ReproCartridgeV1.cc

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#include "ReproCartridgeV1.hh"
#include "DummyAY8910Periphery.hh"
#include "MSXCPUInterface.hh"
#include "narrow.hh"
#include "serialize.hh"
#include <array>
 
 
/******************************************************************************
 * DOCUMENTATION AS PROVIDED BY MANUEL PAZOS, WHO DEVELOPED THE CARTRIDGE     *
 ******************************************************************************
 
   Repro Cartridge version 1 is similar to Konami Ultimate Collection. It
   uses the same flashROM, SCC/SCC+. But it only supports Konami SCC mapper.
 
   Released were cartridges with the following content (at least): only Metal
   Gear, only Metal Gear 2
 
[REGISTER (#7FFF)]
If it contains value 0x50, the flash is writable and the mapper is disabled.
Otherwise, the mapper is enabled and the flash is readonly.
 
- Mapper supports 4 different ROMs of 2MB each, with the KonamiSCC mapper
- Cartridge has a PSG at 0x10, write only
- On I/O port 0x13 the 2MB block can be selected (default 0, so up to 3)
 
******************************************************************************/
 
namespace openmsx {
 
ReproCartridgeV1::ReproCartridgeV1(
                const DeviceConfig& config, Rom&& rom_)
        : MSXRom(config, std::move(rom_))
        , flash(rom, AmdFlashChip::M29W640GB, {}, config)
        , scc("ReproCartV1 SCC", config, getCurrentTime(), SCC::Mode::Compatible)
        , psg("ReproCartV1 PSG", DummyAY8910Periphery::instance(), config,
              getCurrentTime())
{
        powerUp(getCurrentTime());
        auto& cpuInterface = getCPUInterface();
        for (auto port : {0x10, 0x11, 0x13}) {
                cpuInterface.register_IO_Out(narrow_cast<byte>(port), this);
        }
}
 
ReproCartridgeV1::~ReproCartridgeV1()
{
        auto& cpuInterface = getCPUInterface();
        for (auto port : {0x10, 0x11, 0x13}) {
                cpuInterface.unregister_IO_Out(narrow_cast<byte>(port), this);
        }
}
 
void ReproCartridgeV1::powerUp(EmuTime::param time)
{
        scc.powerUp(time);
        reset(time);
}
 
void ReproCartridgeV1::reset(EmuTime::param time)
{
        flashRomWriteEnabled = false;
        mainBankReg = 0;
        sccMode = 0;
        ranges::iota(bankRegs, byte(0));
 
        scc.reset(time);
        psgLatch = 0;
        psg.reset(time);
 
        flash.reset();
 
        invalidateDeviceRCache(); // flush all to be sure
}
 
unsigned ReproCartridgeV1::getFlashAddr(unsigned addr) const
{
        unsigned page8kB = (addr >> 13) - 2;
        if (page8kB >= 4) return unsigned(-1); // outside [0x4000, 0xBFFF]
 
        byte bank = bankRegs[page8kB]; // 2MB max
        return (mainBankReg << 21) | (bank << 13) | (addr & 0x1FFF);
}
 
// Note: implementation (mostly) copied from KUC
bool ReproCartridgeV1::isSCCAccess(word addr) const
{
        if (sccMode & 0x10) return false;
 
        if (addr & 0x0100) {
                // Address bit 8 must be zero, this is different from a real
                // SCC/SCC+. According to Manuel Pazos this is a leftover from
                // an earlier version that had 2 SCCs: the SCC on the left or
                // right channel reacts when address bit 8 is respectively 0/1.
                return false;
        }
 
        if (sccMode & 0x20) {
                // SCC+   range: 0xB800..0xBFFF,  excluding 0xBFFE-0xBFFF
                return  (bankRegs[3] & 0x80)          && (0xB800 <= addr) && (addr < 0xBFFE);
        } else {
                // SCC    range: 0x9800..0x9FFF,  excluding 0x9FFE-0x9FFF
                return ((bankRegs[2] & 0x3F) == 0x3F) && (0x9800 <= addr) && (addr < 0x9FFE);
        }
}
 
byte ReproCartridgeV1::readMem(word addr, EmuTime::param time)
{
        if (isSCCAccess(addr)) {
                return scc.readMem(narrow_cast<uint8_t>(addr & 0xFF), time);
        }
 
        unsigned flashAddr = getFlashAddr(addr);
        return (flashAddr != unsigned(-1))
                ? flash.read(flashAddr)
                : 0xFF; // unmapped read
}
 
byte ReproCartridgeV1::peekMem(word addr, EmuTime::param time) const
{
        if (isSCCAccess(addr)) {
                return scc.peekMem(narrow_cast<uint8_t>(addr & 0xFF), time);
        }
 
        unsigned flashAddr = getFlashAddr(addr);
        return (flashAddr != unsigned(-1))
                ? flash.peek(flashAddr)
                : 0xFF; // unmapped read
}
 
const byte* ReproCartridgeV1::getReadCacheLine(word addr) const
{
        if (isSCCAccess(addr)) return nullptr;
 
        unsigned flashAddr = getFlashAddr(addr);
        return (flashAddr != unsigned(-1))
                ? flash.getReadCacheLine(flashAddr)
                : unmappedRead.data();
}
 
void ReproCartridgeV1::writeMem(word addr, byte value, EmuTime::param time)
{
        unsigned page8kB = (addr >> 13) - 2;
        if (page8kB >= 4) return; // outside [0x4000, 0xBFFF]
 
        // There are several overlapping functional regions in the address
        // space. A single write can trigger behaviour in multiple regions. In
        // other words there's no priority amongst the regions where a higher
        // priority region blocks the write from the lower priority regions.
        // This only goes for places where the flash is 'seen', so not for the
        // SCC registers
 
        if (isSCCAccess(addr)) {
                scc.writeMem(narrow_cast<uint8_t>(addr & 0xFF), value, time);
                return; // write to SCC blocks write to other functions
        }
 
        // address is calculated before writes to other regions take effect
        unsigned flashAddr = getFlashAddr(addr);
 
        // Main mapper register
        if (addr == 0x7FFF) {
                flashRomWriteEnabled = (value == 0x50);
                invalidateDeviceRCache(); // flush all to be sure
        }
 
        if (!flashRomWriteEnabled) {
                // Konami-SCC
                if ((addr & 0x1800) == 0x1000) {
                        // [0x5000,0x57FF] [0x7000,0x77FF]
                        // [0x9000,0x97FF] [0xB000,0xB7FF]
                        bankRegs[page8kB] = value;
                        invalidateDeviceRCache(0x4000 + 0x2000 * page8kB, 0x2000);
                }
 
                // SCC mode register
                if ((addr & 0xFFFE) == 0xBFFE) {
                        sccMode = value;
                        scc.setMode((value & 0x20) ? SCC::Mode::Plus
                                                   : SCC::Mode::Compatible);
                        invalidateDeviceRCache(0x9800, 0x800);
                        invalidateDeviceRCache(0xB800, 0x800);
                }
        } else {
                if (flashAddr != unsigned(-1)) {
                        flash.write(flashAddr, value);
                }
        }
}
 
byte* ReproCartridgeV1::getWriteCacheLine(word addr)
{
        return ((0x4000 <= addr) && (addr < 0xC000))
               ? nullptr        // [0x4000,0xBFFF] isn't cacheable
               : unmappedWrite.data();
}
 
void ReproCartridgeV1::writeIO(word port, byte value, EmuTime::param time)
{
        switch (port & 0xFF)
        {
                case 0x10:
                        psgLatch = value & 0x0F;
                        break;
                case 0x11:
                        psg.writeRegister(psgLatch, value, time);
                        break;
                case 0x13:
                        mainBankReg = value & 3;
                        invalidateDeviceRCache(); // flush all to be sure
                        break;
                default: UNREACHABLE;
        }
}
 
template<typename Archive>
void ReproCartridgeV1::serialize(Archive& ar, unsigned /*version*/)
{
        // skip MSXRom base class
        ar.template serializeBase<MSXDevice>(*this);
 
        ar.serialize("flash",       flash,
                     "scc",         scc,
                     "psg",         psg,
                     "psgLatch",    psgLatch,
                     "flashRomWriteEnabled", flashRomWriteEnabled,
                     "mainBankReg", mainBankReg,
                     "sccMode",     sccMode,
                     "bankRegs",    bankRegs);
}
INSTANTIATE_SERIALIZE_METHODS(ReproCartridgeV1);
REGISTER_MSXDEVICE(ReproCartridgeV1, "ReproCartridgeV1");
 
} // namespace openmsx