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hi-ucs/node_modules/pako/lib/zlib/trees.js

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2022-12-16 09:31:38 +08:00
'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.
/* eslint-disable space-unary-ops */
/* Public constants ==========================================================*/
/* ===========================================================================*/
//const Z_FILTERED = 1;
//const Z_HUFFMAN_ONLY = 2;
//const Z_RLE = 3;
const Z_FIXED = 4;
//const Z_DEFAULT_STRATEGY = 0;
/* Possible values of the data_type field (though see inflate()) */
const Z_BINARY = 0;
const Z_TEXT = 1;
//const Z_ASCII = 1; // = Z_TEXT
const Z_UNKNOWN = 2;
/*============================================================================*/
function zero(buf) { let len = buf.length; while (--len >= 0) { buf[len] = 0; } }
// From zutil.h
const STORED_BLOCK = 0;
const STATIC_TREES = 1;
const DYN_TREES = 2;
/* The three kinds of block type */
const MIN_MATCH = 3;
const MAX_MATCH = 258;
/* The minimum and maximum match lengths */
// From deflate.h
/* ===========================================================================
* Internal compression state.
*/
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 Buf_size = 16;
/* size of bit buffer in bi_buf */
/* ===========================================================================
* Constants
*/
const MAX_BL_BITS = 7;
/* Bit length codes must not exceed MAX_BL_BITS bits */
const END_BLOCK = 256;
/* end of block literal code */
const REP_3_6 = 16;
/* repeat previous bit length 3-6 times (2 bits of repeat count) */
const REPZ_3_10 = 17;
/* repeat a zero length 3-10 times (3 bits of repeat count) */
const REPZ_11_138 = 18;
/* repeat a zero length 11-138 times (7 bits of repeat count) */
/* eslint-disable comma-spacing,array-bracket-spacing */
const extra_lbits = /* extra bits for each length code */
new Uint8Array([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]);
const extra_dbits = /* extra bits for each distance code */
new Uint8Array([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]);
const extra_blbits = /* extra bits for each bit length code */
new Uint8Array([0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7]);
const bl_order =
new Uint8Array([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
const DIST_CODE_LEN = 512; /* see definition of array dist_code below */
// !!!! Use flat array instead of structure, Freq = i*2, Len = i*2+1
const 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).
*/
const static_dtree = new Array(D_CODES * 2);
zero(static_dtree);
/* The static distance tree. (Actually a trivial tree since all codes use
* 5 bits.)
*/
const _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.
*/
const _length_code = new Array(MAX_MATCH - MIN_MATCH + 1);
zero(_length_code);
/* length code for each normalized match length (0 == MIN_MATCH) */
const base_length = new Array(LENGTH_CODES);
zero(base_length);
/* First normalized length for each code (0 = MIN_MATCH) */
const 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;
}
let static_l_desc;
let static_d_desc;
let 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 */
}
const 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.
*/
const 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.
*/
const 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;
}
};
const 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
*/
const bi_reverse = (code, len) => {
let 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.
*/
const 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.
*/
const gen_bitlen = (s, desc) => {
// deflate_state *s;
// tree_desc *desc; /* the tree descriptor */
const tree = desc.dyn_tree;
const max_code = desc.max_code;
const stree = desc.stat_desc.static_tree;
const has_stree = desc.stat_desc.has_stree;
const extra = desc.stat_desc.extra_bits;
const base = desc.stat_desc.extra_base;
const max_length = desc.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; 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; }
// Tracev((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) {
// Tracev((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.
*/
const 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 */
const next_code = new Array(MAX_BITS + 1); /* next code value for each bit length */
let code = 0; /* running code value */
let bits; /* bit index */
let n; /* code index */
/* The distribution counts are first used to generate the code values
* without bit reversal.
*/
for (bits = 1; bits <= MAX_BITS; bits++) {
code = (code + bl_count[bits - 1]) << 1;
next_code[bits] = code;
}
/* 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++) {
let 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.
*/
const tr_static_init = () => {
let n; /* iterates over tree elements */
let bits; /* bit counter */
let length; /* length value */
let code; /* code value */
let dist; /* distance index */
const 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.
*/
const init_block = (s) => {
let 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.sym_next = s.matches = 0;
};
/* ===========================================================================
* Flush the bit buffer and align the output on a byte boundary
*/
const 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;
};
/* ===========================================================================
* Compares to subtrees, using the tree depth as tie breaker when
* the subtrees have equal frequency. This minimizes the worst case length.
*/
const smaller = (tree, n, m, depth) => {
const _n2 = n * 2;
const _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).
*/
const pqdownheap = (s, tree, k) => {
// deflate_state *s;
// ct_data *tree; /* the tree to restore */
// int k; /* node to move down */
const v = s.heap[k];
let 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
// const SMALLEST = 1;
/* ===========================================================================
* Send the block data compressed using the given Huffman trees
*/
const compress_block = (s, ltree, dtree) => {
// deflate_state *s;
// const ct_data *ltree; /* literal tree */
// const ct_data *dtree; /* distance tree */
let dist; /* distance of matched string */
let lc; /* match length or unmatched char (if dist == 0) */
let sx = 0; /* running index in sym_buf */
let code; /* the code to send */
let extra; /* number of extra bits to send */
if (s.sym_next !== 0) {
do {
dist = s.pending_buf[s.sym_buf + sx++] & 0xff;
dist += (s.pending_buf[s.sym_buf + sx++] & 0xff) << 8;
lc = s.pending_buf[s.sym_buf + sx++];
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 sym_buf is ok: */
//Assert(s->pending < s->lit_bufsize + sx, "pendingBuf overflow");
} while (sx < s.sym_next);
}
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.
*/
const build_tree = (s, desc) => {
// deflate_state *s;
// tree_desc *desc; /* the tree descriptor */
const tree = desc.dyn_tree;
const stree = desc.stat_desc.static_tree;
const has_stree = desc.stat_desc.has_stree;
const elems = desc.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[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.
*/
const 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 */
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]/*.Len*/; /* 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]/*.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.
*/
const 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 */
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]/*.Len*/; /* 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 */
/* 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.
*/
const build_bl_tree = (s) => {
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(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.
*/
const send_all_trees = (s, lcodes, dcodes, blcodes) => {
// deflate_state *s;
// int lcodes, dcodes, blcodes; /* number of codes for each tree */
let 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
* "block 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.
*/
const detect_data_type = (s) => {
/* block_mask is the bit mask of block-listed bytes
* set bits 0..6, 14..25, and 28..31
* 0xf3ffc07f = binary 11110011111111111100000001111111
*/
let block_mask = 0xf3ffc07f;
let n;
/* Check for non-textual ("block-listed") bytes. */
for (n = 0; n <= 31; n++, block_mask >>>= 1) {
if ((block_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 "block-listed" or "allow-listed" bytes:
* this stream either is empty or has tolerated ("gray-listed") bytes only.
*/
return Z_BINARY;
};
let static_init_done = false;
/* ===========================================================================
* Initialize the tree data structures for a new zlib stream.
*/
const _tr_init = (s) =>
{
if (!static_init_done) {
tr_static_init();
static_init_done = true;
}
s.l_desc = new TreeDesc(s.dyn_ltree, static_l_desc);
s.d_desc = new TreeDesc(s.dyn_dtree, static_d_desc);
s.bl_desc = new TreeDesc(s.bl_tree, static_bl_desc);
s.bi_buf = 0;
s.bi_valid = 0;
/* Initialize the first block of the first file: */
init_block(s);
};
/* ===========================================================================
* Send a stored block
*/
const _tr_stored_block = (s, buf, stored_len, last) => {
//DeflateState *s;
//charf *buf; /* input block */
//ulg stored_len; /* length of input block */
//int last; /* one if this is the last block for a file */
send_bits(s, (STORED_BLOCK << 1) + (last ? 1 : 0), 3); /* send block type */
bi_windup(s); /* align on byte boundary */
put_short(s, stored_len);
put_short(s, ~stored_len);
if (stored_len) {
s.pending_buf.set(s.window.subarray(buf, buf + stored_len), s.pending);
}
s.pending += stored_len;
};
/* ===========================================================================
* Send one empty static block to give enough lookahead for inflate.
* This takes 10 bits, of which 7 may remain in the bit buffer.
*/
const _tr_align = (s) => {
send_bits(s, STATIC_TREES << 1, 3);
send_code(s, END_BLOCK, static_ltree);
bi_flush(s);
};
/* ===========================================================================
* Determine the best encoding for the current block: dynamic trees, static
* trees or store, and write out the encoded block.
*/
const _tr_flush_block = (s, buf, stored_len, last) => {
//DeflateState *s;
//charf *buf; /* input block, or NULL if too old */
//ulg stored_len; /* length of input block */
//int last; /* one if this is the last block for a file */
let opt_lenb, static_lenb; /* opt_len and static_len in bytes */
let max_blindex = 0; /* index of last bit length code of non zero freq */
/* Build the Huffman trees unless a stored block is forced */
if (s.level > 0) {
/* Check if the file is binary or text */
if (s.strm.data_type === Z_UNKNOWN) {
s.strm.data_type = detect_data_type(s);
}
/* Construct the literal and distance trees */
build_tree(s, s.l_desc);
// Tracev((stderr, "\nlit data: dyn %ld, stat %ld", s->opt_len,
// s->static_len));
build_tree(s, s.d_desc);
// Tracev((stderr, "\ndist data: dyn %ld, stat %ld", s->opt_len,
// s->static_len));
/* At this point, opt_len and static_len are the total bit lengths of
* the compressed block data, excluding the tree representations.
*/
/* Build the bit length tree for the above two trees, and get the index
* in bl_order of the last bit length code to send.
*/
max_blindex = build_bl_tree(s);
/* Determine the best encoding. Compute the block lengths in bytes. */
opt_lenb = (s.opt_len + 3 + 7) >>> 3;
static_lenb = (s.static_len + 3 + 7) >>> 3;
// Tracev((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u ",
// opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len,
// s->sym_next / 3));
if (static_lenb <= opt_lenb) { opt_lenb = static_lenb; }
} else {
// Assert(buf != (char*)0, "lost buf");
opt_lenb = static_lenb = stored_len + 5; /* force a stored block */
}
if ((stored_len + 4 <= opt_lenb) && (buf !== -1)) {
/* 4: two words for the lengths */
/* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
* Otherwise we can't have processed more than WSIZE input bytes since
* the last block flush, because compression would have been
* successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
* transform a block into a stored block.
*/
_tr_stored_block(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.
*/
const _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) */
s.pending_buf[s.sym_buf + s.sym_next++] = dist;
s.pending_buf[s.sym_buf + s.sym_next++] = dist >> 8;
s.pending_buf[s.sym_buf + s.sym_next++] = lc;
if (dist === 0) {
/* lc is the unmatched char */
s.dyn_ltree[lc * 2]/*.Freq*/++;
} else {
s.matches++;
/* Here, lc is the match length - MIN_MATCH */
dist--; /* dist = match distance - 1 */
//Assert((ush)dist < (ush)MAX_DIST(s) &&
// (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) &&
// (ush)d_code(dist) < (ush)D_CODES, "_tr_tally: bad match");
s.dyn_ltree[(_length_code[lc] + LITERALS + 1) * 2]/*.Freq*/++;
s.dyn_dtree[d_code(dist) * 2]/*.Freq*/++;
}
return (s.sym_next === s.sym_end);
};
module.exports._tr_init = _tr_init;
module.exports._tr_stored_block = _tr_stored_block;
module.exports._tr_flush_block = _tr_flush_block;
module.exports._tr_tally = _tr_tally;
module.exports._tr_align = _tr_align;