This class stores the pending output of the Deflater. author of the original java version : Jochen Hoenicke
Inheritance: PendingBuffer
        /// <summary>
        /// Creates a new deflater with given compression level.
        /// </summary>
        /// <param name="level">
        /// the compression level, a value between NO_COMPRESSION
        /// and BEST_COMPRESSION.
        /// </param>
        /// <param name="noZlibHeaderOrFooter">
        /// true, if we should suppress the Zlib/RFC1950 header at the
        /// beginning and the adler checksum at the end of the output.  This is
        /// useful for the GZIP/PKZIP formats.
        /// </param>
        /// <exception cref="System.ArgumentOutOfRangeException">if lvl is out of range.</exception>
        public Deflater(int level, bool noZlibHeaderOrFooter)
        {
            if (level == DEFAULT_COMPRESSION)
            {
                level = 6;
            }
            else if (level < NO_COMPRESSION || level > BEST_COMPRESSION)
            {
                throw new ArgumentOutOfRangeException("level");
            }

            pending = new DeflaterPending();
            engine  = new DeflaterEngine(pending);
            this.noZlibHeaderOrFooter = noZlibHeaderOrFooter;
            SetStrategy(DeflateStrategy.Default);
            SetLevel(level);
            Reset();
        }
        /// <summary>
        /// Creates a new deflater with given compression level.
        /// </summary>
        /// <param name="level">
        /// the compression level, a value between NO_COMPRESSION
        /// and BEST_COMPRESSION.
        /// </param>
        /// <param name="noZlibHeaderOrFooter">
        /// true, if we should suppress the Zlib/RFC1950 header at the
        /// beginning and the adler checksum at the end of the output.  This is
        /// useful for the GZIP/PKZIP formats.
        /// </param>
        /// <exception cref="System.ArgumentOutOfRangeException">if lvl is out of range.</exception>
        public Deflater(int level, bool noZlibHeaderOrFooter)
        {
            if (level == DEFAULT_COMPRESSION) {
                level = 6;
            } else if (level < NO_COMPRESSION || level > BEST_COMPRESSION) {
                throw new ArgumentOutOfRangeException("level");
            }

            pending = new DeflaterPending();
            engine = new DeflaterEngine(pending);
            this.noZlibHeaderOrFooter = noZlibHeaderOrFooter;
            SetStrategy(DeflateStrategy.Default);
            SetLevel(level);
            Reset();
        }
        /// <summary>
        /// Construct instance with pending buffer
        /// </summary>
        /// <param name="pending">
        /// Pending buffer to use
        /// </param>>
        public DeflaterEngine(DeflaterPending pending)
        {
            this.pending = pending;
            huffman = new DeflaterHuffman(pending);
            adler = new Adler32();

            window = new byte[2 * WSIZE];
            head = new short[HASH_SIZE];
            prev = new short[WSIZE];

            // We start at index 1, to avoid an implementation deficiency, that
            // we cannot build a repeat pattern at index 0.
            blockStart = strstart = 1;
        }
		/// <summary>
		/// Construct instance with pending buffer
		/// </summary>
		/// <param name="pending">Pending buffer to use</param>
		public DeflaterHuffman(DeflaterPending pending) {
			this.pending = pending;

			literalTree = new Tree(this, LITERAL_NUM, 257, 15);
			distTree = new Tree(this, DIST_NUM, 1, 15);
			blTree = new Tree(this, BITLEN_NUM, 4, 7);

			d_buf = new short[BUFSIZE];
			l_buf = new byte[BUFSIZE];
		}