/*
 * This file is part of the 65816 Emulator Library.
 * Copyright (c) 2018 Francesco Rigoni.
 *
 * https://github.com/FrancescoRigoni/Lib65816
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, version 3.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */

#include "../Interrupt.hpp"
#include "../Cpu65816.hpp"

#define LOG_TAG "Cpu::executeInterrupt"

/**
 * This file contains the implementation for all OpCodes
 * that deal with interrupts.
 */

void Cpu65816::executeInterrupt(OpCode &opCode) {
    switch (opCode.getCode()) {
        case(0x00):  // BRK
        {
            if (mCpuStatus.emulationFlag()) {
                mStack.push16Bit(static_cast<uint16_t>(mProgramAddress.getOffset() + 2));
                mCpuStatus.setBreakFlag();
                mStack.push8Bit(mCpuStatus.getRegisterValue());
                mCpuStatus.setInterruptDisableFlag();
#ifdef EMU_65C02
                mCpuStatus.clearDecimalFlag();
#endif
                setProgramAddress(Address(0x00, mEmulationInterrupts->brkIrq));
                addToCycles(7);
            } else {
                mStack.push8Bit(mProgramAddress.getBank());
                mStack.push16Bit(static_cast<uint16_t>(mProgramAddress.getOffset() + 2));
                mStack.push8Bit(mCpuStatus.getRegisterValue());
                mCpuStatus.setInterruptDisableFlag();
                mCpuStatus.clearDecimalFlag();
                Address newAddress(0x00, mNativeInterrupts->brk);
                setProgramAddress(newAddress);
                addToCycles(8);
            }
            break;
        }
        case(0x02):                 // COP
        {
            if (mCpuStatus.emulationFlag()) {
                mStack.push16Bit(static_cast<uint16_t>(mProgramAddress.getOffset() + 2));
                mStack.push8Bit(mCpuStatus.getRegisterValue());
                mCpuStatus.setInterruptDisableFlag();
                setProgramAddress(Address(0x00, mEmulationInterrupts->coProcessorEnable));
                addToCycles(7);
            } else {
                mStack.push8Bit(mProgramAddress.getBank());
                mStack.push16Bit(static_cast<uint16_t>(mProgramAddress.getOffset() + 2));
                mStack.push8Bit(mCpuStatus.getRegisterValue());
                mCpuStatus.setInterruptDisableFlag();
                setProgramAddress(Address(0x00, mNativeInterrupts->coProcessorEnable));
                addToCycles(8);
            }
            mCpuStatus.clearDecimalFlag();
            break;
        }
        case(0x40):                 // RTI
        {
            // Note: The picture in the 65816 programming manual about this looks wrong.
            // This implementation follows the text instead.
            mCpuStatus.setRegisterValue(mStack.pull8Bit());

            if (mCpuStatus.emulationFlag()) {
                Address newProgramAddress(mProgramAddress.getBank(), mStack.pull16Bit());
                mProgramAddress = newProgramAddress;
                addToCycles(6);
            } else {
                uint16_t offset = mStack.pull16Bit();
                uint8_t bank = mStack.pull8Bit();
                Address newProgramAddress(bank, offset);
                mProgramAddress = newProgramAddress;
                addToCycles(7);
            }
        }
        default: {
            LOG_UNEXPECTED_OPCODE(opCode);
        }
    }
}