Files
Aaru/Aaru.Devices/Device/ScsiCommands/ReadBuffer.cs
2026-01-11 10:23:21 +01:00

731 lines
33 KiB
C#

// /***************************************************************************
// Aaru Data Preservation Suite
// ----------------------------------------------------------------------------
//
// Filename : ReadBuffer.cs
// Author(s) : Rebecca Wallander <sakcheen@gmail.com>
//
// Component : SCSI READ BUFFER command.
//
// --[ Description ] ----------------------------------------------------------
//
// Contains generic SCSI READ BUFFER command implementation.
//
// --[ 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 © 2011-2026 Rebecca Wallander
// ****************************************************************************/
using System;
using System.Collections.Generic;
using Aaru.CommonTypes.Enums;
using Aaru.Helpers;
using Aaru.Logging;
namespace Aaru.Devices;
public partial class Device
{
// ReadBuffer 3C detection fields
private byte _detectedReadBufferMode; // Detected buffer mode (0x00, 0x01, 0x02)
private byte _detectedReadBufferId; // Detected buffer ID (0x00, 0x01, 0x02)
private uint _detectedBufferStride; // Detected stride in bytes per sector
private bool _readBuffer3CDetected; // Flag to track if detection has been performed
// Buffer format and management fields
private enum BufferFormat
{
Unknown = 0,
FullEccInterleaved,
PoOnly,
SectorDataOnly,
FullEccWithPadding
}
private uint _bufferOffset;
private uint _bufferCapacityInSectors;
private BufferFormat _bufferFormat;
private uint _totalSectorsRead; // Tracks cumulative sectors read successfully since last buffer reset
/// <summary>Reads from device buffer using SCSI READ BUFFER command with specified variant</summary>
/// <returns><c>true</c> if the command failed and <paramref name="senseBuffer" /> contains the sense buffer.</returns>
/// <param name="buffer">Buffer where the ReadBuffer response will be stored</param>
/// <param name="senseBuffer">Sense buffer</param>
/// <param name="bufferOffset">The offset to read the buffer at</param>
/// <param name="transferLength">Number of bytes to read</param>
/// <param name="timeout">Timeout in seconds</param>
/// <param name="duration">Duration in milliseconds</param>
/// <param name="mode">Buffer mode (CDB byte 1, e.g., 0x01 for data, 0x02 for descriptors)</param>
/// <param name="bufferId">Buffer ID (CDB byte 2, e.g., 0x01, 0x00)</param>
public bool ScsiReadBuffer(out byte[] buffer, out ReadOnlySpan<byte> senseBuffer, uint bufferOffset,
uint transferLength, uint timeout, out double duration, byte mode, byte bufferId)
{
senseBuffer = SenseBuffer;
Span<byte> cdb = CdbBuffer[..10];
cdb.Clear();
buffer = new byte[transferLength];
cdb[0] = (byte)ScsiCommands.ReadBuffer;
cdb[1] = mode;
cdb[2] = bufferId;
cdb[3] = (byte)((bufferOffset & 0xFF0000) >> 16);
cdb[4] = (byte)((bufferOffset & 0xFF00) >> 8);
cdb[5] = (byte)(bufferOffset & 0xFF);
cdb[6] = (byte)((buffer.Length & 0xFF0000) >> 16);
cdb[7] = (byte)((buffer.Length & 0xFF00) >> 8);
cdb[8] = (byte)(buffer.Length & 0xFF);
LastError = SendScsiCommand(cdb, ref buffer, timeout, ScsiDirection.In, out duration, out bool sense);
return sense;
}
/// <summary>
/// Makes sure the data's sector number is the one expected.
/// </summary>
/// <param name="buffer">Data buffer</param>
/// <param name="firstLba">First consecutive LBA of the buffer</param>
/// <param name="transferLength">How many blocks in buffer</param>
/// <param name="layerbreak">The address in which the layerbreak occur</param>
/// <param name="otp">Set to <c>true</c> if disk is Opposite Track Path (OTP)</param>
/// <returns><c>false</c> if any sector is not matching expected value, else <c>true</c></returns>
static bool CheckSectorNumber(IReadOnlyList<byte> buffer, uint firstLba, uint transferLength, uint layerbreak,
bool otp)
{
for(var i = 0; i < transferLength; i++)
{
var layer = (byte)(buffer[0 + 2064 * i] & 0x1);
byte[] sectorBuffer = [0x0, buffer[1 + 2064 * i], buffer[2 + 2064 * i], buffer[3 + 2064 * i]];
uint sectorNumber = BigEndianBitConverter.ToUInt32(sectorBuffer, 0);
if(otp)
{
if(!IsCorrectDlOtpPsn(sectorNumber, (ulong)(firstLba + i), layer, layerbreak)) return false;
}
else
{
if(!IsCorrectSlPsn(sectorNumber, (ulong)(firstLba + i))) return false;
}
}
return true;
}
/// <summary>
/// Checks if the PSN for a raw sector matches the expected LBA for a single layer DVD
/// </summary>
/// <param name="sectorNumber">The Sector Number from Identification Data (ID)</param>
/// <param name="lba">The expected LBA</param>
/// <returns><c>false</c> if the sector is not matching expected value, else <c>true</c></returns>
static bool IsCorrectSlPsn(uint sectorNumber, ulong lba) => sectorNumber == lba + 0x30000;
/// <summary>
/// Checks if the PSN for a raw sector matches the expected LBA for a dual layer DVD with parallel track path
/// </summary>
/// <param name="sectorNumber">The Sector Number from Identification Data (ID)</param>
/// <param name="lba">The expected LBA</param>
/// <param name="layer">Layer number</param>
/// <param name="layerbreak">The address in which the layerbreak occur</param>
/// <returns><c>false</c> if the sector is not matching expected value, else <c>true</c></returns>
static bool IsCorrectDlPtpPsn(uint sectorNumber, ulong lba, byte layer, uint layerbreak)
{
if(layer != 1) return IsCorrectSlPsn(sectorNumber, lba);
return sectorNumber == lba - layerbreak + 0x30000;
}
/// <summary>
/// Checks if the PSN for a raw sector matches the expected LBA for a dual layer DVD with opposite track path
/// </summary>
/// <param name="sectorNumber">The Sector Number from Identification Data (ID)</param>
/// <param name="lba">The expected LBA</param>
/// <param name="layer">Layer number</param>
/// <param name="layerbreak">The address in which the layerbreak occur</param>
/// <returns><c>false</c> if the sector is not matching expected value, else <c>true</c></returns>
static bool IsCorrectDlOtpPsn(uint sectorNumber, ulong lba, byte layer, uint layerbreak)
{
if(layer != 1) return IsCorrectSlPsn(sectorNumber, lba);
ulong n = ~(layerbreak + 1 + (layerbreak - (lba + 0x30000))) & 0x00ffffff;
return sectorNumber == n;
}
/// <summary>
/// Deinterleave full ECC block with interleaved PI (e.g., 2384 bytes)
/// </summary>
/// <param name="buffer">Data buffer</param>
/// <param name="transferLength">How many blocks in buffer</param>
/// <param name="stride">Bytes per sector in buffer</param>
/// <returns>The deinterleaved sectors</returns>
static byte[] DeinterleaveFullEccInterleaved(byte[] buffer, uint transferLength, uint stride)
{
// TODO: Save ECC instead of just throwing it away
var deinterleaved = new byte[2064 * transferLength];
for(var j = 0; j < transferLength; j++)
{
for(var i = 0; i < 12; i++) Array.Copy(buffer, j * stride + i * 182, deinterleaved, j * 2064 + i * 172, 172);
}
return deinterleaved;
}
/// <summary>
/// Extract sector data from PO-only format (e.g., 2236 bytes)
/// </summary>
/// <param name="buffer">Data buffer</param>
/// <param name="transferLength">How many blocks in buffer</param>
/// <param name="stride">Bytes per sector in buffer</param>
/// <returns>The extracted sector data</returns>
static byte[] DeinterleavePoOnly(byte[] buffer, uint transferLength, uint stride)
{
var deinterleaved = new byte[2064 * transferLength];
for(var j = 0; j < transferLength; j++)
{
Array.Copy(buffer, j * stride, deinterleaved, j * 2064, 2064);
}
return deinterleaved;
}
/// <summary>
/// Deinterleave full ECC block with padding (e.g., 2816 bytes)
/// </summary>
/// <param name="buffer">Data buffer</param>
/// <param name="transferLength">How many blocks in buffer</param>
/// <param name="stride">Bytes per sector in buffer</param>
/// <returns>The deinterleaved sectors</returns>
static byte[] DeinterleaveFullEccWithPadding(byte[] buffer, uint transferLength, uint stride)
{
// Same as FullEccInterleaved, padding is ignored
return DeinterleaveFullEccInterleaved(buffer, transferLength, stride);
}
/// <summary>
/// Detects which ReadBuffer 3C command variant works for this drive
/// Tries variants in order: 3c0000, 3c0100, 3c0101, 3c0102, 3c0200
/// </summary>
/// <param name="lba">LBA to use for filling the buffer</param>
/// <param name="timeout">Timeout in seconds</param>
/// <param name="duration">Duration in milliseconds</param>
/// <returns>Tuple with (mode, bufferId) if a working variant is found, null otherwise</returns>
private (byte mode, byte bufferId)? DetectReadBufferVariant(uint lba, uint timeout, out double duration)
{
duration = 0;
// Variants to try in order: 3c0000, 3c0100, 3c0101, 3c0102, 3c0200
(byte mode, byte bufferId)[] variants =
[
(0x00, 0x00), // 3c0000
(0x01, 0x00), // 3c0100
(0x01, 0x01), // 3c0101
(0x01, 0x02), // 3c0102
(0x02, 0x00) // 3c0200
];
// Fill buffer with sectors 0-16
Read12(out _, out _, 0, false, false, false, false, lba, 2048, 0, 16, false, timeout, out double readDuration);
duration += readDuration;
foreach((byte mode, byte bufferId) variant in variants)
{
// Try to read buffer with this variant
// Read enough for at least 3 sectors (minimum needed for stride detection)
uint readSize = 3 * 3000; // Enough for 3 sectors even with large stride
bool sense = ScsiReadBuffer(out byte[] buffer, out _, 0, readSize, timeout, out double readBufferDuration,
variant.mode, variant.bufferId);
duration += readBufferDuration;
// Check if command succeeded, returned valid data, and has correct sector header (00 03 00)
if(!sense && buffer != null && buffer.Length >= 2236 * 3)
{
// Validate that the data starts with the expected DVD sector header pattern
if(buffer.Length >= 3 &&
buffer[0] == 0x00 &&
buffer[1] == 0x03 &&
buffer[2] == 0x00)
{
AaruLogging.Debug(SCSI_MODULE_NAME, "ReadBuffer 3C variant {0:x2}{1:x2} detected", variant.mode,
variant.bufferId);
return (variant.mode, variant.bufferId);
}
AaruLogging.Debug(SCSI_MODULE_NAME,
"ReadBuffer 3C variant {0:x2}{1:x2} returned data but header pattern incorrect",
variant.mode, variant.bufferId);
}
}
AaruLogging.Debug(SCSI_MODULE_NAME, "No working ReadBuffer 3C variant found");
return null;
}
/// <summary>
/// Detects the stride (bytes per sector) in the buffer by searching for
/// the 00 03 00 pattern that appears at the start of each sector
/// </summary>
/// <param name="lba">LBA to use for filling the buffer (sectors 0-16)</param>
/// <param name="timeout">Timeout in seconds</param>
/// <param name="mode">Buffer mode to use</param>
/// <param name="bufferId">Buffer ID to use</param>
/// <param name="duration">Duration in milliseconds</param>
/// <returns>Detected stride in bytes, or 0 if detection failed</returns>
private uint DetectBufferStride(uint lba, uint timeout, byte mode, byte bufferId, out double duration)
{
// Fill buffer with sectors 0-16
Read12(out _, out _, 0, false, false, false, false, lba, 2048, 0, 16, false, timeout, out duration);
// Read a large buffer chunk (enough for 16+ sectors)
uint readSize = 16 * 3000; // Enough for 16 sectors even with large stride
bool sense = ScsiReadBuffer(out byte[] buffer, out _, 0, readSize, timeout, out double readDuration, mode,
bufferId);
duration += readDuration;
if(sense || buffer == null || buffer.Length < 2236 * 3) // Need at least 3 sectors worth
{
AaruLogging.Debug(SCSI_MODULE_NAME,
"ReadBuffer stride detection failed, sense or buffer too small, using default");
return 0; // Detection failed
}
// Search for pattern 00 03 00 starting from beginning
// Find first occurrence
int firstOffset = -1;
for(int i = 0; i < buffer.Length - 3; i++)
{
if(buffer[i] == 0x00 && buffer[i + 1] == 0x03 && buffer[i + 2] == 0x00)
{
firstOffset = i;
break;
}
}
if(firstOffset != 0)
{
AaruLogging.Debug(SCSI_MODULE_NAME,
"ReadBuffer stride detection failed, pattern not at start, using default");
return 0; // Pattern not at start
}
// Find second occurrence to calculate stride
int secondOffset = -1;
for(int i = firstOffset + 2064; i < Math.Min(firstOffset + 2500, buffer.Length - 3); i++)
{
if(buffer[i] == 0x00 && buffer[i + 1] == 0x03 && buffer[i + 2] == 0x00)
{
secondOffset = i;
break;
}
}
if(secondOffset == -1)
{
AaruLogging.Debug(SCSI_MODULE_NAME,
"ReadBuffer stride detection failed, couldn't find second sector, using default");
return 0; // Couldn't find second sector
}
uint stride = (uint)(secondOffset - firstOffset);
// Verify stride by checking 3rd and 4th sectors
for(int sectorNum = 2; sectorNum <= 3; sectorNum++)
{
int expectedOffset = (int)(firstOffset + stride * sectorNum);
if(expectedOffset + 3 >= buffer.Length) break;
if(buffer[expectedOffset] != 0x00 ||
buffer[expectedOffset + 1] != 0x03 ||
buffer[expectedOffset + 2] != 0x00)
{
return 0; // Verification failed
}
}
AaruLogging.Debug(SCSI_MODULE_NAME, "ReadBuffer stride detection succeeded, stride: {0}", stride);
return stride;
}
/// <summary>
/// Detects ReadBuffer 3C support: finds working variant and stride
/// </summary>
/// <param name="lba">LBA to use for detection</param>
/// <param name="timeout">Timeout in seconds</param>
/// <param name="duration">Duration in milliseconds</param>
/// <returns><c>true</c> if detection succeeded, <c>false</c> otherwise</returns>
private bool DetectReadBuffer3C(uint lba, uint timeout, out double duration)
{
duration = 0;
// If already detected, return success
if(_readBuffer3CDetected)
{
if(_detectedBufferStride == 0) return false;
return true;
}
// Try to detect variant
(byte mode, byte bufferId)? variant = DetectReadBufferVariant(lba, timeout, out double variantDuration);
duration += variantDuration;
if(!variant.HasValue)
{
_readBuffer3CDetected = true; // Mark as attempted even if failed
return false;
}
_detectedReadBufferMode = variant.Value.mode;
_detectedReadBufferId = variant.Value.bufferId;
// Detect stride using the found variant
uint stride = DetectBufferStride(lba, timeout, _detectedReadBufferMode, _detectedReadBufferId,
out double strideDuration);
duration += strideDuration;
if(stride == 0 || stride < 2064 || stride > 10000)
{
AaruLogging.Debug(SCSI_MODULE_NAME,
"ReadBuffer 3C stride detection failed or invalid stride: {0}, using default", stride);
_detectedBufferStride = 2384; // Default to known value
_readBuffer3CDetected = true;
return false; // Detection partially succeeded but stride failed
}
_detectedBufferStride = stride;
_readBuffer3CDetected = true;
AaruLogging.Debug(SCSI_MODULE_NAME,
"ReadBuffer 3C detection succeeded, variant: {0:x2}{1:x2}, stride: {2}",
_detectedReadBufferMode, _detectedReadBufferId, _detectedBufferStride);
return true;
}
/// <summary>Reads a "raw" sector from DVD using ReadBuffer 3C command.</summary>
/// <returns><c>true</c> if the command failed and <paramref name="senseBuffer" /> contains the sense buffer.</returns>
/// <param name="buffer">Buffer where the ReadBuffer (RAW) response will be stored</param>
/// <param name="senseBuffer">Sense buffer.</param>
/// <param name="lba">Start block address.</param>
/// <param name="transferLength">How many blocks to read.</param>
/// <param name="timeout">Timeout in seconds.</param>
/// <param name="duration">Duration in milliseconds it took for the device to execute the command.</param>
/// <param name="layerbreak">The address in which the layerbreak occur</param>
/// <param name="otp">Set to <c>true</c> if disk is Opposite Track Path (OTP)</param>
public bool ReadBuffer3CRawDvd(out byte[] buffer, out ReadOnlySpan<byte> senseBuffer, uint lba, uint transferLength,
uint timeout, out double duration, uint layerbreak, bool otp)
{
// Detect ReadBuffer 3C variant and stride on first call
if(!_readBuffer3CDetected)
{
bool detected = DetectReadBuffer3C(lba, timeout, out double detectDuration);
if(!detected || _detectedBufferStride == 0 || _detectedBufferStride < 2064 || _detectedBufferStride > 10000)
{
// Detection failed - raw reading is not supported on this drive
AaruLogging.Debug(SCSI_MODULE_NAME,
"ReadBuffer 3C detection failed - raw reading is not supported on this drive");
buffer = Array.Empty<byte>();
senseBuffer = SenseBuffer;
duration = detectDuration;
Error = true;
_readBuffer3CDetected = true;
return true; // Return failure - raw reading not supported
}
// Detect format based on stride
_bufferFormat = _detectedBufferStride switch
{
2064 => BufferFormat.SectorDataOnly,
2236 => BufferFormat.PoOnly,
2384 => BufferFormat.FullEccInterleaved,
> 2384 => BufferFormat.FullEccWithPadding,
_ => BufferFormat.FullEccInterleaved // Default for backward compatibility
};
AaruLogging.Debug(SCSI_MODULE_NAME,
"ReadBuffer 3C buffer format detected based on stride: {0}, format: {1}",
_detectedBufferStride, _bufferFormat);
// Initialize buffer capacity with default value (will be refined dynamically when offset is lost)
_bufferCapacityInSectors = 714;
_totalSectorsRead = 0; // Initialize tracking for dynamic capacity detection
_readBuffer3CDetected = true;
}
_bufferOffset %= _bufferCapacityInSectors;
bool sense;
if(layerbreak > 0 && transferLength > 1 && lba + 0x30000 > layerbreak - 256 && lba + 0x30000 < layerbreak + 256)
{
buffer = new byte[transferLength * 2064];
duration = 0;
senseBuffer = SenseBuffer;
return true;
}
if(_bufferCapacityInSectors - _bufferOffset < transferLength)
{
sense = ReadSectorsAcrossBufferBorder(out buffer,
out senseBuffer,
lba,
transferLength,
timeout,
out duration,
layerbreak,
otp);
}
else
{
sense = ReadSectorsFromBuffer(out buffer,
out senseBuffer,
lba,
transferLength,
timeout,
out duration,
layerbreak,
otp);
}
Error = LastError != 0;
AaruLogging.Debug(SCSI_MODULE_NAME, "ReadBuffer 3C READ DVD RAW took {0} ms", duration);
return sense;
}
/// <summary>
/// Reads the device's memory buffer and returns raw sector data
/// </summary>
/// <param name="buffer">Buffer where the ReadBuffer (RAW) response will be stored</param>
/// <param name="senseBuffer">Sense buffer.</param>
/// <param name="bufferOffset">The offset to read the buffer at</param>
/// <param name="transferLength">How many blocks to read.</param>
/// <param name="timeout">Timeout in seconds.</param>
/// <param name="duration">Duration in milliseconds it took for the device to execute the command.</param>
/// <param name="lba">Start block address.</param>
/// <returns><c>true</c> if the command failed and <paramref name="senseBuffer" /> contains the sense buffer.</returns>
private bool ReadBuffer3CInternal(out byte[] buffer, out ReadOnlySpan<byte> senseBuffer, uint bufferOffset,
uint transferLength, uint timeout, out double duration, uint lba)
{
// We need to fill the buffer before reading it with the ReadBuffer command. We don't care about sense,
// because the data can be wrong anyway, so we check the buffer data later instead.
Read12(out _, out _, 0, false, false, false, false, lba, 2048, 0, 16, false, timeout, out duration);
// Use generic ReadBuffer method with detected variant
return ScsiReadBuffer(out buffer, out senseBuffer, bufferOffset, transferLength, timeout, out duration,
_detectedReadBufferMode, _detectedReadBufferId);
}
/// <summary>
/// Reads raw sectors from the device's memory
/// </summary>
/// <returns><c>true</c> if the command failed and <paramref name="senseBuffer" /> contains the sense buffer.</returns>
/// <param name="buffer">Buffer where the ReadBuffer (RAW) response will be stored</param>
/// <param name="senseBuffer">Sense buffer.</param>
/// <param name="timeout">Timeout in seconds.</param>
/// <param name="duration">Duration in milliseconds it took for the device to execute the command.</param>
/// <param name="lba">Start block address.</param>
/// <param name="transferLength">How many blocks to read.</param>
/// <param name="layerbreak">The address in which the layerbreak occur</param>
/// <param name="otp">Set to <c>true</c> if disk is Opposite Track Path (OTP)</param>
private bool ReadSectorsFromBuffer(out byte[] buffer, out ReadOnlySpan<byte> senseBuffer, uint lba,
uint transferLength, uint timeout, out double duration, uint layerbreak,
bool otp)
{
bool sense = ReadBuffer3CInternal(out buffer,
out senseBuffer,
_bufferOffset * _detectedBufferStride,
transferLength * _detectedBufferStride,
timeout,
out duration,
lba);
byte[] deinterleaved = DeinterleaveEccBlock(buffer, transferLength, _detectedBufferStride, _bufferFormat);
if(!CheckSectorNumber(deinterleaved, lba, transferLength, layerbreak, true))
{
// Buffer offset lost - this means we've wrapped around
// Use the number of sectors read to detect buffer capacity
if(_totalSectorsRead > 0 && _totalSectorsRead >= 16 && _totalSectorsRead <= 2000)
{
uint detectedCapacity = _totalSectorsRead;
uint oldCapacity = _bufferCapacityInSectors;
// If we already have a capacity, verify new detection is consistent
if(_bufferCapacityInSectors == 714 || // Update if using default
(detectedCapacity >= _bufferCapacityInSectors * 9 / 10 &&
detectedCapacity <= _bufferCapacityInSectors * 11 / 10)) // Or within 10%
{
_bufferCapacityInSectors = detectedCapacity;
AaruLogging.Debug(SCSI_MODULE_NAME,
"Buffer capacity dynamically detected: {0} sectors (was {1})",
detectedCapacity, oldCapacity);
}
}
// Reset tracking for next cycle
_totalSectorsRead = 0;
// Buffer offset lost, try to find it again
int offset = FindBufferOffset(lba, timeout, layerbreak, otp);
if(offset == -1) return true;
_bufferOffset = (uint)offset;
sense = ReadBuffer3CInternal(out buffer,
out senseBuffer,
_bufferOffset * _detectedBufferStride,
transferLength * _detectedBufferStride,
timeout,
out duration,
lba);
deinterleaved = DeinterleaveEccBlock(buffer, transferLength, _detectedBufferStride, _bufferFormat);
if(!CheckSectorNumber(deinterleaved, lba, transferLength, layerbreak, otp)) return true;
}
if(_decoding.Scramble(deinterleaved, transferLength, out byte[] scrambledBuffer) != ErrorNumber.NoError)
return true;
buffer = scrambledBuffer;
_bufferOffset += transferLength;
_totalSectorsRead += transferLength; // Track successful read for capacity detection
return sense;
}
/// <summary>
/// Reads raw sectors when they cross the device's memory border
/// </summary>
/// <returns><c>true</c> if the command failed and <paramref name="senseBuffer" /> contains the sense buffer.</returns>
/// <param name="buffer">Buffer where the ReadBuffer (RAW) response will be stored</param>
/// <param name="senseBuffer">Sense buffer.</param>
/// <param name="timeout">Timeout in seconds.</param>
/// <param name="duration">Duration in milliseconds it took for the device to execute the command.</param>
/// <param name="lba">Start block address.</param>
/// <param name="transferLength">How many blocks to read.</param>
/// <param name="layerbreak">The address in which the layerbreak occur</param>
/// <param name="otp">Set to <c>true</c> if disk is Opposite Track Path (OTP)</param>
private bool ReadSectorsAcrossBufferBorder(out byte[] buffer, out ReadOnlySpan<byte> senseBuffer, uint lba,
uint transferLength, uint timeout, out double duration,
uint layerbreak, bool otp)
{
uint newTransferLength1 = _bufferCapacityInSectors - _bufferOffset;
uint newTransferLength2 = transferLength - newTransferLength1;
bool sense1 = ReadBuffer3CInternal(out byte[] buffer1,
out _,
_bufferOffset * _detectedBufferStride,
newTransferLength1 * _detectedBufferStride,
timeout,
out double duration1,
lba);
bool sense2 = ReadBuffer3CInternal(out byte[] buffer2,
out _,
0,
newTransferLength2 * _detectedBufferStride,
timeout,
out double duration2,
lba);
senseBuffer = SenseBuffer; // TODO
buffer = new byte[_detectedBufferStride * transferLength];
Array.Copy(buffer1, buffer, buffer1.Length);
Array.Copy(buffer2, 0, buffer, buffer1.Length, buffer2.Length);
duration = duration1 + duration2;
byte[] deinterleaved = DeinterleaveEccBlock(buffer, transferLength, _detectedBufferStride, _bufferFormat);
if(!CheckSectorNumber(deinterleaved, lba, transferLength, layerbreak, otp)) return true;
if(_decoding.Scramble(deinterleaved, transferLength, out byte[] scrambledBuffer) != ErrorNumber.NoError)
return true;
buffer = scrambledBuffer;
_bufferOffset = newTransferLength2;
_totalSectorsRead += transferLength; // Track successful read for capacity detection
return sense1 && sense2;
}
/// <summary>
/// Sometimes the offset on the drive memory can get lost. This tries to find it again.
/// </summary>
/// <param name="lba">The expected LBA</param>
/// <param name="timeout">Timeout in seconds.</param>
/// <param name="layerbreak">The address in which the layerbreak occur</param>
/// <param name="otp">Set to <c>true</c> if disk is Opposite Track Path (OTP)</param>
/// <returns>The offset on the device memory, or -1 if not found</returns>
private int FindBufferOffset(uint lba, uint timeout, uint layerbreak, bool otp)
{
for(uint i = 0; i < _bufferCapacityInSectors; i++)
{
ReadBuffer3CInternal(out byte[] buffer, out _, i * _detectedBufferStride, _detectedBufferStride, timeout,
out double _, lba);
byte[] deinterleaved = DeinterleaveEccBlock(buffer, 1, _detectedBufferStride, _bufferFormat);
if(CheckSectorNumber(deinterleaved, lba, 1, layerbreak, otp)) return (int)i;
}
return -1;
}
/// <summary>
/// Deinterleave the ECC block based on detected format
/// </summary>
/// <param name="buffer">Data buffer</param>
/// <param name="transferLength">How many blocks in buffer</param>
/// <param name="stride">Bytes per sector in buffer</param>
/// <param name="format">Buffer format type</param>
/// <returns>The deinterleaved sectors</returns>
private byte[] DeinterleaveEccBlock(byte[] buffer, uint transferLength, uint stride, BufferFormat format)
{
return format switch
{
BufferFormat.FullEccInterleaved => DeinterleaveFullEccInterleaved(buffer, transferLength, stride),
BufferFormat.PoOnly => DeinterleavePoOnly(buffer, transferLength, stride),
BufferFormat.SectorDataOnly => buffer, // No deinterleaving needed for sector-data-only format
BufferFormat.FullEccWithPadding => DeinterleaveFullEccWithPadding(buffer, transferLength, stride),
_ => DeinterleaveFullEccInterleaved(buffer, transferLength, stride) // Default fallback
};
}
}