RomMatraCompilation.cc

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#include "RomMatraCompilation.hh"
#include "one_of.hh"
#include "serialize.hh"
#include "xrange.hh"
 
// This is basically a generic 8kB mapper (Konami like, but without fixed page
// at 0x4000), with an extra offset register accessible at 0xBA00.
// The software only writes to 0x5000, 0x6000, 0x8000, 0xA000 to switch mapper
// page. I took these as unique switching addresses, as some of the compilation
// software would write to others, causing crashes.
// It seems that a write of 1 (and probably 0, but the software doesn't do
// that) to the offset register should be ignored and will disable the mapper
// switch addresses. Values of 2 or larger written there must be lowered by 2
// to get the actual offset to use.
 
namespace openmsx {
 
RomMatraCompilation::RomMatraCompilation(const DeviceConfig& config, Rom&& rom_)
        : Rom8kBBlocks(config, std::move(rom_))
{
        reset(EmuTime::dummy());
}
 
void RomMatraCompilation::reset(EmuTime::param /*time*/)
{
        setUnmapped(0);
        setUnmapped(1);
        for (auto i : xrange(2, 6)) {
                setRom(i, i - 2);
        }
        setUnmapped(6);
        setUnmapped(7);
 
        blockOffset = 2;
}
 
void RomMatraCompilation::writeMem(word address, byte value, EmuTime::param /*time*/)
{
        if (address == 0xBA00) {
                // write of block offset
                blockOffset = value;
                // retro-actively select the blocks for this offset
                if (blockOffset >= 2) {
                        for (auto i : xrange(2, 6)) {
                                setRom(i, blockNr[i] + blockOffset - 2);
                        }
                }
        } else if ((blockOffset >= 2) &&
                   (address == one_of(0x5000, 0x6000, 0x8000, 0xA000))) {
                setRom(address >> 13, value + blockOffset - 2);
        }
}
 
byte* RomMatraCompilation::getWriteCacheLine(word address)
{
        if ((0x5000 <= address) && (address < 0xC000)) {
                return nullptr;
        } else {
                return unmappedWrite.data();
        }
}
 
template<typename Archive>
void RomMatraCompilation::serialize(Archive& ar, unsigned /*version*/)
{
        ar.template serializeBase<Rom8kBBlocks>(*this);
 
        ar.serialize("blockOffset", blockOffset);
}
INSTANTIATE_SERIALIZE_METHODS(RomMatraCompilation);
REGISTER_MSXDEVICE(RomMatraCompilation, "RomMatraCompilation");
 
} // namespace openmsx