/// <summary>
/// When overridden in a derived class, sets the position within the current stream.
/// </summary>
/// <param name="offset">A byte offset relative to the <paramref name="origin"/> parameter.</param>
/// <param name="origin">A value of type <see cref="T:System.IO.SeekOrigin"/> indicating the reference point used to obtain the new position.</param>
/// <returns>
/// The new position within the current stream.
/// </returns>
/// <exception cref="T:System.IO.IOException">
/// An I/O error occurs.
/// </exception>
/// <exception cref="T:System.NotSupportedException">
/// The stream does not support seeking, such as if the stream is constructed from a pipe or console output.
/// </exception>
/// <exception cref="T:System.ObjectDisposedException">
/// Methods were called after the stream was closed.
/// </exception>
public override long Seek(long offset, System.IO.SeekOrigin origin)
{
// FIXME: off-by-one bug when new position modulus 512 = 0
long newposition = position;
switch (origin)
{
case System.IO.SeekOrigin.Begin: newposition = offset; break;
case System.IO.SeekOrigin.Current: newposition = position + offset; break;
case System.IO.SeekOrigin.End: newposition = length + offset; break;
}
// find cluster number of new position
uint newNthCluster = (uint)(newposition / clusterSize);
uint currentNthCluster = (uint)(position / clusterSize);
int diff = (int)(newNthCluster - currentNthCluster);
uint newCluster = 0;
if (newNthCluster == currentNthCluster)
{
newCluster = currentCluster;
}
else
if (newNthCluster > currentNthCluster)
{
newCluster = fs.FindNthCluster(currentCluster, (uint)diff);
currentNthCluster = currentNthCluster + (uint)diff;
}
else
if (newNthCluster < currentNthCluster)
{
newCluster = fs.FindNthCluster(this.startCluster, newNthCluster);
currentNthCluster = newNthCluster;
}
ReadCluster(newCluster);
position = newposition;
return(position);
}
