function deflate_slow()

in TestApplications/JDIChromePlugin/DevPanel/libs/jszip/jszip.js [4650:4804]


function deflate_slow(s, flush) {
  var hash_head;          /* head of hash chain */
  var bflush;              /* set if current block must be flushed */

  var max_insert;

  /* Process the input block. */
  for (;;) {
    /* 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.
     */
    if (s.lookahead < MIN_LOOKAHEAD) {
      fill_window(s);
      if (s.lookahead < MIN_LOOKAHEAD && flush === Z_NO_FLUSH) {
        return BS_NEED_MORE;
      }
      if (s.lookahead === 0) { break; } /* flush the current block */
    }

    /* Insert the string window[strstart .. strstart+2] in the
     * dictionary, and set hash_head to the head of the hash chain:
     */
    hash_head = 0/*NIL*/;
    if (s.lookahead >= MIN_MATCH) {
      /*** INSERT_STRING(s, s.strstart, hash_head); ***/
      s.ins_h = ((s.ins_h << s.hash_shift) ^ s.window[s.strstart + MIN_MATCH - 1]) & s.hash_mask;
      hash_head = s.prev[s.strstart & s.w_mask] = s.head[s.ins_h];
      s.head[s.ins_h] = s.strstart;
      /***/
    }

    /* Find the longest match, discarding those <= prev_length.
     */
    s.prev_length = s.match_length;
    s.prev_match = s.match_start;
    s.match_length = MIN_MATCH-1;

    if (hash_head !== 0/*NIL*/ && s.prev_length < s.max_lazy_match &&
        s.strstart - hash_head <= (s.w_size-MIN_LOOKAHEAD)/*MAX_DIST(s)*/) {
      /* 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).
       */
      s.match_length = longest_match(s, hash_head);
      /* longest_match() sets match_start */

      if (s.match_length <= 5 &&
         (s.strategy === Z_FILTERED || (s.match_length === MIN_MATCH && s.strstart - s.match_start > 4096/*TOO_FAR*/))) {

        /* If prev_match is also MIN_MATCH, match_start is garbage
         * but we will ignore the current match anyway.
         */
        s.match_length = MIN_MATCH-1;
      }
    }
    /* If there was a match at the previous step and the current
     * match is not better, output the previous match:
     */
    if (s.prev_length >= MIN_MATCH && s.match_length <= s.prev_length) {
      max_insert = s.strstart + s.lookahead - MIN_MATCH;
      /* Do not insert strings in hash table beyond this. */

      //check_match(s, s.strstart-1, s.prev_match, s.prev_length);

      /***_tr_tally_dist(s, s.strstart - 1 - s.prev_match,
                     s.prev_length - MIN_MATCH, bflush);***/
      bflush = trees._tr_tally(s, s.strstart - 1- s.prev_match, s.prev_length - MIN_MATCH);
      /* Insert in hash table all strings up to the end of the match.
       * strstart-1 and strstart are already inserted. If there is not
       * enough lookahead, the last two strings are not inserted in
       * the hash table.
       */
      s.lookahead -= s.prev_length-1;
      s.prev_length -= 2;
      do {
        if (++s.strstart <= max_insert) {
          /*** INSERT_STRING(s, s.strstart, hash_head); ***/
          s.ins_h = ((s.ins_h << s.hash_shift) ^ s.window[s.strstart + MIN_MATCH - 1]) & s.hash_mask;
          hash_head = s.prev[s.strstart & s.w_mask] = s.head[s.ins_h];
          s.head[s.ins_h] = s.strstart;
          /***/
        }
      } while (--s.prev_length !== 0);
      s.match_available = 0;
      s.match_length = MIN_MATCH-1;
      s.strstart++;

      if (bflush) {
        /*** FLUSH_BLOCK(s, 0); ***/
        flush_block_only(s, false);
        if (s.strm.avail_out === 0) {
          return BS_NEED_MORE;
        }
        /***/
      }

    } else if (s.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", s->window[s->strstart-1]));
      /*** _tr_tally_lit(s, s.window[s.strstart-1], bflush); ***/
      bflush = trees._tr_tally(s, 0, s.window[s.strstart-1]);

      if (bflush) {
        /*** FLUSH_BLOCK_ONLY(s, 0) ***/
        flush_block_only(s, false);
        /***/
      }
      s.strstart++;
      s.lookahead--;
      if (s.strm.avail_out === 0) {
        return BS_NEED_MORE;
      }
    } else {
      /* There is no previous match to compare with, wait for
       * the next step to decide.
       */
      s.match_available = 1;
      s.strstart++;
      s.lookahead--;
    }
  }
  //Assert (flush != Z_NO_FLUSH, "no flush?");
  if (s.match_available) {
    //Tracevv((stderr,"%c", s->window[s->strstart-1]));
    /*** _tr_tally_lit(s, s.window[s.strstart-1], bflush); ***/
    bflush = trees._tr_tally(s, 0, s.window[s.strstart-1]);

    s.match_available = 0;
  }
  s.insert = s.strstart < MIN_MATCH-1 ? s.strstart : MIN_MATCH-1;
  if (flush === Z_FINISH) {
    /*** FLUSH_BLOCK(s, 1); ***/
    flush_block_only(s, true);
    if (s.strm.avail_out === 0) {
      return BS_FINISH_STARTED;
    }
    /***/
    return BS_FINISH_DONE;
  }
  if (s.last_lit) {
    /*** FLUSH_BLOCK(s, 0); ***/
    flush_block_only(s, false);
    if (s.strm.avail_out === 0) {
      return BS_NEED_MORE;
    }
    /***/
  }

  return BS_BLOCK_DONE;
}