private bool DeflateFast()

in src/ICSharpCode.SharpZipLib/Zip/Compression/DeflaterEngine.cs [651:739]
76 lines of code
21 McCabe index (conditional complexity)

		private bool DeflateFast(bool flush, bool finish)
		{
			if (lookahead < DeflaterConstants.MIN_LOOKAHEAD && !flush)
			{
				return false;
			}

			while (lookahead >= DeflaterConstants.MIN_LOOKAHEAD || flush)
			{
				if (lookahead == 0)
				{
					// We are flushing everything
					huffman.FlushBlock(window, blockStart, strstart - blockStart, finish);
					blockStart = strstart;
					return false;
				}

				if (strstart > 2 * DeflaterConstants.WSIZE - DeflaterConstants.MIN_LOOKAHEAD)
				{
					/* slide window, as FindLongestMatch needs this.
					 * This should only happen when flushing and the window
					 * is almost full.
					 */
					SlideWindow();
				}

				int hashHead;
				if (lookahead >= DeflaterConstants.MIN_MATCH &&
					(hashHead = InsertString()) != 0 &&
					strategy != DeflateStrategy.HuffmanOnly &&
					strstart - hashHead <= DeflaterConstants.MAX_DIST &&
					FindLongestMatch(hashHead))
				{
					// longestMatch sets matchStart and matchLen
#if DebugDeflation
					if (DeflaterConstants.DEBUGGING)
					{
						for (int i = 0 ; i < matchLen; i++) {
							if (window[strstart + i] != window[matchStart + i]) {
								throw new SharpZipBaseException("Match failure");
							}
						}
					}
#endif

					bool full = huffman.TallyDist(strstart - matchStart, matchLen);

					lookahead -= matchLen;
					if (matchLen <= max_lazy && lookahead >= DeflaterConstants.MIN_MATCH)
					{
						while (--matchLen > 0)
						{
							++strstart;
							InsertString();
						}
						++strstart;
					}
					else
					{
						strstart += matchLen;
						if (lookahead >= DeflaterConstants.MIN_MATCH - 1)
						{
							UpdateHash();
						}
					}
					matchLen = DeflaterConstants.MIN_MATCH - 1;
					if (!full)
					{
						continue;
					}
				}
				else
				{
					// No match found
					huffman.TallyLit(window[strstart] & 0xff);
					++strstart;
					--lookahead;
				}

				if (huffman.IsFull())
				{
					bool lastBlock = finish && (lookahead == 0);
					huffman.FlushBlock(window, blockStart, strstart - blockStart, lastBlock);
					blockStart = strstart;
					return !lastBlock;
				}
			}
			return true;
		}