RomRType.cc

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// R-Type cartridges
//
// The address to change banks:
//  first  16kb: fixed at 0x0f or 0x17 (both have the same content)
//  second 16kb: 0x4000 - 0x7FFF (0x7000 and 0x7800 used)
//               bit 4 selects ROM chip,
//                if low  bit 3-0 select page
//                   high     2-0
// Thanks to n_n for investigating this on a real cartridge.
 
#include "RomRType.hh"
#include "serialize.hh"
 
namespace openmsx {
 
RomRType::RomRType(const DeviceConfig& config, Rom&& rom_)
        : Rom16kBBlocks(config, std::move(rom_))
{
        reset(EmuTime::dummy());
}
 
void RomRType::reset(EmuTime::param /*time*/)
{
        setUnmapped(0);
        setRom(1, 0x17);
        setRom(2, 0);
        setUnmapped(3);
}
 
void RomRType::writeMem(word address, byte value, EmuTime::param /*time*/)
{
        if ((0x4000 <= address) && (address < 0x8000)) {
                value &= (value & 0x10) ? 0x17 : 0x1F;
                setRom(2, value);
        }
}
 
byte* RomRType::getWriteCacheLine(word address)
{
        if ((0x4000 <= address) && (address < 0x8000)) {
                return nullptr;
        } else {
                return unmappedWrite.data();
        }
}
 
REGISTER_MSXDEVICE(RomRType, "RomRType");
 
} // namespace openmsx