/// <summary>
/// Writes a block of file data, possibly compressing it.
/// </summary>
/// <param name="buffer">The data to write</param>
/// <param name="offset">Offset of the first byte to write</param>
/// <param name="count">The number of bytes to write</param>
/// <returns>
/// The 'length' of the (possibly compressed) data written, including
/// a flag indicating compression (or not).
/// </returns>
private uint WriteDataBlock(byte[] buffer, int offset, int count)
{
MemoryStream compressed = new MemoryStream();
using (ZlibStream compStream = new ZlibStream(compressed, CompressionMode.Compress, true))
{
compStream.Write(buffer, offset, count);
}
byte[] writeData;
int writeOffset;
int writeLen;
if (compressed.Length < count)
{
writeData = compressed.GetBuffer();
writeOffset = 0;
writeLen = (int)compressed.Length;
}
else
{
writeData = buffer;
writeOffset = offset;
writeLen = count | 0x01000000;
}
_context.RawStream.Write(writeData, writeOffset, writeLen & 0xFFFFFF);
return (uint)writeLen;
}
private void NextBlock()
{
MemoryStream compressed = new MemoryStream();
using (ZlibStream compStream = new ZlibStream(compressed, CompressionMode.Compress, true))
{
compStream.Write(_currentBlock, 0, _currentOffset);
}
byte[] writeData;
ushort writeLen;
if (compressed.Length < _currentOffset)
{
writeData = compressed.GetBuffer();
writeLen = (ushort)compressed.Length;
}
else
{
writeData = _currentBlock;
writeLen = (ushort)(_currentOffset | 0x8000);
}
byte[] header = new byte[2];
Utilities.WriteBytesLittleEndian(writeLen, header, 0);
_buffer.Write(header, 0, 2);
_buffer.Write(writeData, 0, writeLen & 0x7FFF);
++_currentBlockNum;
}