RomDooly.cc

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//
// Agigongnyong Dooly
//
 
#include "RomDooly.hh"
#include "CacheLine.hh"
#include "MSXException.hh"
#include "serialize.hh"
 
namespace openmsx {
 
RomDooly::RomDooly(const DeviceConfig& config, Rom&& rom_)
        : MSXRom(config, std::move(rom_))
        , romBlockDebug(*this, std::span{&conversion, 1}, 0x4000, 0x8000, 15)
{
        if (rom.size() != 0x8000) {
                throw MSXException("Dooly ROM-size must be exactly 32kB");
        }
}
 
void RomDooly::reset(EmuTime::param /*time*/)
{
        conversion = 0;
}
 
byte RomDooly::peekMem(word address, EmuTime::param /*time*/) const
{
        if ((0x4000 <= address) && (address < 0xc000)) {
                byte value = rom[address - 0x4000];
                switch (conversion) {
                case 0:
                        return value;
                case 1:
                        return (value & 0xf8) | (value << 2 & 0x04) | (value >> 1 & 0x03);
                case 4:
                        return (value & 0xf8) | (value >> 2 & 0x01) | (value << 1 & 0x06);
                case 2:
                case 5:
                case 6:
                        switch (value & 0x07) {
                        case 1:
                        case 2:
                        case 4:
                                return value & 0xf8;
                        case 3:
                        case 5:
                        case 6:
                                if (conversion == 2) return (value & 0xf8) | (((value << 2 & 0x04) | (value >> 1 & 0x03)) ^ 0x07);
                                if (conversion == 5) return value ^ 0x07;
                                if (conversion == 6) return (value & 0xf8) | (((value >> 2 & 0x01) | (value << 1 & 0x06)) ^ 0x07);
                                [[fallthrough]];
                        default:
                                return value;
                        }
                default:
                        return value | 0x07;
                }
        }
        return 0xff;
}
 
byte RomDooly::readMem(word address, EmuTime::param time)
{
        return peekMem(address, time);
}
 
void RomDooly::writeMem(word address, byte value, EmuTime::param /*time*/)
{
        // TODO: To what region does the real cartridge react?
        // * Using the full region [0x4000,0xc000) interferes with the
        //   RAM-check routine of many MSX machines (game doesn't boot)
        // * The game seems to write at many different addresses. The min/max
        //   I've seen is 0x8780/0x8f86. So my best *guess* is to extend this
        //   region to [0x8000,0x9000).
        // * This smaller region seems to make the game work (on the above
        //   machines that failed before).
        if ((0x8000 <= address) && (address < 0x9000)) {
                conversion = value & 0x07;
        }
}
 
byte* RomDooly::getWriteCacheLine(word address)
{
        if (((0x4000 & CacheLine::HIGH) <= address) && (address < (0xc000 & CacheLine::HIGH))) {
                return nullptr;
        } else {
                return unmappedWrite.data();
        }
}
 
template<typename Archive>
void RomDooly::serialize(Archive& ar, unsigned /*version*/)
{
        ar.template serializeBase<MSXDevice>(*this);
        ar.serialize("conversion", conversion);
}
INSTANTIATE_SERIALIZE_METHODS(RomDooly);
REGISTER_MSXDEVICE(RomDooly, "RomDooly");
 
} // namespace openmsx