RomZemina90in1.cc

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// Zemina 90-in-1 cartridge
//
//  90 in 1 uses Port &H77 for mapping:
//    bits 0-5: selected 16KB page
//    bits 6-7: addressing mode...
//      00 = same page at 4000-7FFF and 8000-BFFF (normal mode)
//      01 = same page at 4000-7FFF and 8000-BFFF (normal mode)
//      10 = [page AND 3E] at 4000-7FFF, [page AND 3E OR 01] at 8000-BFFF
//           (32KB mode)
//      11 = same page at 4000-7FFF and 8000-BFFF, but 8000-BFFF has high 8KB
//           and low 8KB swapped (Namco mode)
 
#include "RomZemina90in1.hh"
#include "MSXCPUInterface.hh"
#include "serialize.hh"
#include "unreachable.hh"
 
namespace openmsx {
 
RomZemina90in1::RomZemina90in1(const DeviceConfig& config, Rom&& rom_)
        : Rom8kBBlocks(config, std::move(rom_))
{
        reset(EmuTime::dummy());
        getCPUInterface().register_IO_Out(0x77, this);
}
 
RomZemina90in1::~RomZemina90in1()
{
        getCPUInterface().unregister_IO_Out(0x77, this);
}
 
void RomZemina90in1::reset(EmuTime::param time)
{
        setUnmapped(0);
        setUnmapped(1);
        setUnmapped(6);
        setUnmapped(7);
        writeIO(0x77, 0, time);
}
 
void RomZemina90in1::writeIO(word /*port*/, byte value, EmuTime::param /*time*/)
{
        byte page = 2 * (value & 0x3F);
        switch (value & 0xC0) {
        case 0x00:
        case 0x40:
                setRom(2, page + 0);
                setRom(3, page + 1);
                setRom(4, page + 0);
                setRom(5, page + 1);
                break;
        case 0x80:
                setRom(2, (page & ~2) + 0);
                setRom(3, (page & ~2) + 1);
                setRom(4, (page |  2) + 0);
                setRom(5, (page |  2) + 1);
                break;
        case 0xC0:
                setRom(2, page + 0);
                setRom(3, page + 1);
                setRom(4, page + 1);
                setRom(5, page + 0);
                break;
        default:
                UNREACHABLE;
        }
}
 
byte* RomZemina90in1::getWriteCacheLine(word /*address*/) const
{
        return unmappedWrite.data();
}
 
REGISTER_MSXDEVICE(RomZemina90in1, "RomZemina90in1");
 
} // namespace openmsx