SabreTools/SabreTools.Serialization
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Separate out some helper methods

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This commit is contained in:
Matt Nadareski
2025-11-05 09:14:37 -05:00
parent d0006a4653
commit 3bb501ce0c
3 changed files with 186 additions and 104 deletions
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240
SabreTools.Serialization/Extensions/CDROM.cs
View File

@@ -1,13 +1,106 @@
using System;
using System.IO;
using SabreTools.Data.Models.CDROM;
using SabreTools.IO;
using SabreTools.IO.Extensions;
namespace SabreTools.Data.Extensions
{
public static class CDROM
{
/// <summary>
/// Get the sector mode for a CD-ROM stream
/// </summary>
/// <param name="stream">Stream to derive the sector mode from</param>
/// <returns>Sector mode from the stream on success, <see cref="SectorMode.UNKNOWN"/> on error</returns>
public static SectorMode GetSectorMode(this Stream stream)
{
try
{
byte modeByte = stream.ReadByteValue();
if (modeByte == 0)
{
return SectorMode.MODE0;
}
else if (modeByte == 1)
{
return SectorMode.MODE1;
}
else if (modeByte == 2)
{
stream.SeekIfPossible(2, SeekOrigin.Current);
byte submode = stream.ReadByteValue();
if ((submode & 0x20) == 0x20)
return SectorMode.MODE2_FORM2;
else
return SectorMode.MODE2_FORM1;
}
else
{
return SectorMode.UNKNOWN;
}
}
catch
{
// Ignore the actual error
return SectorMode.UNKNOWN;
}
}
/// <summary>
/// Get the user data size for a sector mode
/// </summary>
/// <param name="mode">Sector mode to get a value for</param>
/// <returns>User data size, if possible</returns>
public static long GetUserDataSize(this SectorMode mode)
{
return mode switch
{
SectorMode.MODE0 => Constants.Mode0DataSize,
SectorMode.MODE1 => Constants.Mode1DataSize,
SectorMode.MODE2 => Constants.Mode0DataSize,
SectorMode.MODE2_FORM1 => Constants.Mode2Form1DataSize,
SectorMode.MODE2_FORM2 => Constants.Mode2Form2DataSize,
_ => Constants.Mode0DataSize,
};
}
/// <summary>
/// Get the user data end offset for a sector mode
/// </summary>
/// <param name="mode">Sector mode to get a value for</param>
/// <returns>User data end offset, if possible</returns>
public static long GetUserDataEnd(this SectorMode mode)
{
return mode switch
{
SectorMode.MODE0 => Constants.Mode0UserDataEnd, // TODO: Support flexible sector length (2352)
SectorMode.MODE1 => Constants.Mode1UserDataEnd,
SectorMode.MODE2 => Constants.Mode0UserDataEnd, // TODO: Support flexible sector length (2352)
SectorMode.MODE2_FORM1 => Constants.Mode2Form1UserDataEnd,
SectorMode.MODE2_FORM2 => Constants.Mode2Form2UserDataEnd, // TODO: Support flexible sector length (2348)
_ => Constants.Mode0UserDataEnd,
};
}
/// <summary>
/// Get the user data start offset for a sector mode
/// </summary>
/// <param name="mode">Sector mode to get a value for</param>
/// <returns>User data start offset, if possible</returns>
public static long GetUserDataStart(this SectorMode mode)
{
return mode switch
{
SectorMode.MODE0 => Constants.Mode0UserDataStart,
SectorMode.MODE1 => Constants.Mode1UserDataStart,
SectorMode.MODE2 => Constants.Mode0UserDataStart,
SectorMode.MODE2_FORM1 => Constants.Mode2Form1UserDataStart,
SectorMode.MODE2_FORM2 => Constants.Mode2Form2UserDataStart,
_ => Constants.Mode0UserDataStart,
};
}
/// <summary>
/// Creates a stream that provides only the user data of a CDROM stream
/// </summary>
@@ -19,26 +112,31 @@ namespace SabreTools.Data.Extensions
// State variables
private long _position = 0;
private SectorMode _currentMode = SectorMode.UNKNOWN;
private long _userDataStart = 16;
private long _userDataEnd = 2064;
private long _userDataStart = Constants.Mode1UserDataStart;
private long _userDataEnd = Constants.Mode1UserDataEnd;
private long _isoSectorSize = Constants.Mode1DataSize;
public ISO9660Stream(Stream inputStream)
{
if (!inputStream.CanSeek || !inputStream.CanRead)
throw new ArgumentException("Stream must be readable and seekable.", nameof(inputStream));
_baseStream = inputStream;
}
public override bool CanRead => true;
public override bool CanSeek => true;
/// <inheritdoc/>
public override bool CanRead => _baseStream.CanRead;
/// <inheritdoc/>
public override bool CanSeek => _baseStream.CanSeek;
/// <inheritdoc/>
public override bool CanWrite => false;
public override void Flush()
{
_baseStream.Flush();
}
/// <inheritdoc/>
public override void Flush() => _baseStream.Flush();
/// <inheritdoc/>
public override long Length
{
get
@@ -47,25 +145,28 @@ namespace SabreTools.Data.Extensions
}
}
/// <inheritdoc/>
public override void SetLength(long value)
{
throw new NotSupportedException("Setting the length of this stream is not supported.");
}
/// <inheritdoc/>
public override void Write(byte[] buffer, int offset, int count)
{
throw new NotSupportedException("Writing to this stream is not supported.");
}
/// <inheritdoc/>
protected override void Dispose(bool disposing)
{
if (disposing)
{
_baseStream.Dispose();
}
base.Dispose(disposing);
}
/// <inheritdoc/>
public override long Position
{
// Get the position of the underlying ISO9660 stream
@@ -93,16 +194,16 @@ namespace SabreTools.Data.Extensions
}
}
/// <inheritdoc/>
public override int Read(byte[] buffer, int offset, int count)
{
bool readEntireSector = false;
int totalRead = 0;
int remaining = count;
while (remaining > 0 && _position < _baseStream.Length)
{
// Determine location of current sector
long baseStreamOffset = (_position / Constants.CDROMSectorSize) * Constants.CDROMSectorSize;
long baseStreamOffset = _position - (_position % Constants.CDROMSectorSize);
// Set the current sector's mode and user data location
SetState(baseStreamOffset);
@@ -123,16 +224,16 @@ namespace SabreTools.Data.Extensions
_position += Constants.CDROMSectorSize - _userDataEnd + _userDataStart;
}
else
{
baseStreamOffset += remainder;
}
// Sanity check on read location before seeking
if (baseStreamOffset < 0 || baseStreamOffset > _baseStream.Length)
{
throw new ArgumentOutOfRangeException(nameof(offset), "Attempted to seek outside the stream boundaries.");
}
// Seek to target position in base CDROM stream
_baseStream.Seek(baseStreamOffset, SeekOrigin.Begin);
_baseStream.SeekIfPossible(baseStreamOffset, SeekOrigin.Begin);
// Read the remaining bytes, up to max of one ISO sector (2048 bytes)
int bytesToRead = (int)Math.Min(remaining, _isoSectorSize - sectorOffset);
@@ -140,11 +241,6 @@ namespace SabreTools.Data.Extensions
// Don't overshoot end of stream
bytesToRead = (int)Math.Min(bytesToRead, _baseStream.Length - _position);
if (bytesToRead == (_isoSectorSize - sectorOffset))
readEntireSector = true;
else
readEntireSector = false;
// Finish reading if no more bytes to be read
if (bytesToRead <= 0)
break;
@@ -154,7 +250,7 @@ namespace SabreTools.Data.Extensions
// Update state for base stream
_position = _baseStream.Position;
if (readEntireSector)
if (bytesToRead == (_isoSectorSize - sectorOffset))
_position += (Constants.CDROMSectorSize - _userDataEnd) + _userDataStart;
// Update state for ISO stream
@@ -168,24 +264,17 @@ namespace SabreTools.Data.Extensions
return totalRead;
}
/// <inheritdoc/>
public override long Seek(long offset, SeekOrigin origin)
{
// Get the intended position for the ISO9660 stream
long targetPosition;
switch (origin)
var targetPosition = origin switch
{
case SeekOrigin.Begin:
targetPosition = offset;
break;
case SeekOrigin.Current:
targetPosition = Position + offset;
break;
case SeekOrigin.End:
targetPosition = Length + offset;
break;
default:
throw new ArgumentException("Invalid SeekOrigin.", nameof(origin));
}
SeekOrigin.Begin => offset,
SeekOrigin.Current => Position + offset,
SeekOrigin.End => Length + offset,
_ => throw new ArgumentException("Invalid SeekOrigin.", nameof(origin)),
};
// Get the number of ISO sectors before current position
long newPosition = (targetPosition / _isoSectorSize) * Constants.CDROMSectorSize;
@@ -195,80 +284,33 @@ namespace SabreTools.Data.Extensions
// Add the within-sector position
newPosition += _userDataStart + (targetPosition % _isoSectorSize);
if (newPosition < 0 || newPosition > _baseStream.Length)
{
throw new ArgumentOutOfRangeException(nameof(offset), "Attempted to seek outside the stream boundaries.");
}
_position = _baseStream.Seek(newPosition, SeekOrigin.Begin);
_position = _baseStream.SeekIfPossible(newPosition, SeekOrigin.Begin);
return Position;
}
/// <summary>
/// Update the current stream state based on the location
/// </summary>
/// <param name="sectorLocation">Sector location to update from</param>
private void SetState(long sectorLocation)
{
long oldPosition = _baseStream.Position;
long modePosition = (sectorLocation - sectorLocation % Constants.CDROMSectorSize) + 15;
_baseStream.Seek(modePosition, SeekOrigin.Begin);
byte modeByte = _baseStream.ReadByteValue();
if (modeByte == 0)
_currentMode = SectorMode.MODE0;
else if (modeByte == 1)
_currentMode = SectorMode.MODE1;
else if (modeByte == 2)
{
_baseStream.Seek(modePosition + 3, SeekOrigin.Begin);
byte submode = _baseStream.ReadByteValue();
if ((submode & 0x20) == 0x20)
_currentMode = SectorMode.MODE2_FORM2;
else
_currentMode = SectorMode.MODE2_FORM1;
}
else
_currentMode = SectorMode.UNKNOWN;
long current = _baseStream.Position;
long modePosition = sectorLocation - (sectorLocation % Constants.CDROMSectorSize) + 15;
// Get the current sector mode
_baseStream.SeekIfPossible(modePosition, SeekOrigin.Begin);
_currentMode = _baseStream.GetSectorMode();
// Set the user data location variables
switch (_currentMode)
{
case SectorMode.MODE1:
_userDataStart = 16;
_userDataEnd = 2064;
//_isoSectorSize = Constants.Mode1DataSize;
break;
_userDataStart = _currentMode.GetUserDataStart();
_userDataEnd = _currentMode.GetUserDataEnd();
// _isoSectorSize = _currentMode.GetUserDataSize();
case SectorMode.MODE2_FORM1:
_userDataStart = 24;
_userDataEnd = 2072;
//_isoSectorSize = Constants.Form1DataSize;
break;
case SectorMode.MODE2_FORM2:
_userDataStart = 24;
_userDataEnd = 2072;
// TODO: Support flexible sector length
//_userDataEnd = 2348;
//_isoSectorSize = Constants.Form2DataSize;
break;
case SectorMode.MODE0:
case SectorMode.MODE2:
_userDataStart = 16;
_userDataEnd = 2064;
// TODO: Support flexible sector length
//_userDataEnd = 2352;
//_isoSectorSize = Constants.Mode0DataSize;
break;
case SectorMode.UNKNOWN:
_userDataStart = 16;
_userDataEnd = 2064;
//_isoSectorSize = Constants.Mode1DataSize;
break;
}
_baseStream.Seek(oldPosition, SeekOrigin.Begin);
return;
// Reset the stream position
_baseStream.SeekIfPossible(current, SeekOrigin.Begin);
}
}
}

48
SabreTools.Serialization/Models/CDROM/Constants.cs
View File

@@ -17,18 +17,58 @@ namespace SabreTools.Data.Models.CDROM
public const long Mode0DataSize = 2336;
/// <summary>
/// Size of user data length for Mode1 / Mode2 Form1
/// Offset in a Mode0 sector where user data starts
/// </summary>
public const long Mode0UserDataStart = 16;
/// <summary>
/// Offset in a Mode0 sector where user data ends
/// </summary>
public const long Mode0UserDataEnd = 2064;
/// <summary>
/// Size of user data length for Mode1
/// </summary>
public const long Mode1DataSize = 2048;
/// <summary>
/// Size of user data length for Mode1 / Mode2 Form1
/// Offset in a Mode1 sector where user data starts
/// </summary>
public const long Form1DataSize = 2048;
public const long Mode1UserDataStart = 16;
/// <summary>
/// Offset in a Mode1 sector where user data ends
/// </summary>
public const long Mode1UserDataEnd = 2064;
/// <summary>
/// Size of user data length for Mode2 Form1
/// </summary>
public const long Mode2Form1DataSize = 2048;
/// <summary>
/// Offset in a Mode2 Form1 sector where user data starts
/// </summary>
public const long Mode2Form1UserDataStart = 24;
/// <summary>
/// Offset in a Mode2 Form1 sector where user data ends
/// </summary>
public const long Mode2Form1UserDataEnd = 2072;
/// <summary>
/// Size of user data length for Mode2 Form2
/// </summary>
public const long Form2DataSize = 2324;
public const long Mode2Form2DataSize = 2324;
/// <summary>
/// Offset in a Mode2 Form2 sector where user data starts
/// </summary>
public const long Mode2Form2UserDataStart = 24;
/// <summary>
/// Offset in a Mode2 Form2 sector where user data ends
/// </summary>
public const long Mode2Form2UserDataEnd = 2072;
}
}

2
SabreTools.Serialization/Wrappers/CDROM.cs
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@@ -71,7 +71,7 @@ namespace SabreTools.Serialization.Wrappers
try
{
// Create user data sub-stream
SabreTools.Data.Extensions.CDROM.ISO9660Stream userData = new(data);
var userData = new Data.Extensions.CDROM.ISO9660Stream(data);
// Cache the current offset
long currentOffset = userData.Position;