RealDrive.cc

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#include "RealDrive.hh"
#include "Disk.hh"
#include "DiskChanger.hh"
#include "MSXMotherBoard.hh"
#include "Reactor.hh"
#include "LedStatus.hh"
#include "MSXCommandController.hh"
#include "CliComm.hh"
#include "GlobalSettings.hh"
#include "MSXException.hh"
#include "serialize.hh"
#include "unreachable.hh"
#include <memory>
 
using std::string;
 
namespace openmsx {
 
RealDrive::RealDrive(MSXMotherBoard& motherBoard_, EmuDuration::param motorTimeout_,
                     bool signalsNeedMotorOn_, bool doubleSided,
                     DiskDrive::TrackMode trackMode_)
        : syncLoadingTimeout(motherBoard_.getScheduler())
        , syncMotorTimeout  (motherBoard_.getScheduler())
        , motherBoard(motherBoard_)
        , loadingIndicator(
                motherBoard.getReactor().getGlobalSettings().getThrottleManager())
        , motorTimeout(motorTimeout_)
        , motorTimer(getCurrentTime())
        , headPos(0), side(0), startAngle(0)
        , motorStatus(false)
        , doubleSizedDrive(doubleSided)
        , signalsNeedMotorOn(signalsNeedMotorOn_)
        , trackMode(trackMode_)
        , trackValid(false), trackDirty(false)
{
        drivesInUse = motherBoard.getSharedStuff<DrivesInUse>("drivesInUse");
 
        unsigned i = 0;
        while ((*drivesInUse)[i]) {
                if (++i == MAX_DRIVES) {
                        throw MSXException("Too many disk drives.");
                }
        }
        (*drivesInUse)[i] = true;
        string driveName = "diskX"; driveName[4] = char('a' + i);
 
        if (motherBoard.getMSXCommandController().hasCommand(driveName)) {
                throw MSXException("Duplicated drive name: ", driveName);
        }
        motherBoard.getMSXCliComm().update(CliComm::HARDWARE, driveName, "add");
        changer = std::make_unique<DiskChanger>(motherBoard, driveName, true, doubleSizedDrive,
                                                [this]() { invalidateTrack(); });
}
 
RealDrive::~RealDrive()
{
        try {
                flushTrack();
        } catch (MSXException&) {
                // ignore
        }
        doSetMotor(false, getCurrentTime()); // to send LED event
 
        const auto& driveName = changer->getDriveName();
        motherBoard.getMSXCliComm().update(CliComm::HARDWARE, driveName, "remove");
 
        unsigned driveNum = driveName[4] - 'a';
        assert((*drivesInUse)[driveNum]);
        (*drivesInUse)[driveNum] = false;
}
 
bool RealDrive::isDiskInserted() const
{
        // The game 'Trojka' mentions on the disk label that it works on a
        // single-sided drive. The 2nd side of the disk actually contains a
        // copy protection (obviously only checked on machines with a double
        // sided drive). This copy-protection works fine in openMSX (when using
        // a proper DMK disk image). The real disk also runs fine on machines
        // with single sided drives. Though when we initially ran this game in
        // an emulated machine with a single sided drive, the copy-protection
        // check didn't pass. Initially we emulated single sided drives by
        // simply ignoring the side-select signal. Now when the 2nd side is
        // selected on a single sided drive, we disable the drive-ready signal.
        // This makes the 'Trojka' copy-protection check pass.
        // TODO verify that this is indeed how single sided drives behave
        if (!doubleSizedDrive && (side != 0)) return false;
 
        return !changer->getDisk().isDummyDisk();
}
 
bool RealDrive::isWriteProtected() const
{
        // On a NMS8280 the write protected signal is never active when the
        // drive motor is turned off. See also isTrack00().
        if (signalsNeedMotorOn && !motorStatus) return false;
        return changer->getDisk().isWriteProtected();
}
 
bool RealDrive::isDoubleSided() const
{
        return doubleSizedDrive ? changer->getDisk().isDoubleSided()
                                : false;
}
 
void RealDrive::setSide(bool side_)
{
        invalidateTrack();
        side = side_ ? 1 : 0; // also for single-sided drives
}
 
bool RealDrive::getSide() const
{
        return side;
}
 
unsigned RealDrive::getMaxTrack() const
{
        constexpr unsigned MAX_TRACK = 85;
        switch (trackMode) {
        case DiskDrive::TrackMode::NORMAL:
                return MAX_TRACK;
        case DiskDrive::TrackMode::YAMAHA_FD_03:
                // Yamaha FD-03: Tracks are calibrated around 4 steps per track, max 3 step further than base
                return MAX_TRACK * 4 + 3;
        default:
                UNREACHABLE;
                return 0;
        }
}
 
std::optional<unsigned> RealDrive::getDiskReadTrack() const
{
        // Translate head-position to track number on disk.
        // Normally this is a 1-to-1 mapping, but on the Yamaha-FD-03 the head
        // moves 4 steps for every track on disk. This means it can be
        // between disk tracks so that it can't read valid data.
        switch (trackMode) {
        case DiskDrive::TrackMode::NORMAL:
                return headPos;
        case DiskDrive::TrackMode::YAMAHA_FD_03:
                // Tracks are at a multiple of 4 steps.
                // But also make sure the track at 1 step lower and 1 step up correctly reads.
                // This makes the driver (calibration routine) use a trackoffset of 0 (so at a multiple of 4 steps).
                if ((headPos >= 2) && ((headPos % 4) != 2)) {
                        return (headPos - 2) / 4;
                } else {
                        return {};
                }
        default:
                UNREACHABLE;
                return {};
        }
}
 
std::optional<unsigned> RealDrive::getDiskWriteTrack() const
{
        switch (trackMode) {
        case DiskDrive::TrackMode::NORMAL:
                return headPos;
        case DiskDrive::TrackMode::YAMAHA_FD_03:
                // For writes allow only exact multiples of 4. But track 0 is at step 4
                if ((headPos >= 4) && ((headPos % 4) == 0)) {
                        return (headPos - 4) / 4;
                } else {
                        return {};
                }
        default:
                UNREACHABLE;
                return {};
        }
}
 
void RealDrive::step(bool direction, EmuTime::param time)
{
        invalidateTrack();
 
        if (direction) {
                // step in
                if (headPos < getMaxTrack()) {
                        headPos++;
                }
        } else {
                // step out
                if (headPos > 0) {
                        headPos--;
                }
        }
        // ThrottleManager heuristic:
        //  If the motor is turning and there is head movement, assume the
        //  MSX program is (still) loading/saving to disk
        if (motorStatus) setLoading(time);
}
 
bool RealDrive::isTrack00() const
{
        // On a Philips-NMS8280 the track00 signal is never active when the
        // drive motor is turned off. On a National-FS-5500F2 the motor status
        // doesn't matter, the single/dual drive detection routine (during
        // the MSX boot sequence) even depends on this signal with motor off.
        if (signalsNeedMotorOn && !motorStatus) return false;
        return headPos == 0;
}
 
void RealDrive::setMotor(bool status, EmuTime::param time)
{
        // If status = true, motor is immediately turned on. If status = false,
        // the motor is only turned off after some (configurable) amount of
        // time (can be zero). Let's call the last passed status parameter the
        // 'logical' motor status.
        //
        // Loading indicator heuristic:
        // Loading indicator only reacts to _changes_ in the _logical_ motor
        // status. So when the motor is turned off, we immediately assume the
        // MSX program is done loading (or saving) (we don't wait for the motor
        // timeout). Turning the motor on when it already was logically on has
        // no effect. But turning it back on while it was logically off but
        // still in the motor-off-timeout phase does reset the loading
        // indicator.
        //
        if (status) {
                // (Try to) remove scheduled action to turn motor off.
                if (syncMotorTimeout.removeSyncPoint()) {
                        // If there actually was such an action scheduled, we
                        // need to turn on the loading indicator.
                        assert(motorStatus);
                        setLoading(time);
                        return;
                }
                if (motorStatus) {
                        // Motor was still turning, we're done.
                        // Note: no effect on loading indicator.
                        return;
                }
                // Actually turn motor on (it was off before).
                doSetMotor(true, time);
                setLoading(time);
        } else {
                if (!motorStatus) {
                        // Motor was already off, we're done.
                        return;
                }
                if (syncMotorTimeout.pendingSyncPoint()) {
                        // We had already scheduled an action to turn the motor
                        // off, we're done.
                        return;
                }
                // Heuristic:
                //  Immediately react to 'logical' motor status, even if the
                //  motor will (possibly) still keep rotating for a few
                //  seconds.
                syncLoadingTimeout.removeSyncPoint();
                loadingIndicator.update(false);
 
                // Turn the motor off after some timeout (timeout could be 0)
                syncMotorTimeout.setSyncPoint(time + motorTimeout);
        }
}
 
bool RealDrive::getMotor() const
{
        // note: currently unused because of the implementation in DriveMultiplexer
        // note: currently returns the actual motor status, could be different from the
        //       last set status because of 'syncMotorTimeout'.
        return motorStatus;
}
 
unsigned RealDrive::getCurrentAngle(EmuTime::param time) const
{
        if (motorStatus) {
                // rotating, take passed time into account
                auto deltaAngle = motorTimer.getTicksTillUp(time);
                return (startAngle + deltaAngle) % TICKS_PER_ROTATION;
        } else {
                // not rotating, angle didn't change
                return startAngle;
        }
}
 
void RealDrive::doSetMotor(bool status, EmuTime::param time)
{
        if (!status) {
                invalidateTrack(); // flush and ignore further writes
        }
 
        startAngle = getCurrentAngle(time);
        motorStatus = status;
        motorTimer.advance(time);
 
        // TODO The following is a hack to emulate the drive LED behaviour.
        //      This should be moved to the FDC mapping code.
        // TODO Each drive should get it's own independent LED.
        motherBoard.getLedStatus().setLed(LedStatus::FDD, status);
}
 
void RealDrive::setLoading(EmuTime::param time)
{
        assert(motorStatus);
        loadingIndicator.update(true);
 
        // ThrottleManager heuristic:
        //  We want to avoid getting stuck in 'loading state' when the MSX
        //  program forgets to turn off the motor.
        syncLoadingTimeout.removeSyncPoint();
        syncLoadingTimeout.setSyncPoint(time + EmuDuration::sec(1));
}
 
void RealDrive::execLoadingTimeout()
{
        loadingIndicator.update(false);
}
 
void RealDrive::execMotorTimeout(EmuTime::param time)
{
        doSetMotor(false, time);
}
 
bool RealDrive::indexPulse(EmuTime::param time)
{
        // Tested on real NMS8250:
        //  Only when there's a disk inserted and when the motor is spinning
        //  there are index pulses generated.
        if (!(motorStatus && isDiskInserted())) {
                return false;
        }
        return getCurrentAngle(time) < INDEX_DURATION;
}
 
EmuTime RealDrive::getTimeTillIndexPulse(EmuTime::param time, int count)
{
        if (!motorStatus || !isDiskInserted()) { // TODO is this correct?
                return EmuTime::infinity();
        }
        unsigned delta = TICKS_PER_ROTATION - getCurrentAngle(time);
        auto dur1 = MotorClock::duration(delta);
        auto dur2 = MotorClock::duration(TICKS_PER_ROTATION) * (count - 1);
        return time + dur1 + dur2;
}
 
void RealDrive::invalidateTrack()
{
        try {
                flushTrack();
        } catch (MSXException&) {
                // ignore
        }
        trackValid = false;
}
 
void RealDrive::getTrack()
{
        if (!motorStatus) {
                // cannot read track when disk isn't rotating
                assert(!trackValid);
                return;
        }
        if (!trackValid) {
                if (auto rdTrack = getDiskReadTrack()) {
                        changer->getDisk().readTrack(*rdTrack, side, track);
                } else {
                        track.clear(track.getLength());
                }
                trackValid = true;
                trackDirty = false;
        }
}
 
unsigned RealDrive::getTrackLength()
{
        getTrack();
        return track.getLength();
}
 
void RealDrive::writeTrackByte(int idx, byte val, bool addIdam)
{
        getTrack();
        // It's possible 'trackValid==false', but that's fine because in that
        // case track won't be flushed to disk anyway.
        track.write(idx, val, addIdam);
        trackDirty = true;
}
 
byte RealDrive::readTrackByte(int idx)
{
        getTrack();
        return trackValid ? track.read(idx) : 0;
}
 
static constexpr unsigned divUp(unsigned a, unsigned b)
{
        return (a + b - 1) / b;
}
EmuTime RealDrive::getNextSector(EmuTime::param time, RawTrack::Sector& sector)
{
        getTrack();
        int currentAngle = getCurrentAngle(time);
        unsigned trackLen = track.getLength();
        unsigned idx = divUp(currentAngle * trackLen, TICKS_PER_ROTATION);
 
        // 'addrIdx' points to the 'FE' byte in the 'A1 A1 A1 FE' sequence.
        // This method also returns the moment in time when this 'FE' byte is
        // located below the drive head. But when searching for the next sector
        // header, the FDC needs to see this full sequence. So if the rotation
        // distance is only 3 bytes or less we need to skip to the next sector
        // header. IOW we need a sector header that's at least 4 bytes removed
        // from the current position.
        if (auto s = track.decodeNextSector(idx + 4)) {
                sector = *s;
        } else {
                return EmuTime::infinity();
        }
        int sectorAngle = divUp(sector.addrIdx * TICKS_PER_ROTATION, trackLen);
 
        // note that if there is only one sector in this track, we have
        // to do a full rotation.
        int delta = sectorAngle - currentAngle;
        if (delta < 4) delta += TICKS_PER_ROTATION;
        assert(4 <= delta); assert(unsigned(delta) < (TICKS_PER_ROTATION + 4));
 
        return time + MotorClock::duration(delta);
}
 
void RealDrive::flushTrack()
{
        if (trackValid && trackDirty) {
                if (auto wrTrack = getDiskWriteTrack()) {
                        changer->getDisk().writeTrack(*wrTrack, side, track);
                }
                trackDirty = false;
        }
}
 
bool RealDrive::diskChanged()
{
        return changer->diskChanged();
}
 
bool RealDrive::peekDiskChanged() const
{
        return changer->peekDiskChanged();
}
 
bool RealDrive::isDummyDrive() const
{
        return false;
}
 
void RealDrive::applyWd2793ReadTrackQuirk()
{
        track.applyWd2793ReadTrackQuirk();
}
 
void RealDrive::invalidateWd2793ReadTrackQuirk()
{
        trackValid = false;
}
 
 
// version 1: initial version
// version 2: removed 'timeOut', added MOTOR_TIMEOUT schedulable
// version 3: added 'startAngle'
// version 4: removed 'userData' from Schedulable
// version 5: added 'track', 'trackValid', 'trackDirty'
// version 6: removed 'headLoadStatus' and 'headLoadTimer'
template<typename Archive>
void RealDrive::serialize(Archive& ar, unsigned version)
{
        if (ar.versionAtLeast(version, 4)) {
                ar.serialize("syncLoadingTimeout", syncLoadingTimeout,
                             "syncMotorTimeout",   syncMotorTimeout);
        } else {
                Schedulable::restoreOld(ar, {&syncLoadingTimeout, &syncMotorTimeout});
        }
        ar.serialize("motorTimer", motorTimer,
                     "changer",    *changer,
                     "headPos",    headPos,
                     "side",       side,
                     "motorStatus", motorStatus);
        if (ar.versionAtLeast(version, 3)) {
                ar.serialize("startAngle", startAngle);
        } else {
                assert(Archive::IS_LOADER);
                startAngle = 0;
        }
        if (ar.versionAtLeast(version, 5)) {
                ar.serialize("track",      track);
                ar.serialize("trackValid", trackValid);
                ar.serialize("trackDirty", trackDirty);
        }
        if constexpr (Archive::IS_LOADER) {
                // Right after a loadstate, the 'loading indicator' state may
                // be wrong, but that's OK. It's anyway only a heuristic and
                // it will be correct after at most one second.
 
                // This is a workaround for the fact that we can have multiple drives
                // (and only one is on), in which case the 2nd drive will turn off the
                // LED again which the first drive just turned on. TODO: fix by modelling
                // individual drive LEDs properly. See also
                // http://sourceforge.net/tracker/index.php?func=detail&aid=1540929&group_id=38274&atid=421864
                if (motorStatus) {
                        motherBoard.getLedStatus().setLed(LedStatus::FDD, true);
                }
        }
}
INSTANTIATE_SERIALIZE_METHODS(RealDrive);
 
} // namespace openmsx