AbstractIDEDevice.cc

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#include "AbstractIDEDevice.hh"
#include "MSXMotherBoard.hh"
#include "LedStatus.hh"
#include "Version.hh"
#include "narrow.hh"
#include "serialize.hh"
#include "unreachable.hh"
#include "xrange.hh"
#include <cassert>
#include <cstdio>
 
namespace openmsx {
 
AbstractIDEDevice::AbstractIDEDevice(MSXMotherBoard& motherBoard_)
        : motherBoard(motherBoard_)
{
        ranges::fill(buffer, 0);
}
 
byte AbstractIDEDevice::diagnostic() const
{
        // The Execute Device Diagnostic command is executed by both devices in
        // parallel. Fortunately, returning 0x01 is valid in all cases:
        // - for device 0 it means: device 0 passed, device 1 passed or not present
        // - for device 1 it means: device 1 passed
        return 0x01;
}
 
void AbstractIDEDevice::createSignature(bool preserveDevice)
{
        sectorCountReg = 0x01;
        sectorNumReg = 0x01;
        if (isPacketDevice()) {
                cylinderLowReg = 0x14;
                cylinderHighReg = 0xEB;
                if (preserveDevice) {
                        devHeadReg &= 0x10;
                } else {
                        // The current implementation of SunriseIDE will substitute the
                        // current device for DEV, so it will always act like DEV is
                        // preserved.
                        devHeadReg = 0x00;
                }
        } else {
                cylinderLowReg = 0x00;
                cylinderHighReg = 0x00;
                devHeadReg = 0x00;
        }
}
 
void AbstractIDEDevice::reset(EmuTime::param /*time*/)
{
        errorReg = diagnostic();
        statusReg = DRDY | DSC;
        featureReg = 0x00;
        createSignature();
        setTransferRead(false);
        setTransferWrite(false);
}
 
byte AbstractIDEDevice::readReg(nibble reg, EmuTime::param /*time*/)
{
        switch (reg) {
        case 1: // error register
                return errorReg;
 
        case 2: // sector count register
                return sectorCountReg;
 
        case 3: // sector number register / LBA low
                return sectorNumReg;
 
        case 4: // cylinder low register / LBA mid
                return cylinderLowReg;
 
        case 5: // cylinder high register / LBA high
                return cylinderHighReg;
 
        case 6: // device/head register
                // DEV bit is handled by IDE interface
                return devHeadReg;
 
        case 7: // status register
                return statusReg;
 
        case 8:
        case 9:
        case 10:
        case 11:
        case 12:
        case 13:
        case 15:// not used
                return 0x7F;
 
        case 0: // data register, converted to readData by IDE interface
        case 14:// alternate status reg, converted to read from normal
                // status register by IDE interface
        default:
                UNREACHABLE;
        }
}
 
void AbstractIDEDevice::writeReg(
        nibble reg, byte value, EmuTime::param /*time*/
        )
{
        switch (reg) {
        case 1: // feature register
                featureReg = value;
                break;
 
        case 2: // sector count register
                sectorCountReg = value;
                break;
 
        case 3: // sector number register / LBA low
                sectorNumReg = value;
                break;
 
        case 4: // cylinder low register / LBA mid
                cylinderLowReg = value;
                break;
 
        case 5: // cylinder high register / LBA high
                cylinderHighReg = value;
                break;
 
        case 6: // device/head register
                // DEV bit is handled by IDE interface
                devHeadReg = value;
                break;
 
        case 7: // command register
                statusReg &= ~(DRQ | ERR);
                setTransferRead(false);
                setTransferWrite(false);
                executeCommand(value);
                break;
 
        case 8:
        case 9:
        case 10:
        case 11:
        case 12:
        case 13:
        case 15: // not used
        case 14: // device control register, handled by IDE interface
                // do nothing
                break;
 
        case 0: // data register, converted to readData by IDE interface
        default:
                UNREACHABLE;
        }
}
 
word AbstractIDEDevice::readData(EmuTime::param /*time*/)
{
        if (!transferRead) {
                // no read in progress
                return 0x7F7F;
        }
        assert((transferIdx + 1) < sizeof(buffer));
        auto result = word((buffer[transferIdx + 0] << 0) +
                           (buffer[transferIdx + 1] << 8));
        transferIdx += 2;
        bufferLeft -= 2;
        if (bufferLeft == 0) {
                if (transferCount == 0) {
                        // End of transfer.
                        setTransferRead(false);
                        statusReg &= ~DRQ;
                        readEnd();
                } else {
                        // Buffer empty, but transfer not done yet.
                        readNextBlock();
                }
        }
        return result;
}
 
void AbstractIDEDevice::readNextBlock()
{
        bufferLeft = readBlockStart(
                buffer, std::min<unsigned>(sizeof(buffer), transferCount));
        assert((bufferLeft & 1) == 0);
        transferIdx = 0;
        transferCount -= bufferLeft;
}
 
void AbstractIDEDevice::writeData(word value, EmuTime::param /*time*/)
{
        if (!transferWrite) {
                // no write in progress
                return;
        }
        assert((transferIdx + 1) < sizeof(buffer));
        buffer[transferIdx + 0] = narrow_cast<byte>(value & 0xFF);
        buffer[transferIdx + 1] = narrow_cast<byte>(value >> 8);
        transferIdx += 2;
        bufferLeft -= 2;
        if (bufferLeft == 0) {
                unsigned bytesInBuffer = transferIdx;
                if (transferCount == 0) {
                        // End of transfer.
                        setTransferWrite(false);
                        statusReg &= ~DRQ;
                } else {
                        // Buffer full, but transfer not done yet.
                        writeNextBlock();
                }
                // Packet commands can start a second transfer, so the command
                // execution must happen after we close this transfer.
                writeBlockComplete(buffer, bytesInBuffer);
        }
}
 
void AbstractIDEDevice::writeNextBlock()
{
        transferIdx = 0;
        bufferLeft = std::min<unsigned>(sizeof(buffer), transferCount);
        transferCount -= bufferLeft;
}
 
void AbstractIDEDevice::setError(byte error)
{
        errorReg = error;
        if (error) {
                statusReg |= ERR;
        } else {
                statusReg &= ~ERR;
        }
        statusReg &= ~DRQ;
        setTransferWrite(false);
        setTransferRead(false);
}
 
unsigned AbstractIDEDevice::getSectorNumber() const
{
        return sectorNumReg | (cylinderLowReg << 8) |
                (cylinderHighReg << 16) | ((devHeadReg & 0x0F) << 24);
}
 
unsigned AbstractIDEDevice::getNumSectors() const
{
        return (sectorCountReg == 0) ? 256 : sectorCountReg;
}
 
void AbstractIDEDevice::setInterruptReason(byte value)
{
        sectorCountReg = value;
}
 
unsigned AbstractIDEDevice::getByteCount() const
{
        return cylinderLowReg | (cylinderHighReg << 8);
}
 
void AbstractIDEDevice::setByteCount(unsigned count)
{
        cylinderLowReg  = narrow_cast<byte>(count & 0xFF);
        cylinderHighReg = narrow_cast<byte>(count >> 8);
}
 
void AbstractIDEDevice::setSectorNumber(unsigned lba)
{
        sectorNumReg    = (lba & 0x000000FF) >>  0;
        cylinderLowReg  = (lba & 0x0000FF00) >>  8;
        cylinderHighReg = (lba & 0x00FF0000) >> 16;
        devHeadReg      = (lba & 0x0F000000) >> 24; // note: only 4 bits
}
 
void AbstractIDEDevice::readEnd()
{
}
 
void AbstractIDEDevice::executeCommand(byte cmd)
{
        switch (cmd) {
        case 0x08: // Device Reset
                if (isPacketDevice()) {
                        errorReg = diagnostic();
                        createSignature(true);
                        // TODO: Which is correct?
                        //statusReg = 0x00;
                        statusReg = DRDY | DSC;
                } else {
                        // Command is only implemented for packet devices.
                        setError(ABORT);
                }
                break;
 
        case 0x90: // Execute Device Diagnostic
                errorReg = diagnostic();
                createSignature();
                break;
 
        case 0x91: // Initialize Device Parameters
                // ignore command
                break;
 
        case 0xA1: // Identify Packet Device
                if (isPacketDevice()) {
                        createIdentifyBlock(startShortReadTransfer(512));
                } else {
                        setError(ABORT);
                }
                break;
 
        case 0xEC: // Identify Device
                if (isPacketDevice()) {
                        setError(ABORT);
                } else {
                        createIdentifyBlock(startShortReadTransfer(512));
                }
                break;
 
        case 0xEF: // Set Features
                switch (getFeatureReg()) {
                case 0x03: // Set Transfer Mode
                        break;
                default:
                        fprintf(stderr, "Unhandled set feature subcommand: %02X\n",
                                getFeatureReg());
                        setError(ABORT);
                }
                break;
 
        default: // unsupported command
                fprintf(stderr, "unsupported IDE command %02X\n", cmd);
                setError(ABORT);
        }
}
 
AlignedBuffer& AbstractIDEDevice::startShortReadTransfer(unsigned count)
{
        assert(count <= sizeof(buffer));
        assert((count & 1) == 0);
 
        startReadTransfer();
        transferCount = 0;
        bufferLeft = count;
        transferIdx = 0;
        ranges::fill(std::span{buffer.data(), count}, 0);
        return buffer;
}
 
void AbstractIDEDevice::startLongReadTransfer(unsigned count)
{
        assert((count & 1) == 0);
        startReadTransfer();
        transferCount = count;
        readNextBlock();
}
 
void AbstractIDEDevice::startReadTransfer()
{
        statusReg |= DRQ;
        setTransferRead(true);
}
 
void AbstractIDEDevice::abortReadTransfer(byte error)
{
        setError(error | ABORT);
        setTransferRead(false);
}
 
void AbstractIDEDevice::startWriteTransfer(unsigned count)
{
        statusReg |= DRQ;
        setTransferWrite(true);
        transferCount = count;
        writeNextBlock();
}
 
void AbstractIDEDevice::abortWriteTransfer(byte error)
{
        setError(error | ABORT);
        setTransferWrite(false);
}
 
void AbstractIDEDevice::setTransferRead(bool status)
{
        if (status != transferRead) {
                transferRead = status;
                if (!transferWrite) {
                        // (this is a bit of a hack!)
                        motherBoard.getLedStatus().setLed(LedStatus::FDD, transferRead);
                }
        }
}
 
void AbstractIDEDevice::setTransferWrite(bool status)
{
        if (status != transferWrite) {
                transferWrite = status;
                if (!transferRead) {
                        // (this is a bit of a hack!)
                        motherBoard.getLedStatus().setLed(LedStatus::FDD, transferWrite);
                }
        }
}
 
static void writeIdentifyString(std::span<byte> dst, std::string s)
{
        assert((dst.size() % 2) == 0);
        s.resize(dst.size(), ' ');
        for (size_t i = 0; i < dst.size(); i += 2) {
                // copy and swap
                dst[i + 0] = s[i + 1];
                dst[i + 1] = s[i + 0];
        }
}
 
void AbstractIDEDevice::createIdentifyBlock(AlignedBuffer& buf)
{
        // According to the spec, the combination of model and serial should be
        // unique. But I don't know any MSX software that cares about this.
        writeIdentifyString(std::span{&buf[10 * 2], 2 * 10}, "s00000001"); // serial
        writeIdentifyString(std::span{&buf[23 * 2], 2 * 4},
                // Use openMSX version as firmware revision, because most of our
                // IDE emulation code is in fact emulating the firmware.
                Version::RELEASE ? strCat('v', Version::VERSION)
                                 : strCat('d', Version::REVISION));
        writeIdentifyString(std::span{&buf[27 * 2], 2 * 20}, std::string(getDeviceName())); // model
 
        fillIdentifyBlock(buf);
}
 
 
template<typename Archive>
void AbstractIDEDevice::serialize(Archive& ar, unsigned /*version*/)
{
        // no need to serialize IDEDevice base class
        ar.serialize_blob("buffer", buffer);
        ar.serialize("transferIdx",     transferIdx,
                     "bufferLeft",      bufferLeft,
                     "transferCount",   transferCount,
                     "errorReg",        errorReg,
                     "sectorCountReg",  sectorCountReg,
                     "sectorNumReg",    sectorNumReg,
                     "cylinderLowReg",  cylinderLowReg,
                     "cylinderHighReg", cylinderHighReg,
                     "devHeadReg",      devHeadReg,
                     "statusReg",       statusReg,
                     "featureReg",      featureReg);
        bool transferIdentifyBlock = false; // remove on next version increment
                                            // no need to break bw-compat now
        ar.serialize("transferIdentifyBlock", transferIdentifyBlock,
                     "transferRead",          transferRead,
                     "transferWrite",         transferWrite);
}
INSTANTIATE_SERIALIZE_METHODS(AbstractIDEDevice);
 
} // namespace openmsx