RomKonami.cc

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// KONAMI 8kB cartridges (without SCC)
//
// this type is used by Konami cartridges without SCC and some others
// examples of cartridges: Nemesis, Penguin Adventure, Usas, Metal Gear, Shalom,
// The Maze of Galious, Aleste 1, 1942, Heaven, Mystery World, ...
// (the latter four are hacked ROM images with modified mappers)
//
// page at 4000 is fixed, other banks are switched by writing at
// 0x6000, 0x8000 and 0xA000 (those addresses are used by the games, but any
// other address in a page switches that page as well)
 
#include "RomKonami.hh"
#include "MSXMotherBoard.hh"
#include "MSXCliComm.hh"
#include "serialize.hh"
#include "xrange.hh"
 
namespace openmsx {
 
RomKonami::RomKonami(const DeviceConfig& config, Rom&& rom_)
        : Rom8kBBlocks(config, std::move(rom_))
{
        // Konami mapper is 256kB in size, even if ROM is smaller.
        setBlockMask(31);
 
        // warn if a ROM is used that would not work on a real Konami mapper
        if (rom.size() > 256 * 1024) {
                getMotherBoard().getMSXCliComm().printWarning(
                        "The size of this ROM image is larger than 256kB, "
                        "which is not supported on real Konami mapper chips!");
        }
 
        // Do not call reset() here, since it can be overridden and the subclass
        // constructor has not been run yet. And there will be a reset() at power
        // up anyway.
}
 
void RomKonami::bankSwitch(unsigned page, unsigned block)
{
        setRom(page, block);
 
        // Note: the mirror behavior is different from RomKonamiSCC !
        if (page == 2 || page == 3) {
                // [0x4000-0x8000), mirrored in [0x0000-0x4000)
                setRom(page - 2, block);
        } else if (page == 4 || page == 5) {
                // [0x8000-0xC000), mirrored in [0xC000-0x10000)
                setRom(page + 2, block);
        } else {
                assert(false);
        }
}
 
void RomKonami::reset(EmuTime::param /*time*/)
{
        for (auto i : xrange(2, 6)) {
                bankSwitch(i, i - 2);
        }
}
 
void RomKonami::writeMem(word address, byte value, EmuTime::param /*time*/)
{
        // Note: [0x4000..0x6000) is fixed at segment 0.
        if (0x6000 <= address && address < 0xC000) {
                bankSwitch(address >> 13, value);
        }
}
 
byte* RomKonami::getWriteCacheLine(word address) const
{
        return (0x6000 <= address && address < 0xC000) ? nullptr : unmappedWrite.data();
}
 
template<typename Archive>
void RomKonami::serialize(Archive& ar, unsigned /*version*/)
{
        ar.template serializeBase<Rom8kBBlocks>(*this);
}
INSTANTIATE_SERIALIZE_METHODS(RomKonami);
REGISTER_MSXDEVICE(RomKonami, "RomKonami");
 
} // namespace openmsx