byte[] ReadDynamic(int count)
{
int positionInBuffer = 0;
int bytesRemaining = count;
byte[] destBuffer = new byte[count];
while (positionInBuffer < count)
{
byte[] data = new byte[0];
if (Position < StaticDataLength)
{
// Read a chunk from non-dynamic area, next iteration will read dynamic data
int maxReadLength = (int)(StaticDataLength - Position);
int length = bytesRemaining > maxReadLength ? maxReadLength : bytesRemaining;
data = InternalRead(length);
}
else
{
// Lookup block allocation table for real data offset
var targetVirtualOffset = (ulong)(Position - StaticDataLength);
ulong blockNumber = XvdMath.OffsetToBlockNumber(targetVirtualOffset);
long inBlockOffset = (long)XvdMath.InBlockOffset(targetVirtualOffset);
int maxReadLength = (int)(XvdFile.BLOCK_SIZE - inBlockOffset);
int length = bytesRemaining > maxReadLength ? maxReadLength : bytesRemaining;
var targetPage = _xvdFile.ReadBat(blockNumber);
if (targetPage == XvdFile.INVALID_SECTOR)
{
data = new byte[length];
// Advance stream position cause we are not actually reading data
Position += length;
}
else
{
long targetPhysicalOffset = DynamicBaseOffset
+ (long)XvdMath.PageNumberToOffset(targetPage)
+ inBlockOffset;
data = InternalReadAbsolute(targetPhysicalOffset, length);
}
}
Array.Copy(data, 0, destBuffer, positionInBuffer, data.Length);
positionInBuffer += data.Length;
bytesRemaining -= data.Length;
}
return(destBuffer);
}
