'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< { 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;