MegaFlashRomSCCPlus.cc

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#include "MegaFlashRomSCCPlus.hh"
#include "DummyAY8910Periphery.hh"
#include "MSXCPUInterface.hh"
#include "CacheLine.hh"
#include "narrow.hh"
#include "ranges.hh"
#include "serialize.hh"
#include "xrange.hh"
#include <array>
#include <cassert>
 
/******************************************************************************
 * DOCUMENTATION AS PROVIDED BY MANUEL PAZOS, WHO DEVELOPED THE CARTRIDGE     *
 ******************************************************************************
 
--------------------------------------------------------------------------------
MegaFlashROM SCC+ Technical Details
(c) Manuel Pazos 28-09-2010
--------------------------------------------------------------------------------
 
Main features:
 - 1024KB flashROM memory (M29W800DB)
 - SCC-I (2312P001)
 - PSG (AY-3-8910/YM2149)
 - Mappers: ASCII8, ASCII16, Konami, Konami SCC, linear 64K
 - Subslot simulation (4 x 256K)
 
 
--------------------------------------------------------------------------------
[Memory]
 
 - Model Numonyx M29W800DB TSOP48
 - Datasheet: https://media-www.micron.com/-/media/client/global/documents/products/data-sheet/nor-flash/parallel/m29w/m29w800d.pdf
 - Block layout:
     #00000 16K
     #04000  8K
     #06000  8K
     #08000 32K
     #10000 64K x 15
 - Command addresses #4555 and #5AAA
 - Commands:
    AUTOSELECT  #90
    WRITE       #A0
    CHIP_ERASE  #10
    BLOCK_ERASE #30
    RESET       #F0
 - FlashROM ID = #5B
 
 
--------------------------------------------------------------------------------
[PSG]
 
 The PSG included in the cartridge is mapped to ports #10-#12
 
 Port #A0 -> #10
 Port #A1 -> #11
 Port #A2 -> #12
 
 The PSG is read only.
 
--------------------------------------------------------------------------------
[REGISTERS]
 
 -#7FFE or #7FFF = CONFIGURATION REGISTER:
    7 mapper mode 1: \ %00 = SCC,  %01 = 64K
    6 mapper mode 0: / %10 = ASC8, %11 = ASC16
    5 mapper mode  :   Select Konami mapper (0 = SCC, 1 = normal)
    4 Enable subslot mode and register #FFFF (1 = Enable, 0 = Disable)
    3 Disable #4000-#5FFF mapper in Konami mode (0 = Enable, 1 = Disable)
    2 Disable configuration register (1 = Disabled)
    1 Disable mapper registers (0 = Enable, 1 = Disable)
    0 Enable 512K mapper limit in SCC mapper or 256K limit in Konami mapper
(1 = Enable, 0 = Disable)
 
 
--------------------------------------------------------------------------------
[MAPPERS]
 
 - ASCII 8:    Common ASC8 mapper
 
 - ASCII 16:   Common ASC16 mapper
 
 - Konami:     Common Konami mapper.
               Bank0 (#4000-#5FFF) can be also changed unless CONF_REG bit3 is 1
 
 - Konami SCC: Common Konami SCC mapper
               Bank0 mapper register: if bank number bit 7 is 1 then bit 6-0 sets mapper offset.
 
 - Linear 64:  #0000-#3FFF bank0
               #4000-#7FFF bank1
               #8000-#BFFF bank2
               #C000-#FFFF bank3
               Banks mapper registers addresses = Konami
 
--------------------------------------------------------------------------------
[DEFAULT VALUES]
 - CONFIGURATION REGISTER = 0
 - Bank0 = 0
 - Bank1 = 1
 - Bank2 = 2
 - Bank3 = 3
 - Bank offset = 0
 - Subslot register = 0
 
--------------------------------------------------------------------------------
[LOGIC]
 
  Banks0-3: are set depending on the mapper mode.
  Subslots: are set writing to #FFFF in the MegaFlashROM SCC+ slot when CONFIG_REG bit 4 is set.
  Offset:   is set by writing offset value + #80 to bank0 mapper register in Konami SCC mode.
 
  -- Subslots offsets
  SubOff0 = subslot(1-0) & "0000" + mapOff;     -- In 64K mode, the banks are 16K, with the offsets halved
  SubOff1 = subslot(3-2) & "0000" + mapOff when maptyp = "10" else subslot(3-2) & "00000" + mapOff;
  SubOff2 = subslot(5-4) & "0000" + mapOff when maptyp = "10" else subslot(5-4) & "00000" + mapOff;
  SubOff3 = subslot(7-6) & "0000" + mapOff when maptyp = "10" else subslot(7-6) & "00000";
 
  -- Calculate the bank mapper to use taking into account the offset
  Bank0 =  SubBank0(x) + SubOff0 when SccModeA(4) = '1' and subslot(1 downto 0) = "00" and maptyp = "10" else
           SubBank0(1) + SubOff0 when SccModeA(4) = '1' and subslot(1 downto 0) = "01" and maptyp = "10" else
           SubBank0(2) + SubOff0 when SccModeA(4) = '1' and subslot(1 downto 0) = "10" and maptyp = "10" else
           SubBank0(3) + SubOff0 when SccModeA(4) = '1' and subslot(1 downto 0) = "11" and maptyp = "10" else
 
           SubBank0(0) + SubOff1 when SccModeA(4) = '1' and subslot(3 downto 2) = "00" else
           SubBank0(1) + SubOff1 when SccModeA(4) = '1' and subslot(3 downto 2) = "01" else
           SubBank0(2) + SubOff1 when SccModeA(4) = '1' and subslot(3 downto 2) = "10" else
           SubBank0(3) + SubOff1 when SccModeA(4) = '1' and subslot(3 downto 2) = "11" else
           SccBank0    + mapOff;
 
  Bank1 <= SubBank1(0) + SubOff1 when SccModeA(4) = '1' and subslot(3 downto 2) = "00" else
           SubBank1(1) + SubOff1 when SccModeA(4) = '1' and subslot(3 downto 2) = "01" else
           SubBank1(2) + SubOff1 when SccModeA(4) = '1' and subslot(3 downto 2) = "10" else
           SubBank1(3) + SubOff1 when SccModeA(4) = '1' and subslot(3 downto 2) = "11" else
           SccBank1    + mapOff;
 
  Bank2 <= SubBank2(0) + SubOff2 when SccModeA(4) = '1' and subslot(5 downto 4) = "00" else
           SubBank2(1) + SubOff2 when SccModeA(4) = '1' and subslot(5 downto 4) = "01" else
           SubBank2(2) + SubOff2 when SccModeA(4) = '1' and subslot(5 downto 4) = "10" else
           SubBank2(3) + SubOff2 when SccModeA(4) = '1' and subslot(5 downto 4) = "11" else
           SccBank2    + mapOff;
 
  Bank3 <= SubBank3(0) + SubOff3 when SccModeA(4) = '1' and subslot(7 downto 6) = "00" and maptyp = "10" else
           SubBank3(1) + SubOff3 when SccModeA(4) = '1' and subslot(7 downto 6) = "01" and maptyp = "10" else
           SubBank3(2) + SubOff3 when SccModeA(4) = '1' and subslot(7 downto 6) = "10" and maptyp = "10" else
           SubBank3(3) + SubOff3 when SccModeA(4) = '1' and subslot(7 downto 6) = "11" and maptyp = "10" else
 
           SubBank3(0) + SubOff2 when SccModeA(4) = '1' and subslot(5 downto 4) = "00" else
           SubBank3(1) + SubOff2 when SccModeA(4) = '1' and subslot(5 downto 4) = "01" else
           SubBank3(2) + SubOff2 when SccModeA(4) = '1' and subslot(5 downto 4) = "10" else
           SubBank3(3) + SubOff2 when SccModeA(4) = '1' and subslot(5 downto 4) = "11" else
           SccBank3    + mapOff;
 
 
            -- 64K Mode
  RamAdr <= Bank0(5 downto 0) & adr(13 downto 0) when adr(15 downto 14) = "00" and maptyp = "10" else   --#0000-#3FFF
            Bank1(5 downto 0) & adr(13 downto 0) when adr(15 downto 14) = "01" and maptyp = "10" else   --#4000-#7FFF
            Bank2(5 downto 0) & adr(13 downto 0) when adr(15 downto 14) = "10" and maptyp = "10" else   --#8000-#BFFF
            Bank3(5 downto 0) & adr(13 downto 0) when adr(15 downto 14) = "11" and maptyp = "10" else   --#C000-#FFFF
            -- Modes SCC, ASC8 and ASC16
            Bank0(6 downto 0) & adr(12 downto 0) when adr(14 downto 13) = "10" else     --#4000-#5FFF
            Bank1(6 downto 0) & adr(12 downto 0) when adr(14 downto 13) = "11" else     --#6000-#7FFF
            Bank2(6 downto 0) & adr(12 downto 0) when adr(14 downto 13) = "00" else     --#8000-#9FFF
            Bank3(6 downto 0) & adr(12 downto 0);
 
--------------------------------------------------------------------------------
[FLASH ROM ADDRESSING]
 
 In order to be compatible with OPFX which sends command sequences like
 (0x555) = 0xAA, (0xAAA) = 0x55, whilst dual mode 8/16-bit chips like the
 M29W800DB expect (0xAAA) = 0xAA, (0x555) = 0x55 when operating in byte mode,
 CPU line A12 is connected to Flash line A0.
 
  CPU line | Flash line (-1 on datasheet)
 ----------+------------------------------
  A0-A11   |  A1-A12
  A12      |  A0
  A13-A15  |  A13-A19 (through mapper)
 
 Since the smallest sector size is 8 kB, sector numbers are unaffected, only
 sector offsets are. Unfortunately, this prohibits read caching.
 
******************************************************************************/
 
namespace openmsx {
 
MegaFlashRomSCCPlus::MegaFlashRomSCCPlus(
                const DeviceConfig& config, Rom&& rom_)
        : MSXRom(config, std::move(rom_))
        , scc("MFR SCC+ SCC-I", config, getCurrentTime(), SCC::Mode::Compatible)
        , psg("MFR SCC+ PSG", DummyAY8910Periphery::instance(), config,
              getCurrentTime())
        , flash(rom, AmdFlashChip::M29W800DB, {}, config)
{
        powerUp(getCurrentTime());
        getCPUInterface().register_IO_Out_range(0x10, 2, this);
}
 
MegaFlashRomSCCPlus::~MegaFlashRomSCCPlus()
{
        getCPUInterface().unregister_IO_Out_range(0x10, 2, this);
}
 
void MegaFlashRomSCCPlus::powerUp(EmuTime::param time)
{
        scc.powerUp(time);
        reset(time);
}
 
void MegaFlashRomSCCPlus::reset(EmuTime::param time)
{
        configReg = 0;
        offsetReg = 0;
        subslotReg = 0;
        for (auto& regs : bankRegs) {
                ranges::iota(regs, byte(0));
        }
 
        sccMode = 0;
        ranges::iota(sccBanks, byte(0));
        scc.reset(time);
 
        psgLatch = 0;
        psg.reset(time);
 
        flash.reset();
 
        invalidateDeviceRCache(); // flush all to be sure
}
 
MegaFlashRomSCCPlus::SCCEnable MegaFlashRomSCCPlus::getSCCEnable() const
{
        if ((sccMode & 0x20) && (sccBanks[3] & 0x80)) {
                return EN_SCCPLUS;
        } else if ((!(sccMode & 0x20)) && ((sccBanks[2] & 0x3F) == 0x3F)) {
                return EN_SCC;
        } else {
                return EN_NONE;
        }
}
 
unsigned MegaFlashRomSCCPlus::getSubslot(unsigned addr) const
{
        return (configReg & 0x10)
             ? (subslotReg >> (2 * (addr >> 14))) & 0x03
             : 0;
}
 
unsigned MegaFlashRomSCCPlus::getFlashAddr(unsigned addr) const
{
        // Pazos: FlashROM A0 (A-1 on datasheet) is connected to CPU A12.
        addr = (addr & 0xE000) | ((addr & 0x1000) >> 12) | ((addr & 0x0FFF) << 1);
 
        unsigned subslot = getSubslot(addr);
        unsigned tmp = [&] {
                if ((configReg & 0xC0) == 0x40) {
                        unsigned bank = bankRegs[subslot][addr >> 14] + offsetReg;
                        return (bank * 0x4000) + (addr & 0x3FFF);
                } else {
                        unsigned page = (addr >> 13) - 2;
                        if (page >= 4) {
                                // Bank: -2, -1, 4, 5. So not mapped in this region,
                                // returned value should not be used. But querying it
                                // anyway is easier, see start of writeMem().
                                return unsigned(-1);
                        }
                        unsigned bank = bankRegs[subslot][page] + offsetReg;
                        return (bank * 0x2000) + (addr & 0x1FFF);
                }
        }();
        return ((0x40000 * subslot) + tmp) & 0xFFFFF; // wrap at 1MB
}
 
byte MegaFlashRomSCCPlus::peekMem(word addr, EmuTime::param time) const
{
        if ((configReg & 0x10) && (addr == 0xFFFF)) {
                // read subslot register
                return subslotReg ^ 0xFF;
        }
 
        if ((configReg & 0xE0) == 0x00) {
                SCCEnable enable = getSCCEnable();
                if (((enable == EN_SCC)     && (0x9800 <= addr) && (addr < 0xA000)) ||
                    ((enable == EN_SCCPLUS) && (0xB800 <= addr) && (addr < 0xC000))) {
                        return scc.peekMem(narrow_cast<uint8_t>(addr & 0xFF), time);
                }
        }
 
        if (((configReg & 0xC0) == 0x40) ||
            ((0x4000 <= addr) && (addr < 0xC000))) {
                // read (flash)rom content
                unsigned flashAddr = getFlashAddr(addr);
                assert(flashAddr != unsigned(-1));
                return flash.peek(flashAddr);
        } else {
                // unmapped read
                return 0xFF;
        }
}
 
byte MegaFlashRomSCCPlus::readMem(word addr, EmuTime::param time)
{
        if ((configReg & 0x10) && (addr == 0xFFFF)) {
                // read subslot register
                return subslotReg ^ 0xFF;
        }
 
        if ((configReg & 0xE0) == 0x00) {
                SCCEnable enable = getSCCEnable();
                if (((enable == EN_SCC)     && (0x9800 <= addr) && (addr < 0xA000)) ||
                    ((enable == EN_SCCPLUS) && (0xB800 <= addr) && (addr < 0xC000))) {
                        return scc.readMem(narrow_cast<uint8_t>(addr & 0xFF), time);
                }
        }
 
        if (((configReg & 0xC0) == 0x40) ||
            ((0x4000 <= addr) && (addr < 0xC000))) {
                // read (flash)rom content
                unsigned flashAddr = getFlashAddr(addr);
                assert(flashAddr != unsigned(-1));
                return flash.read(flashAddr);
        } else {
                // unmapped read
                return 0xFF;
        }
}
 
const byte* MegaFlashRomSCCPlus::getReadCacheLine(word addr) const
{
        if ((configReg & 0x10) &&
            ((addr & CacheLine::HIGH) == (0xFFFF & CacheLine::HIGH))) {
                // read subslot register
                return nullptr;
        }
 
        if ((configReg & 0xE0) == 0x00) {
                SCCEnable enable = getSCCEnable();
                if (((enable == EN_SCC)     && (0x9800 <= addr) && (addr < 0xA000)) ||
                    ((enable == EN_SCCPLUS) && (0xB800 <= addr) && (addr < 0xC000))) {
                        return nullptr;
                }
        }
 
        if (((configReg & 0xC0) == 0x40) ||
            ((0x4000 <= addr) && (addr < 0xC000))) {
                return nullptr; // uncacheable due to address swizzling
        } else {
                // unmapped read
                return unmappedRead.data();
        }
}
 
void MegaFlashRomSCCPlus::writeMem(word addr, byte value, EmuTime::param time)
{
        // address is calculated before writes to other regions take effect
        unsigned flashAddr = getFlashAddr(addr);
 
        // 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.
        if ((configReg & 0x10) && (addr == 0xFFFF)) {
                // write subslot register
                byte diff = value ^ subslotReg;
                subslotReg = value;
                for (auto i : xrange(4)) {
                        if (diff & (3 << (2 * i))) {
                                invalidateDeviceRCache(0x4000 * i, 0x4000);
                        }
                }
        }
 
        if (((configReg & 0x04) == 0x00) && ((addr & 0xFFFE) == 0x7FFE)) {
                // write config register
                configReg = value;
                invalidateDeviceRCache(); // flush all to be sure
        }
 
        if ((configReg & 0xE0) == 0x00) {
                // Konami-SCC
                if ((addr & 0xFFFE) == 0xBFFE) {
                        sccMode = value;
                        scc.setMode((value & 0x20) ? SCC::Mode::Plus
                                                   : SCC::Mode::Compatible);
                        invalidateDeviceRCache(0x9800, 0x800);
                        invalidateDeviceRCache(0xB800, 0x800);
                }
                SCCEnable enable = getSCCEnable();
                bool isRamSegment2 = ((sccMode & 0x24) == 0x24) ||
                                     ((sccMode & 0x10) == 0x10);
                bool isRamSegment3 = ((sccMode & 0x10) == 0x10);
                if (((enable == EN_SCC)     && !isRamSegment2 &&
                     (0x9800 <= addr) && (addr < 0xA000)) ||
                    ((enable == EN_SCCPLUS) && !isRamSegment3 &&
                     (0xB800 <= addr) && (addr < 0xC000))) {
                        scc.writeMem(narrow_cast<uint8_t>(addr & 0xFF), value, time);
                        return; // Pazos: when SCC registers are selected flashROM is not seen, so it does not accept commands.
                }
        }
 
        unsigned subslot = getSubslot(addr);
        unsigned page8kB = (addr >> 13) - 2;
        if (((configReg & 0x02) == 0x00) && (page8kB < 4)) {
                // (possibly) write to bank registers
                switch (configReg & 0xE0) {
                case 0x00:
                        // Konami-SCC
                        if ((addr & 0x1800) == 0x1000) {
                                // Storing 'sccBanks' may seem redundant at
                                // first, but it's required to calculate
                                // whether the SCC is enabled or not.
                                sccBanks[page8kB] = value;
                                if ((value & 0x80) && (page8kB == 0)) {
                                        offsetReg = value & 0x7F;
                                        invalidateDeviceRCache(0x4000, 0x8000);
                                } else {
                                        // Masking of the mapper bits is done on
                                        // write (and only in Konami(-scc) mode)
                                        byte mask = (configReg & 0x01) ? 0x3F : 0x7F;
                                        bankRegs[subslot][page8kB] = value & mask;
                                        invalidateDeviceRCache(0x4000 + 0x2000 * page8kB, 0x2000);
                                }
                        }
                        break;
                case 0x20: {
                        // Konami
                        if (((configReg & 0x08) == 0x08) && (addr < 0x6000)) {
                                // Switching 0x4000-0x5FFF disabled.
                                // This bit blocks writing to the bank register
                                // (an alternative was forcing a 0 on read).
                                // It only has effect in Konami mode.
                                break;
                        }
                        // Making of the mapper bits is done on
                        // write (and only in Konami(-scc) mode)
                        if ((addr < 0x5000) || ((0x5800 <= addr) && (addr < 0x6000))) break; // only SCC range works
                        byte mask = (configReg & 0x01) ? 0x1F : 0x7F;
                        bankRegs[subslot][page8kB] = value & mask;
                        invalidateDeviceRCache(0x4000 + 0x2000 * page8kB, 0x2000);
                        break;
                }
                case 0x40:
                case 0x60:
                        // 64kB
                        bankRegs[subslot][page8kB] = value;
                        invalidateDeviceRCache(0x0000 + 0x4000 * page8kB, 0x4000);
                        break;
                case 0x80:
                case 0xA0:
                        // ASCII-8
                        if ((0x6000 <= addr) && (addr < 0x8000)) {
                                byte bank = (addr >> 11) & 0x03;
                                bankRegs[subslot][bank] = value;
                                invalidateDeviceRCache(0x4000 + 0x2000 * bank, 0x2000);
                        }
                        break;
                case 0xC0:
                case 0xE0:
                        // ASCII-16
                        // This behaviour is confirmed by Manuel Pazos (creator
                        // of the cartridge): ASCII-16 uses all 4 bank registers
                        // and one bank switch changes 2 registers at once.
                        // This matters when switching mapper mode, because
                        // the content of the bank registers is unchanged after
                        // a switch.
                        if ((0x6000 <= addr) && (addr < 0x6800)) {
                                bankRegs[subslot][0] = narrow_cast<uint8_t>(2 * value + 0);
                                bankRegs[subslot][1] = narrow_cast<uint8_t>(2 * value + 1);
                                invalidateDeviceRCache(0x4000, 0x4000);
                        }
                        if ((0x7000 <= addr) && (addr < 0x7800)) {
                                bankRegs[subslot][2] = narrow_cast<uint8_t>(2 * value + 0);
                                bankRegs[subslot][3] = narrow_cast<uint8_t>(2 * value + 1);
                                invalidateDeviceRCache(0x8000, 0x4000);
                        }
                        break;
                }
        }
 
        // write to flash
        if (((configReg & 0xC0) == 0x40) ||
            ((0x4000 <= addr) && (addr < 0xC000))) {
                assert(flashAddr != unsigned(-1));
                return flash.write(flashAddr, value);
        }
}
 
byte* MegaFlashRomSCCPlus::getWriteCacheLine(word /*addr*/)
{
        return nullptr;
}
 
 
void MegaFlashRomSCCPlus::writeIO(word port, byte value, EmuTime::param time)
{
        if ((port & 0xFF) == 0x10) {
                psgLatch = value & 0x0F;
        } else {
                assert((port & 0xFF) == 0x11);
                psg.writeRegister(psgLatch, value, time);
        }
}
 
 
template<typename Archive>
void MegaFlashRomSCCPlus::serialize(Archive& ar, unsigned /*version*/)
{
        // skip MSXRom base class
        ar.template serializeBase<MSXDevice>(*this);
 
        ar.serialize("scc",        scc,
                     "psg",        psg,
                     "flash",      flash,
 
                     "configReg",  configReg,
                     "offsetReg",  offsetReg,
                     "subslotReg", subslotReg,
                     "bankRegs",   bankRegs,
                     "psgLatch",   psgLatch,
                     "sccMode",    sccMode,
                     "sccBanks",   sccBanks);
}
INSTANTIATE_SERIALIZE_METHODS(MegaFlashRomSCCPlus);
REGISTER_MSXDEVICE(MegaFlashRomSCCPlus, "MegaFlashRomSCCPlus");
 
} // namespace openmsx