126 lines
3.3 KiB
C++
126 lines
3.3 KiB
C++
/*
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* This file is part of the 65816 Emulator Library.
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* Copyright (c) 2018 Francesco Rigoni.
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*
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* https://github.com/FrancescoRigoni/Lib65816
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, version 3.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "Cpu65816.hpp"
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#include <cmath>
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#ifdef EMU_65C02
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#define LOG_TAG "Cpu65C02"
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#else
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#define LOG_TAG (mCpuStatus.emulationFlag() ? "Cpu6502" : "Cpu65816")
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#endif
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Cpu65816::Cpu65816(SystemBus &systemBus, EmulationModeInterrupts *emulationInterrupts, NativeModeInterrupts *nativeInterrupts) :
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mSystemBus(systemBus),
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mEmulationInterrupts(emulationInterrupts),
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mNativeInterrupts(nativeInterrupts),
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mStack(&mSystemBus) {
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}
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/**
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* Resets the cpu to its initial state.
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* */
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void Cpu65816::reset() {
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setRESPin(true);
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mCpuStatus.setEmulationFlag();
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mCpuStatus.setAccumulatorWidthFlag();
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mCpuStatus.setIndexWidthFlag();
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mX &= 0xFF;
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mY &= 0xFF;
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mD = 0x0;
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mStack = Stack(&mSystemBus);
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mProgramAddress = Address(0x00, mEmulationInterrupts->reset);
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}
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void Cpu65816::setRESPin(bool value) {
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if (value == false && mPins.RES == true) {
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reset();
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}
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mPins.RES = value;
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}
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void Cpu65816::setRDYPin(bool value) {
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mPins.RDY = value;
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}
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bool Cpu65816::executeNextInstruction() {
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if (mPins.RES) {
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return false;
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}
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// Fetch the instruction
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const uint8_t instruction = mSystemBus.readByte(mProgramAddress);
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OpCode opCode = OP_CODE_TABLE[instruction];
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// Execute it
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return opCode.execute(*this);
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}
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bool Cpu65816::accumulatorIs8BitWide() {
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// Accumulator is always 8 bit in emulation mode.
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if (mCpuStatus.emulationFlag()) return true;
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// Accumulator width set to one means 8 bit accumulator.
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else return mCpuStatus.accumulatorWidthFlag();
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}
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bool Cpu65816::accumulatorIs16BitWide() {
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return !accumulatorIs8BitWide();
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}
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bool Cpu65816::indexIs8BitWide() {
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// Index is always 8 bit in emulation mode.
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if (mCpuStatus.emulationFlag()) return true;
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// Index width set to one means 8 bit accumulator.
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else return mCpuStatus.indexWidthFlag();
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}
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bool Cpu65816::indexIs16BitWide() {
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return !indexIs8BitWide();
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}
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void Cpu65816::addToCycles(int cycles) {
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mTotalCyclesCounter += cycles;
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}
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void Cpu65816::subtractFromCycles(int cycles) {
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mTotalCyclesCounter -= cycles;
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}
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void Cpu65816::addToProgramAddress(int bytes) {
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mProgramAddress.incrementOffsetBy(bytes);
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}
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void Cpu65816::addToProgramAddressAndCycles(int bytes, int cycles) {
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addToCycles(cycles);
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addToProgramAddress(bytes);
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}
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uint16_t Cpu65816::indexWithXRegister() {
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return indexIs8BitWide() ? Binary::lower8BitsOf(mX) : mX;
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}
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uint16_t Cpu65816::indexWithYRegister() {
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return indexIs8BitWide() ? Binary::lower8BitsOf(mY) : mY;
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}
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void Cpu65816::setProgramAddress(const Address &address) {
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mProgramAddress = address;
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}
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