NowindHost.cc

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#include "NowindHost.hh"
#include "DiskContainer.hh"
#include "SectorAccessibleDisk.hh"
#include "serialize.hh"
#include "serialize_stl.hh"
#include "unreachable.hh"
#include <algorithm>
#include <cassert>
#include <cctype>
#include <cstdio>
#include <cstdarg>
#include <ctime>
#include <fstream>
#include <memory>

using std::string;
using std::vector;
using std::fstream;
using std::ios;

namespace openmsx {

static const unsigned SECTOR_SIZE = sizeof(SectorBuffer);

static void DBERR(const char* message, ...)
{
        (void)message;
#if 0
        va_list args;
        va_start(args, message);
        printf("nowind: ");
        vprintf(message, args);
        va_end(args);
#endif
}


NowindHost::NowindHost(const Drives& drives_)
        : drives(drives_)
        , lastTime(0)
        , state(STATE_SYNC1)
        , romdisk(255)
        , allowOtherDiskroms(false)
        , enablePhantomDrives(true)
{
}

NowindHost::~NowindHost() = default;

byte NowindHost::peek() const
{
        return isDataAvailable() ? hostToMsxFifo.front() : 0xFF;
}

// receive:  msx <- pc
byte NowindHost::read()
{
        return isDataAvailable() ? hostToMsxFifo.pop_front() : 0xFF;
}

bool NowindHost::isDataAvailable() const
{
        return !hostToMsxFifo.empty();
}


// send:  msx -> pc
void NowindHost::write(byte data, unsigned time)
{
        unsigned duration = time - lastTime;
        lastTime = time;
        if (duration >= 500) {
                // timeout (500ms), start looking for AF05
                purge();
                state = STATE_SYNC1;
        }

        switch (state) {
        case STATE_SYNC1:
                if (data == 0xAF) state = STATE_SYNC2;
                break;
        case STATE_SYNC2:
                switch (data) {
                case 0x05: state = STATE_COMMAND; recvCount = 0; break;
                case 0xAF: state = STATE_SYNC2; break;
                case 0xFF: state = STATE_SYNC1; msxReset(); break;
                default:   state = STATE_SYNC1; break;
                }
                break;
        case STATE_COMMAND:
                assert(recvCount < 9);
                cmdData[recvCount] = data;
                if (++recvCount == 9) {
                        executeCommand();
                }
                break;
        case STATE_DISKREAD:
                assert(recvCount < 2);
                extraData[recvCount] = data;
                if (++recvCount == 2) {
                        doDiskRead2();
                }
                break;
        case STATE_DISKWRITE:
                assert(recvCount < (transferSize + 2));
                extraData[recvCount] = data;
                if (++recvCount == (transferSize + 2)) {
                        doDiskWrite2();
                }
                break;
        case STATE_DEVOPEN:
                assert(recvCount < 11);
                extraData[recvCount] = data;
                if (++recvCount == 11) {
                        deviceOpen();
                }
                break;
        case STATE_IMAGE:
                assert(recvCount < 40);
                extraData[recvCount] = data;
                if ((data == 0) || (data == ':') ||
                    (++recvCount == 40)) {
                        char* eData = reinterpret_cast<char*>(extraData);
                        callImage(string(eData, recvCount));
                        state = STATE_SYNC1;
                }
                break;
        case STATE_MESSAGE:
                assert(recvCount < (240 - 1));
                extraData[recvCount] = data;
                if ((data == 0) || (++recvCount == (240 - 1))) {
                        extraData[recvCount] = 0;
                        DBERR("%s\n", reinterpret_cast<char*>(extraData));
                        state = STATE_SYNC1;
                }
                break;
        default:
                UNREACHABLE;
        }
}

void NowindHost::msxReset()
{
        for (auto& dev : devices) {
                dev.fs.reset();
        }
        DBERR("MSX reset\n");
}

SectorAccessibleDisk* NowindHost::getDisk() const
{
        byte num = cmdData[7]; // reg_a
        if (num >= drives.size()) {
                return nullptr;
        }
        return drives[num]->getSectorAccessibleDisk();
}

void NowindHost::executeCommand()
{
        assert(recvCount == 9);
        byte cmd = cmdData[8];
        switch (cmd) {
        //case 0x0D: BDOS_0DH_DiskReset();
        //case 0x0F: BDOS_0FH_OpenFile();
        //case 0x10: BDOS_10H_CloseFile();
        //case 0x11: BDOS_11H_FindFirst();
        //case 0x12: BDOS_12H_FindNext();
        //case 0x13: BDOS_13H_DeleteFile();
        //case 0x14: BDOS_14H_ReadSeq();
        //case 0x15: BDOS_15H_WriteSeq();
        //case 0x16: BDOS_16H_CreateFile();
        //case 0x17: BDOS_17H_RenameFile();
        //case 0x21: BDOS_21H_ReadRandomFile();
        //case 0x22: BDOS_22H_WriteRandomFile();
        //case 0x23: BDOS_23H_GetFileSize();
        //case 0x24: BDOS_24H_SetRandomRecordField();
        //case 0x26: BDOS_26H_WriteRandomBlock();
        //case 0x27: BDOS_27H_ReadRandomBlock();
        //case 0x28: BDOS_28H_WriteRandomFileWithZeros();
        //case 0x2A: BDOS_2AH_GetDate();
        //case 0x2B: BDOS_2BH_SetDate();
        //case 0x2C: BDOS_2CH_GetTime();
        //case 0x2D: BDOS_2DH_SetTime();
        //case 0x2E: BDOS_2EH_Verify();
        //case 0x2F: BDOS_2FH_ReadLogicalSector();
        //case 0x30: BDOS_30H_WriteLogicalSector();

        case 0x80: { // DSKIO
                auto* disk = getDisk();
                if (!disk) {
                        // no such drive or no disk inserted
                        // (causes a timeout on the MSX side)
                        state = STATE_SYNC1;
                        return;
                }
                byte reg_f = cmdData[6];
                if (reg_f & 1) { // carry flag
                        diskWriteInit(*disk);
                } else {
                        diskReadInit(*disk);
                }
                break;
        }

        case 0x81: DSKCHG();      state = STATE_SYNC1; break;
        //case 0x82: GETDPB();
        //case 0x83: CHOICE();
        //case 0x84: DSKFMT();
        case 0x85: DRIVES();      state = STATE_SYNC1; break;
        case 0x86: INIENV();      state = STATE_SYNC1; break;
        case 0x87: setDateMSX();  state = STATE_SYNC1; break;
        case 0x88: state = STATE_DEVOPEN; recvCount = 0; break;
        case 0x89: deviceClose(); state = STATE_SYNC1; break;
        //case 0x8A: deviceRandomIO(fcb);
        case 0x8B: deviceWrite(); state = STATE_SYNC1; break;
        case 0x8C: deviceRead();  state = STATE_SYNC1; break;
        //case 0x8D: deviceEof(fcb);
        //case 0x8E: auxIn();
        //case 0x8F: auxOut();
        case 0x90: state = STATE_MESSAGE; recvCount = 0; break;
        case 0xA0: state = STATE_IMAGE;   recvCount = 0; break;
        //case 0xFF: vramDump();
        default:
                // Unknown USB command!
                state = STATE_SYNC1;
                break;
        }
}

// send:  pc -> msx
void NowindHost::send(byte value)
{
        hostToMsxFifo.push_back(value);
}
void NowindHost::send16(word value)
{
        hostToMsxFifo.push_back(value & 255);
        hostToMsxFifo.push_back(value >> 8);
}

void NowindHost::purge()
{
        hostToMsxFifo.clear();
}

void NowindHost::sendHeader()
{
        send(0xFF); // needed because first read might fail!
        send(0xAF);
        send(0x05);
}

void NowindHost::DSKCHG()
{
        auto* disk = getDisk();
        if (!disk) {
                // no such drive or no disk inserted
                return;
        }

        sendHeader();
        byte num = cmdData[7]; // reg_a
        assert(num < drives.size());
        if (drives[num]->diskChanged()) {
                send(255); // changed
                // read first FAT sector (contains media descriptor)
                SectorBuffer sectorBuffer;
                if (disk->readSectors(&sectorBuffer, 1, 1)) {
                        // TODO read error
                        sectorBuffer.raw[0] = 0;
                }
                send(sectorBuffer.raw[0]); // new mediadescriptor
        } else {
                send(0); // not changed
                // TODO shouldn't we send some (dummy) byte here?
                //      nowind-diskrom seems to read it (but doesn't use it)
        }
}

void NowindHost::DRIVES()
{
        // at least one drive (MSXDOS1 cannot handle 0 drives)
        byte numberOfDrives = std::max<byte>(1, byte(drives.size()));

        byte reg_a = cmdData[7];
        sendHeader();
        send(getEnablePhantomDrives() ? 0x02 : 0);
        send(reg_a | (getAllowOtherDiskroms() ? 0 : 0x80));
        send(numberOfDrives);

        romdisk = 255; // no romdisk
        for (size_t i = 0; i < drives.size(); ++i) {
                if (drives[i]->isRomdisk()) {
                        romdisk = i;
                        break;
                }
        }
}

void NowindHost::INIENV()
{
        sendHeader();
        send(romdisk); // calculated in DRIVES()
}

void NowindHost::setDateMSX()
{
        auto td = time(nullptr);
        auto* tm = localtime(&td);

        sendHeader();
        send(tm->tm_mday);          // day
        send(tm->tm_mon + 1);       // month
        send16(tm->tm_year + 1900); // year
}


unsigned NowindHost::getSectorAmount() const
{
        byte reg_b = cmdData[1];
        return reg_b;
}
unsigned NowindHost::getStartSector() const
{
        byte reg_c = cmdData[0];
        byte reg_e = cmdData[2];
        byte reg_d = cmdData[3];
        unsigned startSector = reg_e + (reg_d * 256);
        if (reg_c < 0x80) {
                // FAT16 read/write sector
                startSector += reg_c << 16;
        }
        return startSector;
}
unsigned NowindHost::getStartAddress() const
{
        byte reg_l = cmdData[4];
        byte reg_h = cmdData[5];
        return reg_h * 256 + reg_l;
}
unsigned NowindHost::getCurrentAddress() const
{
        unsigned startAdress = getStartAddress();
        return startAdress + transfered;
}


void NowindHost::diskReadInit(SectorAccessibleDisk& disk)
{
        unsigned sectorAmount = getSectorAmount();
        buffer.resize(sectorAmount);
        unsigned startSector = getStartSector();
        if (disk.readSectors(buffer.data(), startSector, sectorAmount)) {
                // read error
                state = STATE_SYNC1;
                return;
        }

        transfered = 0;
        retryCount = 0;
        doDiskRead1();
}

void NowindHost::doDiskRead1()
{
        unsigned bytesLeft = unsigned(buffer.size() * SECTOR_SIZE) - transfered;
        if (bytesLeft == 0) {
                sendHeader();
                send(0x01); // end of receive-loop
                send(0x00); // no more data
                state = STATE_SYNC1;
                return;
        }

        static const unsigned NUMBEROFBLOCKS = 32; // 32 * 64 bytes = 2048 bytes
        transferSize = std::min(bytesLeft, NUMBEROFBLOCKS * 64); // hardcoded in firmware

        unsigned address = getCurrentAddress();
        if (address >= 0x8000) {
                if (transferSize & 0x003F) {
                        transferSectors(address, transferSize);
                } else {
                        transferSectorsBackwards(address, transferSize);
                }
        } else {
                // transfer below 0x8000
                // TODO shouldn't we also test for (transferSize & 0x3F)?
                unsigned endAddress = address + transferSize;
                if (endAddress <= 0x8000) {
                        transferSectorsBackwards(address, transferSize);
                } else {
                        transferSize = 0x8000 - address;
                        transferSectors(address, transferSize);
                }
        }

        // wait for 2 bytes
        state = STATE_DISKREAD;
        recvCount = 0;
}

void NowindHost::doDiskRead2()
{
        // diskrom sends back the last two bytes read
        assert(recvCount == 2);
        byte tail1 = extraData[0];
        byte tail2 = extraData[1];
        if ((tail1 == 0xAF) && (tail2 == 0x07)) {
                transfered += transferSize;
                retryCount = 0;

                unsigned address = getCurrentAddress();
                size_t bytesLeft = (buffer.size() * SECTOR_SIZE) - transfered;
                if ((address == 0x8000) && (bytesLeft > 0)) {
                        sendHeader();
                        send(0x01); // end of receive-loop
                        send(0xff); // more data for page 2/3
                }

                // continue the rest of the disk read
                doDiskRead1();
        } else {
                purge();
                if (++retryCount == 10) {
                        // do nothing, timeout on MSX
                        // too many retries, aborting readDisk()
                        state = STATE_SYNC1;
                        return;
                }

                // try again, wait for two bytes
                state = STATE_DISKREAD;
                recvCount = 0;
        }
}

// sends "02" + "transfer_addr" + "amount" + "data" + "0F 07"
void NowindHost::transferSectors(unsigned transferAddress, unsigned amount)
{
        sendHeader();
        send(0x00); // don't exit command, (more) data is coming
        send16(transferAddress);
        send16(amount);

        auto* bufferPointer = buffer[0].raw + transfered;
        for (unsigned i = 0; i < amount; ++i) {
                send(bufferPointer[i]);
        }
        send(0xAF);
        send(0x07); // used for validation
}

 // sends "02" + "transfer_addr" + "amount" + "data" + "0F 07"
void NowindHost::transferSectorsBackwards(unsigned transferAddress, unsigned amount)
{
        sendHeader();
        send(0x02); // don't exit command, (more) data is coming
        send16(transferAddress + amount);
        send(amount / 64);

        auto* bufferPointer = buffer[0].raw + transfered;
        for (int i = amount - 1; i >= 0; --i) {
                send(bufferPointer[i]);
        }
        send(0xAF);
        send(0x07); // used for validation
}


void NowindHost::diskWriteInit(SectorAccessibleDisk& disk)
{
        if (disk.isWriteProtected()) {
                sendHeader();
                send(1);
                send(0); // WRITEPROTECTED
                state = STATE_SYNC1;
                return;
        }

        unsigned sectorAmount = std::min(128u, getSectorAmount());
        buffer.resize(sectorAmount);
        transfered = 0;
        doDiskWrite1();
}

void NowindHost::doDiskWrite1()
{
        unsigned bytesLeft = unsigned(buffer.size() * SECTOR_SIZE) - transfered;
        if (bytesLeft == 0) {
                // All data transferred!
                auto sectorAmount = unsigned(buffer.size());
                unsigned startSector = getStartSector();
                if (auto* disk = getDisk()) {
                        if (disk->writeSectors(&buffer[0], startSector, sectorAmount)) {
                                // TODO write error
                        }
                }
                sendHeader();
                send(255);
                state = STATE_SYNC1;
                return;
        }

        static const unsigned BLOCKSIZE = 240;
        transferSize = std::min(bytesLeft, BLOCKSIZE);

        unsigned address = getCurrentAddress();
        unsigned endAddress = address + transferSize;
        if ((address ^ endAddress) & 0x8000) {
                // would cross page 1-2 boundary -> limit to page 1
                transferSize = 0x8000 - address;
        }

        sendHeader();
        send(0);          // data ahead!
        send16(address);
        send16(transferSize);
        send(0xaa);

        // wait for data
        state = STATE_DISKWRITE;
        recvCount = 0;
}

void NowindHost::doDiskWrite2()
{
        assert(recvCount == (transferSize + 2));
        auto* buf = buffer[0].raw + transfered;
        for (unsigned i = 0; i < transferSize; ++i) {
                buf[i] = extraData[i + 1];
        }

        byte seq1 = extraData[0];
        byte seq2 = extraData[transferSize + 1];
        if ((seq1 == 0xaa) && (seq2 == 0xaa)) {
                // good block received
                transfered += transferSize;

                unsigned address = getCurrentAddress();
                size_t bytesLeft = (buffer.size() * SECTOR_SIZE) - transfered;
                if ((address == 0x8000) && (bytesLeft > 0)) {
                        sendHeader();
                        send(254); // more data for page 2/3
                }
        } else {
                // ERROR!!!
                // This situation is still not handled correctly!
                purge();
        }

        // continue the rest of the disk write
        doDiskWrite1();
}


unsigned NowindHost::getFCB() const
{
        // note: same code as getStartAddress(), merge???
        byte reg_l = cmdData[4];
        byte reg_h = cmdData[5];
        return reg_h * 256 + reg_l;
}

string NowindHost::extractName(int begin, int end) const
{
        string result;
        for (int i = begin; i < end; ++i) {
                char c = extraData[i];
                if (c == ' ') break;
                result += char(toupper(c));
        }
        return result;
}

int NowindHost::getDeviceNum() const
{
        unsigned fcb = getFCB();
        for (unsigned i = 0; i < MAX_DEVICES; ++i) {
                if (devices[i].fs && devices[i].fcb == fcb) {
                        return i;
                }
        }
        return -1;
}

int NowindHost::getFreeDeviceNum()
{
        int dev = getDeviceNum();
        if (dev != -1) {
                // There already was a device open with this fcb address,
                // reuse that device.
                return dev;
        }
        // Search for free device.
        for (unsigned i = 0; i < MAX_DEVICES; ++i) {
                if (!devices[i].fs) {
                        return i;
                }
        }
        // All devices are in use. This can't happen when the MSX software
        // functions correctly. We'll simply reuse the first device. It would
        // be nicer if we reuse the oldest device, but that's harder to
        // implement, and actually it doesn't really matter.
        return 0;
}

void NowindHost::deviceOpen()
{
        state = STATE_SYNC1;

        assert(recvCount == 11);
        string filename = extractName(0, 8);
        string ext      = extractName(8, 11);
        if (!ext.empty()) {
                strAppend(filename, '.', ext);
        }

        unsigned fcb = getFCB();
        unsigned dev = getFreeDeviceNum();
        devices[dev].fs = std::make_unique<fstream>(); // takes care of deleting old fs
        devices[dev].fcb = fcb;

        sendHeader();
        byte errorCode = 0;
        byte openMode = cmdData[2]; // reg_e
        switch (openMode) {
        case 1: // read-only mode
                devices[dev].fs->open(filename.c_str(), ios::in  | ios::binary);
                errorCode = 53; // file not found
                break;
        case 2: // create new file, write-only
                devices[dev].fs->open(filename.c_str(), ios::out | ios::binary);
                errorCode = 56; // bad file name
                break;
        case 8: // append to existing file, write-only
                devices[dev].fs->open(filename.c_str(), ios::out | ios::binary | ios::app);
                errorCode = 53; // file not found
                break;
        case 4:
                send(58); // sequential I/O only
                return;
        default:
                send(0xFF); // TODO figure out a good error number
                return;
        }
        assert(errorCode != 0);
        if (devices[dev].fs->fail()) {
                devices[dev].fs.reset();
                send(errorCode);
                return;
        }

        unsigned readLen = 0;
        bool eof = false;
        char buf[256];
        if (openMode == 1) {
                // read-only mode, already buffer first 256 bytes
                readLen = readHelper1(dev, buf);
                assert(readLen <= 256);
                eof = readLen < 256;
        }

        send(0x00); // no error
        send16(fcb);
        send16(9 + readLen + (eof ? 1 : 0)); // number of bytes to transfer

        send(openMode);
        send(0);
        send(0);
        send(0);
        send(cmdData[3]); // reg_d
        send(0);
        send(0);
        send(0);
        send(0);

        if (openMode == 1) {
                readHelper2(readLen, buf);
        }
}

void NowindHost::deviceClose()
{
        int dev = getDeviceNum();
        if (dev == -1) return;
        devices[dev].fs.reset();
}

void NowindHost::deviceWrite()
{
        int dev = getDeviceNum();
        if (dev == -1) return;
        char data = cmdData[0]; // reg_c
        devices[dev].fs->write(&data, 1);
}

void NowindHost::deviceRead()
{
        int dev = getDeviceNum();
        if (dev == -1) return;

        char buf[256];
        unsigned readLen = readHelper1(dev, buf);
        bool eof = readLen < 256;
        send(0xAF);
        send(0x05);
        send(0x00); // dummy
        send16(getFCB() + 9);
        send16(readLen + (eof ? 1 : 0));
        readHelper2(readLen, buf);
}

unsigned NowindHost::readHelper1(unsigned dev, char* buf)
{
        assert(dev < MAX_DEVICES);
        unsigned len = 0;
        for (; len < 256; ++len) {
                devices[dev].fs->read(&buf[len], 1);
                if (devices[dev].fs->eof()) break;
        }
        return len;
}

void NowindHost::readHelper2(unsigned len, const char* buf)
{
        for (unsigned i = 0; i < len; ++i) {
                send(buf[i]);
        }
        if (len < 256) {
                send(0x1A); // end-of-file
        }
}


// strips a string from outer double-quotes and anything outside them
// ie: 'pre("foo")bar' will result in 'foo'
static string_view stripquotes(string_view str)
{
        auto first = str.find_first_of('\"');
        if (first == string::npos) {
                // There are no quotes, return the whole string.
                return str;
        }
        auto last = str.find_last_of ('\"');
        if (first == last) {
                // Error, there's only a single double-quote char.
                return {};
        }
        // Return the part between the quotes.
        return str.substr(first + 1, last - first - 1);
}

void NowindHost::callImage(const string& filename)
{
        byte num = cmdData[7]; // reg_a
        if (num >= drives.size()) {
                // invalid drive number
                return;
        }
        if (drives[num]->insertDisk(stripquotes(filename))) {
                // TODO error handling
        }
}


static std::initializer_list<enum_string<NowindHost::State>> stateInfo = {
        { "SYNC1",     NowindHost::STATE_SYNC1     },
        { "SYNC2",     NowindHost::STATE_SYNC2     },
        { "COMMAND",   NowindHost::STATE_COMMAND   },
        { "DISKREAD",  NowindHost::STATE_DISKREAD  },
        { "DISKWRITE", NowindHost::STATE_DISKWRITE },
        { "DEVOPEN",   NowindHost::STATE_DEVOPEN   },
        { "IMAGE",     NowindHost::STATE_IMAGE     },
};
SERIALIZE_ENUM(NowindHost::State, stateInfo);

template<typename Archive>
void NowindHost::serialize(Archive& ar, unsigned /*version*/)
{
        // drives is serialized elsewhere

        ar.serialize("hostToMsxFifo", hostToMsxFifo);
        ar.serialize("lastTime", lastTime);
        ar.serialize("state", state);
        ar.serialize("recvCount", recvCount);
        ar.serialize("cmdData", cmdData);
        ar.serialize("extraData", extraData);

        // for backwards compatibility, serialize buffer as a vector<byte>
        size_t bufSize = buffer.size() * sizeof(SectorBuffer);
        byte* bufRaw = buffer.data()->raw;
        vector<byte> tmp(bufRaw, bufRaw + bufSize);
        ar.serialize("buffer", tmp);
        memcpy(bufRaw, tmp.data(), bufSize);

        ar.serialize("transfered", transfered);
        ar.serialize("retryCount", retryCount);
        ar.serialize("transferSize", transferSize);
        ar.serialize("romdisk", romdisk);
        ar.serialize("allowOtherDiskroms", allowOtherDiskroms);
        ar.serialize("enablePhantomDrives", enablePhantomDrives);

        // Note: We don't serialize 'devices'. So after a loadstate it will be
        // as-if the devices are closed again. The reason for not serializing
        // this is that it's very hard to serialize a fstream (and we anyway
        // can't restore the state of the host filesystem).
}
INSTANTIATE_SERIALIZE_METHODS(NowindHost);

} // namspace openmsx