@airgap/coinlib-core/dependencies/src/pako-2.0.3/lib/zlib/deflate.js

The @airgap/coinlib-core is a protocol agnostic library to prepare, sign and broadcast cryptocurrency transactions.

'use strict'

// (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 } = require('./trees')
const adler32 = require('./adler32')
const crc32 = require('./crc32')
const msg = require('./messages')

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

const {
  Z_NO_FLUSH,
  Z_PARTIAL_FLUSH,
  Z_FULL_FLUSH,
  Z_FINISH,
  Z_BLOCK,
  Z_OK,
  Z_STREAM_END,
  Z_STREAM_ERROR,
  Z_DATA_ERROR,
  Z_BUF_ERROR,
  Z_DEFAULT_COMPRESSION,
  Z_FILTERED,
  Z_HUFFMAN_ONLY,
  Z_RLE,
  Z_FIXED,
  Z_DEFAULT_STRATEGY,
  Z_UNKNOWN,
  Z_DEFLATED
} = require('./constants')

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

const MAX_MEM_LEVEL = 9
/* Maximum value for memLevel in deflateInit2 */
const MAX_WBITS = 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
const EXTRA_STATE = 69
const NAME_STATE = 73
const COMMENT_STATE = 91
const HCRC_STATE = 103
const BUSY_STATE = 113
const FINISH_STATE = 666

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 = msg[errorCode]
  return errorCode
}

const rank = (f) => {
  return (f << 1) - (f > 4 ? 9 : 0)
}

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

/* 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 goes
 * through this function so some applications may wish to modify it
 * to avoid allocating a large strm->output 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(strm.adler, buf, len, start)
  } else if (strm.state.wrap === 2) {
    strm.adler = crc32(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 p, n, m, 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), 0)
      s.match_start -= _w_size
      s.strstart -= _w_size
      /* we now have strstart >= MAX_DIST */
      s.block_start -= _w_size

      /* Slide the hash table (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. (Using level 0 permanently is not an optimal usage of
       zlib, so we don't care about this pathological case.)
       */

      n = s.hash_size
      p = n

      do {
        m = s.head[--p]
        s.head[p] = m >= _w_size ? m - _w_size : 0
      } while (--n)

      n = _w_size
      p = n

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

      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.
 * This function does not insert new strings in the dictionary since
 * uncompressible data is probably not useful. This function is used
 * only for the level=0 compression option.
 * NOTE: this function should be optimized to avoid extra copying from
 * window to pending_buf.
 */
const deflate_stored = (s, flush) => {
  /* Stored blocks are limited to 0xffff bytes, pending_buf is limited
   * to pending_buf_size, and each stored block has a 5 byte header:
   */
  let max_block_size = 0xffff

  if (max_block_size > s.pending_buf_size - 5) {
    max_block_size = s.pending_buf_size - 5
  }

  /* Copy as much as possible from input to output: */
  for (;;) {
    /* Fill the window as much as possible: */
    if (s.lookahead <= 1) {
      //Assert(s->strstart < s->w_size+MAX_DIST(s) ||
      //  s->block_start >= (long)s->w_size, "slide too late");
      //      if (!(s.strstart < s.w_size + (s.w_size - MIN_LOOKAHEAD) ||
      //        s.block_start >= s.w_size)) {
      //        throw  new Error("slide too late");
      //      }

      fill_window(s)
      if (s.lookahead === 0 && flush === Z_NO_FLUSH) {
        return BS_NEED_MORE
      }

      if (s.lookahead === 0) {
        break
      }
      /* flush the current block */
    }
    //Assert(s->block_start >= 0L, "block gone");
    //    if (s.block_start < 0) throw new Error("block gone");

    s.strstart += s.lookahead
    s.lookahead = 0

    /* Emit a stored block if pending_buf will be full: */
    const max_start = s.block_start + max_block_size

    if (s.strstart === 0 || s.strstart >= max_start) {
      /* strstart == 0 is possible when wraparound on 16-bit machine */
      s.lookahead = s.strstart - max_start
      s.strstart = max_start
      /*** FLUSH_BLOCK(s, 0); ***/
      flush_block_only(s, false)
      if (s.strm.avail_out === 0) {
        return BS_NEED_MORE
      }
      /***/
    }
    /* Flush if we may have to slide, otherwise block_start may become
     * negative and the data will be gone:
     */
    if (s.strstart - s.block_start >= s.w_size - MIN_LOOKAHEAD) {
      /*** FLUSH_BLOCK(s, 0); ***/
      flush_block_only(s, false)
      if (s.strm.avail_out === 0) {
        return BS_NEED_MORE
      }
      /***/
    }
  }

  s.insert = 0

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

  return BS_NEED_MORE
}

/* ===========================================================================
 * Compress as much as possible from the input stream, return the current
 * block state.
 * This function does not perform lazy evaluation of matches and inserts
 * new strings in the dictionary only for unmatched strings or for short
 * matches. It is used only for the fast compression options.
 */
const deflate_fast = (s, flush) => {
  let hash_head /* head of the hash chain */
  let bflush /* set if current block must be flushed */

  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 = HASH(s, s.ins_h, s.window[s.strstart + MIN_MATCH - 1])
      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.
     * At this point we have always match_length < MIN_MATCH
     */
    if (hash_head !== 0 /*NIL*/ && s.strstart - hash_head <= s.w_size - MIN_LOOKAHEAD) {
      /* 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 >= MIN_MATCH) {
      // check_match(s, s.strstart, s.match_start, s.match_length); // for debug only

      /*** _tr_tally_dist(s, s.strstart - s.match_start,
                     s.match_length - MIN_MATCH, bflush); ***/
      bflush = _tr_tally(s, s.strstart - s.match_start, s.match_length - MIN_MATCH)

      s.lookahead -= s.match_length

      /* Insert new strings in the hash table only if the match length
       * is not too large. This saves time but degrades compression.
       */
      if (s.match_length <= s.max_lazy_match /*max_insert_length*/ && s.lookahead >= MIN_MATCH) {
        s.match_length-- /* string at strstart already in table */
        do {
          s.strstart++
          /*** INSERT_STRING(s, s.strstart, hash_head); ***/
          s.ins_h = HASH(s, s.ins_h, s.window[s.strstart + MIN_MATCH - 1])
          hash_head = s.prev[s.strstart & s.w_mask] = s.head[s.ins_h]
          s.head[s.ins_h] = s.strstart
          /***/
          /* strstart never exceeds WSIZE-MAX_MATCH, so there are
           * always MIN_MATCH bytes ahead.
           */
        } while (--s.match_length !== 0)
        s.strstart++
      } else {
        s.strstart += s.match_length
        s.match_length = 0
        s.ins_h = s.window[s.strstart]
        /* UPDATE_HASH(s, s.ins_h, s.window[s.strstart+1]); */
        s.ins_h = HASH(s, s.ins_h, s.window[s.strstart + 1])

        //#if MIN_MATCH != 3
        //                Call UPDATE_HASH() MIN_MATCH-3 more times
        //#endif
        /* If lookahead < MIN_MATCH, ins_h is garbage, but it does not
         * matter since it will be recomputed at next deflate call.
         */
      }
    } else {
      /* No match, output a literal byte */
      //Tracevv((stderr,"%c", s.window[s.strstart]));
      /*** _tr_tally_lit(s, s.window[s.strstart], bflush); ***/
      bflush = _tr_tally(s, 0, s.window[s.strstart])

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

/* ===========================================================================
 * Same as above, but achieves better compression. We use a lazy
 * evaluation for matches: a match is finally adopted only if there is
 * no better match at the next window position.
 */
const deflate_slow = (s, flush) => {
  let hash_head /* head of hash chain */
  let bflush /* set if current block must be flushed */

  let 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 = HASH(s, s.ins_h, s.window[s.strstart + MIN_MATCH - 1])
      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 = _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 = HASH(s, s.ins_h, s.window[s.strstart + MIN_MATCH - 1])
          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 = _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 = _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
}

/* ===========================================================================
 * For Z_RLE, simply look for runs of bytes, generate matches only of distance
 * one.  Do not maintain a hash table.  (It will be regenerated if this run of
 * deflate switches away from Z_RLE.)
 */
const deflate_rle = (s, flush) => {
  let bflush /* set if current block must be flushed */
  let prev /* byte at distance one to match */
  let scan, strend /* scan goes up to strend for length of run */

  const _win = s.window

  for (;;) {
    /* Make sure that we always have enough lookahead, except
     * at the end of the input file. We need MAX_MATCH bytes
     * for the longest run, plus one for the unrolled loop.
     */
    if (s.lookahead <= MAX_MATCH) {
      fill_window(s)
      if (s.lookahead <= MAX_MATCH && flush === Z_NO_FLUSH) {
        return BS_NEED_MORE
      }
      if (s.lookahead === 0) {
        break
      } /* flush the current block */
    }

    /* See how many times the previous byte repeats */
    s.match_length = 0
    if (s.lookahead >= MIN_MATCH && s.strstart > 0) {
      scan = s.strstart - 1
      prev = _win[scan]
      if (prev === _win[++scan] && prev === _win[++scan] && prev === _win[++scan]) {
        strend = s.strstart + MAX_MATCH
        do {
          /*jshint noempty:false*/
        } while (
          prev === _win[++scan] &&
          prev === _win[++scan] &&
          prev === _win[++scan] &&
          prev === _win[++scan] &&
          prev === _win[++scan] &&
          prev === _win[++scan] &&
          prev === _win[++scan] &&
          prev === _win[++scan] &&
          scan < strend
        )
        s.match_length = MAX_MATCH - (strend - scan)
        if (s.match_length > s.lookahead) {
          s.match_length = s.lookahead
        }
      }
      //Assert(scan <= s->window+(uInt)(s->window_size-1), "wild scan");
    }

    /* Emit match if have run of MIN_MATCH or longer, else emit literal */
    if (s.match_length >= MIN_MATCH) {
      //check_match(s, s.strstart, s.strstart - 1, s.match_length);

      /*** _tr_tally_dist(s, 1, s.match_length - MIN_MATCH, bflush); ***/
      bflush = _tr_tally(s, 1, s.match_length - MIN_MATCH)

      s.lookahead -= s.match_length
      s.strstart += s.match_length
      s.match_length = 0
    } else {
      /* No match, output a literal byte */
      //Tracevv((stderr,"%c", s->window[s->strstart]));
      /*** _tr_tally_lit(s, s.window[s.strstart], bflush); ***/
      bflush = _tr_tally(s, 0, s.window[s.strstart])

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

/* ===========================================================================
 * For Z_HUFFMAN_ONLY, do not look for matches.  Do not maintain a hash table.
 * (It will be regenerated if this run of deflate switches away from Huffman.)
 */
const deflate_huff = (s, flush) => {
  let bflush /* set if current block must be flushed */

  for (;;) {
    /* Make sure that we have a literal to write. */
    if (s.lookahead === 0) {
      fill_window(s)
      if (s.lookahead === 0) {
        if (flush === Z_NO_FLUSH) {
          return BS_NEED_MORE
        }
        break /* flush the current block */
      }
    }

    /* Output a literal byte */
    s.match_length = 0
    //Tracevv((stderr,"%c", s->window[s->strstart]));
    /*** _tr_tally_lit(s, s.window[s.strstart], bflush); ***/
    bflush = _tr_tally(s, 0, s.window[s.strstart])
    s.lookahead--
    s.strstart++
    if (bflush) {
      /*** FLUSH_BLOCK(s, 0); ***/
      flush_block_only(s, false)
      if (s.strm.avail_out === 0) {
        return BS_NEED_MORE
      }
      /***/
    }
  }
  s.insert = 0
  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
}

/* Values for max_lazy_match, good_match and max_chain_length, depending on
 * the desired pack level (0..9). The values given below have been tuned to
 * exclude worst case performance for pathological files. Better values may be
 * found for specific files.
 */
function Config(good_length, max_lazy, nice_length, max_chain, func) {
  this.good_length = good_length
  this.max_lazy = max_lazy
  this.nice_length = nice_length
  this.max_chain = max_chain
  this.func = func
}

const configuration_table = [
  /*      good lazy nice chain */
  new Config(0, 0, 0, 0, deflate_stored) /* 0 store only */,
  new Config(4, 4, 8, 4, deflate_fast) /* 1 max speed, no lazy matches */,
  new Config(4, 5, 16, 8, deflate_fast) /* 2 */,
  new Config(4, 6, 32, 32, deflate_fast) /* 3 */,

  new Config(4, 4, 16, 16, deflate_slow) /* 4 lazy matches */,
  new Config(8, 16, 32, 32, deflate_slow) /* 5 */,
  new Config(8, 16, 128, 128, deflate_slow) /* 6 */,
  new Config(8, 32, 128, 256, deflate_slow) /* 7 */,
  new Config(32, 128, 258, 1024, deflate_slow) /* 8 */,
  new Config(32, 258, 258, 4096, deflate_slow) /* 9 max compression */
]

/* ===========================================================================
 * Initialize the "longest match" routines for a new zlib stream
 */
const lm_init = (s) => {
  s.window_size = 2 * s.w_size

  /*** CLEAR_HASH(s); ***/
  zero(s.head) // Fill with NIL (= 0);

  /* Set the default configuration parameters:
   */
  s.max_lazy_match = configuration_table[s.level].max_lazy
  s.good_match = configuration_table[s.level].good_length
  s.nice_match = configuration_table[s.level].nice_length
  s.max_chain_length = configuration_table[s.level].max_chain

  s.strstart = 0
  s.block_start = 0
  s.lookahead = 0
  s.insert = 0
  s.match_length = s.prev_length = MIN_MATCH - 1
  s.match_available = 0
  s.ins_h = 0
}

function DeflateState() {
  this.strm = null /* pointer back to this zlib stream */
  this.status = 0 /* as the name implies */
  this.pending_buf = null /* output still pending */
  this.pending_buf_size = 0 /* size of pending_buf */
  this.pending_out = 0 /* next pending byte to output to the stream */
  this.pending = 0 /* nb of bytes in the pending buffer */
  this.wrap = 0 /* bit 0 true for zlib, bit 1 true for gzip */
  this.gzhead = null /* gzip header information to write */
  this.gzindex = 0 /* where in extra, name, or comment */
  this.method = Z_DEFLATED /* can only be DEFLATED */
  this.last_flush = -1 /* value of flush param for previous deflate call */

  this.w_size = 0 /* LZ77 window size (32K by default) */
  this.w_bits = 0 /* log2(w_size)  (8..16) */
  this.w_mask = 0 /* w_size - 1 */

  this.window = null
  /* Sliding window. Input bytes are read into the second half of the window,
   * and move to the first half later to keep a dictionary of at least wSize
   * bytes. With this organization, matches are limited to a distance of
   * wSize-MAX_MATCH bytes, but this ensures that IO is always
   * performed with a length multiple of the block size.
   */

  this.window_size = 0
  /* Actual size of window: 2*wSize, except when the user input buffer
   * is directly used as sliding window.
   */

  this.prev = null
  /* Link to older string with same hash index. To limit the size of this
   * array to 64K, this link is maintained only for the last 32K strings.
   * An index in this array is thus a window index modulo 32K.
   */

  this.head = null /* Heads of the hash chains or NIL. */

  this.ins_h = 0 /* hash index of string to be inserted */
  this.hash_size = 0 /* number of elements in hash table */
  this.hash_bits = 0 /* log2(hash_size) */
  this.hash_mask = 0 /* hash_size-1 */

  this.hash_shift = 0
  /* Number of bits by which ins_h must be shifted at each input
   * step. It must be such that after MIN_MATCH steps, the oldest
   * byte no longer takes part in the hash key, that is:
   *   hash_shift * MIN_MATCH >= hash_bits
   */

  this.block_start = 0
  /* Window position at the beginning of the current output block. Gets
   * negative when the window is moved backwards.
   */

  this.match_length = 0 /* length of best match */
  this.prev_match = 0 /* previous match */
  this.match_available = 0 /* set if previous match exists */
  this.strstart = 0 /* start of string to insert */
  this.match_start = 0 /* start of matching string */
  this.lookahead = 0 /* number of valid bytes ahead in window */

  this.prev_length = 0
  /* Length of the best match at previous step. Matches not greater than this
   * are discarded. This is used in the lazy match evaluation.
   */

  this.max_chain_length = 0
  /* To speed up deflation, hash chains are never searched beyond this
   * length.  A higher limit improves compression ratio but degrades the
   * speed.
   */

  this.max_lazy_match = 0
  /* Attempt to find a better match only when the current match is strictly
   * smaller than this value. This mechanism is used only for compression
   * levels >= 4.
   */
  // That's alias to max_lazy_match, don't use directly
  //this.max_insert_length = 0;
  /* Insert new strings in the hash table only if the match length is not
   * greater than this length. This saves time but degrades compression.
   * max_insert_length is used only for compression levels <= 3.
   */

  this.level = 0 /* compression level (1..9) */
  this.strategy = 0 /* favor or force Huffman coding*/

  this.good_match = 0
  /* Use a faster search when the previous match is longer than this */

  this.nice_match = 0 /* Stop searching when current match exceeds this */

  /* used by trees.c: */

  /* Didn't use ct_data typedef below to suppress compiler warning */

  // struct ct_data_s dyn_ltree[HEAP_SIZE];   /* literal and length tree */
  // struct ct_data_s dyn_dtree[2*D_CODES+1]; /* distance tree */
  // struct ct_data_s bl_tree[2*BL_CODES+1];  /* Huffman tree for bit lengths */

  // Use flat array of DOUBLE size, with interleaved fata,
  // because JS does not support effective
  this.dyn_ltree = new Uint16Array(HEAP_SIZE * 2)
  this.dyn_dtree = new Uint16Array((2 * D_CODES + 1) * 2)
  this.bl_tree = new Uint16Array((2 * BL_CODES + 1) * 2)
  zero(this.dyn_ltree)
  zero(this.dyn_dtree)
  zero(this.bl_tree)

  this.l_desc = null /* desc. for literal tree */
  this.d_desc = null /* desc. for distance tree */
  this.bl_desc = null /* desc. for bit length tree */

  //ush bl_count[MAX_BITS+1];
  this.bl_count = new Uint16Array(MAX_BITS + 1)
  /* number of codes at each bit length for an optimal tree */

  //int heap[2*L_CODES+1];      /* heap used to build the Huffman trees */
  this.heap = new Uint16Array(2 * L_CODES + 1) /* heap used to build the Huffman trees */
  zero(this.heap)

  this.heap_len = 0 /* number of elements in the heap */
  this.heap_max = 0 /* element of largest frequency */
  /* The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used.
   * The same heap array is used to build all trees.
   */

  this.depth = new Uint16Array(2 * L_CODES + 1) //uch depth[2*L_CODES+1];
  zero(this.depth)
  /* Depth of each subtree used as tie breaker for trees of equal frequency
   */

  this.l_buf = 0 /* buffer index for literals or lengths */

  this.lit_bufsize = 0
  /* Size of match buffer for literals/lengths.  There are 4 reasons for
   * limiting lit_bufsize to 64K:
   *   - frequencies can be kept in 16 bit counters
   *   - if compression is not successful for the first block, all input
   *     data is still in the window so we can still emit a stored block even
   *     when input comes from standard input.  (This can also be done for
   *     all blocks if lit_bufsize is not greater than 32K.)
   *   - if compression is not successful for a file smaller than 64K, we can
   *     even emit a stored file instead of a stored block (saving 5 bytes).
   *     This is applicable only for zip (not gzip or zlib).
   *   - creating new Huffman trees less frequently may not provide fast
   *     adaptation to changes in the input data statistics. (Take for
   *     example a binary file with poorly compressible code followed by
   *     a highly compressible string table.) Smaller buffer sizes give
   *     fast adaptation but have of course the overhead of transmitting
   *     trees more frequently.
   *   - I can't count above 4
   */

  this.last_lit = 0 /* running index in l_buf */

  this.d_buf = 0
  /* Buffer index for distances. To simplify the code, d_buf and l_buf have
   * the same number of elements. To use different lengths, an extra flag
   * array would be necessary.
   */

  this.opt_len = 0 /* bit length of current block with optimal trees */
  this.static_len = 0 /* bit length of current block with static trees */
  this.matches = 0 /* number of string matches in current block */
  this.insert = 0 /* bytes at end of window left to insert */

  this.bi_buf = 0
  /* Output buffer. bits are inserted starting at the bottom (least
   * significant bits).
   */
  this.bi_valid = 0
  /* Number of valid bits in bi_buf.  All bits above the last valid bit
   * are always zero.
   */

  // Used for window memory init. We safely ignore it for JS. That makes
  // sense only for pointers and memory check tools.
  //this.high_water = 0;
  /* High water mark offset in window for initialized bytes -- bytes above
   * this are set to zero in order to avoid memory check warnings when
   * longest match routines access bytes past the input.  This is then
   * updated to the new high water mark.
   */
}

const deflateResetKeep = (strm) => {
  if (!strm || !strm.state) {
    return err(strm, Z_STREAM_ERROR)
  }

  strm.total_in = strm.total_out = 0
  strm.data_type = Z_UNKNOWN

  const s = strm.state
  s.pending = 0
  s.pending_out = 0

  if (s.wrap < 0) {
    s.wrap = -s.wrap
    /* was made negative by deflate(..., Z_FINISH); */
  }
  s.status = s.wrap ? INIT_STATE : BUSY_STATE
  strm.adler =
    s.wrap === 2
      ? 0 // crc32(0, Z_NULL, 0)
      : 1 // adler32(0, Z_NULL, 0)
  s.last_flush = Z_NO_FLUSH
  _tr_init(s)
  return Z_OK
}

const deflateReset = (strm) => {
  const ret = deflateResetKeep(strm)
  if (ret === Z_OK) {
    lm_init(strm.state)
  }
  return ret
}

const deflateSetHeader = (strm, head) => {
  if (!strm || !strm.state) {
    return Z_STREAM_ERROR
  }
  if (strm.state.wrap !== 2) {
    return Z_STREAM_ERROR
  }
  strm.state.gzhead = head
  return Z_OK
}

const deflateInit2 = (strm, level, method, windowBits, memLevel, strategy) => {
  if (!strm) {
    // === Z_NULL
    return Z_STREAM_ERROR
  }
  let wrap = 1

  if (level === Z_DEFAULT_COMPRESSION) {
    level = 6
  }

  if (windowBits < 0) {
    /* suppress zlib wrapper */
    wrap = 0
    windowBits = -windowBits
  } else if (windowBits > 15) {
    wrap = 2 /* write gzip wrapper instead */
    windowBits -= 16
  }

  if (
    memLevel < 1 ||
    memLevel > MAX_MEM_LEVEL ||
    method !== Z_DEFLATED ||
    windowBits < 8 ||
    windowBits > 15 ||
    level < 0 ||
    level > 9 ||
    strategy < 0 ||
    strategy > Z_FIXED
  ) {
    return err(strm, Z_STREAM_ERROR)
  }

  if (windowBits === 8) {
    windowBits = 9
  }
  /* until 256-byte window bug fixed */

  const s = new DeflateState()

  strm.state = s
  s.strm = strm

  s.wrap = wrap
  s.gzhead = null
  s.w_bits = windowBits
  s.w_size = 1 << s.w_bits
  s.w_mask = s.w_size - 1

  s.hash_bits = memLevel + 7
  s.hash_size = 1 << s.hash_bits
  s.hash_mask = s.hash_size - 1
  s.hash_shift = ~~((s.hash_bits + MIN_MATCH - 1) / MIN_MATCH)

  s.window = new Uint8Array(s.w_size * 2)
  s.head = new Uint16Array(s.hash_size)
  s.prev = new Uint16Array(s.w_size)

  // Don't need mem init magic for JS.
  //s.high_water = 0;  /* nothing written to s->window yet */

  s.lit_bufsize = 1 << (memLevel + 6) /* 16K elements by default */

  s.pending_buf_size = s.lit_bufsize * 4

  //overlay = (ushf *) ZALLOC(strm, s->lit_bufsize, sizeof(ush)+2);
  //s->pending_buf = (uchf *) overlay;
  s.pending_buf = new Uint8Array(s.pending_buf_size)

  // It is offset from `s.pending_buf` (size is `s.lit_bufsize * 2`)
  //s->d_buf = overlay + s->lit_bufsize/sizeof(ush);
  s.d_buf = 1 * s.lit_bufsize

  //s->l_buf = s->pending_buf + (1+sizeof(ush))*s->lit_bufsize;
  s.l_buf = (1 + 2) * s.lit_bufsize

  s.level = level
  s.strategy = strategy
  s.method = method

  return deflateReset(strm)
}

const deflateInit = (strm, level) => {
  return deflateInit2(strm, level, Z_DEFLATED, MAX_WBITS, DEF_MEM_LEVEL, Z_DEFAULT_STRATEGY)
}

const deflate = (strm, flush) => {
  let beg, val // for gzip header write only

  if (!strm || !strm.state || flush > Z_BLOCK || flush < 0) {
    return strm ? err(strm, Z_STREAM_ERROR) : Z_STREAM_ERROR
  }

  const s = strm.state

  if (!strm.output || (!strm.input && strm.avail_in !== 0) || (s.status === FINISH_STATE && flush !== Z_FINISH)) {
    return err(strm, strm.avail_out === 0 ? Z_BUF_ERROR : Z_STREAM_ERROR)
  }

  s.strm = strm /* just in case */
  const old_flush = s.last_flush
  s.last_flush = flush

  /* Write the header */
  if (s.status === INIT_STATE) {
    if (s.wrap === 2) {
      // GZIP header
      strm.adler = 0 //crc32(0L, Z_NULL, 0);
      put_byte(s, 31)
      put_byte(s, 139)
      put_byte(s, 8)
      if (!s.gzhead) {
        // s->gzhead == Z_NULL
        put_byte(s, 0)
        put_byte(s, 0)
        put_byte(s, 0)
        put_byte(s, 0)
        put_byte(s, 0)
        put_byte(s, s.level === 9 ? 2 : s.strategy >= Z_HUFFMAN_ONLY || s.level < 2 ? 4 : 0)
        put_byte(s, OS_CODE)
        s.status = BUSY_STATE
      } else {
        put_byte(
          s,
          (s.gzhead.text ? 1 : 0) +
            (s.gzhead.hcrc ? 2 : 0) +
            (!s.gzhead.extra ? 0 : 4) +
            (!s.gzhead.name ? 0 : 8) +
            (!s.gzhead.comment ? 0 : 16)
        )
        put_byte(s, s.gzhead.time & 0xff)
        put_byte(s, (s.gzhead.time >> 8) & 0xff)
        put_byte(s, (s.gzhead.time >> 16) & 0xff)
        put_byte(s, (s.gzhead.time >> 24) & 0xff)
        put_byte(s, s.level === 9 ? 2 : s.strategy >= Z_HUFFMAN_ONLY || s.level < 2 ? 4 : 0)
        put_byte(s, s.gzhead.os & 0xff)
        if (s.gzhead.extra && s.gzhead.extra.length) {
          put_byte(s, s.gzhead.extra.length & 0xff)
          put_byte(s, (s.gzhead.extra.length >> 8) & 0xff)
        }
        if (s.gzhead.hcrc) {
          strm.adler = crc32(strm.adler, s.pending_buf, s.pending, 0)
        }
        s.gzindex = 0
        s.status = EXTRA_STATE
      }
    } // DEFLATE header
    else {
      let header = (Z_DEFLATED + ((s.w_bits - 8) << 4)) << 8
      let level_flags = -1

      if (s.strategy >= Z_HUFFMAN_ONLY || s.level < 2) {
        level_flags = 0
      } else if (s.level < 6) {
        level_flags = 1
      } else if (s.level === 6) {
        level_flags = 2
      } else {
        level_flags = 3
      }
      header |= level_flags << 6
      if (s.strstart !== 0) {
        header |= PRESET_DICT
      }
      header += 31 - (header % 31)

      s.status = BUSY_STATE
      putShortMSB(s, header)

      /* Save the adler32 of the preset dictionary: */
      if (s.strstart !== 0) {
        putShortMSB(s, strm.adler >>> 16)
        putShortMSB(s, strm.adler & 0xffff)
      }
      strm.adler = 1 // adler32(0L, Z_NULL, 0);
    }
  }

  //#ifdef GZIP
  if (s.status === EXTRA_STATE) {
    if (s.gzhead.extra /* != Z_NULL*/) {
      beg = s.pending /* start of bytes to update crc */

      while (s.gzindex < (s.gzhead.extra.length & 0xffff)) {
        if (s.pending === s.pending_buf_size) {
          if (s.gzhead.hcrc && s.pending > beg) {
            strm.adler = crc32(strm.adler, s.pending_buf, s.pending - beg, beg)
          }
          flush_pending(strm)
          beg = s.pending
          if (s.pending === s.pending_buf_size) {
            break
          }
        }
        put_byte(s, s.gzhead.extra[s.gzindex] & 0xff)
        s.gzindex++
      }
      if (s.gzhead.hcrc && s.pending > beg) {
        strm.adler = crc32(strm.adler, s.pending_buf, s.pending - beg, beg)
      }
      if (s.gzindex === s.gzhead.extra.length) {
        s.gzindex = 0
        s.status = NAME_STATE
      }
    } else {
      s.status = NAME_STATE
    }
  }
  if (s.status === NAME_STATE) {
    if (s.gzhead.name /* != Z_NULL*/) {
      beg = s.pending /* start of bytes to update crc */
      //int val;

      do {
        if (s.pending === s.pending_buf_size) {
          if (s.gzhead.hcrc && s.pending > beg) {
            strm.adler = crc32(strm.adler, s.pending_buf, s.pending - beg, beg)