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DeterousDeterous
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Custom ISO Stream for full CDROM support (#40)
* Implement custom ISO stream for CDROM support * Delete old files * Delete old test * Leaner CDROM wrapper * Fix custom stream * WrapperBase using ISO stream * Reset stream after deserializing * Fix SeekOrigin * Return to cached position * CDROM Constants * correct ns * fix href
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16 files changed

+350
-328
lines changed

16 files changed

+350
-328
lines changed

‎SabreTools.Serialization.Test/Readers/CDROMVolumeTests.cs‎

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This file was deleted.

‎SabreTools.Serialization/Extensions/CDROM.cs‎

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using System;
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using System.IO;
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using SabreTools.Data.Models.CDROM;
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using SabreTools.IO;
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using SabreTools.IO.Extensions;
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namespace SabreTools.Data.Extensions
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{
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public static class CDROM
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{
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/// <summary>
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/// Creates a stream that provides only the user data of a CDROM stream
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/// </summary>
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public class ISO9660Stream : Stream
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{
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// Base CDROM stream (2352-byte sector)
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private readonly Stream _baseStream;
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// State variables
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private long _position = 0;
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private SectorMode _currentMode = SectorMode.UNKNOWN;
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private long _userDataStart = 16;
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private long _userDataEnd = 2064;
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private long _isoSectorSize = Constants.Mode1DataSize;
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public ISO9660Stream(Stream inputStream)
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{
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if (!inputStream.CanSeek || !inputStream.CanRead)
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throw new ArgumentException("Stream must be readable and seekable.", nameof(inputStream));
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_baseStream = inputStream;
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}
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public override bool CanRead => true;
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public override bool CanSeek => true;
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public override bool CanWrite => false;
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public override void Flush()
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{
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_baseStream.Flush();
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}
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public override long Length
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{
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get
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{
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return (_baseStream.Length / Constants.CDROMSectorSize) * _isoSectorSize;
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}
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}
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public override void SetLength(long value)
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{
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throw new NotSupportedException("Setting the length of this stream is not supported.");
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}
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public override void Write(byte[] buffer, int offset, int count)
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{
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throw new NotSupportedException("Writing to this stream is not supported.");
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}
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protected override void Dispose(bool disposing)
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{
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if (disposing)
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{
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_baseStream.Dispose();
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}
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base.Dispose(disposing);
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}
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public override long Position
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{
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// Get the position of the underlying ISO9660 stream
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get
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{
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// Get the user data location based on the current sector mode
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SetState(_position);
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// Get the number of ISO sectors before current position
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long isoPosition = (_position / Constants.CDROMSectorSize) * _isoSectorSize;
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// Add the within-sector position
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long remainder = _position % Constants.CDROMSectorSize;
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if (remainder > _userDataEnd)
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isoPosition += _isoSectorSize;
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else if (remainder > _userDataStart)
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isoPosition += remainder - _userDataStart;
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return isoPosition;
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}
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set
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{
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// Seek to the underlying ISO9660 position
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Seek(value, SeekOrigin.Begin);
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}
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}
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public override int Read(byte[] buffer, int offset, int count)
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{
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bool readEntireSector = false;
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int totalRead = 0;
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int remaining = count;
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while (remaining > 0 && _position < _baseStream.Length)
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{
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// Determine location of current sector
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long baseStreamOffset = (_position / Constants.CDROMSectorSize) * Constants.CDROMSectorSize;
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// Set the current sector's mode and user data location
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SetState(baseStreamOffset);
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// Deal with case where base position is not in ISO stream
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long remainder = _position % Constants.CDROMSectorSize;
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long sectorOffset = remainder - _userDataStart;
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if (remainder < _userDataStart)
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{
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baseStreamOffset += _userDataStart;
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sectorOffset = 0;
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_position += _userDataStart;
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}
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else if (remainder >= _userDataEnd)
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{
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baseStreamOffset += Constants.CDROMSectorSize;
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sectorOffset = 0;
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_position += Constants.CDROMSectorSize - _userDataEnd + _userDataStart;
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}
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else
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baseStreamOffset += remainder;
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// Sanity check on read location before seeking
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if (baseStreamOffset < 0 || baseStreamOffset > _baseStream.Length)
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{
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throw new ArgumentOutOfRangeException(nameof(offset), "Attempted to seek outside the stream boundaries.");
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}
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// Seek to target position in base CDROM stream
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_baseStream.Seek(baseStreamOffset, SeekOrigin.Begin);
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// Read the remaining bytes, up to max of one ISO sector (2048 bytes)
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int bytesToRead = (int)Math.Min(remaining, _isoSectorSize - sectorOffset);
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// Don't overshoot end of stream
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bytesToRead = (int)Math.Min(bytesToRead, _baseStream.Length - _position);
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if (bytesToRead == (_isoSectorSize - sectorOffset))
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readEntireSector = true;
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else
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readEntireSector = false;
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// Finish reading if no more bytes to be read
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if (bytesToRead <= 0)
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break;
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// Read up to 2048 bytes from base CDROM stream
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int bytesRead = _baseStream.Read(buffer, offset + totalRead, bytesToRead);
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// Update state for base stream
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_position = _baseStream.Position;
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if (readEntireSector)
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_position += (Constants.CDROMSectorSize - _userDataEnd) + _userDataStart;
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// Update state for ISO stream
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totalRead += bytesRead;
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remaining -= bytesRead;
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if (bytesRead == 0)
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break;
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}
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return totalRead;
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}
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public override long Seek(long offset, SeekOrigin origin)
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{
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// Get the intended position for the ISO9660 stream
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long targetPosition;
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switch (origin)
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{
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case SeekOrigin.Begin:
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targetPosition = offset;
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break;
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case SeekOrigin.Current:
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targetPosition = Position + offset;
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break;
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case SeekOrigin.End:
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targetPosition = Length + offset;
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break;
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default:
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throw new ArgumentException("Invalid SeekOrigin.", nameof(origin));
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}
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// Get the number of ISO sectors before current position
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long newPosition = (targetPosition / _isoSectorSize) * Constants.CDROMSectorSize;
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// Set the current sector's mode and user data location
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SetState(newPosition);
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// Add the within-sector position
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newPosition += _userDataStart + (targetPosition % _isoSectorSize);
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if (newPosition < 0 || newPosition > _baseStream.Length)
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{
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throw new ArgumentOutOfRangeException(nameof(offset), "Attempted to seek outside the stream boundaries.");
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}
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_position = _baseStream.Seek(newPosition, SeekOrigin.Begin);
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return Position;
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}
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private void SetState(long sectorLocation)
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{
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long oldPosition = _baseStream.Position;
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long modePosition = (sectorLocation - sectorLocation % Constants.CDROMSectorSize) + 15;
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_baseStream.Seek(modePosition, SeekOrigin.Begin);
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byte modeByte = _baseStream.ReadByteValue();
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if (modeByte == 0)
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_currentMode = SectorMode.MODE0;
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else if (modeByte == 1)
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_currentMode = SectorMode.MODE1;
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else if (modeByte == 2)
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{
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_baseStream.Seek(modePosition + 3, SeekOrigin.Begin);
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byte submode = _baseStream.ReadByteValue();
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if ((submode & 0x20) == 0x20)
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_currentMode = SectorMode.MODE2_FORM2;
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else
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_currentMode = SectorMode.MODE2_FORM1;
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}
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else
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_currentMode = SectorMode.UNKNOWN;
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// Set the user data location variables
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switch (_currentMode)
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{
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case SectorMode.MODE1:
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_userDataStart = 16;
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_userDataEnd = 2064;
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//_isoSectorSize = Constants.Mode1DataSize;
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break;
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case SectorMode.MODE2_FORM1:
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_userDataStart = 24;
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_userDataEnd = 2072;
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//_isoSectorSize = Constants.Form1DataSize;
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break;
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case SectorMode.MODE2_FORM2:
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_userDataStart = 24;
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_userDataEnd = 2072;
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// TODO: Support flexible sector length
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//_userDataEnd = 2348;
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//_isoSectorSize = Constants.Form2DataSize;
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break;
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case SectorMode.MODE0:
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case SectorMode.MODE2:
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_userDataStart = 16;
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_userDataEnd = 2064;
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// TODO: Support flexible sector length
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//_userDataEnd = 2352;
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//_isoSectorSize = Constants.Mode0DataSize;
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break;
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case SectorMode.UNKNOWN:
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_userDataStart = 16;
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_userDataEnd = 2064;
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//_isoSectorSize = Constants.Mode1DataSize;
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break;
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}
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_baseStream.Seek(oldPosition, SeekOrigin.Begin);
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return;
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}
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}
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}
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}

‎SabreTools.Serialization/Models/CDROM/CDROM.cs‎

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namespace SabreTools.Data.Models.CDROM
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{
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/// <summary>
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/// A CD-ROM disc image, made up of multiple data tracks, ISO 10149 / ECMA-130
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/// Specifically not a mixed-mode CD disc image, pure CD-ROM disc
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/// A CD-ROM disc image, made up of data sectors, ISO 10149 / ECMA-130
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/// Intentionally not a mixed-mode CD disc image, pure CD-ROM disc (no audio sectors)
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/// This model intentionally does not take tracks into consideration
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/// </summary>
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/// <see href="https://ecma-international.org/wp-content/uploads/ECMA-130_2nd_edition_june_1996.pdf"/>
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public sealed class CDROM
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{
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/// <summary>
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/// CD-ROM data tracks
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/// CD-ROM data sectors
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/// </summary>
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public DataTrack[] Tracks { get; set; } = [];
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public DataSector[] Sectors { get; set; } = [];
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}
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}

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