RomKonamiSCC.cc

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// KONAMI 8kB cartridges with SCC
//
// this type is used by Konami cartridges that do have an SCC and some others
// examples of cartridges: Nemesis 2, Nemesis 3, King's Valley 2, Space Manbow
// Solid Snake, Quarth, Ashguine 1, Animal, Arkanoid 2, ...
// Those last 3 were probably modified ROM images, they should be ASCII8
//
// The address to change banks:
//  bank 1: 0x5000 - 0x57ff (0x5000 used)
//  bank 2: 0x7000 - 0x77ff (0x7000 used)
//  bank 3: 0x9000 - 0x97ff (0x9000 used)
//  bank 4: 0xB000 - 0xB7ff (0xB000 used)
 
#include "RomKonamiSCC.hh"
#include "CacheLine.hh"
#include "MSXMotherBoard.hh"
#include "MSXCliComm.hh"
#include "sha1.hh"
#include "serialize.hh"
#include "xrange.hh"
 
namespace openmsx {
 
RomKonamiSCC::RomKonamiSCC(const DeviceConfig& config, Rom&& rom_)
        : Rom8kBBlocks(config, std::move(rom_))
        , scc("SCC", config, getCurrentTime())
{
        // warn if a ROM is used that would not work on a real KonamiSCC mapper
        if (rom.size() > 512 * 1024) {
                getMotherBoard().getMSXCliComm().printWarning(
                        "The size of this ROM image is larger than 512kB, "
                        "which is not supported on real Konami SCC mapper "
                        "chips!");
        }
        powerUp(getCurrentTime());
}
 
void RomKonamiSCC::powerUp(EmuTime::param time)
{
        scc.powerUp(time);
        reset(time);
}
 
void RomKonamiSCC::bankSwitch(unsigned page, unsigned block)
{
        setRom(page, block);
 
        // Note: the mirror behavior is different from RomKonami !
        if (page == 2 || page == 3) {
                // [0x4000-0x8000), mirrored in [0xC000-0x10000)
                setRom(page + 4, block);
        } else if (page == 4 || page == 5) {
                // [0x8000-0xC000), mirrored in [0x0000-0x4000)
                setRom(page - 4, block);
        } else {
                assert(false);
        }
}
 
void RomKonamiSCC::reset(EmuTime::param time)
{
        for (auto i : xrange(2, 6)) {
                bankSwitch(i, i - 2);
        }
 
        sccEnabled = false;
        scc.reset(time);
}
 
byte RomKonamiSCC::peekMem(word address, EmuTime::param time) const
{
        if (sccEnabled && (0x9800 <= address) && (address < 0xA000)) {
                return scc.peekMem(narrow_cast<uint8_t>(address & 0xFF), time);
        } else {
                return Rom8kBBlocks::peekMem(address, time);
        }
}
 
byte RomKonamiSCC::readMem(word address, EmuTime::param time)
{
        if (sccEnabled && (0x9800 <= address) && (address < 0xA000)) {
                return scc.readMem(narrow_cast<uint8_t>(address & 0xFF), time);
        } else {
                return Rom8kBBlocks::readMem(address, time);
        }
}
 
const byte* RomKonamiSCC::getReadCacheLine(word address) const
{
        if (sccEnabled && (0x9800 <= address) && (address < 0xA000)) {
                // don't cache SCC
                return nullptr;
        } else {
                return Rom8kBBlocks::getReadCacheLine(address);
        }
}
 
void RomKonamiSCC::writeMem(word address, byte value, EmuTime::param time)
{
        if ((address < 0x5000) || (address >= 0xC000)) {
                return;
        }
        if (sccEnabled && (0x9800 <= address) && (address < 0xA000)) {
                // write to SCC
                scc.writeMem(narrow_cast<uint8_t>(address & 0xFF), value, time);
                return;
        }
        if ((address & 0xF800) == 0x9000) {
                // SCC enable/disable
                bool newSccEnabled = ((value & 0x3F) == 0x3F);
                if (newSccEnabled != sccEnabled) {
                        sccEnabled = newSccEnabled;
                        invalidateDeviceRWCache(0x9800, 0x0800);
                }
        }
        if ((address & 0x1800) == 0x1000) {
                // page selection
                auto region = address >> 13;
                bankSwitch(region, value);
                if ((region == 4) && sccEnabled) {
                        invalidateDeviceRCache(0x9800, 0x0800);
                }
        }
}
 
byte* RomKonamiSCC::getWriteCacheLine(word address) const
{
        if ((address < 0x5000) || (address >= 0xC000)) {
                return unmappedWrite.data();
        } else if (sccEnabled && (0x9800 <= address) && (address < 0xA000)) {
                // write to SCC
                return nullptr;
        } else if ((address & 0xF800) == (0x9000 & CacheLine::HIGH)) {
                // SCC enable/disable
                return nullptr;
        } else if ((address & 0x1800) == (0x1000 & CacheLine::HIGH)) {
                // page selection
                return nullptr;
        } else {
                return unmappedWrite.data();
        }
}
 
template<typename Archive>
void RomKonamiSCC::serialize(Archive& ar, unsigned /*version*/)
{
        ar.template serializeBase<Rom8kBBlocks>(*this);
        ar.serialize("scc",        scc,
                     "sccEnabled", sccEnabled);
}
INSTANTIATE_SERIALIZE_METHODS(RomKonamiSCC);
REGISTER_MSXDEVICE(RomKonamiSCC, "RomKonamiSCC");
 
} // namespace openmsx