SdCard.cc

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#include "SdCard.hh"
#include "DeviceConfig.hh"
#include "HD.hh"
#include "MSXException.hh"
#include "unreachable.hh"
#include "endian.hh"
#include "serialize.hh"
#include "serialize_stl.hh"
#include <memory>

// TODO:
// - replace transferDelayCounter with 0xFF's in responseQueue?
// - remove duplication between WRITE and MULTI_WRITE (is it worth it?)
// - see TODOs in the code below

namespace openmsx {

// data response tokens
static const byte DRT_ACCEPTED    = 0x05;
static const byte DRT_WRITE_ERROR = 0x0D;

// start block tokens and stop tran token
static const byte START_BLOCK_TOKEN     = 0xFE;
static const byte START_BLOCK_TOKEN_MBW = 0xFC;
static const byte STOP_TRAN_TOKEN       = 0xFD;

// data error token
static const byte DATA_ERROR_TOKEN_ERROR        = 0x01;
static const byte DATA_ERROR_TOKEN_OUT_OF_RANGE = 0x08;

// responses
static const byte R1_BUSY            = 0x00;
static const byte R1_IDLE            = 0x01; // TODO: why is lots of code checking for this instead of R1_BUSY?
static const byte R1_ILLEGAL_COMMAND = 0x04;
static const byte R1_PARAMETER_ERROR = 0x80;

SdCard::SdCard(const DeviceConfig& config)
        : hd(config.getXML() ? std::make_unique<HD>(config) : nullptr)
        , cmdIdx(0)
        , transferDelayCounter(0)
        , mode(COMMAND)
        , currentSector(0)
        , currentByteInSector(0)
{
}

SdCard::~SdCard() = default;

// helper methods for 'transfer' to avoid duplication
byte SdCard::readCurrentByteFromCurrentSector() {
        byte retval;
        if (currentByteInSector == -1) {
                retval = START_BLOCK_TOKEN;
                try {
                        hd->readSector(currentSector, sectorBuf);
                } catch (MSXException&) {
                        retval = DATA_ERROR_TOKEN_ERROR;
                }
        } else {
                // output next byte from stream
                retval = sectorBuf.raw[currentByteInSector];
        }
        currentByteInSector++;
        if (currentByteInSector == sizeof(sectorBuf)) {
                responseQueue.push_back({0x00, 0x00}); // 2 CRC's (dummy)
        }
        return retval;
}

byte SdCard::transfer(byte value, bool cs)
{
        if (!hd) return 0xFF; // no card inserted

        if (cs) {
                // /CS is true: not for this chip
                return 0xFF;
        }

        // process output
        byte retval = 0xFF;
        if (transferDelayCounter > 0) {
                --transferDelayCounter;
        } else {
                if (responseQueue.empty()) {
                        switch (mode) {
                        case READ:
                                retval = readCurrentByteFromCurrentSector();
                                if (currentByteInSector == sizeof(sectorBuf)) {
                                        mode = COMMAND;
                                }
                                break;
                        case MULTI_READ:
                                // when there's an error, you probably have to send a CMD12
                                // to go back to the COMMAND mode. This is not
                                // clear in the spec (it's wrongly suggested
                                // for the MULTI_WRITE mode!)
                                if (currentSector >= hd->getNbSectors()) {
                                        // data out of range, send data error token
                                        retval = DATA_ERROR_TOKEN_OUT_OF_RANGE;
                                } else {
                                        retval = readCurrentByteFromCurrentSector();
                                        if (currentByteInSector == sizeof(sectorBuf)) {
                                                currentSector++;
                                                currentByteInSector = -1;
                                        }
                                }
                                break;
                        case WRITE:
                        case MULTI_WRITE:
                                // apparently nothing is returned while writing
                        case COMMAND:
                        default:
                        break;
                        }
                } else {
                        retval = responseQueue.pop_front();
                }
        }

        // process input
        switch (mode) {
        case WRITE:
                // first check for data token
                if (currentByteInSector == -1) {
                        if (value == START_BLOCK_TOKEN) {
                                currentByteInSector++;
                        }
                        break;
                }
                if (currentByteInSector < int(sizeof(sectorBuf))) {
                        sectorBuf.raw[currentByteInSector] = value;
                }
                currentByteInSector++;
                if (currentByteInSector == (sizeof(sectorBuf) + 2)) {
                        byte response = DRT_ACCEPTED;
                        // copy buffer to SD card
                        try {
                                hd->writeSector(currentSector, sectorBuf);
                        } catch (MSXException&) {
                                response = DRT_WRITE_ERROR;
                        }
                        mode = COMMAND;
                        transferDelayCounter = 1;
                        responseQueue.push_back(response);
                }
                break;
        case MULTI_WRITE:
                // first check for stop or start token
                if (currentByteInSector == -1) {
                        if (value == STOP_TRAN_TOKEN) {
                                mode = COMMAND;
                        }
                        if (value == START_BLOCK_TOKEN_MBW) {
                                currentByteInSector++;
                        }
                        break;
                }
                if (currentByteInSector < int(sizeof(sectorBuf))) {
                        sectorBuf.raw[currentByteInSector] = value;
                }
                currentByteInSector++;
                if (currentByteInSector == (sizeof(sectorBuf) + 2)) {
                        // check if still in valid range
                        byte response = DRT_ACCEPTED;
                        if (currentSector >= hd->getNbSectors()) {
                                response = DRT_WRITE_ERROR;
                                // note: mode is not changed, should be done by
                                // the host with CMD12 (STOP_TRANSMISSION) -
                                // however, this makes no sense, CMD12 is only
                                // for Multiple Block Read!? Wrong in the spec?
                        } else {
                                // copy buffer to SD card
                                try {
                                        hd->writeSector(currentSector, sectorBuf);
                                        currentByteInSector = -1;
                                        currentSector++;
                                } catch (MSXException&) {
                                        response = DRT_WRITE_ERROR;
                                        // note: mode is not changed, should be
                                        // done by the host with CMD12
                                        // (STOP_TRANSMISSION) - however, this
                                        // makes no sense, CMD12 is only for
                                        // Multiple Block Read!? Wrong in the
                                        // spec?
                                }
                        }
                        transferDelayCounter = 1;
                        responseQueue.push_back(response);
                }
                break;
        case COMMAND:
        default:
                if ((cmdIdx == 0 && (value >> 6) == 1) // command start
                                || cmdIdx > 0) { // command in progress
                        cmdBuf[cmdIdx] = value;
                        ++cmdIdx;
                        if (cmdIdx == 6) {
                                executeCommand();
                                cmdIdx = 0;
                        }
                }
                break;
        }
        
        return retval;
}

void SdCard::executeCommand()
{
        // it takes 2 transfers (2x8 cycles) before a reply
        // can be given to a command
        transferDelayCounter = 2;
        byte command = cmdBuf[0] & 0x3F;
        switch (command) {
        case 0:  // GO_IDLE_STATE
                responseQueue.clear();
                mode = COMMAND;
                responseQueue.push_back(R1_IDLE);
                break;
        case 8:  // SEND_IF_COND
                // conditions are always OK
                responseQueue.push_back({
                        R1_IDLE,    // R1 (OK) SDHC (checked by MegaSD and FUZIX)
                        byte(0x02), // command version
                        byte(0x00), // reserved
                        byte(0x01), // voltage accepted
                        cmdBuf[4]});// check pattern
                break;
        case 9:{ // SEND_CSD 
                responseQueue.push_back({
                        R1_BUSY, // OK (ignored on MegaSD code, used in FUZIX)
                // now follows a CSD version 2.0 (for SDHC)
                        START_BLOCK_TOKEN, // data token
                        byte(0x40),        // CSD_STRUCTURE [127:120]
                        byte(0x0E),        // (TAAC)
                        byte(0x00),        // (NSAC)
                        byte(0x32),        // (TRAN_SPEED)
                        byte(0x00),        // CCC
                        byte(0x00),        // CCC / (READ_BL_LEN)
                        byte(0x00)});      // (RBP)/(WBM)/(RBM)/ DSR_IMP
                // SD_CARD_SIZE = (C_SIZE + 1) * 512kByte
                auto c_size = unsigned((hd->getNbSectors() * sizeof(sectorBuf)) / (512 * 1024) - 1);
                responseQueue.push_back({
                        byte((c_size >> 16) & 0x3F), // C_SIZE 1
                        byte((c_size >>  8) & 0xFF), // C_SIZE 2
                        byte((c_size >>  0) & 0xFF), // C_SIZE 3
                        byte(0x00),   // res/(EBE)/(SS1)
                        byte(0x00),   // (SS2)/(WGS)
                        byte(0x00),   // (WGE)/res/(RF)/(WBL1)
                        byte(0x00),   // (WBL2)/(WBP)/res
                        byte(0x00),   // (FFG)/COPY/PWP/TWP/(FF)/res
                        byte(0x01)}); // CRC / 1
                break;}
        case 10: // SEND_CID
                responseQueue.push_back({
                        R1_BUSY, // OK (ignored on MegaSD, unused in FUZIX so far)
                        START_BLOCK_TOKEN, // data token
                        byte(0xAA),   // CID01 // manuf ID
                        byte('o' ),   // CID02 // OEM/App ID 1
                        byte('p' ),   // CID03 // OEM/App ID 2
                        byte('e' ),   // CID04 // Prod name 1
                        byte('n' ),   // CID05 // Prod name 2
                        byte('M' ),   // CID06 // Prod name 3
                        byte('S' ),   // CID07 // Prod name 4
                        byte('X' ),   // CID08 // Prod name 5
                        byte(0x01),   // CID09 // Prod Revision
                        byte(0x12),   // CID10 // Prod Serial 1
                        byte(0x34),   // CID11 // Prod Serial 2
                        byte(0x56),   // CID12 // Prod Serial 3
                        byte(0x78),   // CID13 // Prod Serial 4
                        byte(0x00),   // CID14 // reserved / Y1
                        byte(0xE6),   // CID15 // Y2 / M
                        byte(0x01)}); // CID16 // CRC / not used
                break;
        case 12: // STOP TRANSMISSION
                responseQueue.push_back(R1_IDLE); // R1 (OK)
                mode = COMMAND;
                break;
        case 16: // SET_BLOCKLEN
                responseQueue.push_back(R1_IDLE); // OK, we don't really care
                break;
        case 17: // READ_SINGLE_BLOCK
        case 18: // READ_MULTIPLE_BLOCK
        case 24: // WRITE_BLOCK
        case 25: // WRITE_MULTIPLE_BLOCK
                // SDHC so the address is the sector
                currentSector = Endian::readB32(&cmdBuf[1]);
                if (currentSector >= hd->getNbSectors()) {
                        responseQueue.push_back(R1_PARAMETER_ERROR);
                } else {
                        responseQueue.push_back(R1_BUSY);
                        switch (command) {
                                case 17: mode = READ; break;
                                case 18: mode = MULTI_READ; break;
                                case 24: mode = WRITE; break;
                                case 25: mode = MULTI_WRITE; break;
                                default: UNREACHABLE;
                        }
                        currentByteInSector = -1; // wait for token
                }
                break;
        case 41: // implementation of ACMD 41!!
                 // SD_SEND_OP_COND
                responseQueue.push_back(R1_BUSY);
                break;
        case 55: // APP_CMD
                // TODO: go to ACMD mode, but not necessary now
                responseQueue.push_back(R1_IDLE);
                break;
        case 58: // READ_OCR
                responseQueue.push_back({
                        R1_BUSY,// R1 (OK) (ignored on MegaSD, checked in FUZIX)
                        byte(0x40),   // OCR Reg part 1 (SDHC: CCS=1)
                        byte(0x00),   // OCR Reg part 2
                        byte(0x00),   // OCR Reg part 3
                        byte(0x00)}); // OCR Reg part 4
                break;
        
        default:
                responseQueue.push_back(R1_ILLEGAL_COMMAND);
                break;
        }
}

static std::initializer_list<enum_string<SdCard::Mode>> modeInfo = {
        { "COMMAND",     SdCard::COMMAND  },
        { "READ",        SdCard::READ },
        { "MULTI_READ",  SdCard::MULTI_READ },
        { "WRITE",       SdCard::WRITE },
        { "MULTI_WRITE", SdCard::MULTI_WRITE }
};
SERIALIZE_ENUM(SdCard::Mode, modeInfo);

template<typename Archive>
void SdCard::serialize(Archive& ar, unsigned /*version*/)
{
        ar.serialize("mode",   mode,
                     "cmdBuf", cmdBuf);
        ar.serialize_blob("sectorBuf", sectorBuf.raw, sizeof(sectorBuf));
        if (hd) ar.serialize("hd", *hd);
        ar.serialize("cmdIdx",               cmdIdx,
                     "transferDelayCounter", transferDelayCounter,
                     "responseQueue",        responseQueue,
                     "currentSector",        currentSector,
                     "currentByteInSector",  currentByteInSector);
}
INSTANTIATE_SERIALIZE_METHODS(SdCard);

} // namespace openmsx