RomFSA1FM.cc

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// FS-A1FM mappers
//   based on info from:
//   http://sourceforge.net/tracker/index.php?func=detail&aid=672508&group_id=38274&atid=421864
//
// Slot 3-1
//   0x4000-0x5FFF  16 x 8kB ROM, same 16 pages as mapper in slot 3-3
//   0x6000-0x7FFF  8kB RAM   (mapped ???)
//   0x7FC0-0x7FCF  I/O area
//     0x7FC0 (R/W)   8251 (UART) data register
//     0x7FC1 (R/W)   8251 (UART) command/status register
//     0x7FC4 (?)     ROM switch address, lower 4 bits -> selected bank
//                                        upper 4 bits -> ??? (always preserved)
//     0x7FC5 (W)     ???
//     0x7FC6 (R)     ???
//     0x7FC8 (W)     ???
//     0x7FCC (W)     ???
//
// Slot 3-3
//   Very similar to other Panasonic-8kB rom mappers
//
//   0x0000-0x1FFF  switch address 0x6400, read-back 0x7FF0, initial value 0xA8
//   0x2000-0x3FFF  switch address 0x6C00, read-back 0x7FF1, initial value 0xA8
//   0x4000-0x5FFF  switch address 0x6000, read-back 0x7FF2, initial value 0xA8
//   0x6000-0x7FFF  switch address 0x6800, read-back 0x7FF3, initial value 0xA8
//   0x8000-0x9FFF  switch address 0x7000, read-back 0x7FF4, initial value 0xA8
//   0xA000-0xBFFF  switch address 0x7800, read-back 0x7FF5, initial value 0xA8
//
//   0x7FF6-0x7FF7  always read 0
//   0x7FF9         control byte, bit2 activates 0x7FF0-0x7FF7
//
//   mapper pages 0x10-0x7F            mirrored at 0x90-0xFF
//                0x80-0x83 0x88-0x8B  unmapped (read 0xFF)
//                0x84-0x87 0x8C-0x8F  contain (same) 8kB RAM

#include "RomFSA1FM.hh"
#include "CacheLine.hh"
#include "SRAM.hh"
#include "MSXMotherBoard.hh"
#include "MSXException.hh"
#include "serialize.hh"
#include <memory>

namespace openmsx {

// 8kb shared sram //

static std::shared_ptr<SRAM> getSram(const DeviceConfig& config)
{
        return config.getMotherBoard().getSharedStuff<SRAM>(
                "FSA1FM-sram",
                config.getAttribute("id") + " SRAM", 0x2000, config);
}


// Mapper for slot 3-1 //

RomFSA1FM1::RomFSA1FM1(const DeviceConfig& config, Rom&& rom_)
        : MSXRom(config, std::move(rom_))
        , fsSram(getSram(config))
        , firmwareSwitch(config)
{
        if ((rom.getSize() != 0x100000) &&
            (rom.getSize() != 0x200000)) {
                throw MSXException(
                        "Rom for FSA1FM mapper must be 1MB in size "
                        "(some dumps are 2MB, those can be used as well).");
        }
}

void RomFSA1FM1::reset(EmuTime::param /*time*/)
{
        // initial rom bank is undefined
}

byte RomFSA1FM1::peekMem(word address, EmuTime::param /*time*/) const
{
        if ((0x4000 <= address) && (address < 0x6000)) {
                // read rom
                return rom[(0x2000 * ((*fsSram)[0x1FC4] & 0x0F)) +
                              (address & 0x1FFF)];
        } else if ((0x7FC0 <= address) && (address < 0x7FD0)) {
                switch (address & 0x0F) {
                case 4:
                        return (*fsSram)[address & 0x1FFF];
                case 6:
                        return firmwareSwitch.getStatus() ? 0xFB : 0xFF;
                default:
                        return 0xFF;
                }
        } else if ((0x6000 <= address) && (address < 0x8000)) {
                // read sram
                // TODO are there multiple sram blocks?
                return (*fsSram)[address & 0x1FFF];
        } else {
                return 0xFF;
        }
}

byte RomFSA1FM1::readMem(word address, EmuTime::param time)
{
        return RomFSA1FM1::peekMem(address, time);
}

const byte* RomFSA1FM1::getReadCacheLine(word address) const
{
        if (address == (0x7FC0 & CacheLine::HIGH)) {
                // dont't cache IO area
                return nullptr;
        } else if ((0x4000 <= address) && (address < 0x6000)) {
                // read rom
                return &rom[(0x2000 * ((*fsSram)[0x1FC4] & 0x0F)) +
                               (address & 0x1FFF)];
        } else if ((0x6000 <= address) && (address < 0x8000)) {
                // read sram
                return &(*fsSram)[address & 0x1FFF];
        } else {
                return unmappedRead;
        }
}

void RomFSA1FM1::writeMem(word address, byte value, EmuTime::param /*time*/)
{
        // TODO 0x7FC0 - 0x7FCF is modem IO area

        if ((0x6000 <= address) && (address < 0x8000)) {
                if (address == 0x7FC4) {
                        // switch rom bank
                        invalidateMemCache(0x4000, 0x2000);
                }
                fsSram->write(address & 0x1FFF, value);
        }
}

byte* RomFSA1FM1::getWriteCacheLine(word address) const
{
        if (address == (0x7FC0 & CacheLine::HIGH)) {
                // dont't cache IO area
                return nullptr;
        } else if ((0x6000 <= address) && (address < 0x8000)) {
                // don't cache SRAM writes
                return nullptr;
        } else {
                return unmappedWrite;
        }
}

template<typename Archive>
void RomFSA1FM1::serialize(Archive& ar, unsigned /*version*/)
{
        // skip MSXRom base class
        ar.template serializeBase<MSXDevice>(*this);
        // don't serialize (shared) sram here, rely on RomFSA1FM2 to do that
}
INSTANTIATE_SERIALIZE_METHODS(RomFSA1FM1);
REGISTER_MSXDEVICE(RomFSA1FM1, "RomFSA1FM1");


// Mapper for slot 3-3 //

RomFSA1FM2::RomFSA1FM2(const DeviceConfig& config, Rom&& rom_)
        : Rom8kBBlocks(config, std::move(rom_))
        , fsSram(getSram(config))
{
        reset(EmuTime::dummy());
}

void RomFSA1FM2::reset(EmuTime::param /*time*/)
{
        control = 0;
        for (int region = 0; region < 6; ++region) {
                changeBank(region, 0xA8);
        }
        changeBank(6, 0);
        changeBank(7, 0);
}

byte RomFSA1FM2::peekMem(word address, EmuTime::param time) const
{
        byte result;
        if (0xC000 <= address) {
                result = 0xFF;
        } else if ((control & 0x04) && (0x7FF0 <= address) && (address < 0x7FF8)) {
                // read mapper state
                result = bankSelect[address & 7];
        } else if (isRam[address >> 13]) {
                result = (*fsSram)[address & 0x1FFF];
        } else if (isEmpty[address >> 13]) {
                result = 0xFF;
        } else {
                result = Rom8kBBlocks::peekMem(address, time);
        }
        return result;
}

byte RomFSA1FM2::readMem(word address, EmuTime::param time)
{
        return RomFSA1FM2::peekMem(address, time);
}

const byte* RomFSA1FM2::getReadCacheLine(word address) const
{
        if (0xC000 <= address) {
                return unmappedRead;
        } else if ((0x7FF0 & CacheLine::HIGH) == address) {
                return nullptr;
        } else if (isRam[address >> 13]) {
                return &(*fsSram)[address & 0x1FFF];
        } else if (isEmpty[address >> 13]) {
                return unmappedRead;
        } else {
                return Rom8kBBlocks::getReadCacheLine(address);
        }
}

void RomFSA1FM2::writeMem(word address, byte value,
                          EmuTime::param /*time*/)
{
        if ((0x6000 <= address) && (address < 0x7FF0)) {
                // set mapper state
                switch (address & 0x1C00) {
                case 0x0000:
                        changeBank(2, value);
                        break;
                case 0x0400:
                        changeBank(0, value);
                        break;
                case 0x0800:
                        changeBank(3, value);
                        break;
                case 0x0C00:
                        changeBank(1, value);
                        break;
                case 0x1000:
                        changeBank(4, value);
                        break;
                case 0x1400:
                        // nothing
                        break;
                case 0x1800:
                        changeBank(5, value);
                        break;
                case 0x1C00:
                        // nothing
                        break;
                }
        } else if (address == 0x7FF9) {
                // write control byte
                control = value;
        } else if (isRam[address >> 13]) {
                fsSram->write(address & 0x1FFF, value);
        }
}

byte* RomFSA1FM2::getWriteCacheLine(word address) const
{
        if ((0x6000 <= address) && (address < 0x8000)) {
                return nullptr;
        } else if (isRam[address >> 13]) {
                return nullptr;
        } else {
                return unmappedWrite;
        }
}

void RomFSA1FM2::changeBank(byte region, byte bank)
{
        bankSelect[region] = bank;
        if ((0x80 <= bank) && (bank < 0x90)) {
                if (bank & 0x04) {
                        isRam[region]   = true;
                        isEmpty[region] = false;
                } else {
                        isRam[region]   = false;
                        isEmpty[region] = true;
                }
                invalidateMemCache(0x2000 * region, 0x2000);
        } else {
                isRam[region]   = false;
                isEmpty[region] = false;
                setRom(region, bank & 0x7F);
        }
}

template<typename Archive>
void RomFSA1FM2::serialize(Archive& ar, unsigned /*version*/)
{
        ar.template serializeBase<Rom8kBBlocks>(*this);
        // note: SRAM can be serialized in this class (as opposed to
        //       Rom8kBBlocks), because we don't use setBank to map it
        ar.serialize("SRAM",       *fsSram,
                     "bankSelect", bankSelect,
                     "control",    control);
        if (ar.isLoader()) {
                // recalculate 'isRam' and 'isEmpty' from bankSelect
                for (int region = 0; region < 8; ++region) {
                        changeBank(region, bankSelect[region]);
                }
        }
}
INSTANTIATE_SERIALIZE_METHODS(RomFSA1FM2);
REGISTER_MSXDEVICE(RomFSA1FM2, "RomFSA1FM2");

} // namespace openmsx