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CLK/Machines/Atari2600/Cartridges/MegaBoy.hpp

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//
// CartridgeMegaBoy.h
// Clock Signal
//
// Created by Thomas Harte on 18/03/2017.
// Copyright © 2017 Thomas Harte. All rights reserved.
//
#ifndef Atari2600_CartridgeMegaBoy_hpp
#define Atari2600_CartridgeMegaBoy_hpp
#include "Cartridge.hpp"
namespace Atari2600 {
namespace Cartridge {
class MegaBoy: public BusExtender {
public:
MegaBoy(uint8_t *rom_base, size_t rom_size) :
BusExtender(rom_base, rom_size),
rom_ptr_(rom_base),
current_page_(0) {
}
void perform_bus_operation(CPU::MOS6502::BusOperation operation, uint16_t address, uint8_t *value) {
address &= 0x1fff;
if(!(address & 0x1000)) return;
if(address == 0x1ff0) {
current_page_ = (current_page_ + 1) & 15;
rom_ptr_ = rom_base_ + current_page_ * 4096;
}
if(isReadOperation(operation)) {
*value = rom_ptr_[address & 4095];
}
}
private:
uint8_t *rom_ptr_;
uint8_t current_page_;
};
}
}
#endif /* CartridgeMegaBoy_h */