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