WD2793.hh

Go to the documentation of this file.

#ifndef WD2793_HH
#define WD2793_HH
 
#include "EmuTime.hh"
#include "RawTrack.hh"
#include "DynamicClock.hh"
#include "Schedulable.hh"
#include "CRC16.hh"
#include "serialize_meta.hh"
 
namespace openmsx {
 
class Scheduler;
class DiskDrive;
class MSXCliComm;
 
class WD2793 final : public Schedulable
{
public:
        WD2793(Scheduler& scheduler, DiskDrive& drive, MSXCliComm& cliComm,
               EmuTime::param time, bool isWD1770);
 
        void reset(EmuTime::param time);
 
        [[nodiscard]] uint8_t getStatusReg(EmuTime::param time);
        [[nodiscard]] uint8_t getTrackReg (EmuTime::param time) const;
        [[nodiscard]] uint8_t getSectorReg(EmuTime::param time) const;
        [[nodiscard]] uint8_t getDataReg  (EmuTime::param time);
 
        [[nodiscard]] uint8_t peekStatusReg(EmuTime::param time) const;
        [[nodiscard]] uint8_t peekTrackReg (EmuTime::param time) const;
        [[nodiscard]] uint8_t peekSectorReg(EmuTime::param time) const;
        [[nodiscard]] uint8_t peekDataReg  (EmuTime::param time) const;
 
        void setCommandReg(uint8_t value, EmuTime::param time);
        void setTrackReg  (uint8_t value, EmuTime::param time);
        void setSectorReg (uint8_t value, EmuTime::param time);
        void setDataReg   (uint8_t value, EmuTime::param time);
 
        [[nodiscard]] bool getIRQ (EmuTime::param time) const;
        [[nodiscard]] bool getDTRQ(EmuTime::param time) const;
 
        [[nodiscard]] bool peekIRQ (EmuTime::param time) const;
        [[nodiscard]] bool peekDTRQ(EmuTime::param time) const;
 
        template<typename Archive>
        void serialize(Archive& ar, unsigned version);
 
        // public for serialize
        enum class FSM {
                NONE,
                SEEK,
                TYPE2_LOADED,
                TYPE2_NOT_FOUND,
                TYPE2_ROTATED,
                CHECK_WRITE,
                PRE_WRITE_SECTOR,
                WRITE_SECTOR,
                POST_WRITE_SECTOR,
                TYPE3_LOADED,
                TYPE3_ROTATED,
                WRITE_TRACK,
                READ_TRACK,
                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);
        [[nodiscard]] bool isReady() const;
 
        void schedule(FSM state, EmuTime::param time);
 
private:
        DiskDrive& drive;
        MSXCliComm& 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{EmuTime::infinity()};
 
        // INTRQ is high iff current time is past this time.
        EmuTime irqTime = EmuTime::infinity();
 
        EmuTime pulse5 = EmuTime::infinity(); // 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'.
        EmuTime hldTime = EmuTime::infinity(); // HLD=false
 
        RawTrack::Sector sectorInfo;
        int dataCurrent   = 0; // which byte in track is next to be read/write
        int dataAvailable = 0; // how many bytes left to read/write
 
        CRC16 crc;
 
        FSM fsmState;
        uint8_t statusReg;
        uint8_t commandReg = 0;
        uint8_t sectorReg;
        uint8_t trackReg;
        uint8_t dataReg;
        uint8_t dataOutReg = 0;
 
        bool directionIn;
        bool immediateIRQ;
        bool lastWasA1 = false;
        bool dataRegWritten = false;
        bool lastWasCRC = false;
 
        const bool isWD1770;
};
SERIALIZE_CLASS_VERSION(WD2793, 12);
 
} // namespace openmsx
 
#endif