Lib65816/include/SystemBusDevice.hpp
2018-03-04 21:04:25 +01:00

90 lines
2.8 KiB
C++

/*
* 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/>.
*/
#ifndef SYSBUS_DEVICE_H
#define SYSBUS_DEVICE_H
#include <stdint.h>
#define BANK_SIZE_BYTES 0x10000
#define HALF_BANK_SIZE_BYTES 0x8000
#define PAGE_SIZE_BYTES 256
class Address {
private:
uint8_t mBank;
uint16_t mOffset;
public:
static bool offsetsAreOnDifferentPages(uint16_t, uint16_t);
static Address sumOffsetToAddress(const Address &, uint16_t);
static Address sumOffsetToAddressNoWrapAround(const Address &, uint16_t);
static Address sumOffsetToAddressWrapAround(const Address &, uint16_t);
Address() = default;
Address(uint8_t bank, uint16_t offset) : mBank(bank), mOffset(offset) {};
Address newWithOffset(uint16_t);
Address newWithOffsetNoWrapAround(uint16_t);
Address newWithOffsetWrapAround(uint16_t);
void incrementOffsetBy(uint16_t);
void decrementOffsetBy(uint16_t);
void getBankAndOffset(uint8_t *bank, uint16_t *offset) {
*bank = mBank;
*offset = mOffset;
}
uint8_t getBank() const {
return mBank;
}
uint16_t getOffset() const {
return mOffset;
}
};
/**
Every device (PPU, APU, ...) implements this interface.
*/
class SystemBusDevice {
public:
virtual ~SystemBusDevice() {};
/**
Stores one byte to the real address represented by the specified virtual address.
That is: maps the virtual address to the real one and stores one byte in it.
*/
virtual void storeByte(const Address &, uint8_t) = 0;
/**
Reads one byte from the real address represented by the specified virtual address.
That is: maps the virtual address to the real one and reads from it.
*/
virtual uint8_t readByte(const Address &) = 0;
/**
Returns true if the address was decoded successfully by this device.
*/
virtual bool decodeAddress(const Address &, Address &) = 0;
};
#endif // SYSBUS_DEVICE_H