text: import * as utils from "../utils/common.js";
  
  /* Public constants ==========================================================*/
  /* ===========================================================================*/
  
  
  //var Z_FILTERED          = 1;
  //var Z_HUFFMAN_ONLY      = 2;
  //var Z_RLE               = 3;
  var Z_FIXED               = 4;
  //var Z_DEFAULT_STRATEGY  = 0;
  
  /* Possible values of the data_type field (though see inflate()) */
  var Z_BINARY              = 0;
  var Z_TEXT                = 1;
  //var Z_ASCII             = 1; // = Z_TEXT
  var Z_UNKNOWN             = 2;
  
  /*============================================================================*/
  
  
  function zero(buf) { var len = buf.length; while (--len >= 0) { buf[len] = 0; } }
  
  // From zutil.h
  
  var STORED_BLOCK = 0;
  var STATIC_TREES = 1;
  var DYN_TREES    = 2;
  /* The three kinds of block type */
  
  var MIN_MATCH    = 3;
  var MAX_MATCH    = 258;
  /* The minimum and maximum match lengths */
  
  // From deflate.h
  /* ===========================================================================
   * Internal compression state.
   */
  
  var LENGTH_CODES  = 29;
  /* number of length codes, not counting the special END_BLOCK code */
  
  var LITERALS      = 256;
  /* number of literal bytes 0..255 */
  
  var L_CODES       = LITERALS + 1 + LENGTH_CODES;
  /* number of Literal or Length codes, including the END_BLOCK code */
  
  var D_CODES       = 30;
  /* number of distance codes */
  
  var BL_CODES      = 19;
  /* number of codes used to transfer the bit lengths */
  
  var HEAP_SIZE     = 2 * L_CODES + 1;
  /* maximum heap size */
  
  var MAX_BITS      = 15;
  /* All codes must not exceed MAX_BITS bits */
  
  var Buf_size      = 16;
  /* size of bit buffer in bi_buf */
  
  
  /* ===========================================================================
   * Constants
   */
  
  var MAX_BL_BITS = 7;
  /* Bit length codes must not exceed MAX_BL_BITS bits */
  
  var END_BLOCK   = 256;
  /* end of block literal code */
  
  var REP_3_6     = 16;
  /* repeat previous bit length 3-6 times (2 bits of repeat count) */
  
  var REPZ_3_10   = 17;
  /* repeat a zero length 3-10 times  (3 bits of repeat count) */
  
  var REPZ_11_138 = 18;
  /* repeat a zero length 11-138 times  (7 bits of repeat count) */
  
  /* eslint-disable comma-spacing,array-bracket-spacing */
  var extra_lbits =   /* extra bits for each length code */
    [0,0,0,0,0,0,0,0,1,1,1,1,2,2,2,2,3,3,3,3,4,4,4,4,5,5,5,5,0];
  
  var extra_dbits =   /* extra bits for each distance code */
    [0,0,0,0,1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,13,13];
  
  var extra_blbits =  /* extra bits for each bit length code */
    [0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7];
  
  var bl_order =
    [16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15];
  /* eslint-enable comma-spacing,array-bracket-spacing */
  
  /* The lengths of the bit length codes are sent in order of decreasing
   * probability, to avoid transmitting the lengths for unused bit length codes.
   */
  
  /* ===========================================================================
   * Local data. These are initialized only once.
   */
  
  // We pre-fill arrays with 0 to avoid uninitialized gaps
  
  var DIST_CODE_LEN = 512; /* see definition of array dist_code below */
  
  // !!!! Use flat array insdead of structure, Freq = i*2, Len = i*2+1
  var static_ltree  = new Array((L_CODES + 2) * 2);
  zero(static_ltree);
  /* The static literal tree. Since the bit lengths are imposed, there is no
   * need for the L_CODES extra codes used during heap construction. However
   * The codes 286 and 287 are needed to build a canonical tree (see _tr_init
   * below).
   */
  
  var static_dtree  = new Array(D_CODES * 2);
  zero(static_dtree);
  /* The static distance tree. (Actually a trivial tree since all codes use
   * 5 bits.)
   */
  
  var _dist_code    = new Array(DIST_CODE_LEN);
  zero(_dist_code);
  /* Distance codes. The first 256 values correspond to the distances
   * 3 .. 258, the last 256 values correspond to the top 8 bits of
   * the 15 bit distances.
   */
  
  var _length_code  = new Array(MAX_MATCH - MIN_MATCH + 1);
  zero(_length_code);
  /* length code for each normalized match length (0 == MIN_MATCH) */
  
  var base_length   = new Array(LENGTH_CODES);
  zero(base_length);
  /* First normalized length for each code (0 = MIN_MATCH) */
  
  var base_dist     = new Array(D_CODES);
  zero(base_dist);
  /* First normalized distance for each code (0 = distance of 1) */
  
  
  function StaticTreeDesc(static_tree, extra_bits, extra_base, elems, max_length) {
  
    this.static_tree  = static_tree;  /* static tree or NULL */
    this.extra_bits   = extra_bits;   /* extra bits for each code or NULL */
    this.extra_base   = extra_base;   /* base index for extra_bits */
    this.elems        = elems;        /* max number of elements in the tree */
    this.max_length   = max_length;   /* max bit length for the codes */
  
    // show if `static_tree` has data or dummy - needed for monomorphic objects
    this.has_stree    = static_tree && static_tree.length;
  }
  
  
  var static_l_desc;
  var static_d_desc;
  var static_bl_desc;
  
  
  function TreeDesc(dyn_tree, stat_desc) {
    this.dyn_tree = dyn_tree;     /* the dynamic tree */
    this.max_code = 0;            /* largest code with non zero frequency */
    this.stat_desc = stat_desc;   /* the corresponding static tree */
  }
  
  
  
  function d_code(dist) {
    return dist < 256 ? _dist_code[dist] : _dist_code[256 + (dist >>> 7)];
  }
  
  
  /* ===========================================================================
   * Output a short LSB first on the stream.
   * IN assertion: there is enough room in pendingBuf.
   */
  function put_short(s, w) {
  //    put_byte(s, (uch)((w) & 0xff));
  //    put_byte(s, (uch)((ush)(w) >> 8));
    s.pending_buf[s.pending++] = (w) & 0xff;
    s.pending_buf[s.pending++] = (w >>> 8) & 0xff;
  }
  
  
  /* ===========================================================================
   * Send a value on a given number of bits.
   * IN assertion: length <= 16 and value fits in length bits.
   */
  function send_bits(s, value, length) {
    if (s.bi_valid > (Buf_size - length)) {
      s.bi_buf |= (value << s.bi_valid) & 0xffff;
      put_short(s, s.bi_buf);
      s.bi_buf = value >> (Buf_size - s.bi_valid);
      s.bi_valid += length - Buf_size;
    } else {
      s.bi_buf |= (value << s.bi_valid) & 0xffff;
      s.bi_valid += length;
    }
  }
  
  
  function send_code(s, c, tree) {
    send_bits(s, tree[c * 2]/*.Code*/, tree[c * 2 + 1]/*.Len*/);
  }
  
  
  /* ===========================================================================
   * Reverse the first len bits of a code, using straightforward code (a faster
   * method would use a table)
   * IN assertion: 1 <= len <= 15
   */
  function bi_reverse(code, len) {
    var res = 0;
    do {
      res |= code & 1;
      code >>>= 1;
      res <<= 1;
    } while (--len > 0);
    return res >>> 1;
  }
  
  
  /* ===========================================================================
   * Flush the bit buffer, keeping at most 7 bits in it.
   */
  function bi_flush(s) {
    if (s.bi_valid === 16) {
      put_short(s, s.bi_buf);
      s.bi_buf = 0;
      s.bi_valid = 0;
  
    } else if (s.bi_valid >= 8) {
      s.pending_buf[s.pending++] = s.bi_buf & 0xff;
      s.bi_buf >>= 8;
      s.bi_valid -= 8;
    }
  }
  
  
  /* ===========================================================================
   * Compute the optimal bit lengths for a tree and update the total bit length
   * for the current block.
   * IN assertion: the fields freq and dad are set, heap[heap_max] and
   *    above are the tree nodes sorted by increasing frequency.
   * OUT assertions: the field len is set to the optimal bit length, the
   *     array bl_count contains the frequencies for each bit length.
   *     The length opt_len is updated; static_len is also updated if stree is
   *     not null.
   */
  function gen_bitlen(s, desc)
  //    deflate_state *s;
  //    tree_desc *desc;    /* the tree descriptor */
  {
    var tree            = desc.dyn_tree;
    var max_code        = desc.max_code;
    var stree           = desc.stat_desc.static_tree;
    var has_stree       = desc.stat_desc.has_stree;
    var extra           = desc.stat_desc.extra_bits;
    var base            = desc.stat_desc.extra_base;
    var max_length      = desc.stat_desc.max_length;
    var h;              /* heap index */
    var n, m;           /* iterate over the tree elements */
    var bits;           /* bit length */
    var xbits;          /* extra bits */
    var f;              /* frequency */
    var overflow = 0;   /* number of elements with bit length too large */
  
    for (bits = 0; bits <= MAX_BITS; bits++) {
      s.bl_count[bits] = 0;
    }
  
    /* In a first pass, compute the optimal bit lengths (which may
     * overflow in the case of the bit length tree).
     */
    tree[s.heap[s.heap_max] * 2 + 1]/*.Len*/ = 0; /* root of the heap */
  
    for (h = s.heap_max + 1; h < HEAP_SIZE; h++) {
      n = s.heap[h];
      bits = tree[tree[n * 2 + 1]/*.Dad*/ * 2 + 1]/*.Len*/ + 1;
      if (bits > max_length) {
        bits = max_length;
        overflow++;
      }
      tree[n * 2 + 1]/*.Len*/ = bits;
      /* We overwrite tree[n].Dad which is no longer needed */
  
      if (n > max_code) { continue; } /* not a leaf node */
  
      s.bl_count[bits]++;
      xbits = 0;
      if (n >= base) {
        xbits = extra[n - base];
      }
      f = tree[n * 2]/*.Freq*/;
      s.opt_len += f * (bits + xbits);
      if (has_stree) {
        s.static_len += f * (stree[n * 2 + 1]/*.Len*/ + xbits);
      }
    }
    if (overflow === 0) { return; }
  
    // Trace((stderr,"\nbit length overflow\n"));
    /* This happens for example on obj2 and pic of the Calgary corpus */
  
    /* Find the first bit length which could increase: */
    do {
      bits = max_length - 1;
      while (s.bl_count[bits] === 0) { bits--; }
      s.bl_count[bits]--;      /* move one leaf down the tree */
      s.bl_count[bits + 1] += 2; /* move one overflow item as its brother */
      s.bl_count[max_length]--;
      /* The brother of the overflow item also moves one step up,
       * but this does not affect bl_count[max_length]
       */
      overflow -= 2;
    } while (overflow > 0);
  
    /* Now recompute all bit lengths, scanning in increasing frequency.
     * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
     * lengths instead of fixing only the wrong ones. This idea is taken
     * from 'ar' written by Haruhiko Okumura.)
     */
    for (bits = max_length; bits !== 0; bits--) {
      n = s.bl_count[bits];
      while (n !== 0) {
        m = s.heap[--h];
        if (m > max_code) { continue; }
        if (tree[m * 2 + 1]/*.Len*/ !== bits) {
          // Trace((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits));
          s.opt_len += (bits - tree[m * 2 + 1]/*.Len*/) * tree[m * 2]/*.Freq*/;
          tree[m * 2 + 1]/*.Len*/ = bits;
        }
        n--;
      }
    }
  }
  
  
  /* ===========================================================================
   * Generate the codes for a given tree and bit counts (which need not be
   * optimal).
   * IN assertion: the array bl_count contains the bit length statistics for
   * the given tree and the field len is set for all tree elements.
   * OUT assertion: the field code is set for all tree elements of non
   *     zero code length.
   */
  function gen_codes(tree, max_code, bl_count)
  //    ct_data *tree;             /* the tree to decorate */
  //    int max_code;              /* largest code with non zero frequency */
  //    ushf *bl_count;            /* number of codes at each bit length */
  {
    var next_code = new Array(MAX_BITS + 1); /* next code value for each bit length */
    var code = 0;              /* running code value */
    var bits;                  /* bit index */
    var n;                     /* code index */
  
    /* The distribution counts are first used to generate the code values
     * without bit reversal.
     */
    for (bits = 1; bits <= MAX_BITS; bits++) {
      next_code[bits] = code = (code + bl_count[bits - 1]) << 1;
    }
    /* Check that the bit counts in bl_count are consistent. The last code
     * must be all ones.
     */
    //Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1,
    //        "inconsistent bit counts");
    //Tracev((stderr,"\ngen_codes: max_code %d ", max_code));
  
    for (n = 0;  n <= max_code; n++) {
      var len = tree[n * 2 + 1]/*.Len*/;
      if (len === 0) { continue; }
      /* Now reverse the bits */
      tree[n * 2]/*.Code*/ = bi_reverse(next_code[len]++, len);
  
      //Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ",
      //     n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1));
    }
  }
  
  
  /* ===========================================================================
   * Initialize the various 'constant' tables.
   */
  function tr_static_init() {
    var n;        /* iterates over tree elements */
    var bits;     /* bit counter */
    var length;   /* length value */
    var code;     /* code value */
    var dist;     /* distance index */
    var bl_count = new Array(MAX_BITS + 1);
    /* number of codes at each bit length for an optimal tree */
  
    // do check in _tr_init()
    //if (static_init_done) return;
  
    /* For some embedded targets, global variables are not initialized: */
  /*#ifdef NO_INIT_GLOBAL_POINTERS
    static_l_desc.static_tree = static_ltree;
    static_l_desc.extra_bits = extra_lbits;
    static_d_desc.static_tree = static_dtree;
    static_d_desc.extra_bits = extra_dbits;
    static_bl_desc.extra_bits = extra_blbits;
  #endif*/
  
    /* Initialize the mapping length (0..255) -> length code (0..28) */
    length = 0;
    for (code = 0; code < LENGTH_CODES - 1; code++) {
      base_length[code] = length;
      for (n = 0; n < (1 << extra_lbits[code]); n++) {
        _length_code[length++] = code;
      }
    }
    //Assert (length == 256, "tr_static_init: length != 256");
    /* Note that the length 255 (match length 258) can be represented
     * in two different ways: code 284 + 5 bits or code 285, so we
     * overwrite length_code[255] to use the best encoding:
     */
    _length_code[length - 1] = code;
  
    /* Initialize the mapping dist (0..32K) -> dist code (0..29) */
    dist = 0;
    for (code = 0; code < 16; code++) {
      base_dist[code] = dist;
      for (n = 0; n < (1 << extra_dbits[code]); n++) {
        _dist_code[dist++] = code;
      }
    }
    //Assert (dist == 256, "tr_static_init: dist != 256");
    dist >>= 7; /* from now on, all distances are divided by 128 */
    for (; code < D_CODES; code++) {
      base_dist[code] = dist << 7;
      for (n = 0; n < (1 << (extra_dbits[code] - 7)); n++) {
        _dist_code[256 + dist++] = code;
      }
    }
    //Assert (dist == 256, "tr_static_init: 256+dist != 512");
  
    /* Construct the codes of the static literal tree */
    for (bits = 0; bits <= MAX_BITS; bits++) {
      bl_count[bits] = 0;
    }
  
    n = 0;
    while (n <= 143) {
      static_ltree[n * 2 + 1]/*.Len*/ = 8;
      n++;
      bl_count[8]++;
    }
    while (n <= 255) {
      static_ltree[n * 2 + 1]/*.Len*/ = 9;
      n++;
      bl_count[9]++;
    }
    while (n <= 279) {
      static_ltree[n * 2 + 1]/*.Len*/ = 7;
      n++;
      bl_count[7]++;
    }
    while (n <= 287) {
      static_ltree[n * 2 + 1]/*.Len*/ = 8;
      n++;
      bl_count[8]++;
    }
    /* Codes 286 and 287 do not exist, but we must include them in the
     * tree construction to get a canonical Huffman tree (longest code
     * all ones)
     */
    gen_codes(static_ltree, L_CODES + 1, bl_count);
  
    /* The static distance tree is trivial: */
    for (n = 0; n < D_CODES; n++) {
      static_dtree[n * 2 + 1]/*.Len*/ = 5;
      static_dtree[n * 2]/*.Code*/ = bi_reverse(n, 5);
    }
  
    // Now data ready and we can init static trees
    static_l_desc = new StaticTreeDesc(static_ltree, extra_lbits, LITERALS + 1, L_CODES, MAX_BITS);
    static_d_desc = new StaticTreeDesc(static_dtree, extra_dbits, 0,          D_CODES, MAX_BITS);
    static_bl_desc = new StaticTreeDesc(new Array(0), extra_blbits, 0,         BL_CODES, MAX_BL_BITS);
  
    //static_init_done = true;
  }
  
  
  /* ===========================================================================
   * Initialize a new block.
   */
  function init_block(s) {
    var n; /* iterates over tree elements */
  
    /* Initialize the trees. */
    for (n = 0; n < L_CODES;  n++) { s.dyn_ltree[n * 2]/*.Freq*/ = 0; }
    for (n = 0; n < D_CODES;  n++) { s.dyn_dtree[n * 2]/*.Freq*/ = 0; }
    for (n = 0; n < BL_CODES; n++) { s.bl_tree[n * 2]/*.Freq*/ = 0; }
  
    s.dyn_ltree[END_BLOCK * 2]/*.Freq*/ = 1;
    s.opt_len = s.static_len = 0;
    s.last_lit = s.matches = 0;
  }
  
  
  /* ===========================================================================
   * Flush the bit buffer and align the output on a byte boundary
   */
  function bi_windup(s)
  {
    if (s.bi_valid > 8) {
      put_short(s, s.bi_buf);
    } else if (s.bi_valid > 0) {
      //put_byte(s, (Byte)s->bi_buf);
      s.pending_buf[s.pending++] = s.bi_buf;
    }
    s.bi_buf = 0;
    s.bi_valid = 0;
  }
  
  /* ===========================================================================
   * Copy a stored block, storing first the length and its
   * one's complement if requested.
   */
  function copy_block(s, buf, len, header)
  //DeflateState *s;
  //charf    *buf;    /* the input data */
  //unsigned len;     /* its length */
  //int      header;  /* true if block header must be written */
  {
    bi_windup(s);        /* align on byte boundary */
  
    if (header) {
      put_short(s, len);
      put_short(s, ~len);
    }
  //  while (len--) {
  //    put_byte(s, *buf++);
  //  }
    utils.arraySet(s.pending_buf, s.window, buf, len, s.pending);
    s.pending += len;
  }
  
  /* ===========================================================================
   * Compares to subtrees, using the tree depth as tie breaker when
   * the subtrees have equal frequency. This minimizes the worst case length.
   */
  function smaller(tree, n, m, depth) {
    var _n2 = n * 2;
    var _m2 = m * 2;
    return (tree[_n2]/*.Freq*/ < tree[_m2]/*.Freq*/ ||
           (tree[_n2]/*.Freq*/ === tree[_m2]/*.Freq*/ && depth[n] <= depth[m]));
  }
  
  /* ===========================================================================
   * Restore the heap property by moving down the tree starting at node k,
   * exchanging a node with the smallest of its two sons if necessary, stopping
   * when the heap property is re-established (each father smaller than its
   * two sons).
   */
  function pqdownheap(s, tree, k)
  //    deflate_state *s;
  //    ct_data *tree;  /* the tree to restore */
  //    int k;               /* node to move down */
  {
    var v = s.heap[k];
    var j = k << 1;  /* left son of k */
    while (j <= s.heap_len) {
      /* Set j to the smallest of the two sons: */
      if (j < s.heap_len &&
        smaller(tree, s.heap[j + 1], s.heap[j], s.depth)) {
        j++;
      }
      /* Exit if v is smaller than both sons */
      if (smaller(tree, v, s.heap[j], s.depth)) { break; }
  
      /* Exchange v with the smallest son */
      s.heap[k] = s.heap[j];
      k = j;
  
      /* And continue down the tree, setting j to the left son of k */
      j <<= 1;
    }
    s.heap[k] = v;
  }
  
  
  // inlined manually
  // var SMALLEST = 1;
  
  /* ===========================================================================
   * Send the block data compressed using the given Huffman trees
   */
  function compress_block(s, ltree, dtree)
  //    deflate_state *s;
  //    const ct_data *ltree; /* literal tree */
  //    const ct_data *dtree; /* distance tree */
  {
    var dist;           /* distance of matched string */
    var lc;             /* match length or unmatched char (if dist == 0) */
    var lx = 0;         /* running index in l_buf */
    var code;           /* the code to send */
    var extra;          /* number of extra bits to send */
  
    if (s.last_lit !== 0) {
      do {
        dist = (s.pending_buf[s.d_buf + lx * 2] << 8) | (s.pending_buf[s.d_buf + lx * 2 + 1]);
        lc = s.pending_buf[s.l_buf + lx];
        lx++;
  
        if (dist === 0) {
          send_code(s, lc, ltree); /* send a literal byte */
          //Tracecv(isgraph(lc), (stderr," '%c' ", lc));
        } else {
          /* Here, lc is the match length - MIN_MATCH */
          code = _length_code[lc];
          send_code(s, code + LITERALS + 1, ltree); /* send the length code */
          extra = extra_lbits[code];
          if (extra !== 0) {
            lc -= base_length[code];
            send_bits(s, lc, extra);       /* send the extra length bits */
          }
          dist--; /* dist is now the match distance - 1 */
          code = d_code(dist);
          //Assert (code < D_CODES, "bad d_code");
  
          send_code(s, code, dtree);       /* send the distance code */
          extra = extra_dbits[code];
          if (extra !== 0) {
            dist -= base_dist[code];
            send_bits(s, dist, extra);   /* send the extra distance bits */
          }
        } /* literal or match pair ? */
  
        /* Check that the overlay between pending_buf and d_buf+l_buf is ok: */
        //Assert((uInt)(s->pending) < s->lit_bufsize + 2*lx,
        //       "pendingBuf overflow");
  
      } while (lx < s.last_lit);
    }
  
    send_code(s, END_BLOCK, ltree);
  }
  
  
  /* ===========================================================================
   * Construct one Huffman tree and assigns the code bit strings and lengths.
   * Update the total bit length for the current block.
   * IN assertion: the field freq is set for all tree elements.
   * OUT assertions: the fields len and code are set to the optimal bit length
   *     and corresponding code. The length opt_len is updated; static_len is
   *     also updated if stree is not null. The field max_code is set.
   */
  function build_tree(s, desc)
  //    deflate_state *s;
  //    tree_desc *desc; /* the tree descriptor */
  {
    var tree     = desc.dyn_tree;
    var stree    = desc.stat_desc.static_tree;
    var has_stree = desc.stat_desc.has_stree;
    var elems    = desc.stat_desc.elems;
    var n, m;          /* iterate over heap elements */
    var max_code = -1; /* largest code with non zero frequency */
    var node;          /* new node being created */
  
    /* Construct the initial heap, with least frequent element in
     * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
     * heap[0] is not used.
     */
    s.heap_len = 0;
    s.heap_max = HEAP_SIZE;
  
    for (n = 0; n < elems; n++) {
      if (tree[n * 2]/*.Freq*/ !== 0) {
        s.heap[++s.heap_len] = max_code = n;
        s.depth[n] = 0;
  
      } else {
        tree[n * 2 + 1]/*.Len*/ = 0;
      }
    }
  
    /* The pkzip format requires that at least one distance code exists,
     * and that at least one bit should be sent even if there is only one
     * possible code. So to avoid special checks later on we force at least
     * two codes of non zero frequency.
     */
    while (s.heap_len < 2) {
      node = s.heap[++s.heap_len] = (max_code < 2 ? ++max_code : 0);
      tree[node * 2]/*.Freq*/ = 1;
      s.depth[node] = 0;
      s.opt_len--;
  
      if (has_stree) {
        s.static_len -= stree[node * 2 + 1]/*.Len*/;
      }
      /* node is 0 or 1 so it does not have extra bits */
    }
    desc.max_code = max_code;
  
    /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
     * establish sub-heaps of increasing lengths:
     */
    for (n = (s.heap_len >> 1/*int /2*/); n >= 1; n--) { pqdownheap(s, tree, n); }
  
    /* Construct the Huffman tree by repeatedly combining the least two
     * frequent nodes.
     */
    node = elems;              /* next internal node of the tree */
    do {
      //pqremove(s, tree, n);  /* n = node of least frequency */
      /*** pqremove ***/
      n = s.heap[1/*SMALLEST*/];
      s.heap[1/*SMALLEST*/] = s.heap[s.heap_len--];
      pqdownheap(s, tree, 1/*SMALLEST*/);
      /***/
  
      m = s.heap[1/*SMALLEST*/]; /* m = node of next least frequency */
  
      s.heap[--s.heap_max] = n; /* keep the nodes sorted by frequency */
      s.heap[--s.heap_max] = m;
  
      /* Create a new node father of n and m */
      tree[node * 2]/*.Freq*/ = tree[n * 2]/*.Freq*/ + tree[m * 2]/*.Freq*/;
      s.depth[node] = (s.depth[n] >= s.depth[m] ? s.depth[n] : s.depth[m]) + 1;
      tree[n * 2 + 1]/*.Dad*/ = tree[m * 2 + 1]/*.Dad*/ = node;
  
      /* and insert the new node in the heap */
      s.heap[1/*SMALLEST*/] = node++;
      pqdownheap(s, tree, 1/*SMALLEST*/);
  
    } while (s.heap_len >= 2);
  
    s.heap[--s.heap_max] = s.heap[1/*SMALLEST*/];
  
    /* At this point, the fields freq and dad are set. We can now
     * generate the bit lengths.
     */
    gen_bitlen(s, desc);
  
    /* The field len is now set, we can generate the bit codes */
    gen_codes(tree, max_code, s.bl_count);
  }
  
  
  /* ===========================================================================
   * Scan a literal or distance tree to determine the frequencies of the codes
   * in the bit length tree.
   */
  function scan_tree(s, tree, max_code)
  //    deflate_state *s;
  //    ct_data *tree;   /* the tree to be scanned */
  //    int max_code;    /* and its largest code of non zero frequency */
  {
    var n;                     /* iterates over all tree elements */
    var prevlen = -1;          /* last emitted length */
    var curlen;                /* length of current code */
  
    var nextlen = tree[0 * 2 + 1]/*.Len*/; /* length of next code */
  
    var count = 0;             /* repeat count of the current code */
    var max_count = 7;         /* max repeat count */
    var min_count = 4;         /* min repeat count */
  
    if (nextlen === 0) {
      max_count = 138;
      min_count = 3;
    }
    tree[(max_code + 1) * 2 + 1]/*.Len*/ = 0xffff; /* guard */
  
    for (n = 0; n <= max_code; n++) {
      curlen = nextlen;
      nextlen = tree[(n + 1) * 2 + 1]/*.Len*/;
  
      if (++count < max_count && curlen === nextlen) {
        continue;
  
      } else if (count < min_count) {
        s.bl_tree[curlen * 2]/*.Freq*/ += count;
  
      } else if (curlen !== 0) {
  
        if (curlen !== prevlen) { s.bl_tree[curlen * 2]/*.Freq*/++; }
        s.bl_tree[REP_3_6 * 2]/*.Freq*/++;
  
      } else if (count <= 10) {
        s.bl_tree[REPZ_3_10 * 2]/*.Freq*/++;
  
      } else {
        s.bl_tree[REPZ_11_138 * 2]/*.Freq*/++;
      }
  
      count = 0;
      prevlen = curlen;
  
      if (nextlen === 0) {
        max_count = 138;
        min_count = 3;
  
      } else if (curlen === nextlen) {
        max_count = 6;
        min_count = 3;
  
      } else {
        max_count = 7;
        min_count = 4;
      }
    }
  }
  
  
  /* ===========================================================================
   * Send a literal or distance tree in compressed form, using the codes in
   * bl_tree.
   */
  function send_tree(s, tree, max_code)
  //    deflate_state *s;
  //    ct_data *tree; /* the tree to be scanned */
  //    int max_code;       /* and its largest code of non zero frequency */
  {
    var n;                     /* iterates over all tree elements */
    var prevlen = -1;          /* last emitted length */
    var curlen;                /* length of current code */
  
    var nextlen = tree[0 * 2 + 1]/*.Len*/; /* length of next code */
  
    var count = 0;             /* repeat count of the current code */
    var max_count = 7;         /* max repeat count */
    var min_count = 4;         /* min repeat count */
  
    /* tree[max_code+1].Len = -1; */  /* guard already set */
    if (nextlen === 0) {
      max_count = 138;
      min_count = 3;
    }
  
    for (n = 0; n <= max_code; n++) {
      curlen = nextlen;
      nextlen = tree[(n + 1) * 2 + 1]/*.Len*/;
  
      if (++count < max_count && curlen === nextlen) {
        continue;
  
      } else if (count < min_count) {
        do { send_code(s, curlen, s.bl_tree); } while (--count !== 0);
  
      } else if (curlen !== 0) {
        if (curlen !== prevlen) {
          send_code(s, curlen, s.bl_tree);
          count--;
        }
        //Assert(count >= 3 && count <= 6, " 3_6?");
        send_code(s, REP_3_6, s.bl_tree);
        send_bits(s, count - 3, 2);
  
      } else if (count <= 10) {
        send_code(s, REPZ_3_10, s.bl_tree);
        send_bits(s, count - 3, 3);
  
      } else {
        send_code(s, REPZ_11_138, s.bl_tree);
        send_bits(s, count - 11, 7);
      }
  
      count = 0;
      prevlen = curlen;
      if (nextlen === 0) {
        max_count = 138;
        min_count = 3;
  
      } else if (curlen === nextlen) {
        max_count = 6;
        min_count = 3;
  
      } else {
        max_count = 7;
        min_count = 4;
      }
    }
  }
  
  
  /* ===========================================================================
   * Construct the Huffman tree for the bit lengths and return the index in
   * bl_order of the last bit length code to send.
   */
  function build_bl_tree(s) {
    var max_blindex;  /* index of last bit length code of non zero freq */
  
    /* Determine the bit length frequencies for literal and distance trees */
    scan_tree(s, s.dyn_ltree, s.l_desc.max_code);
    scan_tree(s, s.dyn_dtree, s.d_desc.max_code);
  
    /* Build the bit length tree: */
    build_tree(s, s.bl_desc);
    /* opt_len now includes the length of the tree representations, except
     * the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
     */
  
    /* Determine the number of bit length codes to send. The pkzip format
     * requires that at least 4 bit length codes be sent. (appnote.txt says
     * 3 but the actual value used is 4.)
     */
    for (max_blindex = BL_CODES - 1; max_blindex >= 3; max_blindex--) {
      if (s.bl_tree[bl_order[max_blindex] * 2 + 1]/*.Len*/ !== 0) {
        break;
      }
    }
    /* Update opt_len to include the bit length tree and counts */
    s.opt_len += 3 * (max_blindex + 1) + 5 + 5 + 4;
    //Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld",
    //        s->opt_len, s->static_len));
  
    return max_blindex;
  }
  
  
  /* ===========================================================================
   * Send the header for a block using dynamic Huffman trees: the counts, the
   * lengths of the bit length codes, the literal tree and the distance tree.
   * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
   */
  function send_all_trees(s, lcodes, dcodes, blcodes)
  //    deflate_state *s;
  //    int lcodes, dcodes, blcodes; /* number of codes for each tree */
  {
    var rank;                    /* index in bl_order */
  
    //Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");
    //Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES,
    //        "too many codes");
    //Tracev((stderr, "\nbl counts: "));
    send_bits(s, lcodes - 257, 5); /* not +255 as stated in appnote.txt */
    send_bits(s, dcodes - 1,   5);
    send_bits(s, blcodes - 4,  4); /* not -3 as stated in appnote.txt */
    for (rank = 0; rank < blcodes; rank++) {
      //Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
      send_bits(s, s.bl_tree[bl_order[rank] * 2 + 1]/*.Len*/, 3);
    }
    //Tracev((stderr, "\nbl tree: sent %ld", s->bits_sent));
  
    send_tree(s, s.dyn_ltree, lcodes - 1); /* literal tree */
    //Tracev((stderr, "\nlit tree: sent %ld", s->bits_sent));
  
    send_tree(s, s.dyn_dtree, dcodes - 1); /* distance tree */
    //Tracev((stderr, "\ndist tree: sent %ld", s->bits_sent));
  }
  
  
  /* ===========================================================================
   * Check if the data type is TEXT or BINARY, using the following algorithm:
   * - TEXT if the two conditions below are satisfied:
   *    a) There are no non-portable control characters belonging to the
   *       "deny list" (0..6, 14..25, 28..31).
   *    b) There is at least one printable character belonging to the
   *       "allow list" (9 {TAB}, 10 {LF}, 13 {CR}, 32..255).
   * - BINARY otherwise.
   * - The following partially-portable control characters form a
   *   "gray list" that is ignored in this detection algorithm:
   *   (7 {BEL}, 8 {BS}, 11 {VT}, 12 {FF}, 26 {SUB}, 27 {ESC}).
   * IN assertion: the fields Freq of dyn_ltree are set.
   */
  function detect_data_type(s) {
    /* deny_mask is the bit mask of deny-listed bytes
     * set bits 0..6, 14..25, and 28..31
     * 0xf3ffc07f = binary 11110011111111111100000001111111
     */
    var deny_mask = 0xf3ffc07f;
    var n;
  
    /* Check for non-textual ("deny-listed") bytes. */
    for (n = 0; n <= 31; n++, deny_mask >>>= 1) {
      if ((deny_mask & 1) && (s.dyn_ltree[n * 2]/*.Freq*/ !== 0)) {
        return Z_BINARY;
      }
    }
  
    /* Check for textual ("allow-listed") bytes. */
    if (s.dyn_ltree[9 * 2]/*.Freq*/ !== 0 || s.dyn_ltree[10 * 2]/*.Freq*/ !== 0 ||
        s.dyn_ltree[13 * 2]/*.Freq*/ !== 0) {
      return Z_TEXT;
    }
    for (n = 32; n < LITERALS; n++) {
      if (s.dyn_ltree[n * 2]/*.Freq*/ !== 0) {
        return Z_TEXT;
      }
    }
  
    /* There are no "deny-listed" or "allow-listed" bytes:
     * this stream either is empty or has tolerated ("gray-listed") bytes only.
     */
    return Z_BINARY;
  }
  
  
  var static_init_done = false;
  
  /* ===========================================================================
   * Initialize the tree data structures for a new zlib stream.
   */
  function _tr_init(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
   */
  function _tr_stored_block(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 */
    copy_block(s, buf, stored_len, true); /* with header */
  }
  
  
  /* ===========================================================================
   * Send one empty static block to give enough lookahead for inflate.
   * This takes 10 bits, of which 7 may remain in the bit buffer.
   */
  function _tr_align(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 output the encoded block to the zip file.
   */
  function _tr_flush_block(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 */
  {
    var opt_lenb, static_lenb;  /* opt_len and static_len in bytes */
    var 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) {
        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->last_lit));
  
      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(s, buf, stored_len, last);
  
    } else if (s.strategy === Z_FIXED || 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.
   */
  function _tr_tally(s, dist, lc)
  //    deflate_state *s;
  //    unsigned dist;  /* distance of matched string */
  //    unsigned lc;    /* match length-MIN_MATCH or unmatched char (if dist==0) */
  {
    //var out_length, in_length, dcode;
  
    s.pending_buf[s.d_buf + s.last_lit * 2]     = (dist >>> 8) & 0xff;
    s.pending_buf[s.d_buf + s.last_lit * 2 + 1] = dist & 0xff;
  
    s.pending_buf[s.l_buf + s.last_lit] = lc & 0xff;
    s.last_lit++;
  
    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) * 2]/*.Freq*/++;
      s.dyn_dtree[d_code(dist) * 2]/*.Freq*/++;
    }
  
  // (!) This block is disabled in zlib defailts,
  // don't enable it for binary compatibility
  
  //#ifdef TRUNCATE_BLOCK
  //  /* Try to guess if it is profitable to stop the current block here */
  //  if ((s.last_lit & 0x1fff) === 0 && s.level > 2) {
  //    /* Compute an upper bound for the compressed length */
  //    out_length = s.last_lit*8;
  //    in_length = s.strstart - s.block_start;
  //
  //    for (dcode = 0; dcode < D_CODES; dcode++) {
  //      out_length += s.dyn_dtree[dcode*2]/*.Freq*/ * (5 + extra_dbits[dcode]);
  //    }
  //    out_length >>>= 3;
  //    //Tracev((stderr,"\nlast_lit %u, in %ld, out ~%ld(%ld%%) ",
  //    //       s->last_lit, in_length, out_length,
  //    //       100L - out_length*100L/in_length));
  //    if (s.matches < (s.last_lit>>1)/*int /2*/ && out_length < (in_length>>1)/*int /2*/) {
  //      return true;
  //    }
  //  }
  //#endif
  
    return (s.last_lit === s.lit_bufsize - 1);
    /* We avoid equality with lit_bufsize because of wraparound at 64K
     * on 16 bit machines and because stored blocks are restricted to
     * 64K-1 bytes.
     */
  }
  
  export { _tr_init, _tr_stored_block, _tr_flush_block, _tr_tally, _tr_align };
  