WD2793.hh

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#ifndef WD2793_HH
#define WD2793_HH

#include "RawTrack.hh"
#include "DynamicClock.hh"
#include "Schedulable.hh"
#include "CRC16.hh"
#include "serialize_meta.hh"

namespace openmsx {

class Scheduler;
class DiskDrive;
class CliComm;

class WD2793 final : public Schedulable
{
public:
        WD2793(Scheduler& scheduler, DiskDrive& drive, CliComm& cliComm,
               EmuTime::param time, bool isWD1770);

        void reset(EmuTime::param time);

        byte getStatusReg(EmuTime::param time);
        byte getTrackReg (EmuTime::param time);
        byte getSectorReg(EmuTime::param time);
        byte getDataReg  (EmuTime::param time);

        byte peekStatusReg(EmuTime::param time) const;
        byte peekTrackReg (EmuTime::param time) const;
        byte peekSectorReg(EmuTime::param time) const;
        byte peekDataReg  (EmuTime::param time) const;

        void setCommandReg(byte value, EmuTime::param time);
        void setTrackReg  (byte value, EmuTime::param time);
        void setSectorReg (byte value, EmuTime::param time);
        void setDataReg   (byte value, EmuTime::param time);

        bool getIRQ (EmuTime::param time);
        bool getDTRQ(EmuTime::param time);

        bool peekIRQ (EmuTime::param time) const;
        bool peekDTRQ(EmuTime::param time) const;

        template<typename Archive>
        void serialize(Archive& ar, unsigned version);

        // public for serialize
        enum FSMState {
                FSM_NONE,
                FSM_SEEK,
                FSM_TYPE2_LOADED,
                FSM_TYPE2_NOT_FOUND,
                FSM_TYPE2_ROTATED,
                FSM_CHECK_WRITE,
                FSM_PRE_WRITE_SECTOR,
                FSM_WRITE_SECTOR,
                FSM_POST_WRITE_SECTOR,
                FSM_TYPE3_LOADED,
                FSM_TYPE3_ROTATED,
                FSM_WRITE_TRACK,
                FSM_READ_TRACK,
                FSM_IDX_IRQ
        };

private:
        void executeUntil(EmuTime::param time) override;

        void startType1Cmd(EmuTime::param time);

        void seek(EmuTime::param time);
        void step(EmuTime::param time);
        void seekNext(EmuTime::param time);
        void endType1Cmd(EmuTime::param time);

        void startType2Cmd   (EmuTime::param time);
        void type2Loaded     (EmuTime::param time);
        void type2Search     (EmuTime::param time);
        void type2NotFound   (EmuTime::param time);
        void type2Rotated    (EmuTime::param time);
        void startReadSector (EmuTime::param time);
        void startWriteSector(EmuTime::param time);
        void checkStartWrite (EmuTime::param time);
        void preWriteSector  (EmuTime::param time);
        void writeSectorData (EmuTime::param time);
        void postWriteSector (EmuTime::param time);

        void startType3Cmd   (EmuTime::param time);
        void type3Loaded     (EmuTime::param time);
        void type3Rotated    (EmuTime::param time);
        void readAddressCmd  (EmuTime::param time);
        void readTrackCmd    (EmuTime::param time);
        void startWriteTrack (EmuTime::param time);
        void writeTrackData  (EmuTime::param time);

        void startType4Cmd(EmuTime::param time);

        void endCmd(EmuTime::param time);

        void setDrqRate(unsigned trackLength);
        bool isReady() const;

        void schedule(FSMState state, EmuTime::param time);

private:
        DiskDrive& drive;
        CliComm& cliComm;

        // DRQ is high iff current time is past this time.
        //  This clock ticks at the 'byte-rate' of the current track,
        //  typically '6250 bytes/rotation * 5 rotations/second'.
        DynamicClock drqTime;

        // INTRQ is high iff current time is past this time.
        EmuTime irqTime;

        EmuTime pulse5; // time at which the 5th index pulse will be received

        // HLD/HLT timing
        // 1) now < hldTime   (typically: hldTime == EmuTime::infinity)
        //     ==> HLD=false, WD2793 did not request head to be loaded
        // 2) hldTime <= now < hldTime + LOAD
        //     ==> HLD=true, HLT=false, head loading is in progress
        // 3) hldTime + LOAD <= now < hldTime + LOAD + IDLE
        //     ==> HLD=true, HLT=true, head is loaded
        // 4) hldTime + LOAD + IDLE <= now
        //     ==> HLD=false, idle for 15 revolutions HLD made deactive again
        // Note: is all MSX machines I've checked so far, WD2793 pins
        //  - HLD (pin 28) is unconnected
        //  - HLT (pin 40) is connected to +5V
        // This means there is no head-load delay, or IOW as soon as the WD2793
        // requests to load the disk head, the drive responds with "ok, done".
        // So 'LOAD' is zero, and phase 2) doesn't exist. Therefor the current
        // implementation mostly ignores 'LOAD'.
        static const EmuDuration IDLE;
        EmuTime hldTime;

        RawTrack::Sector sectorInfo;
        int dataCurrent;   // which byte in track is next to be read/write
        int dataAvailable; // how many bytes left to read/write

        CRC16 crc;

        FSMState fsmState;
        byte statusReg;
        byte commandReg;
        byte sectorReg;
        byte trackReg;
        byte dataReg;
        byte dataOutReg;

        bool directionIn;
        bool immediateIRQ;
        bool lastWasA1;
        bool dataRegWritten;
        bool lastWasCRC;

        const bool isWD1770;
};
SERIALIZE_CLASS_VERSION(WD2793, 12);

} // namespace openmsx

#endif