void LSR_Memory() { LSRAddr(); }
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void ROL_Acc() { SetA(ROL(A())); }
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void ROL_Memory() { ROLAddr(); }
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void ROR_Acc() { SetA(ROR(A())); }
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void ROR_Memory() { RORAddr(); }
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void JMP_Abs() {
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JMP(GetAbsAddr());
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}
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void JMP_Ind() { JMP(GetInd()); }
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void JSR() {
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uint16_t addr = GetAbsAddr();
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Push((uint16_t)(PC() - 1));
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JMP(addr);
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}
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void RTS() {
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uint16_t addr = PopWord();
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SetPC(addr + 1);
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}
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void BCC() {
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BranchRelative(!CheckFlag(PSFlags::Carry));
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}
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void BCS() {
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BranchRelative(CheckFlag(PSFlags::Carry));
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}
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void BEQ() {
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BranchRelative(CheckFlag(PSFlags::Zero));
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}
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void BMI() {
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BranchRelative(CheckFlag(PSFlags::Negative));
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}
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void BNE() {
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BranchRelative(!CheckFlag(PSFlags::Zero));
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}
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void BPL() {
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BranchRelative(!CheckFlag(PSFlags::Negative));
|
|
}
|
|
|
|
void BVC() {
|
|
BranchRelative(!CheckFlag(PSFlags::Overflow));
|
|
}
|
|
|
|
void BVS() {
|
|
BranchRelative(CheckFlag(PSFlags::Overflow));
|
|
}
|
|
|
|
void CLC() { ClearFlags(PSFlags::Carry); }
|
|
void CLD() { ClearFlags(PSFlags::Decimal); }
|
|
void CLI() { ClearFlags(PSFlags::Interrupt); }
|
|
void CLV() { ClearFlags(PSFlags::Overflow); }
|
|
void SEC() { SetFlags(PSFlags::Carry); }
|
|
void SED() { SetFlags(PSFlags::Decimal); }
|
|
void SEI() { SetFlags(PSFlags::Interrupt); }
|
|
|
|
void BRK() {
|
|
Push((uint16_t)(PC() + 1));
|
|
|
|
uint8_t flags = PS() | PSFlags::Break;
|
|
if(CPU::NMIFlag) {
|
|
Push((uint8_t)flags);
|
|
SetFlags(PSFlags::Interrupt);
|
|
|
|
SetPC(MemoryReadWord(CPU::NMIVector));
|
|
} else {
|
|
|
|
Push((uint8_t)flags);
|
|
SetFlags(PSFlags::Interrupt);
|
|
|
|
SetPC(MemoryReadWord(CPU::IRQVector));
|
|
}
|
|
}
|
|
|
|
void NMI() {
|
|
Push((uint16_t)(PC()));
|
|
Push((uint8_t)PS());
|
|
SetFlags(PSFlags::Interrupt);
|
|
SetPC(MemoryReadWord(CPU::NMIVector));
|
|
}
|
|
|
|
void IRQ() {
|
|
Push((uint16_t)(PC()));
|
|
|
|
if(CPU::NMIFlag) {
|
|
Push((uint8_t)PS());
|
|
SetFlags(PSFlags::Interrupt);
|
|
|
|
SetPC(MemoryReadWord(CPU::NMIVector));
|
|
} else {
|
|
Push((uint8_t)PS());
|
|
SetFlags(PSFlags::Interrupt);
|
|
SetPC(MemoryReadWord(CPU::IRQVector));
|
|
}
|
|
}
|
|
|
|
void RTI() {
|
|
SetPS(Pop());
|
|
SetPC(PopWord());
|
|
}
|
|
|
|
void NOP() {
|
|
GetOperand();
|
|
}
|
|
|
|
#pragma endregion
|
|
|
|
protected:
|
|
void StreamState(bool saving);
|
|
|
|
public:
|
|
static const uint32_t ClockRate = 1789773;
|
|
|
|
CPU(MemoryManager *memoryManager);
|
|
static int32_t GetCycleCount() { return CPU::CycleCount; }
|
|
static int32_t GetRelativeCycleCount() { return CPU::RelativeCycleCount + CPU::CycleCount; }
|
|
static void IncCycleCount(uint32_t cycles) {
|
|
CPU::CyclePenalty += cycles;
|
|
CPU::CycleCount += cycles;
|
|
}
|
|
static void SetNMIFlag() { CPU::NMIFlag = true; }
|
|
static void ClearNMIFlag() { CPU::NMIFlag = false; }
|
|
static void SetIRQSource(IRQSource source)
|
|
{
|
|
CPU::IRQFlag |= (int)source;
|
|
}
|
|
static void ClearIRQSource(IRQSource source)
|
|
{
|
|
CPU::IRQFlag &= ~(int)source;
|
|
}
|
|
|
|
void Reset(bool softReset);
|
|
uint32_t Exec();
|
|
void EndFrame();
|
|
|
|
State GetState() { return _state; }
|
|
|
|
}; |