136 lines
4.7 KiB
C++
136 lines
4.7 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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#define LOG_TAG "Cpu::executeROR"
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#define DO_ROR_8_BIT(value) { \
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bool carryWasSet = mCpuStatus.carryFlag(); \
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bool carryWillBeSet = (value & 0x01) != 0; \
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value = value >> 1; \
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if (carryWasSet) Binary::setBitIn8BitValue(&value, 7); \
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else Binary::clearBitIn8BitValue(&value, 7); \
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if (carryWillBeSet) mCpuStatus.setCarryFlag(); \
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else mCpuStatus.clearCarryFlag(); \
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mCpuStatus.updateSignAndZeroFlagFrom8BitValue(value); \
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}
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#define DO_ROR_16_BIT(value) { \
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bool carryWasSet = mCpuStatus.carryFlag(); \
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bool carryWillBeSet = (value & 0x0001) != 0; \
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value = value >> 1; \
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if (carryWasSet) Binary::setBitIn16BitValue(&value, 15); \
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else Binary::clearBitIn16BitValue(&value, 15); \
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if (carryWillBeSet) mCpuStatus.setCarryFlag(); \
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else mCpuStatus.clearCarryFlag(); \
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mCpuStatus.updateSignAndZeroFlagFrom16BitValue(value); \
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}
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/**
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* This file contains implementations for all ROR OpCodes.
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*/
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void Cpu65816::executeMemoryROR(OpCode &opCode) {
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Address opCodeDataAddress = getAddressOfOpCodeData(opCode);
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if(accumulatorIs8BitWide()) {
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uint8_t value = mSystemBus.readByte(opCodeDataAddress);
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DO_ROR_8_BIT(value);
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mSystemBus.storeByte(opCodeDataAddress, value);
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} else {
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uint16_t value = mSystemBus.readTwoBytes(opCodeDataAddress);
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DO_ROR_16_BIT(value);
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mSystemBus.storeTwoBytes(opCodeDataAddress, value);
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}
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}
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void Cpu65816::executeAccumulatorROR(OpCode &opCode) {
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if(accumulatorIs8BitWide()) {
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uint8_t value = Binary::lower8BitsOf(mA);
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DO_ROR_8_BIT(value);
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Binary::setLower8BitsOf16BitsValue(&mA, value);
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} else {
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uint16_t value = mA;
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DO_ROR_16_BIT(value);
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mA = value;
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}
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}
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void Cpu65816::executeROR(OpCode &opCode) {
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switch (opCode.getCode()) {
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case (0x6A): // ROR accumulator
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{
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executeAccumulatorROR(opCode);
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addToProgramAddressAndCycles(1, 2);
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break;
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}
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case (0x6E): // ROR #addr
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{
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executeMemoryROR(opCode);
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if (accumulatorIs8BitWide()) {
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addToProgramAddressAndCycles(3, 6);
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} else {
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addToProgramAddressAndCycles(3, 8);
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}
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break;
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}
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case (0x66): // ROR Direct Page
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{
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executeMemoryROR(opCode);
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int opCycles = Binary::lower8BitsOf(mD) != 0 ? 1 : 0;
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if (accumulatorIs8BitWide()) {
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addToProgramAddressAndCycles(2, 5+opCycles);
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} else {
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addToProgramAddressAndCycles(2, 7+opCycles);
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}
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break;
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}
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case (0x7E): // ROR Absolute Indexed, X
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{
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executeMemoryROR(opCode);
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#ifdef EMU_65C02
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short opCycles = opCodeAddressingCrossesPageBoundary(opCode) ? 0 : -1;
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#else
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short opCycles = 0;
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#endif
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if (accumulatorIs8BitWide()) {
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addToProgramAddressAndCycles(3, 7+opCycles);
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} else {
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addToProgramAddressAndCycles(3, 9+opCycles);
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}
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break;
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}
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case (0x76): // ROR Direct Page Indexed, X
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{
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executeMemoryROR(opCode);
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int opCycles = Binary::lower8BitsOf(mD) != 0 ? 1 : 0;
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if (accumulatorIs8BitWide()) {
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addToProgramAddressAndCycles(2, 6+opCycles);
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} else {
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addToProgramAddressAndCycles(2, 8+opCycles);
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}
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break;
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}
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default:
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{
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LOG_UNEXPECTED_OPCODE(opCode);
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}
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}
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}
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