'use strict';

Object.defineProperty(exports, '__esModule', { value: true });

/*

Copyright (c) 2022 Gildas Lormeau. All rights reserved.

Redistribution and use in source and binary forms, with or without

modification, are permitted provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice,

this list of conditions and the following disclaimer.

2. Redistributions in binary form must reproduce the above copyright

notice, this list of conditions and the following disclaimer in

the documentation and/or other materials provided with the distribution.

3. The names of the authors may not be used to endorse or promote products

derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED ''AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES,

INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND

FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL JCRAFT,

INC. OR ANY CONTRIBUTORS TO THIS SOFTWARE BE LIABLE FOR ANY DIRECT, INDIRECT,

INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT

LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,

OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF

LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING

NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,

EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

*/

/*

* This program is based on JZlib 1.0.2 ymnk, JCraft,Inc.

* JZlib is based on zlib-1.1.3, so all credit should go authors

* Jean-loup Gailly(jloup@gzip.org) and Mark Adler(madler@alumni.caltech.edu)

* and contributors of zlib.

*/

// deno-lint-ignore-file no-this-alias prefer-const

// Global

const MAX_BITS$1 = 15;

const D_CODES = 30;

const BL_CODES = 19;

const LENGTH_CODES = 29;

const LITERALS = 256;

const L_CODES = (LITERALS + 1 + LENGTH_CODES);

const HEAP_SIZE = (2 * L_CODES + 1);

const END_BLOCK = 256;

// Bit length codes must not exceed MAX_BL_BITS bits

const MAX_BL_BITS = 7;

// repeat previous bit length 3-6 times (2 bits of repeat count)

const REP_3_6 = 16;

// repeat a zero length 3-10 times (3 bits of repeat count)

const REPZ_3_10 = 17;

// repeat a zero length 11-138 times (7 bits of repeat count)

const REPZ_11_138 = 18;

// The lengths of the bit length codes are sent in order of decreasing

// probability, to avoid transmitting the lengths for unused bit

// length codes.

const Buf_size = 8 * 2;

// JZlib version : "1.0.2"

const Z_DEFAULT_COMPRESSION = -1;

// compression strategy

const Z_FILTERED = 1;

const Z_HUFFMAN_ONLY = 2;

const Z_DEFAULT_STRATEGY = 0;

const Z_NO_FLUSH$1 = 0;

const Z_PARTIAL_FLUSH = 1;

const Z_FULL_FLUSH = 3;

const Z_FINISH$1 = 4;

const Z_OK$1 = 0;

const Z_STREAM_END$1 = 1;

const Z_NEED_DICT$1 = 2;

const Z_STREAM_ERROR$1 = -2;

const Z_DATA_ERROR$1 = -3;

const Z_BUF_ERROR$1 = -5;

// Tree

function extractArray(array) {

return flatArray(array.map(([length, value]) => (new Array(length)).fill(value, 0, length)));

}

function flatArray(array) {

return array.reduce((a, b) => a.concat(Array.isArray(b) ? flatArray(b) : b), []);

}

// see definition of array dist_code below

const _dist_code = [0, 1, 2, 3].concat(...extractArray([

[2, 4], [2, 5], [4, 6], [4, 7], [8, 8], [8, 9], [16, 10], [16, 11], [32, 12], [32, 13], [64, 14], [64, 15], [2, 0], [1, 16],

[1, 17], [2, 18], [2, 19], [4, 20], [4, 21], [8, 22], [8, 23], [16, 24], [16, 25], [32, 26], [32, 27], [64, 28], [64, 29]

]));

function Tree() {

const that = this;

// dyn_tree; // the dynamic tree

// max_code; // largest code with non zero frequency

// stat_desc; // the corresponding static tree

// 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) {

const tree = that.dyn_tree;

const stree = that.stat_desc.static_tree;

const extra = that.stat_desc.extra_bits;

const base = that.stat_desc.extra_base;

const max_length = that.stat_desc.max_length;

let h; // heap index

let n, m; // iterate over the tree elements

let bits; // bit length

let xbits; // extra bits

let f; // frequency

let overflow = 0; // number of elements with bit length too large

for (bits = 0; bits <= MAX_BITS$1; 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] = 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] * 2 + 1] + 1;

if (bits > max_length) {

bits = max_length;

overflow++;

}

tree[n * 2 + 1] = bits;

// We overwrite tree[n*2+1] which is no longer needed

if (n > that.max_code)

continue; // not a leaf node

s.bl_count[bits]++;

xbits = 0;

if (n >= base)

xbits = extra[n - base];

f = tree[n * 2];

s.opt_len += f * (bits + xbits);

if (stree)

s.static_len += f * (stree[n * 2 + 1] + xbits);

}

if (overflow === 0)

return;

// 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);

for (bits = max_length; bits !== 0; bits--) {

n = s.bl_count[bits];

while (n !== 0) {

m = s.heap[--h];

if (m > that.max_code)

continue;

if (tree[m * 2 + 1] != bits) {

s.opt_len += (bits - tree[m * 2 + 1]) * tree[m * 2];

tree[m * 2 + 1] = bits;

}

n--;

}

}

}

// 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, // the value to invert

len // its bit length

) {

let res = 0;

do {

res |= code & 1;

code >>>= 1;

res <<= 1;

} while (--len > 0);

return res >>> 1;

}

// 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, // the tree to decorate

max_code, // largest code with non zero frequency

bl_count // number of codes at each bit length

) {

const next_code = []; // next code value for each

// bit length

let code = 0; // running code value

let bits; // bit index

let n; // code index

let len;

// The distribution counts are first used to generate the code values

// without bit reversal.

for (bits = 1; bits <= MAX_BITS$1; 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,"gen_codes: max_code %d ", max_code));

for (n = 0; n <= max_code; n++) {

len = tree[n * 2 + 1];

if (len === 0)

continue;

// Now reverse the bits

tree[n * 2] = bi_reverse(next_code[len]++, len);

}

}

// 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.

that.build_tree = function (s) {

const tree = that.dyn_tree;

const stree = that.stat_desc.static_tree;

const elems = that.stat_desc.elems;

let n, m; // iterate over heap elements

let max_code = -1; // largest code with non zero frequency

let node; // new node being created

// Construct the initial heap, with least frequent element in

// heap[1]. 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] !== 0) {

s.heap[++s.heap_len] = max_code = n;

s.depth[n] = 0;

} else {

tree[n * 2 + 1] = 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] = 1;

s.depth[node] = 0;

s.opt_len--;

if (stree)

s.static_len -= stree[node * 2 + 1];

// node is 0 or 1 so it does not have extra bits

}

that.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 = Math.floor(s.heap_len / 2); n >= 1; n--)

s.pqdownheap(tree, n);

// Construct the Huffman tree by repeatedly combining the least two

// frequent nodes.

node = elems; // next internal node of the tree

do {

// n = node of least frequency

n = s.heap[1];

s.heap[1] = s.heap[s.heap_len--];

s.pqdownheap(tree, 1);

m = s.heap[1]; // 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] = (tree[n * 2] + tree[m * 2]);

s.depth[node] = Math.max(s.depth[n], s.depth[m]) + 1;

tree[n * 2 + 1] = tree[m * 2 + 1] = node;

// and insert the new node in the heap

s.heap[1] = node++;

s.pqdownheap(tree, 1);

} while (s.heap_len >= 2);

s.heap[--s.heap_max] = s.heap[1];

// At this point, the fields freq and dad are set. We can now

// generate the bit lengths.

gen_bitlen(s);

// The field len is now set, we can generate the bit codes

gen_codes(tree, that.max_code, s.bl_count);

};

}

Tree._length_code = [0, 1, 2, 3, 4, 5, 6, 7].concat(...extractArray([

[2, 8], [2, 9], [2, 10], [2, 11], [4, 12], [4, 13], [4, 14], [4, 15], [8, 16], [8, 17], [8, 18], [8, 19],

[16, 20], [16, 21], [16, 22], [16, 23], [32, 24], [32, 25], [32, 26], [31, 27], [1, 28]]));

Tree.base_length = [0, 1, 2, 3, 4, 5, 6, 7, 8, 10, 12, 14, 16, 20, 24, 28, 32, 40, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224, 0];

Tree.base_dist = [0, 1, 2, 3, 4, 6, 8, 12, 16, 24, 32, 48, 64, 96, 128, 192, 256, 384, 512, 768, 1024, 1536, 2048, 3072, 4096, 6144, 8192, 12288, 16384,

24576];

// Mapping from a distance to a distance code. dist is the distance - 1 and

// must not have side effects. _dist_code[256] and _dist_code[257] are never

// used.

Tree.d_code = function (dist) {

return ((dist) < 256 ? _dist_code[dist] : _dist_code[256 + ((dist) >>> 7)]);

};

// extra bits for each length code

Tree.extra_lbits = [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];

// extra bits for each distance code

Tree.extra_dbits = [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];

// extra bits for each bit length code

Tree.extra_blbits = [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 3, 7];

Tree.bl_order = [16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15];

// StaticTree

function StaticTree(static_tree, extra_bits, extra_base, elems, max_length) {

const that = this;

that.static_tree = static_tree;

that.extra_bits = extra_bits;

that.extra_base = extra_base;

that.elems = elems;

that.max_length = max_length;

}

const static_ltree2_first_part = [12, 140, 76, 204, 44, 172, 108, 236, 28, 156, 92, 220, 60, 188, 124, 252, 2, 130, 66, 194, 34, 162, 98, 226, 18, 146, 82,

210, 50, 178, 114, 242, 10, 138, 74, 202, 42, 170, 106, 234, 26, 154, 90, 218, 58, 186, 122, 250, 6, 134, 70, 198, 38, 166, 102, 230, 22, 150, 86,

214, 54, 182, 118, 246, 14, 142, 78, 206, 46, 174, 110, 238, 30, 158, 94, 222, 62, 190, 126, 254, 1, 129, 65, 193, 33, 161, 97, 225, 17, 145, 81,

209, 49, 177, 113, 241, 9, 137, 73, 201, 41, 169, 105, 233, 25, 153, 89, 217, 57, 185, 121, 249, 5, 133, 69, 197, 37, 165, 101, 229, 21, 149, 85,

213, 53, 181, 117, 245, 13, 141, 77, 205, 45, 173, 109, 237, 29, 157, 93, 221, 61, 189, 125, 253, 19, 275, 147, 403, 83, 339, 211, 467, 51, 307,

179, 435, 115, 371, 243, 499, 11, 267, 139, 395, 75, 331, 203, 459, 43, 299, 171, 427, 107, 363, 235, 491, 27, 283, 155, 411, 91, 347, 219, 475,

59, 315, 187, 443, 123, 379, 251, 507, 7, 263, 135, 391, 71, 327, 199, 455, 39, 295, 167, 423, 103, 359, 231, 487, 23, 279, 151, 407, 87, 343, 215,

471, 55, 311, 183, 439, 119, 375, 247, 503, 15, 271, 143, 399, 79, 335, 207, 463, 47, 303, 175, 431, 111, 367, 239, 495, 31, 287, 159, 415, 95,

351, 223, 479, 63, 319, 191, 447, 127, 383, 255, 511, 0, 64, 32, 96, 16, 80, 48, 112, 8, 72, 40, 104, 24, 88, 56, 120, 4, 68, 36, 100, 20, 84, 52,

116, 3, 131, 67, 195, 35, 163, 99, 227];

const static_ltree2_second_part = extractArray([[144, 8], [112, 9], [24, 7], [8, 8]]);

StaticTree.static_ltree = flatArray(static_ltree2_first_part.map((value, index) => [value, static_ltree2_second_part[index]]));

const static_dtree_first_part = [0, 16, 8, 24, 4, 20, 12, 28, 2, 18, 10, 26, 6, 22, 14, 30, 1, 17, 9, 25, 5, 21, 13, 29, 3, 19, 11, 27, 7, 23];

const static_dtree_second_part = extractArray([[30, 5]]);

StaticTree.static_dtree = flatArray(static_dtree_first_part.map((value, index) => [value, static_dtree_second_part[index]]));

StaticTree.static_l_desc = new StaticTree(StaticTree.static_ltree, Tree.extra_lbits, LITERALS + 1, L_CODES, MAX_BITS$1);

StaticTree.static_d_desc = new StaticTree(StaticTree.static_dtree, Tree.extra_dbits, 0, D_CODES, MAX_BITS$1);

StaticTree.static_bl_desc = new StaticTree(null, Tree.extra_blbits, 0, BL_CODES, MAX_BL_BITS);

// Deflate

const MAX_MEM_LEVEL = 9;

const DEF_MEM_LEVEL = 8;

function Config(good_length, max_lazy, nice_length, max_chain, func) {

const that = this;

that.good_length = good_length;

that.max_lazy = max_lazy;

that.nice_length = nice_length;

that.max_chain = max_chain;

that.func = func;

}

const STORED$1 = 0;

const FAST = 1;

const SLOW = 2;

const config_table = [

new Config(0, 0, 0, 0, STORED$1),

new Config(4, 4, 8, 4, FAST),

new Config(4, 5, 16, 8, FAST),

new Config(4, 6, 32, 32, FAST),

new Config(4, 4, 16, 16, SLOW),

new Config(8, 16, 32, 32, SLOW),

new Config(8, 16, 128, 128, SLOW),

new Config(8, 32, 128, 256, SLOW),

new Config(32, 128, 258, 1024, SLOW),

new Config(32, 258, 258, 4096, SLOW)

];

const z_errmsg = ["need dictionary", // Z_NEED_DICT

// 2

"stream end", // Z_STREAM_END 1

"", // Z_OK 0

"", // Z_ERRNO (-1)

"stream error", // Z_STREAM_ERROR (-2)

"data error", // Z_DATA_ERROR (-3)

"", // Z_MEM_ERROR (-4)

"buffer error", // Z_BUF_ERROR (-5)

"",// Z_VERSION_ERROR (-6)

""];

// block not completed, need more input or more output

const NeedMore = 0;

// block flush performed

const BlockDone = 1;

// finish started, need only more output at next deflate

const FinishStarted = 2;

// finish done, accept no more input or output

const FinishDone = 3;

// preset dictionary flag in zlib header

const PRESET_DICT$1 = 0x20;

const INIT_STATE = 42;

const BUSY_STATE = 113;

const FINISH_STATE = 666;

// The deflate compression method

const Z_DEFLATED$1 = 8;

const STORED_BLOCK = 0;

const STATIC_TREES = 1;

const DYN_TREES = 2;

const MIN_MATCH = 3;

const MAX_MATCH = 258;

const MIN_LOOKAHEAD = (MAX_MATCH + MIN_MATCH + 1);

function smaller(tree, n, m, depth) {

const tn2 = tree[n * 2];

const tm2 = tree[m * 2];

return (tn2 < tm2 || (tn2 == tm2 && depth[n] <= depth[m]));

}

function Deflate() {

const that = this;

let strm; // pointer back to this zlib stream

let status; // as the name implies

// pending_buf; // output still pending

let pending_buf_size; // size of pending_buf

// pending_out; // next pending byte to output to the stream

// pending; // nb of bytes in the pending buffer

// dist_buf; // buffer for distances

// lc_buf; // buffer for literals or lengths

// To simplify the code, dist_buf and lc_buf have the same number of elements.

// To use different lengths, an extra flag array would be necessary.

let last_flush; // value of flush param for previous deflate call

let w_size; // LZ77 win size (32K by default)

let w_bits; // log2(w_size) (8..16)

let w_mask; // w_size - 1

let win;

// Sliding win. Input bytes are read into the second half of the win,

// 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. Also, it limits

// the win size to 64K, which is quite useful on MSDOS.

// To do: use the user input buffer as sliding win.

let window_size;

// Actual size of win: 2*wSize, except when the user input buffer

// is directly used as sliding win.

let prev;

// 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 win index modulo 32K.

let head; // Heads of the hash chains or NIL.

let ins_h; // hash index of string to be inserted

let hash_size; // number of elements in hash table

let hash_bits; // log2(hash_size)

let hash_mask; // hash_size-1

// 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

let hash_shift;

// Window position at the beginning of the current output block. Gets

// negative when the win is moved backwards.

let block_start;

let match_length; // length of best match

let prev_match; // previous match

let match_available; // set if previous match exists

let strstart; // start of string to insert

let match_start; // start of matching string

let lookahead; // number of valid bytes ahead in win

// Length of the best match at previous step. Matches not greater than this

// are discarded. This is used in the lazy match evaluation.

let prev_length;

// To speed up deflation, hash chains are never searched beyond this

// length. A higher limit improves compression ratio but degrades the speed.

let max_chain_length;

// 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.

let max_lazy_match;

// 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.

let level; // compression level (1..9)

let strategy; // favor or force Huffman coding

// Use a faster search when the previous match is longer than this

let good_match;

// Stop searching when current match exceeds this

let nice_match;

let dyn_ltree; // literal and length tree

let dyn_dtree; // distance tree

let bl_tree; // Huffman tree for bit lengths

const l_desc = new Tree(); // desc for literal tree

const d_desc = new Tree(); // desc for distance tree

const bl_desc = new Tree(); // desc for bit length tree

// that.heap_len; // number of elements in the heap

// that.heap_max; // 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.

// Depth of each subtree used as tie breaker for trees of equal frequency

that.depth = [];

// 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 win 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

let lit_bufsize;

let last_lit; // running index in dist_buf and lc_buf

// that.opt_len; // bit length of current block with optimal trees

// that.static_len; // bit length of current block with static trees

let matches; // number of string matches in current block

let last_eob_len; // bit length of EOB code for last block

// Output buffer. bits are inserted starting at the bottom (least

// significant bits).

let bi_buf;

// Number of valid bits in bi_buf. All bits above the last valid bit

// are always zero.

let bi_valid;

// number of codes at each bit length for an optimal tree

that.bl_count = [];

// heap used to build the Huffman trees

that.heap = [];

dyn_ltree = [];

dyn_dtree = [];

bl_tree = [];

function lm_init() {

window_size = 2 * w_size;

head[hash_size - 1] = 0;

for (let i = 0; i < hash_size - 1; i++) {

head[i] = 0;

}

// Set the default configuration parameters:

max_lazy_match = config_table[level].max_lazy;

good_match = config_table[level].good_length;

nice_match = config_table[level].nice_length;

max_chain_length = config_table[level].max_chain;

strstart = 0;

block_start = 0;

lookahead = 0;

match_length = prev_length = MIN_MATCH - 1;

match_available = 0;

ins_h = 0;

}

function init_block() {

let i;

// Initialize the trees.

for (i = 0; i < L_CODES; i++)

dyn_ltree[i * 2] = 0;

for (i = 0; i < D_CODES; i++)

dyn_dtree[i * 2] = 0;

for (i = 0; i < BL_CODES; i++)

bl_tree[i * 2] = 0;

dyn_ltree[END_BLOCK * 2] = 1;

that.opt_len = that.static_len = 0;

last_lit = matches = 0;

}

// Initialize the tree data structures for a new zlib stream.

function tr_init() {

l_desc.dyn_tree = dyn_ltree;

l_desc.stat_desc = StaticTree.static_l_desc;

d_desc.dyn_tree = dyn_dtree;

d_desc.stat_desc = StaticTree.static_d_desc;

bl_desc.dyn_tree = bl_tree;

bl_desc.stat_desc = StaticTree.static_bl_desc;

bi_buf = 0;

bi_valid = 0;

last_eob_len = 8; // enough lookahead for inflate

// Initialize the first block of the first file:

init_block();

}

// 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).

that.pqdownheap = function (tree, // the tree to restore

k // node to move down

) {

const heap = that.heap;

const v = heap[k];

let j = k << 1; // left son of k

while (j <= that.heap_len) {

// Set j to the smallest of the two sons:

if (j < that.heap_len && smaller(tree, heap[j + 1], heap[j], that.depth)) {

j++;

}

// Exit if v is smaller than both sons

if (smaller(tree, v, heap[j], that.depth))

break;

// Exchange v with the smallest son

heap[k] = heap[j];

k = j;

// And continue down the tree, setting j to the left son of k

j <<= 1;

}

heap[k] = v;

};

// Scan a literal or distance tree to determine the frequencies of the codes

// in the bit length tree.

function scan_tree(tree,// the tree to be scanned

max_code // and its largest code of non zero frequency

) {

let prevlen = -1; // last emitted length

let curlen; // length of current code

let nextlen = tree[0 * 2 + 1]; // length of next code

let count = 0; // repeat count of the current code

let max_count = 7; // max repeat count

let min_count = 4; // min repeat count

if (nextlen === 0) {

max_count = 138;

min_count = 3;

}

tree[(max_code + 1) * 2 + 1] = 0xffff; // guard

for (let n = 0; n <= max_code; n++) {

curlen = nextlen;

nextlen = tree[(n + 1) * 2 + 1];

if (++count < max_count && curlen == nextlen) {

continue;

} else if (count < min_count) {

bl_tree[curlen * 2] += count;

} else if (curlen !== 0) {

if (curlen != prevlen)

bl_tree[curlen * 2]++;

bl_tree[REP_3_6 * 2]++;

} else if (count <= 10) {

bl_tree[REPZ_3_10 * 2]++;

} else {

bl_tree[REPZ_11_138 * 2]++;

}

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() {

let max_blindex; // index of last bit length code of non zero freq

// Determine the bit length frequencies for literal and distance trees

scan_tree(dyn_ltree, l_desc.max_code);

scan_tree(dyn_dtree, d_desc.max_code);

// Build the bit length tree:

bl_desc.build_tree(that);

// 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 (bl_tree[Tree.bl_order[max_blindex] * 2 + 1] !== 0)

break;

}

// Update opt_len to include the bit length tree and counts

that.opt_len += 3 * (max_blindex + 1) + 5 + 5 + 4;

return max_blindex;

}

// Output a byte on the stream.

// IN assertion: there is enough room in pending_buf.

function put_byte(p) {

that.pending_buf[that.pending++] = p;

}

function put_short(w) {

put_byte(w & 0xff);

put_byte((w >>> 8) & 0xff);

}

function putShortMSB(b) {

put_byte((b >> 8) & 0xff);

put_byte((b & 0xff) & 0xff);

}

function send_bits(value, length) {

let val;

const len = length;

if (bi_valid > Buf_size - len) {

val = value;

// bi_buf |= (val << bi_valid);

bi_buf |= ((val << bi_valid) & 0xffff);

put_short(bi_buf);

bi_buf = val >>> (Buf_size - bi_valid);

bi_valid += len - Buf_size;

} else {

// bi_buf |= (value) << bi_valid;

bi_buf |= (((value) << bi_valid) & 0xffff);

bi_valid += len;

}

}

function send_code(c, tree) {

const c2 = c * 2;

send_bits(tree[c2] & 0xffff, tree[c2 + 1] & 0xffff);

}

// Send a literal or distance tree in compressed form, using the codes in

// bl_tree.

function send_tree(tree,// the tree to be sent

max_code // and its largest code of non zero frequency

) {

let n; // iterates over all tree elements

let prevlen = -1; // last emitted length

let curlen; // length of current code

let nextlen = tree[0 * 2 + 1]; // length of next code

let count = 0; // repeat count of the current code

let max_count = 7; // max repeat count

let min_count = 4; // min repeat count

if (nextlen === 0) {

max_count = 138;

min_count = 3;

}

for (n = 0; n <= max_code; n++) {

curlen = nextlen;

nextlen = tree[(n + 1) * 2 + 1];

if (++count < max_count && curlen == nextlen) {

continue;

} else if (count < min_count) {

do {

send_code(curlen, bl_tree);

} while (--count !== 0);

} else if (curlen !== 0) {

if (curlen != prevlen) {

send_code(curlen, bl_tree);

count--;

}

send_code(REP_3_6, bl_tree);

send_bits(count - 3, 2);

} else if (count <= 10) {

send_code(REPZ_3_10, bl_tree);

send_bits(count - 3, 3);

} else {

send_code(REPZ_11_138, bl_tree);

send_bits(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;

}

}

}

// 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(lcodes, dcodes, blcodes) {

let rank; // index in bl_order

send_bits(lcodes - 257, 5); // not +255 as stated in appnote.txt

send_bits(dcodes - 1, 5);

send_bits(blcodes - 4, 4); // not -3 as stated in appnote.txt

for (rank = 0; rank < blcodes; rank++) {

send_bits(bl_tree[Tree.bl_order[rank] * 2 + 1], 3);

}

send_tree(dyn_ltree, lcodes - 1); // literal tree

send_tree(dyn_dtree, dcodes - 1); // distance tree

}

// Flush the bit buffer, keeping at most 7 bits in it.

function bi_flush() {

if (bi_valid == 16) {

put_short(bi_buf);

bi_buf = 0;

bi_valid = 0;

} else if (bi_valid >= 8) {

put_byte(bi_buf & 0xff);

bi_buf >>>= 8;

bi_valid -= 8;

}

}

// Send one empty static block to give enough lookahead for inflate.

// This takes 10 bits, of which 7 may remain in the bit buffer.

// The current inflate code requires 9 bits of lookahead. If the

// last two codes for the previous block (real code plus EOB) were coded

// on 5 bits or less, inflate may have only 5+3 bits of lookahead to decode

// the last real code. In this case we send two empty static blocks instead

// of one. (There are no problems if the previous block is stored or fixed.)

// To simplify the code, we assume the worst case of last real code encoded

// on one bit only.

function _tr_align() {

send_bits(STATIC_TREES << 1, 3);

send_code(END_BLOCK, StaticTree.static_ltree);

bi_flush();

// Of the 10 bits for the empty block, we have already sent

// (10 - bi_valid) bits. The lookahead for the last real code (before

// the EOB of the previous block) was thus at least one plus the length

// of the EOB plus what we have just sent of the empty static block.

if (1 + last_eob_len + 10 - bi_valid < 9) {

send_bits(STATIC_TREES << 1, 3);

send_code(END_BLOCK, StaticTree.static_ltree);

bi_flush();

}

last_eob_len = 7;

}

// Save the match info and tally the frequency counts. Return true if

// the current block must be flushed.

function _tr_tally(dist, // distance of matched string

lc // match length-MIN_MATCH or unmatched char (if dist==0)

) {

let out_length, in_length, dcode;

that.dist_buf[last_lit] = dist;

that.lc_buf[last_lit] = lc & 0xff;

last_lit++;

if (dist === 0) {

// lc is the unmatched char

dyn_ltree[lc * 2]++;

} else {

matches++;

// Here, lc is the match length - MIN_MATCH

dist--; // dist = match distance - 1

dyn_ltree[(Tree._length_code[lc] + LITERALS + 1) * 2]++;

dyn_dtree[Tree.d_code(dist) * 2]++;

}

if ((last_lit & 0x1fff) === 0 && level > 2) {

// Compute an upper bound for the compressed length

out_length = last_lit * 8;

in_length = strstart - block_start;

for (dcode = 0; dcode < D_CODES; dcode++) {

out_length += dyn_dtree[dcode * 2] * (5 + Tree.extra_dbits[dcode]);

}

out_length >>>= 3;

if ((matches < Math.floor(last_lit / 2)) && out_length < Math.floor(in_length / 2))

return true;

}

return (last_lit == 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.

}

// Send the block data compressed using the given Huffman trees

function compress_block(ltree, dtree) {

let dist; // distance of matched string

let lc; // match length or unmatched char (if dist === 0)

let lx = 0; // running index in dist_buf and lc_buf

let code; // the code to send

let extra; // number of extra bits to send

if (last_lit !== 0) {

do {

dist = that.dist_buf[lx];

lc = that.lc_buf[lx];

lx++;

if (dist === 0) {

send_code(lc, ltree); // send a literal byte

} else {

// Here, lc is the match length - MIN_MATCH

code = Tree._length_code[lc];