public int Read(byte[] data, uint index, int length)
{
if (length > bytesPerSector)
{
uint fixedLength;
//Copy remaining bytes in current sector buffer
Array.Copy(buffer, 0, data, 0, (buffer.Length) - currentPos);
//Calculate remaining bytes to be read
uint bytesToRead = (uint)(length - ((buffer.Length) - currentPos));
//Check whether it ends on a sector boundary
if (bytesToRead % bytesPerSector != 0)
{
//Calculate next sector boundary in bytes
fixedLength = (((uint)bytesToRead / bytesPerSector) + 1) * bytesPerSector;
}
else
{
fixedLength = (uint)bytesToRead;
}
byte[] temp = new byte[fixedLength];
Exports.ReadFile(hFile, temp, fixedLength, ref bytesRead, IntPtr.Zero);
Array.Copy(temp, 0, data, (buffer.Length) - currentPos, bytesToRead);
SeekAbsolute((ulong)(((absolutePos + length) / bytesPerSector) * bytesPerSector));
return(length);
}
//If read is in current buffer sector
if (bufferSector == ((absolutePos + (length - 1)) / bytesPerSector))
{
Array.Copy(buffer, currentPos, data, 0, length);
currentPos += length;
absolutePos += length;
return(length);
}
//If read crosses into next buffer sector
if (bufferSector < ((absolutePos + (length - 1)) / bytesPerSector))
{
Array.Copy(buffer, currentPos, data, 0, buffer.Length - currentPos);
Exports.ReadFile(hFile, buffer, bytesPerSector, ref bytesRead, IntPtr.Zero);
Array.Copy(buffer, 0, data, buffer.Length - currentPos, length - (buffer.Length - currentPos));
currentPos = length % bytesPerSector;
absolutePos += length;
bufferSector++;
return(length);
}
return(0);
}
public BufferedDiskReader(string filename)
{
this.filename = filename;
hFile = Exports.CreateFile(this.filename,
(uint)FileAccess.Read,
(uint)FileShare.None,
IntPtr.Zero,
(uint)FileMode.Open,
Exports.FILE_FLAG_NO_BUFFERING,
IntPtr.Zero);
buffer = new byte[bytesPerSector];
Exports.ReadFile(hFile, buffer, (uint)buffer.Length, ref bytesRead, IntPtr.Zero);
bufferSector = 0;
currentPos = 0;
}
public ulong SeekAbsolute(ulong pos)
{
ulong res = 0;
if ((uint)(pos / bytesPerSector) != bufferSector)
{
ulong closestSector = ((pos / (ulong)bytesPerSector) * (ulong)bytesPerSector);
int positionLow = (int)closestSector;
int positionHigh = (int)((closestSector & 0xFFFFFFFF00000000) >> 32);
res = Exports.SetFilePointer(hFile, positionLow, ref positionHigh, Exports.EMoveMethod.Begin);
int confirmPositionHigh = 0;
ulong confirmRes = Exports.SetFilePointer(hFile, 0, ref confirmPositionHigh, Exports.EMoveMethod.Current);
if (((ulong)confirmPositionHigh << 32 | res) != ((ulong)positionHigh << 32 | confirmRes))
{
int value = Marshal.GetLastWin32Error();
throw new Exception("RUH ROH");
}
bufferSector = (int)(closestSector / bytesPerSector);
Exports.ReadFile(hFile, buffer, (uint)buffer.Length, ref bytesRead, IntPtr.Zero);
}
currentPos = (long)(pos % bytesPerSector);
absolutePos = (long)pos;
return(res);
}
