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livingcomputermuseum.Darkstar/D/IOP/FloppyController.cs
Josh Dersch aedcf2dd71 Initial commit to public repository.
2019-01-15 12:55:18 -08:00

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/*
BSD 2-Clause License
Copyright Vulcan Inc. 2017-2018 and Living Computer Museum + Labs 2018
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED.IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
using D.Logging;
using System;
namespace D.IOP
{
/// <summary>
/// This implements the WD FD1797 controller and the IOP's external floppy state registers.
/// It implements the IDMAInterface so that DMA transfers can take place.
///
/// TODO: This needs a lot of cleanup and refinement. In particular:
/// - Write support needs to be added
/// - Need enforcing of sector formats (if controller is set up to read a double density sector,
/// and a single-density sector is read, something bad needs to happen, rather than nothing.)
/// </summary>
public class FloppyController : IIOPDevice, IDMAInterface
{
public FloppyController(FloppyDrive drive, DSystem system)
{
_system = system;
_drive = drive;
}
public FloppyDrive Drive
{
get { return _drive; }
}
public int[] ReadPorts
{
get { return _readPorts; }
}
public int[] WritePorts
{
get { return _writePorts; }
}
public bool Interrupt
{
get { return _interruptPending; }
}
//
// IDMAInterface methods and properties
//
public bool DRQ
{
get
{
if (_drq)
{
_drqCounter--;
if (_drqCounter == 0)
{
return true;
}
else
{
return false;
}
}
else
{
return false;
}
}
}
public byte DMARead()
{
if (!_drq)
{
throw new InvalidOperationException("Unexpected DMA read with DRQ low.");
}
//
// We cheat (as with reading the Data register): rather than emulating the timing of data moving
// past the floppy drive heads, since we read the entire sector in at once
// we assume the data's always ready so we keep DRQ high until the data has all been read.
// This means we won't be simulating DATA LATE errors.
//
// Return the next byte, if any.
// Keep DRQ raised until all bytes in the buffer have been read.
//
byte dmaRead = _sectorBuffer[_sectorDataIndex];
_sectorDataIndex++;
if (_sectorDataIndex > _sectorBuffer.Length - 1)
{
FinishDataTransfer();
if (Log.Enabled) Log.Write(LogComponent.IOPFloppy, "DMA sector read completed.");
}
else
{
_drqCounter = 16;
}
return dmaRead;
}
public void DMAWrite(byte value)
{
throw new NotImplementedException("DMA write not implemented yet.");
}
public void DMAComplete()
{
}
public void WritePort(int port, byte value)
{
if (Log.Enabled) Log.Write(LogComponent.IOPFloppy, "FDC port {0} write {1:x2}", (FDCPorts)port, value);
switch ((FDCPorts)port)
{
case FDCPorts.ExtFDCState:
_extState = (FDCStateFlags)value;
if (Log.Enabled) Log.Write(LogComponent.IOPFloppy, "FDC Ext state {0} ({1:x2})", (FDCStateFlags)value, value);
_drive.DriveSelect = (_extState & FDCStateFlags.DriveSelect) != 0;
if (Log.Enabled) Log.Write(LogComponent.IOPFloppy, "Drive selected: {0}", _drive.DriveSelect);
// Enable or disable the FDC chip
if ((_extState & FDCStateFlags.EnableFDC) != 0)
{
EnableFDC();
}
else
{
DisableFDC();
}
break;
case FDCPorts.FDCTrack:
_fdcTrack = value;
if (Log.Enabled) Log.Write(LogComponent.IOPFloppy, "FDC track {0}", value);
break;
case FDCPorts.FDCSector:
_fdcSector = value;
if (Log.Enabled) Log.Write(LogComponent.IOPFloppy, "FDC sector {0}", value);
break;
case FDCPorts.FDCData:
_fdcData = value;
if (Log.Enabled) Log.Write(LogComponent.IOPFloppy, "FDC data 0x{0:x}", value);
break;
case FDCPorts.FDCCommand:
if (Log.Enabled) Log.Write(LogComponent.IOPFloppy, "FDC command 0x{0:x}", value);
DoCommand(value);
break;
default:
throw new InvalidOperationException(String.Format("Unexpected write to port {0:x2}", port));
}
}
public byte ReadPort(int port)
{
byte value = 0;
switch ((FDCPorts)port)
{
case FDCPorts.FDCTrack:
value = _fdcTrack;
break;
case FDCPorts.FDCSector:
value = _fdcSector;
break;
case FDCPorts.FDCData:
if (_drq)
{
// There's a read pending, read the next byte in if any.
if (_sectorDataIndex < _sectorBuffer.Length - 1)
{
_fdcData = _sectorBuffer[_sectorDataIndex];
_sectorDataIndex++;
if (_sectorDataIndex > _sectorBuffer.Length - 1)
{
FinishDataTransfer();
if (Log.Enabled) Log.Write(LogComponent.IOPFloppy, "Polled sector read completed.");
}
}
}
value = _fdcData;
break;
case FDCPorts.FDCStatus:
value = ReadStatus();
break;
case FDCPorts.ExtFDCStatusReg:
value = ReadExtStatus();
if (Log.Enabled) Log.Write(LogComponent.IOPFloppy, "Floppy ext status read {0}", (FDCStatusFlags)value);
break;
default:
throw new InvalidOperationException(String.Format("Unexpected read from port {0:x2}", port));
}
return value;
}
public void Reset()
{
_extState = FDCStateFlags.None;
_lastCommand = FDCCommand.Restore;
_fdcEnabled = false;
_sectorDataIndex = 0;
_drqCounter = 16;
_indexReset = false;
_drive.Reset();
ResetFlags();
}
private void ResetFlags()
{
_fdcData = 0;
_fdcSector = 0;
_fdcTrack = 0;
_commandAbort = false;
_crcError = false;
_busy = false;
_headLoaded = false;
_seekError = false;
_recordTypeWriteFault = false;
_rnf = false;
_lostData = false;
_drq = false;
ClearInterrupt();
}
//
// Returns the status given the last command executed.
//
private byte ReadStatus()
{
// Interrupt signal is reset when the status register is read.
ClearInterrupt();
byte value = 0;
switch(_lastCommand)
{
// Type I Commands
case FDCCommand.Restore:
case FDCCommand.Seek:
case FDCCommand.StepNoUpdate:
case FDCCommand.StepUpdate:
case FDCCommand.StepInNoUpdate:
case FDCCommand.StepInUpdate:
case FDCCommand.StepOutNoUpdate:
case FDCCommand.StepOutUpdate:
value =
(byte)((NotReady() ? 0x80 : 0x00) |
(WriteProtect() ? 0x40 : 0x00) |
(_headLoaded ? 0x20 : 0x00) |
(_seekError ? 0x10 : 0x00) |
(_crcError ? 0x08 : 0x00) |
(Track0() ? 0x04 : 0x00) |
(Index() ? 0x02 : 0x00) |
(_busy ? 0x01 : 0x00));
break;
// Type II/III Commands
case FDCCommand.ReadAddress:
value =
(byte)((NotReady() ? 0x80 : 0x00) |
(_rnf ? 0x10 : 0x00) |
(_crcError ? 0x08 : 0x00) |
(_lostData ? 0x04 : 0x00) |
(_drq ? 0x02 : 0x00) |
(_busy ? 0x01 : 0x00));
break;
case FDCCommand.ReadTrack:
value =
(byte)((NotReady() ? 0x80 : 0x00) |
(_lostData ? 0x04 : 0x00) |
(_drq ? 0x02 : 0x00) |
(_busy ? 0x01 : 0x00));
break;
case FDCCommand.ReadSectorMultiple:
case FDCCommand.ReadSectorSingle:
value =
(byte)((NotReady() ? 0x80 : 0x00) |
(_recordTypeWriteFault ? 0x20 : 0x00) |
(_rnf ? 0x10 : 0x00) |
(_crcError ? 0x08 : 0x00) |
(_lostData ? 0x04 : 0x00) |
(_drq ? 0x02 : 0x00) |
(_busy ? 0x01 : 0x00));
break;
case FDCCommand.WriteSectorMultiple:
case FDCCommand.WriteSectorSingle:
value =
(byte)((NotReady() ? 0x80 : 0x00) |
(WriteProtect() ? 0x40 : 0x00) |
(_recordTypeWriteFault ? 0x20 : 0x00) |
(_rnf ? 0x10 : 0x00) |
(_crcError ? 0x08 : 0x00) |
(_lostData ? 0x04 : 0x00) |
(_drq ? 0x02 : 0x00) |
(_busy ? 0x01 : 0x00));
break;
case FDCCommand.WriteTrack:
value =
(byte)((NotReady() ? 0x80 : 0x00) |
(WriteProtect() ? 0x40 : 0x00) |
(_recordTypeWriteFault ? 0x20 : 0x00) |
(_lostData ? 0x04 : 0x00) |
(_drq ? 0x02 : 0x00) |
(_busy ? 0x01 : 0x00));
break;
}
if (Log.Enabled) Log.Write(LogComponent.IOPFloppy, "FDC status read {0:x} ({1})", value, (Type1Status)value);
return value;
}
/// <summary>
/// Reads the IOP's external floppy status register
/// </summary>
private byte ReadExtStatus()
{
bool doubleSided = false;
bool sa800 = false;
bool diskChange = false;
if (_drive.DriveSelect)
{
doubleSided = !_drive.IsSingleSided;
sa800 = !_drive.IsLoaded;
diskChange = _drive.DiskChange;
}
byte extStatus = (byte)(
(diskChange ? 0x80 : 0x00) |
(_system.IOP.DMAController.TC ? 0x40 : 0x00) | // end count
(doubleSided ? 0x20 : 0x00) |
(sa800 ? 0x10 : 0x00));
if (Log.Enabled) Log.Write(LogComponent.IOPFloppy, "Ext Status 0x{0:x2}", extStatus);
return extStatus;
}
private void EnableFDC()
{
if (_fdcEnabled)
{
// Already enabled, no need to do anything.
return;
}
//
// After enabling the FDC, the FDC comes out of reset.
// Technically this takes about 12ms, we're just
// doing it immediately.
//
_fdcEnabled = true;
if (Log.Enabled) Log.Write(LogComponent.IOPFloppy, "FDC enabled.");
// "A logic low on the [-MR] input resets the device and loads HEX 03
// into the command register. The Not Ready (status bit 7) is reset
// during -MR ACTIVE. When -MR is brought to a logic high, a RESTORE
// command is executed, regardless of the state of the Ready signal
// from the drive. Also, HEX 01 is loaded into the sector register."
// Send the RESTORE command.
DoCommand((byte)FDCCommand.Restore << 4);
//
// If DriveSelect is high, we will set INDEX to high and schedule an event
// to reset it after a short duration. This makes FDCTest happy, and
// is undocumented in the WD spec.
//
if (_drive.DriveSelect)
{
_indexReset = true;
_system.Scheduler.Schedule(_resetIndexDuration,
(timestampNsec, context) =>
{
// Reset the index signal now.
_indexReset = false;
if (Log.Enabled) Log.Write(LogComponent.IOPFloppy, "Resetting INDEX signal after FDC reset.");
});
if (Log.Enabled) Log.Write(LogComponent.IOPFloppy, "Setting INDEX signal after FDC reset.");
}
}
private void DisableFDC()
{
if (!_fdcEnabled)
{
// Already disabled, no need to do anything.
return;
}
_fdcEnabled = false;
if (Log.Enabled) Log.Write(LogComponent.IOPFloppy, "FDC disabled. Resetting FDC.");
//
// "A logic low on the [-MR] input resets the device and loads HEX 03
// into the command register. The Not Ready (status bit 7) is reset
// during -MR ACTIVE."
//
// TODO:
// HEX 03 only affects the step rate, which I'm not particularly concerned
// about at the moment.
//
ResetFlags();
_extState = FDCStateFlags.None;
_lastCommand = FDCCommand.Restore;
}
private void DoCommand(int commandData)
{
// Interrupt signal is reset when the command register is written.
ClearInterrupt();
_commandAbort = false;
FDCCommand command = (FDCCommand)(commandData >> 4);
// Save the last command so we know what status register set to access;
// ForceInterrupt is the exception to this rule.
if (command != FDCCommand.ForceInterrupt)
{
if (_busy)
{
// Early abort if a command is already in progress.
if (Log.Enabled) Log.Write(LogComponent.IOPFloppy, "FDC busy, seek aborted.", _stepDirection);
return;
}
_lastCommand = command;
}
int data = commandData & 0x1f;
switch(command)
{
case FDCCommand.Restore:
// Seek inward until the Track 0 sensor trips.
// We use the general Seek mechanism, which we
// cheat by loading the FDC track register with the
// actual physical head position, so a seek to 0
// will actually end up at physical track 0.
_fdcTrack = (byte)_drive.Track;
Seek(0, new Type1CommandParams(data));
break;
case FDCCommand.Seek:
//
// "This command assumes that the Track Register contains the track number
// of the current position of the Read-Write head and the Data Register contains
// the desired track number."
//
Seek(_fdcData, new Type1CommandParams(data));
break;
case FDCCommand.StepNoUpdate:
case FDCCommand.StepUpdate:
Step(StepDirection.Last, new Type1CommandParams(data));
break;
case FDCCommand.StepInNoUpdate:
case FDCCommand.StepInUpdate:
Step(StepDirection.In, new Type1CommandParams(data));
break;
case FDCCommand.StepOutNoUpdate:
case FDCCommand.StepOutUpdate:
Step(StepDirection.Out, new Type1CommandParams(data));
break;
case FDCCommand.ReadSectorSingle:
ReadSector(new Type2CommandParams(data));
break;
case FDCCommand.ForceInterrupt:
ForceInterrupt(data);
break;
default:
throw new NotImplementedException(
String.Format("FDC command {0} not implemented.", command));
}
}
private void Seek(int track, Type1CommandParams p)
{
_seekDestination = track;
_seekError = false;
// Schedule the first step of the heads
_system.Scheduler.Schedule(_commandBeginNsec, p, SeekCallback);
if (Log.Enabled) Log.Write(LogComponent.IOPFloppy, "Seek to {0} initialized.", track);
}
private void Step(StepDirection direction, Type1CommandParams p)
{
if (direction != StepDirection.Last)
{
_stepDirection = direction;
}
_seekError = false;
// Schedule a step of the heads.
if (!_busy)
{
_system.Scheduler.Schedule(
_commandBeginNsec,
(timestampNsec, context) =>
{
if (_commandAbort)
{
//
// Abort the step, perform no head steps and update no registers.
//
if (Log.Enabled) Log.Write(LogComponent.IOPFloppy, "Step aborted by ForceInterrupt.");
return;
}
if (!_busy)
{
// Raise the busy flag -- the command has been accepted.
_busy = true;
// Schedule the actual step
_system.Scheduler.Schedule(
_stepTimeNsec,
(ts, ctx) =>
{
switch (_stepDirection)
{
case StepDirection.Out: // one track closer to the outer edge
_drive.SeekTo(_drive.Track - 1);
if (p.Update)
{
_fdcTrack--;
}
break;
case StepDirection.In: // one track closer to the inner edge
_drive.SeekTo(_drive.Track + 1);
if (p.Update)
{
_fdcTrack++;
}
break;
default:
throw new InvalidOperationException("Unepxected step type.");
}
if (p.Verify && _drive.IsLoaded && (_fdcTrack != _drive.Track))
{
_seekError = true;
}
_headLoaded = p.HeadLoad;
RaiseInterrupt();
//
// Reset the busy flag, the step is complete.
//
_busy = false;
if (Log.Enabled) Log.Write(LogComponent.IOPFloppy, "Step to {0} (physical {1}) completed.", _seekDestination, _drive.Track);
});
}
});
}
if (Log.Enabled) Log.Write(LogComponent.IOPFloppy, "Step {0} initialized.", _stepDirection);
}
private void ReadSector(Type2CommandParams p)
{
// Schedule the read.
_system.Scheduler.Schedule(
_commandBeginNsec,
(timestampNsec, context) =>
{
//
// Set RNF if specified sector is out of range or if the drive's physical
// head position != the FDC's track register.
//
int sectorCount = _drive.Disk.GetTrack(_drive.Track, p.SideSelect ? 1 : 0).SectorCount;
_rnf = (_fdcTrack != _drive.Track) ||
(_fdcSector > sectorCount);
//
// Read the sector into the sector buffer.
// BUSY remains active until the transfer is complete -- whenever DMA or a polled
// read finishes the buffer off.
//
if (!NotReady() && !_rnf)
{
// the FDC's sector value is 1-indexed.
_sectorBuffer = _drive.Disk.GetSector(_drive.Track, p.SideSelect ? 1 : 0, _fdcSector - 1).Data;
_sectorDataIndex = 0;
_busy = true;
_drq = true;
_drqCounter = 16;
if (Log.Enabled) Log.Write(LogComponent.IOPFloppy, "Sector read of C/H/S {0}/{1}/{2} initialized.",
_fdcTrack, p.SideSelect ? 1 : 0, _fdcSector);
}
else
{
_sectorBuffer = null;
_busy = false;
}
});
if (Log.Enabled) Log.Write(LogComponent.IOPFloppy, "Read initialized.");
}
private void ForceInterrupt(int flags)
{
//
// Terminate any pending command.
// and generate an interrupt for the condition specified in
// i0-i3.
// This is only used in FDCTest.asm and doesn't actually use
// the interrupt facilities
// Clear the BUSY flag
_busy = false;
// Cause any pending command to abort before completing.
_commandAbort = true;
if (Log.Enabled) Log.Write(LogComponent.IOPFloppy, "Force Interrupt 0x{0:x2}", flags);
}
private void SeekCallback(ulong skewNsec, object context)
{
if (_commandAbort)
{
//
// Abort the seek, perform no head steps and update no registers.
//
if (Log.Enabled) Log.Write(LogComponent.IOPFloppy, "Seek aborted by ForceInterrupt.");
return;
}
// Set the FDC busy status.
_busy = true;
if (_fdcTrack == _seekDestination)
{
// We've arrived. Everyone out of the car.
// Clear the FDC Type I BUSY status
_busy = false;
//
// Do a verification. Since we're not emulating the floppy at a level
// low enough to verify header CRC and sector IDs, we assume those are OK
// and only compare our Physical track counter with the FDC's track counter.
//
Type1CommandParams p = (Type1CommandParams)context;
if (p.Verify && _drive.IsLoaded && (_fdcTrack != _drive.Track))
{
_seekError = true;
}
_headLoaded = p.HeadLoad;
RaiseInterrupt();
if (Log.Enabled) Log.Write(LogComponent.IOPFloppy, "Seek to {0} (physical {1}) completed.", _seekDestination, _drive.Track);
}
else
{
// Not there yet, move one step in the right direction.
if (_fdcTrack < _seekDestination)
{
_fdcTrack++;
_drive.SeekTo(_drive.Track + 1);
}
else
{
_fdcTrack--;
_drive.SeekTo(_drive.Track - 1);
}
_system.Scheduler.Schedule(_stepTimeNsec, context, SeekCallback);
if (Log.Enabled) Log.Write(LogComponent.IOPFloppy, "Seek step to {0} (physical {1})", _fdcTrack, _drive.Track);
}
}
/// <summary>
/// Invoked when a sector data transfer completes (either by DMA or programmed I/O).
/// </summary>
private void FinishDataTransfer()
{
_drq = false;
_busy = false;
_sectorBuffer = null;
_sectorDataIndex = 0;
RaiseInterrupt();
}
private void ClearInterrupt()
{
_interruptPending = false;
// RST7.5 is edge triggered, no need to clear it here.
}
private void RaiseInterrupt()
{
_interruptPending = true;
_system.IOP.CPU.RaiseExternalInterrupt(InterruptType.RST7_5);
}
private bool NotReady()
{
return _drive.DriveSelect ? !_drive.IsLoaded : true;
}
private bool WriteProtect()
{
return _drive.IsLoaded && _drive.IsWriteProtected;
}
private bool Track0()
{
return _drive.Track0;
}
private bool Index()
{
return _drive.Index || _indexReset;
}
private readonly int[] _readPorts = new int[]
{
(int)FDCPorts.FDCStatus,
(int)FDCPorts.FDCTrack,
(int)FDCPorts.FDCSector,
(int)FDCPorts.FDCData,
(int)FDCPorts.ExtFDCStatusReg,
};
private readonly int[] _writePorts = new int[]
{
(int)FDCPorts.FDCCommand,
(int)FDCPorts.FDCTrack,
(int)FDCPorts.FDCSector,
(int)FDCPorts.FDCData,
(int)FDCPorts.ExtFDCState
};
// FDC data
private byte _fdcTrack;
private byte _fdcSector;
private byte _fdcData;
// Sector data
private byte[] _sectorBuffer;
private int _sectorDataIndex;
// Status flags
// Type 1/2/3:
private bool _crcError; // 0x08
private bool _busy; // 0x01
// Type 1:
private bool _headLoaded; // 0x20
private bool _seekError; // 0x10
// Type 2/3:
private bool _recordTypeWriteFault; // 0x20
private bool _rnf; // 0x10
private bool _lostData; // 0x04
private bool _drq; // 0x02
private int _drqCounter;
// Overrides drive Index signal immediately after FDC reset.
private bool _indexReset;
/// <summary>
/// Current state of the enabled signal for the FDC.
/// </summary>
private bool _fdcEnabled;
// Interrupt flag. This is set when a command completes,
// reset when the status register is read or the command
// register is written to.
private bool _interruptPending;
private FDCCommand _lastCommand;
// External state (written with ExtFDCState port)
private FDCStateFlags _extState;
// Seek state
private int _seekDestination;
private ulong _commandBeginNsec = 12 * Conversion.UsecToNsec;
private ulong _stepTimeNsec = 6 * Conversion.MsecToNsec;
// Step state
private StepDirection _stepDirection;
//
// This exists because the FDCTest code expects undocumented behavior from the FDC chip.
// Specifically, after the FDC is reset, INDEX goes high as long as a drive is selected
// (regardless of whether a disk is in the drive or not).
// After a short (unspecified) interval it goes low again.
// On a reset with drive selected, we will kick off an event to do what the test expects.
//
private ulong _resetIndexDuration = 10 * Conversion.MsecToNsec; // Guesswork
//
// Command execution state
//
private bool _commandAbort;
//
// The floppy drive we're talking to
//
private FloppyDrive _drive;
//
// The system we belong to
//
private DSystem _system;
private enum FDCPorts
{
FDCCommand = 0x84, // Commands (write)
FDCStatus = 0x84, // Status (read)
FDCTrack = 0x85, // Track register (r/w)
FDCSector = 0x86, // Sector register (r/w)
FDCData = 0x87, // Data register (r/w)
// These are external to the actual FDC chip
ExtFDCStatusReg = 0xe8, // External status register (read)
ExtFDCState = 0xe8, // External state register (write)
}
/// <summary>
/// Flags for FDCState port
/// </summary>
[Flags]
private enum FDCStateFlags
{
EnableWaits = 0x80, // Set wait cycles in FDCState (what does this mean?)
Precomp = 0x40, // Apparently the IOP handles write precomp itself? (FDC chip can do this...)
Side = 0x20, // Number of sides?
Density = 0x08, // Connected to DDEN on FDC ( 0 = double, 1 = single)
EnableFDC = 0x04, // Enables the FDC chip
DriveSelect = 0x01, // enables drive select ( 0 = no drive selected, 1 = drive selected)
None = 0x00,
}
/// <summary>
/// Flags for FDCStatusReg port
/// From BootDefs.asm
/// </summary>
[Flags]
private enum FDCStatusFlags
{
IntMask = 0x80, // FDC interrupt request status
EndCount = 0x40, // FDC end count
TwoSided = 0x20, // FDC two-sided bit
SA800 = 0x10, // "now no-floppy bit" (presumably set when no floppy is inserted in the drive)
None = 0x00,
}
private enum FDCCommand
{
Restore = 0,
Seek = 1,
StepNoUpdate = 2,
StepUpdate = 3,
StepInNoUpdate = 4,
StepInUpdate = 5,
StepOutNoUpdate = 6,
StepOutUpdate = 7,
ReadSectorSingle = 8,
ReadSectorMultiple = 9,
WriteSectorSingle = 0xa,
WriteSectorMultiple = 0xb,
ReadAddress = 0xc,
ForceInterrupt = 0x0d,
ReadTrack = 0xe,
WriteTrack = 0xf,
}
private enum StepDirection
{
In = 0,
Out = 1,
Last = 2,
}
/// <summary>
/// Encapsulates Type 1 command options.
/// </summary>
private struct Type1CommandParams
{
public Type1CommandParams(bool update, bool headLoad, bool verify)
{
Update = update;
HeadLoad = headLoad;
Verify = verify;
}
public Type1CommandParams(int p)
{
Update = (p & 0x10) != 0;
HeadLoad = (p & 0x08) != 0;
Verify = (p & 0x04) != 0;
}
public bool Update;
public bool HeadLoad;
public bool Verify;
}
/// <summary>
/// Encapsulates Type 2 and 3 command options
/// </summary>
private struct Type2CommandParams
{
public Type2CommandParams(int p)
{
SectorLength = ((p & 0x8) != 0);
Delay = ((p & 0x4) != 0);
SideSelect = ((p & 0x2) != 0);
DataAddressMark = ((p & 0x1) != 0);
}
public bool SideSelect;
public bool Delay;
public bool SectorLength;
public bool DataAddressMark;
}
//
// WD FD179X status register bits
//
[Flags]
private enum Type1Status
{
NotReady = 0x80,
WriteProtect = 0x40,
HeadLoaded = 0x20,
SeekError = 0x10,
CRCError = 0x08,
Track0 = 0x04,
Index = 0x02,
Busy = 0x01,
}
/// <summary>
/// Actually for type 2 or 3
/// </summary>
[Flags]
private enum Type2Status
{
NotReady = 0x80,
WriteProtect = 0x40,
RecordTypeWriteFault = 0x20,
RNF = 0x10,
CRCError = 0x08,
LostData = 0x04,
DRQ = 0x02,
Busy = 0x01,
}
}
}
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