Aaru/DiscImageChef.DiscImages/TeleDisk.cs

// /***************************************************************************
// The Disc Image Chef
// ----------------------------------------------------------------------------
//
// Filename       : TeleDisk.cs
// Author(s)      : Natalia Portillo <claunia@claunia.com>
//
// Component      : Disk image plugins.
//
// --[ Description ] ----------------------------------------------------------
//
//     Manages Sydex TeleDisk disk images.
//
// --[ License ] --------------------------------------------------------------
//
//     This library is free software; you can redistribute it and/or modify
//     it under the terms of the GNU Lesser General Public License as
//     published by the Free Software Foundation; either version 2.1 of the
//     License, or (at your option) any later version.
//
//     This library is distributed in the hope that it will be useful, but
//     WITHOUT ANY WARRANTY; without even the implied warranty of
//     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
//     Lesser General Public License for more details.
//
//     You should have received a copy of the GNU Lesser General Public
//     License along with this library; if not, see <http://www.gnu.org/licenses/>.
//
// ----------------------------------------------------------------------------
// Copyright © 2011-2018 Natalia Portillo
// For Advanced Compression support (aka LZH):
// Copyright © 2017 Miodrag Milanovic
// Copyright © 1988 Haruhiko OKUMURA
// Copyright © 1988 Haruyasu YOSHIZAKI
// Copyright © 1988 Kenji RIKITAKE
// ****************************************************************************/

using System;
using System.IO;
using System.Collections.Generic;
using DiscImageChef.Console;
using DiscImageChef.CommonTypes;
using DiscImageChef.Filters;

namespace DiscImageChef.ImagePlugins
{
	// Created following notes from Dave Dunfield
	// http://www.classiccmp.org/dunfield/img54306/td0notes.txt
	public class TeleDisk : ImagePlugin
	{
		#region Internal Structures

		struct TD0Header
		{
			/// <summary>"TD" or "td" depending on compression</summary>
			public ushort signature;
			/// <summary>Sequence, but TeleDisk seems to complaing if != 0</summary>
			public byte sequence;
			/// <summary>Random, same byte for all disks in the same set</summary>
			public byte diskSet;
			/// <summary>TeleDisk version, major in high nibble, minor in low nibble</summary>
			public byte version;
			/// <summary>Data rate</summary>
			public byte dataRate;
			/// <summary>BIOS drive type</summary>
			public byte driveType;
			/// <summary>Stepping used</summary>
			public byte stepping;
			/// <summary>If set means image only allocates sectors marked in-use by FAT12</summary>
			public byte dosAllocation;
			/// <summary>Sides of disk</summary>
			public byte sides;
			/// <summary>CRC of all the previous</summary>
			public ushort crc;
		}

		struct TDCommentBlockHeader
		{
			/// <summary>CRC of comment block after crc field</summary>
			public ushort crc;
			/// <summary>Length of comment</summary>
			public ushort length;
			public byte year;
			public byte month;
			public byte day;
			public byte hour;
			public byte minute;
			public byte second;
		}

		struct TDTrackHeader
		{
			/// <summary>Sectors in the track, 0xFF if end of disk image (there is no spoon)</summary>
			public byte sectors;
			/// <summary>Cylinder the head was on</summary>
			public byte cylinder;
			/// <summary>Head/side used</summary>
			public byte head;
			/// <summary>Lower byte of CRC of previous fields</summary>
			public byte crc;
		}

		struct TDSectorHeader
		{
			/// <summary>Cylinder as stored on sector address mark</summary>
			public byte cylinder;
			/// <summary>Head as stored on sector address mark</summary>
			public byte head;
			/// <summary>Sector number as stored on sector address mark</summary>
			public byte sectorNumber;
			/// <summary>Sector size</summary>
			public byte sectorSize;
			/// <summary>Sector flags</summary>
			public byte flags;
			/// <summary>Lower byte of TeleDisk CRC of sector header, data header and data block</summary>
			public byte crc;
		}

		struct TDDataHeader
		{
			/// <summary>Size of all data (encoded) + next field (1)</summary>
			public ushort dataSize;
			/// <summary>Encoding used for data block</summary>
			public byte dataEncoding;
		}

		#endregion

		#region Internal Constants

		// "TD" as little endian uint.
		const ushort tdMagic = 0x4454;
		// "td" as little endian uint. Means whole file is compressed (aka Advanced Compression)
		const ushort tdAdvCompMagic = 0x6474;

		// DataRates
		const byte DataRate250kbps = 0x00;
		const byte DataRate300kbps = 0x01;
		const byte DataRate500kbps = 0x02;

		// TeleDisk drive types
		const byte DriveType525HD_DDDisk = 0x00;
		const byte DriveType525HD = 0x01;
		const byte DriveType525DD = 0x02;
		const byte DriveType35DD = 0x03;
		const byte DriveType35HD = 0x04;
		const byte DriveType8inch = 0x05;
		const byte DriveType35ED = 0x06;

		// Stepping
		const byte SteppingSingle = 0x00;
		const byte SteppingDouble = 0x01;
		const byte SteppingEvenOnly = 0x02;
		// If this bit is set, there is a comment block
		const byte CommentBlockPresent = 0x80;

		// CRC polynomial
		const ushort TeleDiskCRCPoly = 0xA097;

		// Sector sizes table
		const byte SectorSize128 = 0x00;
		const byte SectorSize256 = 0x01;
		const byte SectorSize512 = 0x02;
		const byte SectorSize1K = 0x03;
		const byte SectorSize2K = 0x04;
		const byte SectorSize4K = 0x05;
		const byte SectorSize8K = 0x06;

		// Flags
		// Address mark repeats inside same track
		const byte FlagsSectorDuplicate = 0x01;
		// Sector gave CRC error on reading
		const byte FlagsSectorCRCError = 0x02;
		// Address mark indicates deleted sector
		const byte FlagsSectorDeleted = 0x04;
		// Sector skipped as FAT said it's unused
		const byte FlagsSectorSkipped = 0x10;
		// There was an address mark, but no data following
		const byte FlagsSectorDataless = 0x20;
		// There was data without address mark
		const byte FlagsSectorNoID = 0x40;

		// Data block encodings
		// Data is copied as is
		const byte dataBlockCopy = 0x00;
		// Data is encoded as a pair of len.value uint16s
		const byte dataBlockPattern = 0x01;
		// Data is encoded as RLE
		const byte dataBlockRLE = 0x02;

		#endregion

		#region Internal variables

		TD0Header header;
		TDCommentBlockHeader commentHeader;
		byte[] commentBlock;
		// LBA, data
		uint totalDiskSize;
		bool ADiskCRCHasFailed;
		List<ulong> SectorsWhereCRCHasFailed;
		// Cylinder by head, sector data matrix
		byte[][][][] sectorsData;
		Stream inStream;
		byte[] leadOut;

		#endregion

		public TeleDisk()
		{
			Name = "Sydex TeleDisk";
			PluginUUID = new Guid("0240B7B1-E959-4CDC-B0BD-386D6E467B88");
			ImageInfo = new ImageInfo();
			ImageInfo.readableSectorTags = new List<SectorTagType>();
			ImageInfo.readableMediaTags = new List<MediaTagType>();
			ImageInfo.imageHasPartitions = false;
			ImageInfo.imageHasSessions = false;
			ImageInfo.imageApplication = "Sydex TeleDisk";
			ImageInfo.imageComments = null;
			ImageInfo.imageCreator = null;
			ImageInfo.mediaManufacturer = null;
			ImageInfo.mediaModel = null;
			ImageInfo.mediaSerialNumber = null;
			ImageInfo.mediaBarcode = null;
			ImageInfo.mediaPartNumber = null;
			ImageInfo.mediaSequence = 0;
			ImageInfo.lastMediaSequence = 0;
			ImageInfo.driveManufacturer = null;
			ImageInfo.driveModel = null;
			ImageInfo.driveSerialNumber = null;
			ImageInfo.driveFirmwareRevision = null;
			ADiskCRCHasFailed = false;
			SectorsWhereCRCHasFailed = new List<ulong>();
		}

		public override bool IdentifyImage(Filter imageFilter)
		{
			header = new TD0Header();
			byte[] headerBytes = new byte[12];
			Stream stream = imageFilter.GetDataForkStream();
			stream.Seek(0, SeekOrigin.Begin);

			stream.Read(headerBytes, 0, 12);

			header.signature = BitConverter.ToUInt16(headerBytes, 0);

			if(header.signature != tdMagic && header.signature != tdAdvCompMagic)
				return false;

			header.sequence = headerBytes[2];
			header.diskSet = headerBytes[3];
			header.version = headerBytes[4];
			header.dataRate = headerBytes[5];
			header.driveType = headerBytes[6];
			header.stepping = headerBytes[7];
			header.dosAllocation = headerBytes[8];
			header.sides = headerBytes[9];
			header.crc = BitConverter.ToUInt16(headerBytes, 10);

			byte[] headerBytesForCRC = new byte[10];
			Array.Copy(headerBytes, headerBytesForCRC, 10);
			ushort calculatedHeaderCRC = TeleDiskCRC(0x0000, headerBytesForCRC);

			DicConsole.DebugWriteLine("TeleDisk plugin", "header.signature = 0x{0:X4}", header.signature);
			DicConsole.DebugWriteLine("TeleDisk plugin", "header.sequence = 0x{0:X2}", header.sequence);
			DicConsole.DebugWriteLine("TeleDisk plugin", "header.diskSet = 0x{0:X2}", header.diskSet);
			DicConsole.DebugWriteLine("TeleDisk plugin", "header.version = 0x{0:X2}", header.version);
			DicConsole.DebugWriteLine("TeleDisk plugin", "header.dataRate = 0x{0:X2}", header.dataRate);
			DicConsole.DebugWriteLine("TeleDisk plugin", "header.driveType = 0x{0:X2}", header.driveType);
			DicConsole.DebugWriteLine("TeleDisk plugin", "header.stepping = 0x{0:X2}", header.stepping);
			DicConsole.DebugWriteLine("TeleDisk plugin", "header.dosAllocation = 0x{0:X2}", header.dosAllocation);
			DicConsole.DebugWriteLine("TeleDisk plugin", "header.sides = 0x{0:X2}", header.sides);
			DicConsole.DebugWriteLine("TeleDisk plugin", "header.crc = 0x{0:X4}", header.crc);
			DicConsole.DebugWriteLine("TeleDisk plugin", "calculated header crc = 0x{0:X4}", calculatedHeaderCRC);

			// We need more checks as the magic is too simply.
			// This may deny legal images

			// That would be much of a coincidence
			if(header.crc == calculatedHeaderCRC)
				return true;

			if(header.sequence != 0x00)
				return false;

			if(header.dataRate != DataRate250kbps && header.dataRate != DataRate300kbps && header.dataRate != DataRate500kbps)
				return false;

			if(header.driveType != DriveType35DD && header.driveType != DriveType35ED && header.driveType != DriveType35HD && header.driveType != DriveType525DD &&
				header.driveType != DriveType525HD && header.driveType != DriveType525HD_DDDisk && header.driveType != DriveType8inch)
				return false;

			return true;
		}

		public override bool OpenImage(Filter imageFilter)
		{
			header = new TD0Header();
			byte[] headerBytes = new byte[12];
			inStream = imageFilter.GetDataForkStream();
			MemoryStream stream = new MemoryStream();
			inStream.Seek(0, SeekOrigin.Begin);

			inStream.Read(headerBytes, 0, 12);
			stream.Write(headerBytes, 0, 12);

			header.signature = BitConverter.ToUInt16(headerBytes, 0);

			if(header.signature != tdMagic && header.signature != tdAdvCompMagic)
				return false;

			header.sequence = headerBytes[2];
			header.diskSet = headerBytes[3];
			header.version = headerBytes[4];
			header.dataRate = headerBytes[5];
			header.driveType = headerBytes[6];
			header.stepping = headerBytes[7];
			header.dosAllocation = headerBytes[8];
			header.sides = headerBytes[9];
			header.crc = BitConverter.ToUInt16(headerBytes, 10);

			ImageInfo.imageName = Path.GetFileNameWithoutExtension(imageFilter.GetFilename());
			ImageInfo.imageVersion = string.Format("{0}.{1}", (header.version & 0xF0) >> 4, header.version & 0x0F);
			ImageInfo.imageApplication = ImageInfo.imageVersion;

			byte[] headerBytesForCRC = new byte[10];
			Array.Copy(headerBytes, headerBytesForCRC, 10);
			ushort calculatedHeaderCRC = TeleDiskCRC(0x0000, headerBytesForCRC);

			DicConsole.DebugWriteLine("TeleDisk plugin", "header.signature = 0x{0:X4}", header.signature);
			DicConsole.DebugWriteLine("TeleDisk plugin", "header.sequence = 0x{0:X2}", header.sequence);
			DicConsole.DebugWriteLine("TeleDisk plugin", "header.diskSet = 0x{0:X2}", header.diskSet);
			DicConsole.DebugWriteLine("TeleDisk plugin", "header.version = 0x{0:X2}", header.version);
			DicConsole.DebugWriteLine("TeleDisk plugin", "header.dataRate = 0x{0:X2}", header.dataRate);
			DicConsole.DebugWriteLine("TeleDisk plugin", "header.driveType = 0x{0:X2}", header.driveType);
			DicConsole.DebugWriteLine("TeleDisk plugin", "header.stepping = 0x{0:X2}", header.stepping);
			DicConsole.DebugWriteLine("TeleDisk plugin", "header.dosAllocation = 0x{0:X2}", header.dosAllocation);
			DicConsole.DebugWriteLine("TeleDisk plugin", "header.sides = 0x{0:X2}", header.sides);
			DicConsole.DebugWriteLine("TeleDisk plugin", "header.crc = 0x{0:X4}", header.crc);
			DicConsole.DebugWriteLine("TeleDisk plugin", "calculated header crc = 0x{0:X4}", calculatedHeaderCRC);

			// We need more checks as the magic is too simply.
			// This may deny legal images

			// That would be much of a coincidence
			if(header.crc != calculatedHeaderCRC)
			{
				ADiskCRCHasFailed = true;
				DicConsole.DebugWriteLine("TeleDisk plugin", "Calculated CRC does not coincide with stored one.");
			}

			if(header.sequence != 0x00)
				return false;

			if(header.dataRate != DataRate250kbps && header.dataRate != DataRate300kbps && header.dataRate != DataRate500kbps)
				return false;

			if(header.driveType != DriveType35DD && header.driveType != DriveType35ED && header.driveType != DriveType35HD && header.driveType != DriveType525DD &&
				header.driveType != DriveType525HD && header.driveType != DriveType525HD_DDDisk && header.driveType != DriveType8inch)
				return false;

			if(header.signature == tdAdvCompMagic)
			{
				int rd;
				byte[] obuf = new byte[BUFSZ];
				inStream.Seek(12, SeekOrigin.Begin);
				stream.Seek(12, SeekOrigin.Begin);
				init_Decode();
				do
				{
					if((rd = Decode(out obuf, BUFSZ)) > 0)
						stream.Write(obuf, 0, rd);
				} while(rd == BUFSZ);
			}
			else
			{
				// Not using Stream.CopyTo() because it's failing with LZIP
				byte[] copybuf = new byte[inStream.Length];
				inStream.Seek(0, SeekOrigin.Begin);
				inStream.Read(copybuf, 0, copybuf.Length);
				stream.Seek(0, SeekOrigin.Begin);
				stream.Write(copybuf, 0, copybuf.Length);
				copybuf = null;
			}

			stream.Seek(12, SeekOrigin.Begin);

			ImageInfo.imageCreationTime = DateTime.MinValue;

			if((header.stepping & CommentBlockPresent) == CommentBlockPresent)
			{
				commentHeader = new TDCommentBlockHeader();

				byte[] commentHeaderBytes = new byte[10];
				byte[] commentBlockForCRC;

				stream.Read(commentHeaderBytes, 0, 10);
				commentHeader.crc = BitConverter.ToUInt16(commentHeaderBytes, 0);
				commentHeader.length = BitConverter.ToUInt16(commentHeaderBytes, 2);
				commentHeader.year = commentHeaderBytes[4];
				commentHeader.month = commentHeaderBytes[5];
				commentHeader.day = commentHeaderBytes[6];
				commentHeader.hour = commentHeaderBytes[7];
				commentHeader.minute = commentHeaderBytes[8];
				commentHeader.second = commentHeaderBytes[9];

				commentBlock = new byte[commentHeader.length];
				stream.Read(commentBlock, 0, commentHeader.length);

				commentBlockForCRC = new byte[commentHeader.length + 8];
				Array.Copy(commentHeaderBytes, 2, commentBlockForCRC, 0, 8);
				Array.Copy(commentBlock, 0, commentBlockForCRC, 8, commentHeader.length);

				ushort cmtcrc = TeleDiskCRC(0, commentBlockForCRC);

				DicConsole.DebugWriteLine("TeleDisk plugin", "Comment header");
				DicConsole.DebugWriteLine("TeleDisk plugin", "\tcommentheader.crc = 0x{0:X4}", commentHeader.crc);
				DicConsole.DebugWriteLine("TeleDisk plugin", "\tCalculated CRC = 0x{0:X4}", cmtcrc);
				DicConsole.DebugWriteLine("TeleDisk plugin", "\tcommentheader.length = {0} bytes", commentHeader.length);
				DicConsole.DebugWriteLine("TeleDisk plugin", "\tcommentheader.year = {0}", commentHeader.year);
				DicConsole.DebugWriteLine("TeleDisk plugin", "\tcommentheader.month = {0}", commentHeader.month);
				DicConsole.DebugWriteLine("TeleDisk plugin", "\tcommentheader.day = {0}", commentHeader.day);
				DicConsole.DebugWriteLine("TeleDisk plugin", "\tcommentheader.hour = {0}", commentHeader.hour);
				DicConsole.DebugWriteLine("TeleDisk plugin", "\tcommentheader.minute = {0}", commentHeader.minute);
				DicConsole.DebugWriteLine("TeleDisk plugin", "\tcommentheader.second = {0}", commentHeader.second);

				ADiskCRCHasFailed |= cmtcrc != commentHeader.crc;

				for(int i = 0; i < commentBlock.Length; i++)
				{
					// Replace NULLs, used by TeleDisk as newline markers, with UNIX newline marker
					if(commentBlock[i] == 0x00)
						commentBlock[i] = 0x0A;
				}

				ImageInfo.imageComments = System.Text.Encoding.ASCII.GetString(commentBlock);

				DicConsole.DebugWriteLine("TeleDisk plugin", "Comment");
				DicConsole.DebugWriteLine("TeleDisk plugin", "{0}", ImageInfo.imageComments);

				ImageInfo.imageCreationTime = new DateTime(commentHeader.year + 1900, commentHeader.month + 1, commentHeader.day,
					commentHeader.hour, commentHeader.minute, commentHeader.second, DateTimeKind.Unspecified);
			}

			if(ImageInfo.imageCreationTime == DateTime.MinValue)
				ImageInfo.imageCreationTime = imageFilter.GetCreationTime();
			ImageInfo.imageLastModificationTime = imageFilter.GetLastWriteTime();

			DicConsole.DebugWriteLine("TeleDisk plugin", "Image created on {0}", ImageInfo.imageCreationTime);
			DicConsole.DebugWriteLine("TeleDisk plugin", "Image modified on {0}", ImageInfo.imageLastModificationTime);

			DicConsole.DebugWriteLine("TeleDisk plugin", "Parsing image");

			totalDiskSize = 0;
			ImageInfo.imageSize = 0;

			int totalCylinders = -1;
			int totalHeads = -1;
			int maxSector = -1;
			int totalSectors = 0;
			long currentPos = stream.Position;
			ImageInfo.sectorSize = uint.MaxValue;
			ImageInfo.sectorsPerTrack = uint.MaxValue;

			// Count cylinders
			while(true)
			{
				TDTrackHeader TDTrack = new TDTrackHeader();

				TDTrack.sectors = (byte)stream.ReadByte();
				TDTrack.cylinder = (byte)stream.ReadByte();
				TDTrack.head = (byte)stream.ReadByte();
				TDTrack.crc = (byte)stream.ReadByte();

				if(TDTrack.cylinder > totalCylinders)
					totalCylinders = TDTrack.cylinder;
				if(TDTrack.head > totalHeads)
					totalHeads = TDTrack.head;

				if(TDTrack.sectors == 0xFF) // End of disk image
					break;

				for(byte processedSectors = 0; processedSectors < TDTrack.sectors; processedSectors++)
				{
					TDSectorHeader TDSector = new TDSectorHeader();
					TDDataHeader TDData = new TDDataHeader();
					byte[] dataSizeBytes = new byte[2];
					byte[] data;

					TDSector.cylinder = (byte)stream.ReadByte();
					TDSector.head = (byte)stream.ReadByte();
					TDSector.sectorNumber = (byte)stream.ReadByte();
					TDSector.sectorSize = (byte)stream.ReadByte();
					TDSector.flags = (byte)stream.ReadByte();
					TDSector.crc = (byte)stream.ReadByte();

					if(TDSector.sectorNumber > maxSector)
						maxSector = TDSector.sectorNumber;

					if((TDSector.flags & FlagsSectorDataless) != FlagsSectorDataless && (TDSector.flags & FlagsSectorSkipped) != FlagsSectorSkipped)
					{
						stream.Read(dataSizeBytes, 0, 2);
						TDData.dataSize = BitConverter.ToUInt16(dataSizeBytes, 0);
						TDData.dataSize--; // Sydex decided to including dataEncoding byte as part of it
						TDData.dataEncoding = (byte)stream.ReadByte();
						data = new byte[TDData.dataSize];
						stream.Read(data, 0, TDData.dataSize);
					}

					if(128 << TDSector.sectorSize < ImageInfo.sectorSize)
						ImageInfo.sectorSize = (uint)(128 << TDSector.sectorSize);

					totalSectors++;
				}
			}

			totalCylinders++;
			totalHeads++;

			if(totalCylinders <= 0 || totalHeads <= 0)
				throw new ImageNotSupportedException("No cylinders or heads found");

			bool hasLeadOutOnHead0 = false;
			bool hasLeadOutOnHead1 = false;
			ImageInfo.cylinders = (ushort)totalCylinders;
			ImageInfo.heads = (byte)totalHeads;

			// Count sectors per track
			stream.Seek(currentPos, SeekOrigin.Begin);
			while(true)
			{
				TDTrackHeader TDTrack = new TDTrackHeader();

				TDTrack.sectors = (byte)stream.ReadByte();
				TDTrack.cylinder = (byte)stream.ReadByte();
				TDTrack.head = (byte)stream.ReadByte();
				TDTrack.crc = (byte)stream.ReadByte();

				if(TDTrack.sectors == 0xFF) // End of disk image
					break;

				if(TDTrack.sectors < ImageInfo.sectorsPerTrack)
				{
					if(TDTrack.cylinder + 1 == totalCylinders)
					{
						hasLeadOutOnHead0 |= TDTrack.head == 0;
						hasLeadOutOnHead1 |= TDTrack.head == 1;
						if(ImageInfo.cylinders == totalCylinders)
							ImageInfo.cylinders--;
					}
					else
						ImageInfo.sectorsPerTrack = TDTrack.sectors;
				}
				for(byte processedSectors = 0; processedSectors < TDTrack.sectors; processedSectors++)
				{
					TDSectorHeader TDSector = new TDSectorHeader();
					TDDataHeader TDData = new TDDataHeader();
					byte[] dataSizeBytes = new byte[2];
					byte[] data;

					TDSector.cylinder = (byte)stream.ReadByte();
					TDSector.head = (byte)stream.ReadByte();
					TDSector.sectorNumber = (byte)stream.ReadByte();
					TDSector.sectorSize = (byte)stream.ReadByte();
					TDSector.flags = (byte)stream.ReadByte();
					TDSector.crc = (byte)stream.ReadByte();

					if((TDSector.flags & FlagsSectorDataless) != FlagsSectorDataless && (TDSector.flags & FlagsSectorSkipped) != FlagsSectorSkipped)
					{
						stream.Read(dataSizeBytes, 0, 2);
						TDData.dataSize = BitConverter.ToUInt16(dataSizeBytes, 0);
						TDData.dataSize--; // Sydex decided to including dataEncoding byte as part of it
						TDData.dataEncoding = (byte)stream.ReadByte();
						data = new byte[TDData.dataSize];
						stream.Read(data, 0, TDData.dataSize);
					}
				}
			}

			sectorsData = new byte[totalCylinders][][][];
			// Total sectors per track
			uint[][] spts = new uint[totalCylinders][];

			DicConsole.DebugWriteLine("TeleDisk plugin", "Found {0} cylinders and {1} heads with a maximum sector number of {2}", totalCylinders, totalHeads, maxSector);

			// Create heads
			for(int i = 0; i < totalCylinders; i++)
			{
				sectorsData[i] = new byte[totalHeads][][];
				spts[i] = new uint[totalHeads];

				for(int j = 0; j < totalHeads; j++)
					sectorsData[i][j] = new byte[maxSector + 1][];
			}

			// Decode the image
			stream.Seek(currentPos, SeekOrigin.Begin);
			while(true)
			{
				TDTrackHeader TDTrack = new TDTrackHeader();
				byte[] TDTrackForCRC = new byte[3];
				byte TDTrackCalculatedCRC;

				TDTrack.sectors = (byte)stream.ReadByte();
				TDTrack.cylinder = (byte)stream.ReadByte();
				TDTrack.head = (byte)stream.ReadByte();
				TDTrack.crc = (byte)stream.ReadByte();

				TDTrackForCRC[0] = TDTrack.sectors;
				TDTrackForCRC[1] = TDTrack.cylinder;
				TDTrackForCRC[2] = TDTrack.head;

				TDTrackCalculatedCRC = (byte)(TeleDiskCRC(0, TDTrackForCRC) & 0xFF);

				DicConsole.DebugWriteLine("TeleDisk plugin", "Track follows");
				DicConsole.DebugWriteLine("TeleDisk plugin", "\tTrack cylinder: {0}\t", TDTrack.cylinder);
				DicConsole.DebugWriteLine("TeleDisk plugin", "\tTrack head: {0}\t", TDTrack.head);
				DicConsole.DebugWriteLine("TeleDisk plugin", "\tSectors in track: {0}\t", TDTrack.sectors);
				DicConsole.DebugWriteLine("TeleDisk plugin", "\tTrack header CRC: 0x{0:X2} (calculated 0x{1:X2})\t", TDTrack.crc, TDTrackCalculatedCRC);

				ADiskCRCHasFailed |= TDTrackCalculatedCRC != TDTrack.crc;

				if(TDTrack.sectors == 0xFF) // End of disk image
				{
					DicConsole.DebugWriteLine("TeleDisk plugin", "End of disk image arrived");
					DicConsole.DebugWriteLine("TeleDisk plugin", "Total of {0} data sectors, for {1} bytes", totalSectors, totalDiskSize);

					break;
				}

				for(byte processedSectors = 0; processedSectors < TDTrack.sectors; processedSectors++)
				{
					TDSectorHeader TDSector = new TDSectorHeader();
					TDDataHeader TDData = new TDDataHeader();
					byte[] dataSizeBytes = new byte[2];
					byte[] data;
					byte[] decodedData;

					TDSector.cylinder = (byte)stream.ReadByte();
					TDSector.head = (byte)stream.ReadByte();
					TDSector.sectorNumber = (byte)stream.ReadByte();
					TDSector.sectorSize = (byte)stream.ReadByte();
					TDSector.flags = (byte)stream.ReadByte();
					TDSector.crc = (byte)stream.ReadByte();

					DicConsole.DebugWriteLine("TeleDisk plugin", "\tSector follows");
					DicConsole.DebugWriteLine("TeleDisk plugin", "\t\tAddressMark cylinder: {0}", TDSector.cylinder);
					DicConsole.DebugWriteLine("TeleDisk plugin", "\t\tAddressMark head: {0}", TDSector.head);
					DicConsole.DebugWriteLine("TeleDisk plugin", "\t\tAddressMark sector number: {0}", TDSector.sectorNumber);
					DicConsole.DebugWriteLine("TeleDisk plugin", "\t\tSector size: {0}", TDSector.sectorSize);
					DicConsole.DebugWriteLine("TeleDisk plugin", "\t\tSector flags: 0x{0:X2}", TDSector.flags);
					DicConsole.DebugWriteLine("TeleDisk plugin", "\t\tSector CRC (plus headers): 0x{0:X2}", TDSector.crc);

					uint LBA = (uint)((TDSector.cylinder * header.sides * ImageInfo.sectorsPerTrack) + (TDSector.head * ImageInfo.sectorsPerTrack) + (TDSector.sectorNumber - 1));
					if((TDSector.flags & FlagsSectorDataless) != FlagsSectorDataless && (TDSector.flags & FlagsSectorSkipped) != FlagsSectorSkipped)
					{
						stream.Read(dataSizeBytes, 0, 2);
						TDData.dataSize = BitConverter.ToUInt16(dataSizeBytes, 0);
						TDData.dataSize--; // Sydex decided to including dataEncoding byte as part of it
						ImageInfo.imageSize += TDData.dataSize;
						TDData.dataEncoding = (byte)stream.ReadByte();
						data = new byte[TDData.dataSize];
						stream.Read(data, 0, TDData.dataSize);
						DicConsole.DebugWriteLine("TeleDisk plugin", "\t\tData size (in-image): {0}", TDData.dataSize);
						DicConsole.DebugWriteLine("TeleDisk plugin", "\t\tData encoding: 0x{0:X2}", TDData.dataEncoding);

						decodedData = DecodeTeleDiskData(TDSector.sectorSize, TDData.dataEncoding, data);

						byte TDSectorCalculatedCRC = (byte)(TeleDiskCRC(0, decodedData) & 0xFF);

						if(TDSectorCalculatedCRC != TDSector.crc)
						{
							DicConsole.DebugWriteLine("TeleDisk plugin", "Sector {0}:{3}:{4} calculated CRC 0x{1:X2} differs from stored CRC 0x{2:X2}", TDTrack.cylinder, TDSectorCalculatedCRC, TDSector.crc, TDTrack.cylinder, TDSector.sectorNumber);
							if((TDSector.flags & FlagsSectorNoID) != FlagsSectorNoID)
								SectorsWhereCRCHasFailed.Add(LBA);
						}
					}
					else
						decodedData = new byte[128 << TDSector.sectorSize];

					DicConsole.DebugWriteLine("TeleDisk plugin", "\t\tLBA: {0}", LBA);

					if((TDSector.flags & FlagsSectorNoID) != FlagsSectorNoID)
					{
						if(sectorsData[TDTrack.cylinder][TDTrack.head][TDSector.sectorNumber] != null)
						{
							if((TDSector.flags & FlagsSectorDuplicate) == FlagsSectorDuplicate)
							{
								DicConsole.DebugWriteLine("TeleDisk plugin", "\t\tSector {0} on cylinder {1} head {2} is duplicate, and marked so",
									TDSector.sectorNumber, TDSector.cylinder, TDSector.head);
							}
							else
							{
								DicConsole.DebugWriteLine("TeleDisk plugin", "\t\tSector {0} on cylinder {1} head {2} is duplicate, but is not marked so",
									TDSector.sectorNumber, TDSector.cylinder, TDSector.head);
							}
						}
						else
						{
							sectorsData[TDTrack.cylinder][TDTrack.head][TDSector.sectorNumber] = decodedData;
							totalDiskSize += (uint)decodedData.Length;
						}
					}
				}
			}

			MemoryStream leadOutMs = new MemoryStream();
			if(hasLeadOutOnHead0)
			{
				for(int i = 0; i < sectorsData[totalCylinders - 1][0].Length; i++)
				{
					if(sectorsData[totalCylinders - 1][0][i] != null)
						leadOutMs.Write(sectorsData[totalCylinders - 1][0][i], 0, sectorsData[totalCylinders - 1][0][i].Length);
				}
			}
			if(hasLeadOutOnHead1)
			{
				for(int i = 0; i < sectorsData[totalCylinders - 1][1].Length; i++)
				{
					if(sectorsData[totalCylinders - 1][1][i] != null)
						leadOutMs.Write(sectorsData[totalCylinders - 1][1][i], 0, sectorsData[totalCylinders - 1][1][i].Length);
				}
			}
			if(leadOutMs.Length != 0)
			{
				leadOut = leadOutMs.ToArray();
				ImageInfo.readableMediaTags.Add(MediaTagType.Floppy_LeadOut);
			}

			ImageInfo.sectors = ImageInfo.cylinders * ImageInfo.heads * ImageInfo.sectorsPerTrack;
			ImageInfo.mediaType = DecodeTeleDiskDiskType();

			ImageInfo.xmlMediaType = XmlMediaType.BlockMedia;

			DicConsole.VerboseWriteLine("TeleDisk image contains a disk of type {0}", ImageInfo.mediaType);
			if(!string.IsNullOrEmpty(ImageInfo.imageComments))
				DicConsole.VerboseWriteLine("TeleDisk comments: {0}", ImageInfo.imageComments);

			inStream.Dispose();
			stream.Dispose();

			/*
			FileStream debugFs = new FileStream("debug.img", FileMode.CreateNew, FileAccess.Write);
			for(ulong i = 0; i < ImageInfo.sectors; i++)
				debugFs.Write(ReadSector(i), 0, (int)ImageInfo.sectorSize);
			debugFs.Dispose();
			*/

			return true;
		}

		public override bool ImageHasPartitions()
		{
			return ImageInfo.imageHasPartitions;
		}

		public override ulong GetImageSize()
		{
			return ImageInfo.imageSize;
		}

		public override ulong GetSectors()
		{
			return ImageInfo.sectors;
		}

		public override uint GetSectorSize()
		{
			return ImageInfo.sectorSize;
		}

		public override byte[] ReadSector(ulong sectorAddress)
		{
			(ushort cylinder, byte head, byte sector) = LbaToChs(sectorAddress);

			if(cylinder >= sectorsData.Length)
				throw new ArgumentOutOfRangeException(nameof(sectorAddress), "Sector address not found");

			if(head >= sectorsData[cylinder].Length)
				throw new ArgumentOutOfRangeException(nameof(sectorAddress), "Sector address not found");

			if(sector > sectorsData[cylinder][head].Length)
				throw new ArgumentOutOfRangeException(nameof(sectorAddress), "Sector address not found");

			return sectorsData[cylinder][head][sector];
		}

		public override byte[] ReadSectors(ulong sectorAddress, uint length)
		{
			if(sectorAddress > ImageInfo.sectors - 1)
				throw new ArgumentOutOfRangeException(nameof(sectorAddress), "Sector address not found");

			if(sectorAddress + length > ImageInfo.sectors)
				throw new ArgumentOutOfRangeException(nameof(length), "Requested more sectors than available");

			MemoryStream buffer = new MemoryStream();
			for(uint i = 0; i < length; i++)
			{
				byte[] sector = ReadSector(sectorAddress + i);
				if(sector == null)
					sector = new byte[ImageInfo.sectorSize];
				buffer.Write(sector, 0, sector.Length);
			}

			return buffer.ToArray();
		}

		(ushort cylinder, byte head, byte sector) LbaToChs(ulong lba)
		{
			ushort cylinder = (ushort)(lba / (ImageInfo.heads * ImageInfo.sectorsPerTrack));
			byte head = (byte)((lba / ImageInfo.sectorsPerTrack) % ImageInfo.heads);
			byte sector = (byte)((lba % ImageInfo.sectorsPerTrack) + 1);

			return (cylinder, head, sector);
		}

		public override byte[] ReadSectorLong(ulong sectorAddress)
		{
			return ReadSectors(sectorAddress, 1);
		}

		public override byte[] ReadSectorsLong(ulong sectorAddress, uint length)
		{
			return ReadSectors(sectorAddress, length);
		}

		public override string GetImageFormat()
		{
			return "Sydex TeleDisk";
		}

		public override string GetImageVersion()
		{
			return ImageInfo.imageVersion;
		}

		public override string GetImageApplication()
		{
			return ImageInfo.imageApplication;
		}

		public override string GetImageApplicationVersion()
		{
			return ImageInfo.imageApplicationVersion;
		}

		public override DateTime GetImageCreationTime()
		{
			return ImageInfo.imageCreationTime;
		}

		public override DateTime GetImageLastModificationTime()
		{
			return ImageInfo.imageLastModificationTime;
		}

		public override string GetImageName()
		{
			return ImageInfo.imageName;
		}

		public override MediaType GetMediaType()
		{
			return ImageInfo.mediaType;
		}

		public override bool? VerifySector(ulong sectorAddress)
		{
			return !SectorsWhereCRCHasFailed.Contains(sectorAddress);
		}

		public override bool? VerifySector(ulong sectorAddress, uint track)
		{
			return null;
		}

		public override bool? VerifySectors(ulong sectorAddress, uint length, out List<ulong> FailingLBAs, out List<ulong> UnknownLBAs)
		{
			FailingLBAs = new List<ulong>();
			UnknownLBAs = new List<ulong>();

			for(ulong i = sectorAddress; i < sectorAddress + length; i++)
				if(SectorsWhereCRCHasFailed.Contains(sectorAddress))
					FailingLBAs.Add(sectorAddress);

			return FailingLBAs.Count <= 0;
		}

		public override bool? VerifySectors(ulong sectorAddress, uint length, uint track, out List<ulong> FailingLBAs, out List<ulong> UnknownLBAs)
		{
			FailingLBAs = new List<ulong>();
			UnknownLBAs = new List<ulong>();

			for(ulong i = sectorAddress; i < sectorAddress + length; i++)
				UnknownLBAs.Add(i);

			return null;
		}

		public override bool? VerifyMediaImage()
		{
			return ADiskCRCHasFailed;
		}

		#region Private methods

		static ushort TeleDiskCRC(ushort crc, byte[] buffer)
		{
			int counter = 0;

			while(counter < buffer.Length)
			{
				crc ^= (ushort)((buffer[counter] & 0xFF) << 8);

				for(int i = 0; i < 8; i++)
				{
					if((crc & 0x8000) > 0)
						crc = (ushort)((crc << 1) ^ TeleDiskCRCPoly);
					else
						crc = (ushort)(crc << 1);
				}

				counter++;
			}

			return crc;
		}

		static byte[] DecodeTeleDiskData(byte sectorSize, byte encodingType, byte[] encodedData)
		{
			byte[] decodedData;
			switch(sectorSize)
			{
				case SectorSize128:
					decodedData = new byte[128];
					break;
				case SectorSize256:
					decodedData = new byte[256];
					break;
				case SectorSize512:
					decodedData = new byte[512];
					break;
				case SectorSize1K:
					decodedData = new byte[1024];
					break;
				case SectorSize2K:
					decodedData = new byte[2048];
					break;
				case SectorSize4K:
					decodedData = new byte[4096];
					break;
				case SectorSize8K:
					decodedData = new byte[8192];
					break;
				default:
					throw new ImageNotSupportedException(string.Format("Sector size {0} is incorrect.", sectorSize));
			}

			switch(encodingType)
			{
				case dataBlockCopy:
					Array.Copy(encodedData, decodedData, decodedData.Length);
					break;
				case dataBlockPattern:
					{
						int ins = 0;
						int outs = 0;
						while(ins < encodedData.Length)
						{
							ushort repeatNumber;
							byte[] repeatValue = new byte[2];

							repeatNumber = BitConverter.ToUInt16(encodedData, ins);
							Array.Copy(encodedData, ins + 2, repeatValue, 0, 2);
							byte[] decodedPiece = new byte[repeatNumber * 2];
							ArrayHelpers.ArrayFill(decodedPiece, repeatValue);
							Array.Copy(decodedPiece, 0, decodedData, outs, decodedPiece.Length);
							ins += 4;
							outs += decodedPiece.Length;
						}

						DicConsole.DebugWriteLine("TeleDisk plugin", "(Block pattern decoder): Input data size: {0} bytes", encodedData.Length);
						DicConsole.DebugWriteLine("TeleDisk plugin", "(Block pattern decoder): Processed input: {0} bytes", ins);
						DicConsole.DebugWriteLine("TeleDisk plugin", "(Block pattern decoder): Output data size: {0} bytes", decodedData.Length);
						DicConsole.DebugWriteLine("TeleDisk plugin", "(Block pattern decoder): Processed Output: {0} bytes", outs);
						break;
					}
				case dataBlockRLE:
					{
						int ins = 0;
						int outs = 0;
						while(ins < encodedData.Length)
						{
							byte Run;
							byte Length;
							byte Encoding;
							byte[] Piece;

							Encoding = encodedData[ins];
							if(Encoding == 0x00)
							{
								Length = encodedData[ins + 1];
								Array.Copy(encodedData, ins + 2, decodedData, outs, Length);
								ins += (2 + Length);
								outs += Length;
							}
							else
							{
								Length = (byte)(Encoding * 2);
								Run = encodedData[ins + 1];
								byte[] Part = new byte[Length];
								Array.Copy(encodedData, ins + 2, Part, 0, Length);
								Piece = new byte[Length * Run];
								ArrayHelpers.ArrayFill(Piece, Part);
								Array.Copy(Piece, 0, decodedData, outs, Piece.Length);
								ins += (2 + Length);
								outs += Piece.Length;
							}
						}

						DicConsole.DebugWriteLine("TeleDisk plugin", "(RLE decoder): Input data size: {0} bytes", encodedData.Length);
						DicConsole.DebugWriteLine("TeleDisk plugin", "(RLE decoder): Processed input: {0} bytes", ins);
						DicConsole.DebugWriteLine("TeleDisk plugin", "(RLE decoder): Output data size: {0} bytes", decodedData.Length);
						DicConsole.DebugWriteLine("TeleDisk plugin", "(RLE decoder): Processed Output: {0} bytes", outs);

						break;
					}
				default:
					throw new ImageNotSupportedException(string.Format("Data encoding {0} is incorrect.", encodingType));
			}

			return decodedData;
		}

		MediaType DecodeTeleDiskDiskType()
		{
			switch(header.driveType)
			{
				case DriveType525DD:
				case DriveType525HD_DDDisk:
				case DriveType525HD:
					{
						switch(totalDiskSize)
						{
							case 163840:
								{
									// Acorn disk uses 256 bytes/sector
									if(ImageInfo.sectorSize == 256)
										return MediaType.ACORN_525_SS_DD_40;
									// DOS disks use 512 bytes/sector
									return MediaType.DOS_525_SS_DD_8;
								}
							case 184320:
								{
									// Atari disk uses 256 bytes/sector
									if(ImageInfo.sectorSize == 256)
										return MediaType.ATARI_525_DD;
									// DOS disks use 512 bytes/sector
									return MediaType.DOS_525_SS_DD_9;
								}
							case 327680:
								{
									// Acorn disk uses 256 bytes/sector
									if(ImageInfo.sectorSize == 256)
										return MediaType.ACORN_525_SS_DD_80;
									// DOS disks use 512 bytes/sector
									return MediaType.DOS_525_DS_DD_8;
								}
							case 368640:
								return MediaType.DOS_525_DS_DD_9;
							case 1228800:
								return MediaType.DOS_525_HD;
							case 102400:
								return MediaType.ACORN_525_SS_SD_40;
							case 204800:
								return MediaType.ACORN_525_SS_SD_80;
							case 655360:
								return MediaType.ACORN_525_DS_DD;
							case 92160:
								return MediaType.ATARI_525_SD;
							case 133120:
								return MediaType.ATARI_525_ED;
							case 1310720:
								return MediaType.NEC_525_HD;
							case 1261568:
								return MediaType.SHARP_525;
							case 839680:
								return MediaType.FDFORMAT_525_DD;
							case 1304320:
								return MediaType.ECMA_99_8;
							case 1223424:
								return MediaType.ECMA_99_15;
							case 1061632:
								return MediaType.ECMA_99_26;
							case 80384:
								return MediaType.ECMA_66;
							case 325632:
								return MediaType.ECMA_70;
							case 653312:
								return MediaType.ECMA_78;
							case 737280:
								return MediaType.ECMA_78_2;
							default:
								{
									DicConsole.DebugWriteLine("TeleDisk plugin", "Unknown 5,25\" disk with {0} bytes", totalDiskSize);
									return MediaType.Unknown;
								}
						}
					}
				case DriveType35DD:
				case DriveType35ED:
				case DriveType35HD:
					{
						switch(totalDiskSize)
						{
							case 322560:
								return MediaType.Apricot_35;
							case 327680:
								return MediaType.DOS_35_SS_DD_8;
							case 368640:
								return MediaType.DOS_35_SS_DD_9;
							case 655360:
								return MediaType.DOS_35_DS_DD_8;
							case 737280:
								return MediaType.DOS_35_DS_DD_9;
							case 1474560:
								return MediaType.DOS_35_HD;
							case 2949120:
								return MediaType.DOS_35_ED;
							case 1720320:
								return MediaType.DMF;
							case 1763328:
								return MediaType.DMF_82;
							case 1884160: // Irreal size, seen as BIOS with TSR, 23 sectors/track
							case 1860608: // Real data size, sum of all sectors
								return MediaType.XDF_35;
							case 819200:
								return MediaType.CBM_35_DD;
							case 901120:
								return MediaType.CBM_AMIGA_35_DD;
							case 1802240:
								return MediaType.CBM_AMIGA_35_HD;
							case 1310720:
								return MediaType.NEC_35_HD_8;
							case 1228800:
								return MediaType.NEC_35_HD_15;
							case 1261568:
								return MediaType.SHARP_35;
							default:
								{
									DicConsole.DebugWriteLine("TeleDisk plugin", "Unknown 3,5\" disk with {0} bytes", totalDiskSize);
									return MediaType.Unknown;
								}
						}
					}
				case DriveType8inch:
					{
						switch(totalDiskSize)
						{
							case 81664:
								return MediaType.IBM23FD;
							case 242944:
								return MediaType.IBM33FD_128;
							case 287488:
								return MediaType.IBM33FD_256;
							case 306432:
								return MediaType.IBM33FD_512;
							case 499200:
								return MediaType.IBM43FD_128;
							case 574976:
								return MediaType.IBM43FD_256;
							case 995072:
								return MediaType.IBM53FD_256;
							case 1146624:
								return MediaType.IBM53FD_512;
							case 1222400:
								return MediaType.IBM53FD_1024;
							case 256256:
								// Same size, with same disk geometry, for DEC RX01, NEC and ECMA, return ECMA
								return MediaType.ECMA_54;
							case 512512:
								{
									// DEC disk uses 256 bytes/sector
									if(ImageInfo.sectorSize == 256)
										return MediaType.RX02;
									// ECMA disks use 128 bytes/sector
									return MediaType.ECMA_59;
								}
							case 1261568:
								return MediaType.NEC_8_DD;
							case 1255168:
								return MediaType.ECMA_69_8;
							case 1177344:
								return MediaType.ECMA_69_15;
							case 1021696:
								return MediaType.ECMA_69_26;
							default:
								{
									DicConsole.DebugWriteLine("TeleDisk plugin", "Unknown 8\" disk with {0} bytes", totalDiskSize);
									return MediaType.Unknown;
								}
						}
					}
				default:
					{
						DicConsole.DebugWriteLine("TeleDisk plugin", "Unknown drive type {1} with {0} bytes", totalDiskSize, header.driveType);
						return MediaType.Unknown;
					}

			}
		}

		public override byte[] ReadDiskTag(MediaTagType tag)
		{
			if(tag == MediaTagType.Floppy_LeadOut)
			{
				if(leadOut != null)
					return leadOut;
				throw new FeatureNotPresentImageException("Lead-out not present in disk image");
			}
			else
				throw new FeatureUnsupportedImageException("Feature not supported by image format");
		}

		#endregion

		#region Unsupported features

		public override byte[] ReadSectorTag(ulong sectorAddress, SectorTagType tag)
		{
			throw new FeatureUnsupportedImageException("Feature not supported by image format");
		}

		public override byte[] ReadSectorsTag(ulong sectorAddress, uint length, SectorTagType tag)
		{
			throw new FeatureUnsupportedImageException("Feature not supported by image format");
		}

		public override string GetImageCreator()
		{
			return ImageInfo.imageCreator;
		}

		public override string GetImageComments()
		{
			return ImageInfo.imageComments;
		}

		public override string GetMediaManufacturer()
		{
			return ImageInfo.mediaManufacturer;
		}

		public override string GetMediaModel()
		{
			return ImageInfo.mediaModel;
		}

		public override string GetMediaSerialNumber()
		{
			return ImageInfo.mediaSerialNumber;
		}

		public override string GetMediaBarcode()
		{
			return ImageInfo.mediaBarcode;
		}

		public override string GetMediaPartNumber()
		{
			return ImageInfo.mediaPartNumber;
		}

		public override int GetMediaSequence()
		{
			return ImageInfo.mediaSequence;
		}

		public override int GetLastDiskSequence()
		{
			return ImageInfo.lastMediaSequence;
		}

		public override string GetDriveManufacturer()
		{
			return ImageInfo.driveManufacturer;
		}

		public override string GetDriveModel()
		{
			return ImageInfo.driveModel;
		}

		public override string GetDriveSerialNumber()
		{
			return ImageInfo.driveSerialNumber;
		}

		public override List<Partition> GetPartitions()
		{
			throw new FeatureUnsupportedImageException("Feature not supported by image format");
		}

		public override List<Track> GetTracks()
		{
			throw new FeatureUnsupportedImageException("Feature not supported by image format");
		}

		public override List<Track> GetSessionTracks(Session session)
		{
			throw new FeatureUnsupportedImageException("Feature not supported by image format");
		}

		public override List<Track> GetSessionTracks(ushort session)
		{
			throw new FeatureUnsupportedImageException("Feature not supported by image format");
		}

		public override List<Session> GetSessions()
		{
			throw new FeatureUnsupportedImageException("Feature not supported by image format");
		}

		public override byte[] ReadSector(ulong sectorAddress, uint track)
		{
			throw new FeatureUnsupportedImageException("Feature not supported by image format");
		}

		public override byte[] ReadSectorTag(ulong sectorAddress, uint track, SectorTagType tag)
		{
			throw new FeatureUnsupportedImageException("Feature not supported by image format");
		}

		public override byte[] ReadSectors(ulong sectorAddress, uint length, uint track)
		{
			throw new FeatureUnsupportedImageException("Feature not supported by image format");
		}

		public override byte[] ReadSectorsTag(ulong sectorAddress, uint length, uint track, SectorTagType tag)
		{
			throw new FeatureUnsupportedImageException("Feature not supported by image format");
		}

		public override byte[] ReadSectorLong(ulong sectorAddress, uint track)
		{
			throw new FeatureUnsupportedImageException("Feature not supported by image format");
		}

		public override byte[] ReadSectorsLong(ulong sectorAddress, uint length, uint track)
		{
			throw new FeatureUnsupportedImageException("Feature not supported by image format");
		}

		#endregion Unsupported features

		#region LZH decompression from MAME
		/* This region is under following license:
		 * Copyright © 2017 Miodrag Milanovic
		 * Adapted to C#, Copyright © 2017 Natalia Portillo
		 * 
		 * Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
		 * 
		 * 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
		 * 
		 * 2. 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.
		 * 
		 * 3. Neither the name of the copyright holder nor the names of its contributors may be used to endorse or promote products derived from this software
		 * without specific prior written permission.
		 * 
		 * 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.
		 */

		/*
		 * Based on Japanese version 29-NOV-1988
		 * LZSS coded by Haruhiko OKUMURA
		 * Adaptive Huffman Coding coded by Haruyasu YOSHIZAKI
		 * Edited and translated to English by Kenji RIKITAKE
		 */

		const int BUFSZ = 512;

		/* LZSS Parameters */

		const int N = 4096;    /* Size of string buffer */
		const int F = 60;    /* Size of look-ahead buffer */
		const int THRESHOLD = 2;
		const int NIL = N;    /* End of tree's node  */

		/* Huffman coding parameters */

		const int N_CHAR = (256 - THRESHOLD + F);
		/* character code (= 0..N_CHAR-1) */
		const int T = (N_CHAR * 2 - 1);    /* Size of table */
		const int R = (T - 1);            /* root position */
		const int MAX_FREQ = 0x8000;
		/* update when cumulative frequency */
		/* reaches to this value */

		struct tdlzhuf
		{
			public ushort r,
							bufcnt, bufndx, bufpos,  // string buffer
													 // the following to allow block reads from input in next_word()
							ibufcnt, ibufndx; // input buffer counters
			public byte[] inbuf;    // input buffer
		};

		tdlzhuf tdctl;
		byte[] text_buf = new byte[N + F - 1];
		ushort[] freq = new ushort[T + 1];    /* cumulative freq table */

		/*
		 * pointing parent nodes.
		 * area [T..(T + N_CHAR - 1)] are pointers for leaves
		 */
		short[] prnt = new short[T + N_CHAR];

		/* pointing children nodes (son[], son[] + 1)*/
		short[] son = new short[T];

		ushort getbuf;
		byte getlen;

		long data_read(out byte[] buf, long size)
		{
			if(size > inStream.Length - inStream.Position)
				size = inStream.Length - inStream.Position;

			buf = new byte[size];
			inStream.Read(buf, 0, (int)size);
			return size;
		}

		/*
		 * Tables for encoding/decoding upper 6 bits of
		 * sliding dictionary pointer
		 */

		/* decoder table */
		readonly byte[] d_code = {
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
			0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
			0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02,
			0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02,
			0x03, 0x03, 0x03, 0x03, 0x03, 0x03, 0x03, 0x03,
			0x03, 0x03, 0x03, 0x03, 0x03, 0x03, 0x03, 0x03,
			0x04, 0x04, 0x04, 0x04, 0x04, 0x04, 0x04, 0x04,
			0x05, 0x05, 0x05, 0x05, 0x05, 0x05, 0x05, 0x05,
			0x06, 0x06, 0x06, 0x06, 0x06, 0x06, 0x06, 0x06,
			0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07,
			0x08, 0x08, 0x08, 0x08, 0x08, 0x08, 0x08, 0x08,
			0x09, 0x09, 0x09, 0x09, 0x09, 0x09, 0x09, 0x09,
			0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A,
			0x0B, 0x0B, 0x0B, 0x0B, 0x0B, 0x0B, 0x0B, 0x0B,
			0x0C, 0x0C, 0x0C, 0x0C, 0x0D, 0x0D, 0x0D, 0x0D,
			0x0E, 0x0E, 0x0E, 0x0E, 0x0F, 0x0F, 0x0F, 0x0F,
			0x10, 0x10, 0x10, 0x10, 0x11, 0x11, 0x11, 0x11,
			0x12, 0x12, 0x12, 0x12, 0x13, 0x13, 0x13, 0x13,
			0x14, 0x14, 0x14, 0x14, 0x15, 0x15, 0x15, 0x15,
			0x16, 0x16, 0x16, 0x16, 0x17, 0x17, 0x17, 0x17,
			0x18, 0x18, 0x19, 0x19, 0x1A, 0x1A, 0x1B, 0x1B,
			0x1C, 0x1C, 0x1D, 0x1D, 0x1E, 0x1E, 0x1F, 0x1F,
			0x20, 0x20, 0x21, 0x21, 0x22, 0x22, 0x23, 0x23,
			0x24, 0x24, 0x25, 0x25, 0x26, 0x26, 0x27, 0x27,
			0x28, 0x28, 0x29, 0x29, 0x2A, 0x2A, 0x2B, 0x2B,
			0x2C, 0x2C, 0x2D, 0x2D, 0x2E, 0x2E, 0x2F, 0x2F,
			0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37,
			0x38, 0x39, 0x3A, 0x3B, 0x3C, 0x3D, 0x3E, 0x3F,
		};

		readonly byte[] d_len = {
			0x03, 0x03, 0x03, 0x03, 0x03, 0x03, 0x03, 0x03,
			0x03, 0x03, 0x03, 0x03, 0x03, 0x03, 0x03, 0x03,
			0x03, 0x03, 0x03, 0x03, 0x03, 0x03, 0x03, 0x03,
			0x03, 0x03, 0x03, 0x03, 0x03, 0x03, 0x03, 0x03,
			0x04, 0x04, 0x04, 0x04, 0x04, 0x04, 0x04, 0x04,
			0x04, 0x04, 0x04, 0x04, 0x04, 0x04, 0x04, 0x04,
			0x04, 0x04, 0x04, 0x04, 0x04, 0x04, 0x04, 0x04,
			0x04, 0x04, 0x04, 0x04, 0x04, 0x04, 0x04, 0x04,
			0x04, 0x04, 0x04, 0x04, 0x04, 0x04, 0x04, 0x04,
			0x04, 0x04, 0x04, 0x04, 0x04, 0x04, 0x04, 0x04,
			0x05, 0x05, 0x05, 0x05, 0x05, 0x05, 0x05, 0x05,
			0x05, 0x05, 0x05, 0x05, 0x05, 0x05, 0x05, 0x05,
			0x05, 0x05, 0x05, 0x05, 0x05, 0x05, 0x05, 0x05,
			0x05, 0x05, 0x05, 0x05, 0x05, 0x05, 0x05, 0x05,
			0x05, 0x05, 0x05, 0x05, 0x05, 0x05, 0x05, 0x05,
			0x05, 0x05, 0x05, 0x05, 0x05, 0x05, 0x05, 0x05,
			0x05, 0x05, 0x05, 0x05, 0x05, 0x05, 0x05, 0x05,
			0x05, 0x05, 0x05, 0x05, 0x05, 0x05, 0x05, 0x05,
			0x06, 0x06, 0x06, 0x06, 0x06, 0x06, 0x06, 0x06,
			0x06, 0x06, 0x06, 0x06, 0x06, 0x06, 0x06, 0x06,
			0x06, 0x06, 0x06, 0x06, 0x06, 0x06, 0x06, 0x06,
			0x06, 0x06, 0x06, 0x06, 0x06, 0x06, 0x06, 0x06,
			0x06, 0x06, 0x06, 0x06, 0x06, 0x06, 0x06, 0x06,
			0x06, 0x06, 0x06, 0x06, 0x06, 0x06, 0x06, 0x06,
			0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07,
			0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07,
			0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07,
			0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07,
			0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07,
			0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07,
			0x08, 0x08, 0x08, 0x08, 0x08, 0x08, 0x08, 0x08,
			0x08, 0x08, 0x08, 0x08, 0x08, 0x08, 0x08, 0x08,
		};

		int next_word()
		{
			if(tdctl.ibufndx >= tdctl.ibufcnt)
			{
				tdctl.ibufndx = 0;
				tdctl.ibufcnt = (ushort)data_read(out tdctl.inbuf, BUFSZ);
				if(tdctl.ibufcnt <= 0)
					return (-1);
			}
			while(getlen <= 8)
			{ // typically reads a word at a time
				getbuf |= (ushort)(tdctl.inbuf[tdctl.ibufndx++] << (8 - getlen));
				getlen += 8;
			}
			return (0);
		}

		int GetBit()    /* get one bit */
		{
			short i;
			if(next_word() < 0)
				return (-1);
			i = (short)getbuf;
			getbuf <<= 1;
			getlen--;
			if(i < 0)
				return (1);
			else
				return (0);
		}

		int GetByte()    /* get a byte */
		{
			ushort i;
			if(next_word() != 0)
				return (-1);
			i = getbuf;
			getbuf <<= 8;
			getlen -= 8;
			i = (ushort)(i >> 8);
			return ((int)i);
		}

		/* initialize freq tree */

		void StartHuff()
		{
			int i, j;

			for(i = 0; i < N_CHAR; i++)
			{
				freq[i] = 1;
				son[i] = (short)(i + T);
				prnt[i + T] = (short)i;
			}
			i = 0; j = N_CHAR;
			while(j <= R)
			{
				freq[j] = (ushort)(freq[i] + freq[i + 1]);
				son[j] = (short)i;
				prnt[i] = prnt[i + 1] = (short)j;
				i += 2; j++;
			}
			freq[T] = 0xffff;
			prnt[R] = 0;
		}

		/* reconstruct freq tree */

		void reconst()
		{
			short i, j, k;
			ushort f, l;

			/* halven cumulative freq for leaf nodes */
			j = 0;
			for(i = 0; i < T; i++)
			{
				if(son[i] >= T)
				{
					freq[j] = (ushort)((freq[i] + 1) / 2);
					son[j] = son[i];
					j++;
				}
			}
			/* make a tree : first, connect children nodes */
			for(i = 0, j = N_CHAR; j < T; i += 2, j++)
			{
				k = (short)(i + 1);
				f = freq[j] = (ushort)(freq[i] + freq[k]);
				for(k = (short)(j - 1); f < freq[k]; k--) { };
				k++;
				l = (ushort)((j - k) * 2);


				Array.ConstrainedCopy(freq, k, freq, k + 1, l);
				freq[k] = f;
				Array.ConstrainedCopy(son, k, son, k + 1, l);
				son[k] = i;
			}
			/* connect parent nodes */
			for(i = 0; i < T; i++)
			{
				if((k = son[i]) >= T)
				{
					prnt[k] = i;
				}
				else
				{
					prnt[k] = prnt[k + 1] = i;
				}
			}
		}

		/* update freq tree */

		void update(int c)
		{
			int i, j, k, l;

			if(freq[R] == MAX_FREQ)
			{
				reconst();
			}
			c = prnt[c + T];
			do
			{
				k = ++freq[c];

				/* swap nodes to keep the tree freq-ordered */
				if(k > freq[l = c + 1])
				{
					while(k > freq[++l]) { };
					l--;
					freq[c] = freq[l];
					freq[l] = (ushort)k;

					i = son[c];
					prnt[i] = (short)l;
					if(i < T) prnt[i + 1] = (short)l;

					j = son[l];
					son[l] = (short)i;

					prnt[j] = (short)c;
					if(j < T) prnt[j + 1] = (short)c;
					son[c] = (short)j;

					c = l;
				}
			} while((c = prnt[c]) != 0);    /* do it until reaching the root */
		}

		short DecodeChar()
		{
			int ret;
			ushort c;

			c = (ushort)son[R];

			/*
			 * start searching tree from the root to leaves.
			 * choose node #(son[]) if input bit == 0
			 * else choose #(son[]+1) (input bit == 1)
			 */
			while(c < T)
			{
				if((ret = GetBit()) < 0)
					return (-1);
				c += (ushort)ret;
				c = (ushort)son[c];
			}
			c -= T;
			update(c);
			return (short)c;
		}

		short DecodePosition()
		{
			short bit;
			ushort i, j, c;

			/* decode upper 6 bits from given table */
			if((bit = (short)GetByte()) < 0)
				return (-1);
			i = (ushort)bit;
			c = (ushort)(d_code[i] << 6);
			j = d_len[i];

			/* input lower 6 bits directly */
			j -= 2;
			while(j-- > 0)
			{
				if((bit = (short)GetBit()) < 0)
					return (-1);
				i = (ushort)((i << 1) + bit);
			}
			return (short)(c | (i & 0x3f));
		}

		/* DeCompression

		split out initialization code to init_Decode()

		*/

		void init_Decode()
		{
			int i;
			getbuf = 0;
			getlen = 0;
			tdctl = new tdlzhuf();
			tdctl.ibufcnt = tdctl.ibufndx = 0; // input buffer is empty
			tdctl.bufcnt = 0;
			StartHuff();
			for(i = 0; i < N - F; i++)
				text_buf[i] = 0x20;
			tdctl.r = N - F;
		}

		int Decode(out byte[] buf, int len)  /* Decoding/Uncompressing */
		{
			short c, pos;
			buf = new byte[len];
			int count;  // was an unsigned long, seems unnecessary
			for(count = 0; count < len;)
			{
				if(tdctl.bufcnt == 0)
				{
					if((c = DecodeChar()) < 0)
						return (count); // fatal error
					if(c < 256)
					{
						buf[count] = (byte)c;
						text_buf[tdctl.r++] = (byte)c;
						tdctl.r &= (N - 1);
						count++;
					}
					else
					{
						if((pos = DecodePosition()) < 0)
							return (count); // fatal error
						tdctl.bufpos = (ushort)((tdctl.r - pos - 1) & (N - 1));
						tdctl.bufcnt = (ushort)(c - 255 + THRESHOLD);
						tdctl.bufndx = 0;
					}
				}
				else
				{ // still chars from last string
					while(tdctl.bufndx < tdctl.bufcnt && count < len)
					{
						c = text_buf[(tdctl.bufpos + tdctl.bufndx) & (N - 1)];
						buf[count] = (byte)c;
						tdctl.bufndx++;
						text_buf[tdctl.r++] = (byte)c;
						tdctl.r &= (N - 1);
						count++;
					}
					// reset bufcnt after copy string from text_buf[]
					if(tdctl.bufndx >= tdctl.bufcnt)
						tdctl.bufndx = tdctl.bufcnt = 0;
				}
			}
			return (count); // count == len, success
		}
		#endregion LZH decompression from MAME
	}
}