void ReadHeader() 
		{
			/* 1. Check the two magic bytes */
			Crc32 headCRC = new Crc32();
			int magic = baseInputStream.ReadByte();
			if (magic < 0) {
				eos = true;
				return;
			}
			headCRC.Update(magic);
			if (magic != (GZipConstants.GZIP_MAGIC >> 8)) {
				throw new GZipException("Error baseInputStream GZIP header, first byte doesn't match");
			}
				
			magic = baseInputStream.ReadByte();
			if (magic != (GZipConstants.GZIP_MAGIC & 0xFF)) {
				throw new GZipException("Error baseInputStream GZIP header,  second byte doesn't match");
			}
			headCRC.Update(magic);
			
			/* 2. Check the compression type (must be 8) */
			int CM = baseInputStream.ReadByte();
			if (CM != 8) {
				throw new GZipException("Error baseInputStream GZIP header, data not baseInputStream deflate format");
			}
			headCRC.Update(CM);
			
			/* 3. Check the flags */
			int flags = baseInputStream.ReadByte();
			if (flags < 0) {
				throw new GZipException("Early EOF baseInputStream GZIP header");
			}
			headCRC.Update(flags);
			
			/*    This flag byte is divided into individual bits as follows:
				
				bit 0   FTEXT
				bit 1   FHCRC
				bit 2   FEXTRA
				bit 3   FNAME
				bit 4   FCOMMENT
				bit 5   reserved
				bit 6   reserved
				bit 7   reserved
				*/
				
			/* 3.1 Check the reserved bits are zero */
			
			if ((flags & 0xd0) != 0) {
				throw new GZipException("Reserved flag bits baseInputStream GZIP header != 0");
			}
			
			/* 4.-6. Skip the modification time, extra flags, and OS type */
			for (int i=0; i< 6; i++) {
				int readByte = baseInputStream.ReadByte();
				if (readByte < 0) {
					throw new GZipException("Early EOF baseInputStream GZIP header");
				}
				headCRC.Update(readByte);
			}
			
			/* 7. Read extra field */
			if ((flags & GZipConstants.FEXTRA) != 0) {
				/* Skip subfield id */
				for (int i=0; i< 2; i++) {
					int readByte = baseInputStream.ReadByte();
					if (readByte < 0) {
						throw new GZipException("Early EOF baseInputStream GZIP header");
					}
					headCRC.Update(readByte);
				}
				if (baseInputStream.ReadByte() < 0 || baseInputStream.ReadByte() < 0) {
					throw new GZipException("Early EOF baseInputStream GZIP header");
				}
				
				int len1, len2, extraLen;
				len1 = baseInputStream.ReadByte();
				len2 = baseInputStream.ReadByte();
				if ((len1 < 0) || (len2 < 0)) {
					throw new GZipException("Early EOF baseInputStream GZIP header");
				}
				headCRC.Update(len1);
				headCRC.Update(len2);
				
				extraLen = (len1 << 8) | len2;
				for (int i = 0; i < extraLen;i++) {
					int readByte = baseInputStream.ReadByte();
					if (readByte < 0) 
					{
						throw new GZipException("Early EOF baseInputStream GZIP header");
					}
					headCRC.Update(readByte);
				}
			}
			
			/* 8. Read file name */
			if ((flags & GZipConstants.FNAME) != 0) {
				int readByte;
				while ( (readByte = baseInputStream.ReadByte()) > 0) {
					headCRC.Update(readByte);
				}
				if (readByte < 0) {
					throw new GZipException("Early EOF baseInputStream GZIP file name");
				}
				headCRC.Update(readByte);
			}
			
			/* 9. Read comment */
			if ((flags & GZipConstants.FCOMMENT) != 0) {
				int readByte;
				while ( (readByte = baseInputStream.ReadByte()) > 0) {
					headCRC.Update(readByte);
				}
				
				if (readByte < 0) {
					throw new GZipException("Early EOF baseInputStream GZIP comment");
				}
				headCRC.Update(readByte);
			}
			
			/* 10. Read header CRC */
			if ((flags & GZipConstants.FHCRC) != 0) {
				int tempByte;
				int crcval = baseInputStream.ReadByte();
				if (crcval < 0) {
					throw new GZipException("Early EOF baseInputStream GZIP header");
				}
				
				tempByte = baseInputStream.ReadByte();
				if (tempByte < 0) {
					throw new GZipException("Early EOF baseInputStream GZIP header");
				}
				
				crcval = (crcval << 8) | tempByte;
				if (crcval != ((int) headCRC.Value & 0xffff)) {
					throw new GZipException("Header CRC value mismatch");
				}
			}
			
			readGZIPHeader = true;
		}
		/// <summary>
		/// Closes the zip input stream
		/// </summary>
		public override void Close()
		{
			internalReader = new ReaderDelegate(ReadingNotAvailable);
			crc = null;
			entry = null;

			base.Close();
		}