- /* Process the input block. */
- while (lookahead != 0) {
- /* Insert the string window[strstart .. strstart+2] in the
- * dictionary, and set hash_head to the head of the hash chain:
- */
- INSERT_STRING(strstart, hash_head);
-
- /* Find the longest match, discarding those <= prev_length.
- */
- prev_length = match_length, prev_match = match_start;
- match_length = MIN_MATCH - 1;
-
- if (hash_head != NIL && prev_length < max_lazy_match &&
- strstart - hash_head <= MAX_DIST) {
- /* To simplify the code, we prevent matches with the string
- * of window index 0 (in particular we have to avoid a match
- * of the string with itself at the start of the input file).
- */
- match_length = longest_match(hash_head);
- /* longest_match() sets match_start */
- if (match_length > lookahead)
- match_length = lookahead;
-
- /* Ignore a length 3 match if it is too distant: */
- if (match_length == MIN_MATCH && strstart - match_start > TOO_FAR) {
- /* If prev_match is also MIN_MATCH, match_start is garbage
- * but we will ignore the current match anyway.
- */
- match_length--;
- }
- }
- /* If there was a match at the previous step and the current
- * match is not better, output the previous match:
- */
- if (prev_length >= MIN_MATCH && match_length <= prev_length) {
-
- check_match(strstart - 1, prev_match, prev_length);
-
- flush =
- ct_tally(strstart - 1 - prev_match, prev_length - MIN_MATCH);
-
- /* Insert in hash table all strings up to the end of the match.
- * strstart-1 and strstart are already inserted.
- */
- lookahead -= prev_length - 1;
- prev_length -= 2;
- do {
- strstart++;
- INSERT_STRING(strstart, hash_head);
- /* strstart never exceeds WSIZE-MAX_MATCH, so there are
- * always MIN_MATCH bytes ahead. If lookahead < MIN_MATCH
- * these bytes are garbage, but it does not matter since the
- * next lookahead bytes will always be emitted as literals.
- */
- } while (--prev_length != 0);
- match_available = 0;
- match_length = MIN_MATCH - 1;
- strstart++;
- if (flush)
- FLUSH_BLOCK(0), block_start = strstart;
-
- } else if (match_available) {
- /* If there was no match at the previous position, output a
- * single literal. If there was a match but the current match
- * is longer, truncate the previous match to a single literal.
- */
- Tracevv((stderr, "%c", window[strstart - 1]));
- if (ct_tally(0, window[strstart - 1])) {
- FLUSH_BLOCK(0), block_start = strstart;
- }
- strstart++;
- lookahead--;
- } else {
- /* There is no previous match to compare with, wait for
- * the next step to decide.
- */
- match_available = 1;
- strstart++;
- lookahead--;
- }
- Assert(strstart <= isize && lookahead <= isize, "a bit too far");
-
- /* Make sure that we always have enough lookahead, except
- * at the end of the input file. We need MAX_MATCH bytes
- * for the next match, plus MIN_MATCH bytes to insert the
- * string following the next match.
- */
- while (lookahead < MIN_LOOKAHEAD && !eofile)
- fill_window();
- }
- if (match_available)
- ct_tally(0, window[strstart - 1]);
-
- return FLUSH_BLOCK(1); /* eof */
-}
-
-/* gzip (GNU zip) -- compress files with zip algorithm and 'compress' interface
- * Copyright (C) 1992-1993 Jean-loup Gailly
- * The unzip code was written and put in the public domain by Mark Adler.
- * Portions of the lzw code are derived from the public domain 'compress'
- * written by Spencer Thomas, Joe Orost, James Woods, Jim McKie, Steve Davies,
- * Ken Turkowski, Dave Mack and Peter Jannesen.
- *
- * See the license_msg below and the file COPYING for the software license.
- * See the file algorithm.doc for the compression algorithms and file formats.