pako.js

    /* There are no "block-listed" or "allow-listed" bytes:
     * this stream either is empty or has tolerated ("gray-listed") bytes only.
     */
    return Z_BINARY;
  };


  let static_init_done = false;

  /* ===========================================================================
   * Initialize the tree data structures for a new zlib stream.
   */
  const _tr_init$1 = (s) =>
  {

    if (!static_init_done) {
      tr_static_init();
      static_init_done = true;
    }

    s.l_desc  = new TreeDesc(s.dyn_ltree, static_l_desc);
    s.d_desc  = new TreeDesc(s.dyn_dtree, static_d_desc);
    s.bl_desc = new TreeDesc(s.bl_tree, static_bl_desc);

    s.bi_buf = 0;
    s.bi_valid = 0;

    /* Initialize the first block of the first file: */
    init_block(s);
  };


  /* ===========================================================================
   * Send a stored block
   */
  const _tr_stored_block$1 = (s, buf, stored_len, last) => {
  //DeflateState *s;
  //charf *buf;       /* input block */
  //ulg stored_len;   /* length of input block */
  //int last;         /* one if this is the last block for a file */

    send_bits(s, (STORED_BLOCK << 1) + (last ? 1 : 0), 3);    /* send block type */
    bi_windup(s);        /* align on byte boundary */
    put_short(s, stored_len);
    put_short(s, ~stored_len);
    if (stored_len) {
      s.pending_buf.set(s.window.subarray(buf, buf + stored_len), s.pending);
    }
    s.pending += stored_len;
  };


  /* ===========================================================================
   * Send one empty static block to give enough lookahead for inflate.
   * This takes 10 bits, of which 7 may remain in the bit buffer.
   */
  const _tr_align$1 = (s) => {
    send_bits(s, STATIC_TREES << 1, 3);
    send_code(s, END_BLOCK, static_ltree);
    bi_flush(s);
  };


  /* ===========================================================================
   * Determine the best encoding for the current block: dynamic trees, static
   * trees or store, and write out the encoded block.
   */
  const _tr_flush_block$1 = (s, buf, stored_len, last) => {
  //DeflateState *s;
  //charf *buf;       /* input block, or NULL if too old */
  //ulg stored_len;   /* length of input block */
  //int last;         /* one if this is the last block for a file */

    let opt_lenb, static_lenb;  /* opt_len and static_len in bytes */
    let max_blindex = 0;        /* index of last bit length code of non zero freq */

    /* Build the Huffman trees unless a stored block is forced */
    if (s.level > 0) {

      /* Check if the file is binary or text */
      if (s.strm.data_type === Z_UNKNOWN$1) {
        s.strm.data_type = detect_data_type(s);
      }

      /* Construct the literal and distance trees */
      build_tree(s, s.l_desc);
      // Tracev((stderr, "\nlit data: dyn %ld, stat %ld", s->opt_len,
      //        s->static_len));

      build_tree(s, s.d_desc);
      // Tracev((stderr, "\ndist data: dyn %ld, stat %ld", s->opt_len,
      //        s->static_len));
      /* At this point, opt_len and static_len are the total bit lengths of
       * the compressed block data, excluding the tree representations.
       */

      /* Build the bit length tree for the above two trees, and get the index
       * in bl_order of the last bit length code to send.
       */
      max_blindex = build_bl_tree(s);

      /* Determine the best encoding. Compute the block lengths in bytes. */
      opt_lenb = (s.opt_len + 3 + 7) >>> 3;
      static_lenb = (s.static_len + 3 + 7) >>> 3;

      // Tracev((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u ",
      //        opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len,
      //        s->sym_next / 3));

      if (static_lenb <= opt_lenb) { opt_lenb = static_lenb; }

    } else {
      // Assert(buf != (char*)0, "lost buf");
      opt_lenb = static_lenb = stored_len + 5; /* force a stored block */
    }

    if ((stored_len + 4 <= opt_lenb) && (buf !== -1)) {
      /* 4: two words for the lengths */

      /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
       * Otherwise we can't have processed more than WSIZE input bytes since
       * the last block flush, because compression would have been
       * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
       * transform a block into a stored block.
       */
      _tr_stored_block$1(s, buf, stored_len, last);

    } else if (s.strategy === Z_FIXED$1 || static_lenb === opt_lenb) {

      send_bits(s, (STATIC_TREES << 1) + (last ? 1 : 0), 3);
      compress_block(s, static_ltree, static_dtree);

    } else {
      send_bits(s, (DYN_TREES << 1) + (last ? 1 : 0), 3);
      send_all_trees(s, s.l_desc.max_code + 1, s.d_desc.max_code + 1, max_blindex + 1);
      compress_block(s, s.dyn_ltree, s.dyn_dtree);
    }
    // Assert (s->compressed_len == s->bits_sent, "bad compressed size");
    /* The above check is made mod 2^32, for files larger than 512 MB
     * and uLong implemented on 32 bits.
     */
    init_block(s);

    if (last) {
      bi_windup(s);
    }
    // Tracev((stderr,"\ncomprlen %lu(%lu) ", s->compressed_len>>3,
    //       s->compressed_len-7*last));
  };

  /* ===========================================================================
   * Save the match info and tally the frequency counts. Return true if
   * the current block must be flushed.
   */
  const _tr_tally$1 = (s, dist, lc) => {
  //    deflate_state *s;
  //    unsigned dist;  /* distance of matched string */
  //    unsigned lc;    /* match length-MIN_MATCH or unmatched char (if dist==0) */

    s.pending_buf[s.sym_buf + s.sym_next++] = dist;
    s.pending_buf[s.sym_buf + s.sym_next++] = dist >> 8;
    s.pending_buf[s.sym_buf + s.sym_next++] = lc;
    if (dist === 0) {
      /* lc is the unmatched char */
      s.dyn_ltree[lc * 2]/*.Freq*/++;
    } else {
      s.matches++;
      /* Here, lc is the match length - MIN_MATCH */
      dist--;             /* dist = match distance - 1 */
      //Assert((ush)dist < (ush)MAX_DIST(s) &&
      //       (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) &&
      //       (ush)d_code(dist) < (ush)D_CODES,  "_tr_tally: bad match");

      s.dyn_ltree[(_length_code[lc] + LITERALS$1 + 1) * 2]/*.Freq*/++;
      s.dyn_dtree[d_code(dist) * 2]/*.Freq*/++;
    }

    return (s.sym_next === s.sym_end);
  };

  var _tr_init_1  = _tr_init$1;
  var _tr_stored_block_1 = _tr_stored_block$1;
  var _tr_flush_block_1  = _tr_flush_block$1;
  var _tr_tally_1 = _tr_tally$1;
  var _tr_align_1 = _tr_align$1;

  var trees = {
  	_tr_init: _tr_init_1,
  	_tr_stored_block: _tr_stored_block_1,
  	_tr_flush_block: _tr_flush_block_1,
  	_tr_tally: _tr_tally_1,
  	_tr_align: _tr_align_1
  };

  // Note: adler32 takes 12% for level 0 and 2% for level 6.
  // It isn't worth it to make additional optimizations as in original.
  // Small size is preferable.

  // (C) 1995-2013 Jean-loup Gailly and Mark Adler
  // (C) 2014-2017 Vitaly Puzrin and Andrey Tupitsin
  //
  // This software is provided 'as-is', without any express or implied
  // warranty. In no event will the authors be held liable for any damages
  // arising from the use of this software.
  //
  // Permission is granted to anyone to use this software for any purpose,
  // including commercial applications, and to alter it and redistribute it
  // freely, subject to the following restrictions:
  //
  // 1. The origin of this software must not be misrepresented; you must not
  //   claim that you wrote the original software. If you use this software
  //   in a product, an acknowledgment in the product documentation would be
  //   appreciated but is not required.
  // 2. Altered source versions must be plainly marked as such, and must not be
  //   misrepresented as being the original software.
  // 3. This notice may not be removed or altered from any source distribution.

  const adler32 = (adler, buf, len, pos) => {
    let s1 = (adler & 0xffff) |0,
        s2 = ((adler >>> 16) & 0xffff) |0,
        n = 0;

    while (len !== 0) {
      // Set limit ~ twice less than 5552, to keep
      // s2 in 31-bits, because we force signed ints.
      // in other case %= will fail.
      n = len > 2000 ? 2000 : len;
      len -= n;

      do {
        s1 = (s1 + buf[pos++]) |0;
        s2 = (s2 + s1) |0;
      } while (--n);

      s1 %= 65521;
      s2 %= 65521;
    }

    return (s1 | (s2 << 16)) |0;
  };


  var adler32_1 = adler32;

  // Note: we can't get significant speed boost here.
  // So write code to minimize size - no pregenerated tables
  // and array tools dependencies.

  // (C) 1995-2013 Jean-loup Gailly and Mark Adler
  // (C) 2014-2017 Vitaly Puzrin and Andrey Tupitsin
  //
  // This software is provided 'as-is', without any express or implied
  // warranty. In no event will the authors be held liable for any damages
  // arising from the use of this software.
  //
  // Permission is granted to anyone to use this software for any purpose,
  // including commercial applications, and to alter it and redistribute it
  // freely, subject to the following restrictions:
  //
  // 1. The origin of this software must not be misrepresented; you must not
  //   claim that you wrote the original software. If you use this software
  //   in a product, an acknowledgment in the product documentation would be
  //   appreciated but is not required.
  // 2. Altered source versions must be plainly marked as such, and must not be
  //   misrepresented as being the original software.
  // 3. This notice may not be removed or altered from any source distribution.

  // Use ordinary array, since untyped makes no boost here
  const makeTable = () => {
    let c, table = [];

    for (var n = 0; n < 256; n++) {
      c = n;
      for (var k = 0; k < 8; k++) {
        c = ((c & 1) ? (0xEDB88320 ^ (c >>> 1)) : (c >>> 1));
      }
      table[n] = c;
    }

    return table;
  };

  // Create table on load. Just 255 signed longs. Not a problem.
  const crcTable = new Uint32Array(makeTable());


  const crc32 = (crc, buf, len, pos) => {
    const t = crcTable;
    const end = pos + len;

    crc ^= -1;

    for (let i = pos; i < end; i++) {
      crc = (crc >>> 8) ^ t[(crc ^ buf[i]) & 0xFF];
    }

    return (crc ^ (-1)); // >>> 0;
  };


  var crc32_1 = crc32;

  // (C) 1995-2013 Jean-loup Gailly and Mark Adler
  // (C) 2014-2017 Vitaly Puzrin and Andrey Tupitsin
  //
  // This software is provided 'as-is', without any express or implied
  // warranty. In no event will the authors be held liable for any damages
  // arising from the use of this software.
  //
  // Permission is granted to anyone to use this software for any purpose,
  // including commercial applications, and to alter it and redistribute it
  // freely, subject to the following restrictions:
  //
  // 1. The origin of this software must not be misrepresented; you must not
  //   claim that you wrote the original software. If you use this software
  //   in a product, an acknowledgment in the product documentation would be
  //   appreciated but is not required.
  // 2. Altered source versions must be plainly marked as such, and must not be
  //   misrepresented as being the original software.
  // 3. This notice may not be removed or altered from any source distribution.

  var messages = {
    2:      'need dictionary',     /* Z_NEED_DICT       2  */
    1:      'stream end',          /* Z_STREAM_END      1  */
    0:      '',                    /* Z_OK              0  */
    '-1':   'file error',          /* Z_ERRNO         (-1) */
    '-2':   'stream error',        /* Z_STREAM_ERROR  (-2) */
    '-3':   'data error',          /* Z_DATA_ERROR    (-3) */
    '-4':   'insufficient memory', /* Z_MEM_ERROR     (-4) */
    '-5':   'buffer error',        /* Z_BUF_ERROR     (-5) */
    '-6':   'incompatible version' /* Z_VERSION_ERROR (-6) */
  };

  // (C) 1995-2013 Jean-loup Gailly and Mark Adler
  // (C) 2014-2017 Vitaly Puzrin and Andrey Tupitsin
  //
  // This software is provided 'as-is', without any express or implied
  // warranty. In no event will the authors be held liable for any damages
  // arising from the use of this software.
  //
  // Permission is granted to anyone to use this software for any purpose,
  // including commercial applications, and to alter it and redistribute it
  // freely, subject to the following restrictions:
  //
  // 1. The origin of this software must not be misrepresented; you must not
  //   claim that you wrote the original software. If you use this software
  //   in a product, an acknowledgment in the product documentation would be
  //   appreciated but is not required.
  // 2. Altered source versions must be plainly marked as such, and must not be
  //   misrepresented as being the original software.
  // 3. This notice may not be removed or altered from any source distribution.

  var constants$2 = {

    /* Allowed flush values; see deflate() and inflate() below for details */
    Z_NO_FLUSH:         0,
    Z_PARTIAL_FLUSH:    1,
    Z_SYNC_FLUSH:       2,
    Z_FULL_FLUSH:       3,
    Z_FINISH:           4,
    Z_BLOCK:            5,
    Z_TREES:            6,

    /* Return codes for the compression/decompression functions. Negative values
    * are errors, positive values are used for special but normal events.
    */
    Z_OK:               0,
    Z_STREAM_END:       1,
    Z_NEED_DICT:        2,
    Z_ERRNO:           -1,
    Z_STREAM_ERROR:    -2,
    Z_DATA_ERROR:      -3,
    Z_MEM_ERROR:       -4,
    Z_BUF_ERROR:       -5,
    //Z_VERSION_ERROR: -6,

    /* compression levels */
    Z_NO_COMPRESSION:         0,
    Z_BEST_SPEED:             1,
    Z_BEST_COMPRESSION:       9,
    Z_DEFAULT_COMPRESSION:   -1,


    Z_FILTERED:               1,
    Z_HUFFMAN_ONLY:           2,
    Z_RLE:                    3,
    Z_FIXED:                  4,
    Z_DEFAULT_STRATEGY:       0,

    /* Possible values of the data_type field (though see inflate()) */
    Z_BINARY:                 0,
    Z_TEXT:                   1,
    //Z_ASCII:                1, // = Z_TEXT (deprecated)
    Z_UNKNOWN:                2,

    /* The deflate compression method */
    Z_DEFLATED:               8
    //Z_NULL:                 null // Use -1 or null inline, depending on var type
  };

  // (C) 1995-2013 Jean-loup Gailly and Mark Adler
  // (C) 2014-2017 Vitaly Puzrin and Andrey Tupitsin
  //
  // This software is provided 'as-is', without any express or implied
  // warranty. In no event will the authors be held liable for any damages
  // arising from the use of this software.
  //
  // Permission is granted to anyone to use this software for any purpose,
  // including commercial applications, and to alter it and redistribute it
  // freely, subject to the following restrictions:
  //
  // 1. The origin of this software must not be misrepresented; you must not
  //   claim that you wrote the original software. If you use this software
  //   in a product, an acknowledgment in the product documentation would be
  //   appreciated but is not required.
  // 2. Altered source versions must be plainly marked as such, and must not be
  //   misrepresented as being the original software.
  // 3. This notice may not be removed or altered from any source distribution.

  const { _tr_init, _tr_stored_block, _tr_flush_block, _tr_tally, _tr_align } = trees;




  /* Public constants ==========================================================*/
  /* ===========================================================================*/

  const {
    Z_NO_FLUSH: Z_NO_FLUSH$2, Z_PARTIAL_FLUSH, Z_FULL_FLUSH: Z_FULL_FLUSH$1, Z_FINISH: Z_FINISH$3, Z_BLOCK: Z_BLOCK$1,
    Z_OK: Z_OK$3, Z_STREAM_END: Z_STREAM_END$3, Z_STREAM_ERROR: Z_STREAM_ERROR$2, Z_DATA_ERROR: Z_DATA_ERROR$2, Z_BUF_ERROR: Z_BUF_ERROR$1,
    Z_DEFAULT_COMPRESSION: Z_DEFAULT_COMPRESSION$1,
    Z_FILTERED, Z_HUFFMAN_ONLY, Z_RLE, Z_FIXED, Z_DEFAULT_STRATEGY: Z_DEFAULT_STRATEGY$1,
    Z_UNKNOWN,
    Z_DEFLATED: Z_DEFLATED$2
  } = constants$2;

  /*============================================================================*/


  const MAX_MEM_LEVEL = 9;
  /* Maximum value for memLevel in deflateInit2 */
  const MAX_WBITS$1 = 15;
  /* 32K LZ77 window */
  const DEF_MEM_LEVEL = 8;


  const LENGTH_CODES  = 29;
  /* number of length codes, not counting the special END_BLOCK code */
  const LITERALS      = 256;
  /* number of literal bytes 0..255 */
  const L_CODES       = LITERALS + 1 + LENGTH_CODES;
  /* number of Literal or Length codes, including the END_BLOCK code */
  const D_CODES       = 30;
  /* number of distance codes */
  const BL_CODES      = 19;
  /* number of codes used to transfer the bit lengths */
  const HEAP_SIZE     = 2 * L_CODES + 1;
  /* maximum heap size */
  const MAX_BITS  = 15;
  /* All codes must not exceed MAX_BITS bits */

  const MIN_MATCH = 3;
  const MAX_MATCH = 258;
  const MIN_LOOKAHEAD = (MAX_MATCH + MIN_MATCH + 1);

  const PRESET_DICT = 0x20;

  const INIT_STATE    =  42;    /* zlib header -> BUSY_STATE */
  //#ifdef GZIP
  const GZIP_STATE    =  57;    /* gzip header -> BUSY_STATE | EXTRA_STATE */
  //#endif
  const EXTRA_STATE   =  69;    /* gzip extra block -> NAME_STATE */
  const NAME_STATE    =  73;    /* gzip file name -> COMMENT_STATE */
  const COMMENT_STATE =  91;    /* gzip comment -> HCRC_STATE */
  const HCRC_STATE    = 103;    /* gzip header CRC -> BUSY_STATE */
  const BUSY_STATE    = 113;    /* deflate -> FINISH_STATE */
  const FINISH_STATE  = 666;    /* stream complete */

  const BS_NEED_MORE      = 1; /* block not completed, need more input or more output */
  const BS_BLOCK_DONE     = 2; /* block flush performed */
  const BS_FINISH_STARTED = 3; /* finish started, need only more output at next deflate */
  const BS_FINISH_DONE    = 4; /* finish done, accept no more input or output */

  const OS_CODE = 0x03; // Unix :) . Don't detect, use this default.

  const err = (strm, errorCode) => {
    strm.msg = messages[errorCode];
    return errorCode;
  };

  const rank = (f) => {
    return ((f) * 2) - ((f) > 4 ? 9 : 0);
  };

  const zero = (buf) => {
    let len = buf.length; while (--len >= 0) { buf[len] = 0; }
  };

  /* ===========================================================================
   * Slide the hash table when sliding the window down (could be avoided with 32
   * bit values at the expense of memory usage). We slide even when level == 0 to
   * keep the hash table consistent if we switch back to level > 0 later.
   */
  const slide_hash = (s) => {
    let n, m;
    let p;
    let wsize = s.w_size;

    n = s.hash_size;
    p = n;
    do {
      m = s.head[--p];
      s.head[p] = (m >= wsize ? m - wsize : 0);
    } while (--n);
    n = wsize;
  //#ifndef FASTEST
    p = n;
    do {
      m = s.prev[--p];
      s.prev[p] = (m >= wsize ? m - wsize : 0);
      /* If n is not on any hash chain, prev[n] is garbage but
       * its value will never be used.
       */
    } while (--n);
  //#endif
  };

  /* eslint-disable new-cap */
  let HASH_ZLIB = (s, prev, data) => ((prev << s.hash_shift) ^ data) & s.hash_mask;
  // This hash causes less collisions, https://github.com/nodeca/pako/issues/135
  // But breaks binary compatibility
  //let HASH_FAST = (s, prev, data) => ((prev << 8) + (prev >> 8) + (data << 4)) & s.hash_mask;
  let HASH = HASH_ZLIB;


  /* =========================================================================
   * Flush as much pending output as possible. All deflate() output, except for
   * some deflate_stored() output, goes through this function so some
   * applications may wish to modify it to avoid allocating a large
   * strm->next_out buffer and copying into it. (See also read_buf()).
   */
  const flush_pending = (strm) => {
    const s = strm.state;

    //_tr_flush_bits(s);
    let len = s.pending;
    if (len > strm.avail_out) {
      len = strm.avail_out;
    }
    if (len === 0) { return; }

    strm.output.set(s.pending_buf.subarray(s.pending_out, s.pending_out + len), strm.next_out);
    strm.next_out  += len;
    s.pending_out  += len;
    strm.total_out += len;
    strm.avail_out -= len;
    s.pending      -= len;
    if (s.pending === 0) {
      s.pending_out = 0;
    }
  };


  const flush_block_only = (s, last) => {
    _tr_flush_block(s, (s.block_start >= 0 ? s.block_start : -1), s.strstart - s.block_start, last);
    s.block_start = s.strstart;
    flush_pending(s.strm);
  };


  const put_byte = (s, b) => {
    s.pending_buf[s.pending++] = b;
  };


  /* =========================================================================
   * Put a short in the pending buffer. The 16-bit value is put in MSB order.
   * IN assertion: the stream state is correct and there is enough room in
   * pending_buf.
   */
  const putShortMSB = (s, b) => {

    //  put_byte(s, (Byte)(b >> 8));
  //  put_byte(s, (Byte)(b & 0xff));
    s.pending_buf[s.pending++] = (b >>> 8) & 0xff;
    s.pending_buf[s.pending++] = b & 0xff;
  };


  /* ===========================================================================
   * Read a new buffer from the current input stream, update the adler32
   * and total number of bytes read.  All deflate() input goes through
   * this function so some applications may wish to modify it to avoid
   * allocating a large strm->input buffer and copying from it.
   * (See also flush_pending()).
   */
  const read_buf = (strm, buf, start, size) => {

    let len = strm.avail_in;

    if (len > size) { len = size; }
    if (len === 0) { return 0; }

    strm.avail_in -= len;

    // zmemcpy(buf, strm->next_in, len);
    buf.set(strm.input.subarray(strm.next_in, strm.next_in + len), start);
    if (strm.state.wrap === 1) {
      strm.adler = adler32_1(strm.adler, buf, len, start);
    }

    else if (strm.state.wrap === 2) {
      strm.adler = crc32_1(strm.adler, buf, len, start);
    }

    strm.next_in += len;
    strm.total_in += len;

    return len;
  };


  /* ===========================================================================
   * Set match_start to the longest match starting at the given string and
   * return its length. Matches shorter or equal to prev_length are discarded,
   * in which case the result is equal to prev_length and match_start is
   * garbage.
   * IN assertions: cur_match is the head of the hash chain for the current
   *   string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
   * OUT assertion: the match length is not greater than s->lookahead.
   */
  const longest_match = (s, cur_match) => {

    let chain_length = s.max_chain_length;      /* max hash chain length */
    let scan = s.strstart; /* current string */
    let match;                       /* matched string */
    let len;                           /* length of current match */
    let best_len = s.prev_length;              /* best match length so far */
    let nice_match = s.nice_match;             /* stop if match long enough */
    const limit = (s.strstart > (s.w_size - MIN_LOOKAHEAD)) ?
        s.strstart - (s.w_size - MIN_LOOKAHEAD) : 0/*NIL*/;

    const _win = s.window; // shortcut

    const wmask = s.w_mask;
    const prev  = s.prev;

    /* Stop when cur_match becomes <= limit. To simplify the code,
     * we prevent matches with the string of window index 0.
     */

    const strend = s.strstart + MAX_MATCH;
    let scan_end1  = _win[scan + best_len - 1];
    let scan_end   = _win[scan + best_len];

    /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
     * It is easy to get rid of this optimization if necessary.
     */
    // Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");

    /* Do not waste too much time if we already have a good match: */
    if (s.prev_length >= s.good_match) {
      chain_length >>= 2;
    }
    /* Do not look for matches beyond the end of the input. This is necessary
     * to make deflate deterministic.
     */
    if (nice_match > s.lookahead) { nice_match = s.lookahead; }

    // Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");

    do {
      // Assert(cur_match < s->strstart, "no future");
      match = cur_match;

      /* Skip to next match if the match length cannot increase
       * or if the match length is less than 2.  Note that the checks below
       * for insufficient lookahead only occur occasionally for performance
       * reasons.  Therefore uninitialized memory will be accessed, and
       * conditional jumps will be made that depend on those values.
       * However the length of the match is limited to the lookahead, so
       * the output of deflate is not affected by the uninitialized values.
       */

      if (_win[match + best_len]     !== scan_end  ||
          _win[match + best_len - 1] !== scan_end1 ||
          _win[match]                !== _win[scan] ||
          _win[++match]              !== _win[scan + 1]) {
        continue;
      }

      /* The check at best_len-1 can be removed because it will be made
       * again later. (This heuristic is not always a win.)
       * It is not necessary to compare scan[2] and match[2] since they
       * are always equal when the other bytes match, given that
       * the hash keys are equal and that HASH_BITS >= 8.
       */
      scan += 2;
      match++;
      // Assert(*scan == *match, "match[2]?");

      /* We check for insufficient lookahead only every 8th comparison;
       * the 256th check will be made at strstart+258.
       */
      do {
        /*jshint noempty:false*/
      } while (_win[++scan] === _win[++match] && _win[++scan] === _win[++match] &&
               _win[++scan] === _win[++match] && _win[++scan] === _win[++match] &&
               _win[++scan] === _win[++match] && _win[++scan] === _win[++match] &&
               _win[++scan] === _win[++match] && _win[++scan] === _win[++match] &&
               scan < strend);

      // Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");

      len = MAX_MATCH - (strend - scan);
      scan = strend - MAX_MATCH;

      if (len > best_len) {
        s.match_start = cur_match;
        best_len = len;
        if (len >= nice_match) {
          break;
        }
        scan_end1  = _win[scan + best_len - 1];
        scan_end   = _win[scan + best_len];
      }
    } while ((cur_match = prev[cur_match & wmask]) > limit && --chain_length !== 0);

    if (best_len <= s.lookahead) {
      return best_len;
    }
    return s.lookahead;
  };


  /* ===========================================================================
   * Fill the window when the lookahead becomes insufficient.
   * Updates strstart and lookahead.
   *
   * IN assertion: lookahead < MIN_LOOKAHEAD
   * OUT assertions: strstart <= window_size-MIN_LOOKAHEAD
   *    At least one byte has been read, or avail_in == 0; reads are
   *    performed for at least two bytes (required for the zip translate_eol
   *    option -- not supported here).
   */
  const fill_window = (s) => {

    const _w_size = s.w_size;
    let n, more, str;

    //Assert(s->lookahead < MIN_LOOKAHEAD, "already enough lookahead");

    do {
      more = s.window_size - s.lookahead - s.strstart;

      // JS ints have 32 bit, block below not needed
      /* Deal with !@#$% 64K limit: */
      //if (sizeof(int) <= 2) {
      //    if (more == 0 && s->strstart == 0 && s->lookahead == 0) {
      //        more = wsize;
      //
      //  } else if (more == (unsigned)(-1)) {
      //        /* Very unlikely, but possible on 16 bit machine if
      //         * strstart == 0 && lookahead == 1 (input done a byte at time)
      //         */
      //        more--;
      //    }
      //}


      /* If the window is almost full and there is insufficient lookahead,
       * move the upper half to the lower one to make room in the upper half.
       */
      if (s.strstart >= _w_size + (_w_size - MIN_LOOKAHEAD)) {

        s.window.set(s.window.subarray(_w_size, _w_size + _w_size - more), 0);
        s.match_start -= _w_size;
        s.strstart -= _w_size;
        /* we now have strstart >= MAX_DIST */
        s.block_start -= _w_size;
        if (s.insert > s.strstart) {
          s.insert = s.strstart;
        }
        slide_hash(s);
        more += _w_size;
      }
      if (s.strm.avail_in === 0) {
        break;
      }

      /* If there was no sliding:
       *    strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 &&
       *    more == window_size - lookahead - strstart
       * => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1)
       * => more >= window_size - 2*WSIZE + 2
       * In the BIG_MEM or MMAP case (not yet supported),
       *   window_size == input_size + MIN_LOOKAHEAD  &&
       *   strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD.
       * Otherwise, window_size == 2*WSIZE so more >= 2.
       * If there was sliding, more >= WSIZE. So in all cases, more >= 2.
       */
      //Assert(more >= 2, "more < 2");
      n = read_buf(s.strm, s.window, s.strstart + s.lookahead, more);
      s.lookahead += n;

      /* Initialize the hash value now that we have some input: */
      if (s.lookahead + s.insert >= MIN_MATCH) {
        str = s.strstart - s.insert;
        s.ins_h = s.window[str];

        /* UPDATE_HASH(s, s->ins_h, s->window[str + 1]); */
        s.ins_h = HASH(s, s.ins_h, s.window[str + 1]);
  //#if MIN_MATCH != 3
  //        Call update_hash() MIN_MATCH-3 more times
  //#endif
        while (s.insert) {
          /* UPDATE_HASH(s, s->ins_h, s->window[str + MIN_MATCH-1]); */
          s.ins_h = HASH(s, s.ins_h, s.window[str + MIN_MATCH - 1]);

          s.prev[str & s.w_mask] = s.head[s.ins_h];
          s.head[s.ins_h] = str;
          str++;
          s.insert--;
          if (s.lookahead + s.insert < MIN_MATCH) {
            break;
          }
        }
      }
      /* If the whole input has less than MIN_MATCH bytes, ins_h is garbage,
       * but this is not important since only literal bytes will be emitted.
       */

    } while (s.lookahead < MIN_LOOKAHEAD && s.strm.avail_in !== 0);

    /* If the WIN_INIT bytes after the end of the current data have never been
     * written, then zero those bytes in order to avoid memory check reports of
     * the use of uninitialized (or uninitialised as Julian writes) bytes by
     * the longest match routines.  Update the high water mark for the next
     * time through here.  WIN_INIT is set to MAX_MATCH since the longest match
     * routines allow scanning to strstart + MAX_MATCH, ignoring lookahead.
     */
  //  if (s.high_water < s.window_size) {
  //    const curr = s.strstart + s.lookahead;
  //    let init = 0;
  //
  //    if (s.high_water < curr) {
  //      /* Previous high water mark below current data -- zero WIN_INIT
  //       * bytes or up to end of window, whichever is less.
  //       */
  //      init = s.window_size - curr;
  //      if (init > WIN_INIT)
  //        init = WIN_INIT;
  //      zmemzero(s->window + curr, (unsigned)init);
  //      s->high_water = curr + init;
  //    }
  //    else if (s->high_water < (ulg)curr + WIN_INIT) {
  //      /* High water mark at or above current data, but below current data
  //       * plus WIN_INIT -- zero out to current data plus WIN_INIT, or up
  //       * to end of window, whichever is less.
  //       */
  //      init = (ulg)curr + WIN_INIT - s->high_water;
  //      if (init > s->window_size - s->high_water)
  //        init = s->window_size - s->high_water;
  //      zmemzero(s->window + s->high_water, (unsigned)init);
  //      s->high_water += init;
  //    }
  //  }
  //
  //  Assert((ulg)s->strstart <= s->window_size - MIN_LOOKAHEAD,
  //    "not enough room for search");
  };

  /* ===========================================================================
   * Copy without compression as much as possible from the input stream, return
   * the current block state.
   *
   * In case deflateParams() is used to later switch to a non-zero compression
   * level, s->matches (otherwise unused when storing) keeps track of the number
   * of hash table slides to perform. If s->matches is 1, then one hash table
   * slide will be done when switching. If s->matches is 2, the maximum value
   * allowed here, then the hash table will be cleared, since two or more slides
   * is the same as a clear.
   *
   * deflate_stored() is written to minimize the number of times an input byte is
   * copied. It is most efficient with large input and output buffers, which
   * maximizes the opportunites to have a single copy from next_in to next_out.
   */
  const deflate_stored = (s, flush) => {

    /* Smallest worthy block size when not flushing or finishing. By default
     * this is 32K. This can be as small as 507 bytes for memLevel == 1. For
     * large input and output buffers, the stored block size will be larger.
     */
    let min_block = s.pending_buf_size - 5 > s.w_size ? s.w_size : s.pending_buf_size - 5;

    /* Copy as many min_block or larger stored blocks directly to next_out as
     * possible. If flushing, copy the remaining available input to next_out as
     * stored blocks, if there is enough space.
     */
    let len, left, have, last = 0;
    let used = s.strm.avail_in;
    do {
      /* Set len to the maximum size block that we can copy directly with the
       * available input data and output space. Set left to how much of that
       * would be copied from what's left in the window.
       */
      len = 65535/* MAX_STORED */;     /* maximum deflate stored block length */
      have = (s.bi_valid + 42) >> 3;     /* number of header bytes */
      if (s.strm.avail_out < have) {         /* need room for header */
        break;
      }
        /* maximum stored block length that will fit in avail_out: */
      have = s.strm.avail_out - have;
      left = s.strstart - s.block_start;  /* bytes left in window */
      if (len > left + s.strm.avail_in) {
        len = left + s.strm.avail_in;   /* limit len to the input */
      }
      if (len > have) {
        len = have;             /* limit len to the output */
      }

      /* If the stored block would be less than min_block in length, or if
       * unable to copy all of the available input when flushing, then try
       * copying to the window and the pending buffer instead. Also don't
       * write an empty block when flushing -- deflate() does that.
       */
      if (len < min_block && ((len === 0 && flush !== Z_FINISH$3) ||
                          flush === Z_NO_FLUSH$2 ||
                          len !== left + s.strm.avail_in)) {
        break;
      }

      /* Make a dummy stored block in pending to get the header bytes,
       * including any pending bits. This also updates the debugging counts.
       */
      last = flush === Z_FINISH$3 && len === left + s.strm.avail_in ? 1 : 0;
      _tr_stored_block(s, 0, 0, last);

      /* Replace the lengths in the dummy stored block with len. */
      s.pending_buf[s.pending - 4] = len;
      s.pending_buf[s.pending - 3] = len >> 8;
      s.pending_buf[s.pending - 2] = ~len;
      s.pending_buf[s.pending - 1] = ~len >> 8;

      /* Write the stored block header bytes. */
      flush_pending(s.strm);

  //#ifdef ZLIB_DEBUG
  //    /* Update debugging counts for the data about to be copied. */
  //    s->compressed_len += len << 3;
  //    s->bits_sent += len << 3;
  //#endif

      /* Copy uncompressed bytes from the window to next_out. */
      if (left) {
        if (left > len) {
          left = len;
        }
        //zmemcpy(s->strm->next_out, s->window + s->block_start, left);
        s.strm.output.set(s.window.subarray(s.block_start, s.block_start + left), s.strm.next_out);
        s.strm.next_out += left;
        s.strm.avail_out -= left;
        s.strm.total_out += left;
        s.block_start += left;
        len -= left;
      }

      /* Copy uncompressed bytes directly from next_in to next_out, updating
       * the check value.
       */
      if (len) {
        read_buf(s.strm, s.strm.output, s.strm.next_out, len);
        s.strm.next_out += len;
        s.strm.avail_out -= len;
        s.strm.total_out += len;
      }
    } while (last === 0);

    /* Update the sliding window with the last s->w_size bytes of the copied
     * data, or append all of the copied data to the existing window if less
     * than s->w_size bytes were copied. Also update the number of bytes to
     * insert in the hash tables, in the event that deflateParams() switches to
     * a non-zero compression level.
     */
    used -= s.strm.avail_in;    /* number of input bytes directly copied */
    if (used) {
      /* If any input was used, then no unused input remains in the window,
       * therefore s->block_start == s->strstart.
       */
      if (used >= s.w_size) {  /* supplant the previous history */
        s.matches = 2;     /* clear hash */
        //zmemcpy(s->window, s->strm->next_in - s->w_size, s->w_size);
        s.window.set(s.strm.input.subarray(s.strm.next_in - s.w_size, s.strm.next_in), 0);
        s.strstart = s.w_size;
        s.insert = s.strstart;
      }
      else {
        if (s.window_size - s.strstart <= used) {
          /* Slide the window down. */
          s.strstart -= s.w_size;