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documentation.federated.com.../public/js/deflate.js

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2023-05-30 17:55:11 +00:00
/* Copyright (C) 1999 Masanao Izumo <iz@onicos.co.jp>
* Version: 1.0.1
* LastModified: Dec 25 1999
*/
/* Interface:
* data = deflate(src);
*/
const deflate = (function () {
/* constant parameters */
var zip_WSIZE = 32768; // Sliding Window size
var zip_STORED_BLOCK = 0;
var zip_STATIC_TREES = 1;
var zip_DYN_TREES = 2;
/* for deflate */
var zip_DEFAULT_LEVEL = 6;
var zip_FULL_SEARCH = true;
var zip_INBUFSIZ = 32768; // Input buffer size
var zip_INBUF_EXTRA = 64; // Extra buffer
var zip_OUTBUFSIZ = 1024 * 8;
var zip_window_size = 2 * zip_WSIZE;
var zip_MIN_MATCH = 3;
var zip_MAX_MATCH = 258;
var zip_BITS = 16;
// for SMALL_MEM
var zip_LIT_BUFSIZE = 0x2000;
var zip_HASH_BITS = 13;
// for MEDIUM_MEM
// var zip_LIT_BUFSIZE = 0x4000;
// var zip_HASH_BITS = 14;
// for BIG_MEM
// var zip_LIT_BUFSIZE = 0x8000;
// var zip_HASH_BITS = 15;
//if(zip_LIT_BUFSIZE > zip_INBUFSIZ)
// alert("error: zip_INBUFSIZ is too small");
//if((zip_WSIZE<<1) > (1<<zip_BITS))
// alert("error: zip_WSIZE is too large");
//if(zip_HASH_BITS > zip_BITS-1)
// alert("error: zip_HASH_BITS is too large");
//if(zip_HASH_BITS < 8 || zip_MAX_MATCH != 258)
// alert("error: Code too clever");
var zip_DIST_BUFSIZE = zip_LIT_BUFSIZE;
var zip_HASH_SIZE = 1 << zip_HASH_BITS;
var zip_HASH_MASK = zip_HASH_SIZE - 1;
var zip_WMASK = zip_WSIZE - 1;
var zip_NIL = 0; // Tail of hash chains
var zip_TOO_FAR = 4096;
var zip_MIN_LOOKAHEAD = zip_MAX_MATCH + zip_MIN_MATCH + 1;
var zip_MAX_DIST = zip_WSIZE - zip_MIN_LOOKAHEAD;
var zip_SMALLEST = 1;
var zip_MAX_BITS = 15;
var zip_MAX_BL_BITS = 7;
var zip_LENGTH_CODES = 29;
var zip_LITERALS = 256;
var zip_END_BLOCK = 256;
var zip_L_CODES = zip_LITERALS + 1 + zip_LENGTH_CODES;
var zip_D_CODES = 30;
var zip_BL_CODES = 19;
var zip_REP_3_6 = 16;
var zip_REPZ_3_10 = 17;
var zip_REPZ_11_138 = 18;
var zip_HEAP_SIZE = 2 * zip_L_CODES + 1;
var zip_H_SHIFT = parseInt((zip_HASH_BITS + zip_MIN_MATCH - 1) /
zip_MIN_MATCH);
/* variables */
var zip_free_queue;
var zip_qhead, zip_qtail;
var zip_initflag;
var zip_outbuf = null;
var zip_outcnt, zip_outoff;
var zip_complete;
var zip_window;
var zip_d_buf;
var zip_l_buf;
var zip_prev;
var zip_bi_buf;
var zip_bi_valid;
var zip_block_start;
var zip_ins_h;
var zip_hash_head;
var zip_prev_match;
var zip_match_available;
var zip_match_length;
var zip_prev_length;
var zip_strstart;
var zip_match_start;
var zip_eofile;
var zip_lookahead;
var zip_max_chain_length;
var zip_max_lazy_match;
var zip_compr_level;
var zip_good_match;
var zip_nice_match;
var zip_dyn_ltree;
var zip_dyn_dtree;
var zip_static_ltree;
var zip_static_dtree;
var zip_bl_tree;
var zip_l_desc;
var zip_d_desc;
var zip_bl_desc;
var zip_bl_count;
var zip_heap;
var zip_heap_len;
var zip_heap_max;
var zip_depth;
var zip_length_code;
var zip_dist_code;
var zip_base_length;
var zip_base_dist;
var zip_flag_buf;
var zip_last_lit;
var zip_last_dist;
var zip_last_flags;
var zip_flags;
var zip_flag_bit;
var zip_opt_len;
var zip_static_len;
var zip_deflate_data;
var zip_deflate_pos;
/* objects (deflate) */
function zip_DeflateCT() {
this.fc = 0; // frequency count or bit string
this.dl = 0; // father node in Huffman tree or length of bit string
}
function zip_DeflateTreeDesc() {
this.dyn_tree = null; // the dynamic tree
this.static_tree = null; // corresponding static tree or NULL
this.extra_bits = null; // extra bits for each code or NULL
this.extra_base = 0; // base index for extra_bits
this.elems = 0; // max number of elements in the tree
this.max_length = 0; // max bit length for the codes
this.max_code = 0; // largest code with non zero frequency
}
/* Values for max_lazy_match, good_match and max_chain_length, depending on
* the desired pack level (0..9). The values given below have been tuned to
* exclude worst case performance for pathological files. Better values may be
* found for specific files.
*/
function zip_DeflateConfiguration(a, b, c, d) {
this.good_length = a; // reduce lazy search above this match length
this.max_lazy = b; // do not perform lazy search above this match length
this.nice_length = c; // quit search above this match length
this.max_chain = d;
}
function zip_DeflateBuffer() {
this.next = null;
this.len = 0;
this.ptr = new Array(zip_OUTBUFSIZ);
this.off = 0;
}
/* constant tables */
var zip_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];
var zip_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];
var zip_extra_blbits = [
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 3, 7];
var zip_bl_order = [16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15];
var zip_configuration_table = [
new zip_DeflateConfiguration(0, 0, 0, 0),
new zip_DeflateConfiguration(4, 4, 8, 4),
new zip_DeflateConfiguration(4, 5, 16, 8),
new zip_DeflateConfiguration(4, 6, 32, 32),
new zip_DeflateConfiguration(4, 4, 16, 16),
new zip_DeflateConfiguration(8, 16, 32, 32),
new zip_DeflateConfiguration(8, 16, 128, 128),
new zip_DeflateConfiguration(8, 32, 128, 256),
new zip_DeflateConfiguration(32, 128, 258, 1024),
new zip_DeflateConfiguration(32, 258, 258, 4096)];
/* routines (deflate) */
function zip_deflate_start(level) {
var i;
if (!level)
level = zip_DEFAULT_LEVEL;
else if (level < 1)
level = 1;
else if (level > 9)
level = 9;
zip_compr_level = level;
zip_initflag = false;
zip_eofile = false;
if (zip_outbuf != null)
return;
zip_free_queue = zip_qhead = zip_qtail = null;
zip_outbuf = new Array(zip_OUTBUFSIZ);
zip_window = new Array(zip_window_size);
zip_d_buf = new Array(zip_DIST_BUFSIZE);
zip_l_buf = new Array(zip_INBUFSIZ + zip_INBUF_EXTRA);
zip_prev = new Array(1 << zip_BITS);
zip_dyn_ltree = new Array(zip_HEAP_SIZE);
for (i = 0; i < zip_HEAP_SIZE; i++)
zip_dyn_ltree[i] = new zip_DeflateCT();
zip_dyn_dtree = new Array(2 * zip_D_CODES + 1);
for (i = 0; i < 2 * zip_D_CODES + 1; i++)
zip_dyn_dtree[i] = new zip_DeflateCT();
zip_static_ltree = new Array(zip_L_CODES + 2);
for (i = 0; i < zip_L_CODES + 2; i++)
zip_static_ltree[i] = new zip_DeflateCT();
zip_static_dtree = new Array(zip_D_CODES);
for (i = 0; i < zip_D_CODES; i++)
zip_static_dtree[i] = new zip_DeflateCT();
zip_bl_tree = new Array(2 * zip_BL_CODES + 1);
for (i = 0; i < 2 * zip_BL_CODES + 1; i++)
zip_bl_tree[i] = new zip_DeflateCT();
zip_l_desc = new zip_DeflateTreeDesc();
zip_d_desc = new zip_DeflateTreeDesc();
zip_bl_desc = new zip_DeflateTreeDesc();
zip_bl_count = new Array(zip_MAX_BITS + 1);
zip_heap = new Array(2 * zip_L_CODES + 1);
zip_depth = new Array(2 * zip_L_CODES + 1);
zip_length_code = new Array(zip_MAX_MATCH - zip_MIN_MATCH + 1);
zip_dist_code = new Array(512);
zip_base_length = new Array(zip_LENGTH_CODES);
zip_base_dist = new Array(zip_D_CODES);
zip_flag_buf = new Array(parseInt(zip_LIT_BUFSIZE / 8));
}
function zip_deflate_end() {
zip_free_queue = zip_qhead = zip_qtail = null;
zip_outbuf = null;
zip_window = null;
zip_d_buf = null;
zip_l_buf = null;
zip_prev = null;
zip_dyn_ltree = null;
zip_dyn_dtree = null;
zip_static_ltree = null;
zip_static_dtree = null;
zip_bl_tree = null;
zip_l_desc = null;
zip_d_desc = null;
zip_bl_desc = null;
zip_bl_count = null;
zip_heap = null;
zip_depth = null;
zip_length_code = null;
zip_dist_code = null;
zip_base_length = null;
zip_base_dist = null;
zip_flag_buf = null;
}
function zip_reuse_queue(p) {
p.next = zip_free_queue;
zip_free_queue = p;
}
function zip_new_queue() {
var p;
if (zip_free_queue != null) {
p = zip_free_queue;
zip_free_queue = zip_free_queue.next;
}
else
p = new zip_DeflateBuffer();
p.next = null;
p.len = p.off = 0;
return p;
}
function zip_head1(i) {
return zip_prev[zip_WSIZE + i];
}
function zip_head2(i, val) {
return zip_prev[zip_WSIZE + i] = val;
}
/* put_byte is used for the compressed output, put_ubyte for the
* uncompressed output. However unlzw() uses window for its
* suffix table instead of its output buffer, so it does not use put_ubyte
* (to be cleaned up).
*/
function zip_put_byte(c) {
zip_outbuf[zip_outoff + zip_outcnt++] = c;
if (zip_outoff + zip_outcnt == zip_OUTBUFSIZ)
zip_qoutbuf();
}
/* Output a 16 bit value, lsb first */
function zip_put_short(w) {
w &= 0xffff;
if (zip_outoff + zip_outcnt < zip_OUTBUFSIZ - 2) {
zip_outbuf[zip_outoff + zip_outcnt++] = (w & 0xff);
zip_outbuf[zip_outoff + zip_outcnt++] = (w >>> 8);
} else {
zip_put_byte(w & 0xff);
zip_put_byte(w >>> 8);
}
}
/* ==========================================================================
* Insert string s in the dictionary and set match_head to the previous head
* of the hash chain (the most recent string with same hash key). Return
* the previous length of the hash chain.
* IN assertion: all calls to to INSERT_STRING are made with consecutive
* input characters and the first MIN_MATCH bytes of s are valid
* (except for the last MIN_MATCH-1 bytes of the input file).
*/
function zip_INSERT_STRING() {
zip_ins_h = ((zip_ins_h << zip_H_SHIFT)
^ (zip_window[zip_strstart + zip_MIN_MATCH - 1] & 0xff))
& zip_HASH_MASK;
zip_hash_head = zip_head1(zip_ins_h);
zip_prev[zip_strstart & zip_WMASK] = zip_hash_head;
zip_head2(zip_ins_h, zip_strstart);
}
/* Send a code of the given tree. c and tree must not have side effects */
function zip_SEND_CODE(c, tree) {
zip_send_bits(tree[c].fc, tree[c].dl);
}
/* 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.
*/
function zip_D_CODE(dist) {
return (dist < 256 ? zip_dist_code[dist]
: zip_dist_code[256 + (dist >> 7)]) & 0xff;
}
/* ==========================================================================
* Compares to subtrees, using the tree depth as tie breaker when
* the subtrees have equal frequency. This minimizes the worst case length.
*/
function zip_SMALLER(tree, n, m) {
return tree[n].fc < tree[m].fc ||
(tree[n].fc == tree[m].fc && zip_depth[n] <= zip_depth[m]);
}
/* ==========================================================================
* read string data
*/
function zip_read_buff(buff, offset, n) {
var i;
for (i = 0; i < n && zip_deflate_pos < zip_deflate_data.length; i++)
buff[offset + i] =
zip_deflate_data.charCodeAt(zip_deflate_pos++) & 0xff;
return i;
}
/* ==========================================================================
* Initialize the "longest match" routines for a new file
*/
function zip_lm_init() {
var j;
/* Initialize the hash table. */
for (j = 0; j < zip_HASH_SIZE; j++)
// zip_head2(j, zip_NIL);
zip_prev[zip_WSIZE + j] = 0;
/* prev will be initialized on the fly */
/* Set the default configuration parameters:
*/
zip_max_lazy_match = zip_configuration_table[zip_compr_level].max_lazy;
zip_good_match = zip_configuration_table[zip_compr_level].good_length;
if (!zip_FULL_SEARCH)
zip_nice_match = zip_configuration_table[zip_compr_level].nice_length;
zip_max_chain_length = zip_configuration_table[zip_compr_level].max_chain;
zip_strstart = 0;
zip_block_start = 0;
zip_lookahead = zip_read_buff(zip_window, 0, 2 * zip_WSIZE);
if (zip_lookahead <= 0) {
zip_eofile = true;
zip_lookahead = 0;
return;
}
zip_eofile = false;
/* Make sure that we always have enough lookahead. This is important
* if input comes from a device such as a tty.
*/
while (zip_lookahead < zip_MIN_LOOKAHEAD && !zip_eofile)
zip_fill_window();
/* If lookahead < MIN_MATCH, ins_h is garbage, but this is
* not important since only literal bytes will be emitted.
*/
zip_ins_h = 0;
for (j = 0; j < zip_MIN_MATCH - 1; j++) {
// UPDATE_HASH(ins_h, window[j]);
zip_ins_h = ((zip_ins_h << zip_H_SHIFT) ^ (zip_window[j] & 0xff)) & zip_HASH_MASK;
}
}
/* ==========================================================================
* Set match_start to the longest match starting at the given string and
* return its length. Matches shorter or equal to prev_length are discarded,
* in which case the result is equal to prev_length and match_start is
* garbage.
* IN assertions: cur_match is the head of the hash chain for the current
* string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
*/
function zip_longest_match(cur_match) {
var chain_length = zip_max_chain_length; // max hash chain length
var scanp = zip_strstart; // current string
var matchp; // matched string
var len; // length of current match
var best_len = zip_prev_length; // best match length so far
/* Stop when cur_match becomes <= limit. To simplify the code,
* we prevent matches with the string of window index 0.
*/
var limit = (zip_strstart > zip_MAX_DIST ? zip_strstart - zip_MAX_DIST : zip_NIL);
var strendp = zip_strstart + zip_MAX_MATCH;
var scan_end1 = zip_window[scanp + best_len - 1];
var scan_end = zip_window[scanp + best_len];
/* Do not waste too much time if we already have a good match: */
if (zip_prev_length >= zip_good_match)
chain_length >>= 2;
// Assert(encoder->strstart <= window_size-MIN_LOOKAHEAD, "insufficient lookahead");
do {
// Assert(cur_match < encoder->strstart, "no future");
matchp = cur_match;
/* Skip to next match if the match length cannot increase
* or if the match length is less than 2:
*/
if (zip_window[matchp + best_len] != scan_end ||
zip_window[matchp + best_len - 1] != scan_end1 ||
zip_window[matchp] != zip_window[scanp] ||
zip_window[++matchp] != zip_window[scanp + 1]) {
continue;
}
/* The check at best_len-1 can be removed because it will be made
* again later. (This heuristic is not always a win.)
* It is not necessary to compare scan[2] and match[2] since they
* are always equal when the other bytes match, given that
* the hash keys are equal and that HASH_BITS >= 8.
*/
scanp += 2;
matchp++;
/* We check for insufficient lookahead only every 8th comparison;
* the 256th check will be made at strstart+258.
*/
do {
} while (zip_window[++scanp] == zip_window[++matchp] &&
zip_window[++scanp] == zip_window[++matchp] &&
zip_window[++scanp] == zip_window[++matchp] &&
zip_window[++scanp] == zip_window[++matchp] &&
zip_window[++scanp] == zip_window[++matchp] &&
zip_window[++scanp] == zip_window[++matchp] &&
zip_window[++scanp] == zip_window[++matchp] &&
zip_window[++scanp] == zip_window[++matchp] &&
scanp < strendp);
len = zip_MAX_MATCH - (strendp - scanp);
scanp = strendp - zip_MAX_MATCH;
if (len > best_len) {
zip_match_start = cur_match;
best_len = len;
if (zip_FULL_SEARCH) {
if (len >= zip_MAX_MATCH) break;
} else {
if (len >= zip_nice_match) break;
}
scan_end1 = zip_window[scanp + best_len - 1];
scan_end = zip_window[scanp + best_len];
}
} while ((cur_match = zip_prev[cur_match & zip_WMASK]) > limit
&& --chain_length != 0);
return best_len;
}
/* ==========================================================================
* Fill the window when the lookahead becomes insufficient.
* Updates strstart and lookahead, and sets eofile if end of input file.
* IN assertion: lookahead < MIN_LOOKAHEAD && strstart + lookahead > 0
* OUT assertions: at least one byte has been read, or eofile is set;
* file reads are performed for at least two bytes (required for the
* translate_eol option).
*/
function zip_fill_window() {
var n, m;
// Amount of free space at the end of the window.
var more = zip_window_size - zip_lookahead - zip_strstart;
/* If the window is almost full and there is insufficient lookahead,
* move the upper half to the lower one to make room in the upper half.
*/
if (more == -1) {
/* Very unlikely, but possible on 16 bit machine if strstart == 0
* and lookahead == 1 (input done one byte at time)
*/
more--;
} else if (zip_strstart >= zip_WSIZE + zip_MAX_DIST) {
/* By the IN assertion, the window is not empty so we can't confuse
* more == 0 with more == 64K on a 16 bit machine.
*/
// Assert(window_size == (ulg)2*WSIZE, "no sliding with BIG_MEM");
// System.arraycopy(window, WSIZE, window, 0, WSIZE);
for (n = 0; n < zip_WSIZE; n++)
zip_window[n] = zip_window[n + zip_WSIZE];
zip_match_start -= zip_WSIZE;
zip_strstart -= zip_WSIZE; /* we now have strstart >= MAX_DIST: */
zip_block_start -= zip_WSIZE;
for (n = 0; n < zip_HASH_SIZE; n++) {
m = zip_head1(n);
zip_head2(n, m >= zip_WSIZE ? m - zip_WSIZE : zip_NIL);
}
for (n = 0; n < zip_WSIZE; n++) {
/* If n is not on any hash chain, prev[n] is garbage but
* its value will never be used.
*/
m = zip_prev[n];
zip_prev[n] = (m >= zip_WSIZE ? m - zip_WSIZE : zip_NIL);
}
more += zip_WSIZE;
}
// At this point, more >= 2
if (!zip_eofile) {
n = zip_read_buff(zip_window, zip_strstart + zip_lookahead, more);
if (n <= 0)
zip_eofile = true;
else
zip_lookahead += n;
}
}
/* ==========================================================================
* Processes a new input file and return its compressed length. This
* function does not perform lazy evaluationof matches and inserts
* new strings in the dictionary only for unmatched strings or for short
* matches. It is used only for the fast compression options.
*/
function zip_deflate_fast() {
while (zip_lookahead != 0 && zip_qhead == null) {
var flush; // set if current block must be flushed
/* Insert the string window[strstart .. strstart+2] in the
* dictionary, and set hash_head to the head of the hash chain:
*/
zip_INSERT_STRING();
/* Find the longest match, discarding those <= prev_length.
* At this point we have always match_length < MIN_MATCH
*/
if (zip_hash_head != zip_NIL &&
zip_strstart - zip_hash_head <= zip_MAX_DIST) {
/* To simplify the code, we prevent matches with the string
* of window index 0 (in particular we have to avoid a match
* of the string with itself at the start of the input file).
*/
zip_match_length = zip_longest_match(zip_hash_head);
/* longest_match() sets match_start */
if (zip_match_length > zip_lookahead)
zip_match_length = zip_lookahead;
}
if (zip_match_length >= zip_MIN_MATCH) {
// check_match(strstart, match_start, match_length);
flush = zip_ct_tally(zip_strstart - zip_match_start,
zip_match_length - zip_MIN_MATCH);
zip_lookahead -= zip_match_length;
/* Insert new strings in the hash table only if the match length
* is not too large. This saves time but degrades compression.
*/
if (zip_match_length <= zip_max_lazy_match) {
zip_match_length--; // string at strstart already in hash table
do {
zip_strstart++;
zip_INSERT_STRING();
/* strstart never exceeds WSIZE-MAX_MATCH, so there are
* always MIN_MATCH bytes ahead. If lookahead < MIN_MATCH
* these bytes are garbage, but it does not matter since
* the next lookahead bytes will be emitted as literals.
*/
} while (--zip_match_length != 0);
zip_strstart++;
} else {
zip_strstart += zip_match_length;
zip_match_length = 0;
zip_ins_h = zip_window[zip_strstart] & 0xff;
// UPDATE_HASH(ins_h, window[strstart + 1]);
zip_ins_h = ((zip_ins_h << zip_H_SHIFT) ^ (zip_window[zip_strstart + 1] & 0xff)) & zip_HASH_MASK;
//#if MIN_MATCH != 3
// Call UPDATE_HASH() MIN_MATCH-3 more times
//#endif
}
} else {
/* No match, output a literal byte */
flush = zip_ct_tally(0, zip_window[zip_strstart] & 0xff);
zip_lookahead--;
zip_strstart++;
}
if (flush) {
zip_flush_block(0);
zip_block_start = zip_strstart;
}
/* Make sure that we always have enough lookahead, except
* at the end of the input file. We need MAX_MATCH bytes
* for the next match, plus MIN_MATCH bytes to insert the
* string following the next match.
*/
while (zip_lookahead < zip_MIN_LOOKAHEAD && !zip_eofile)
zip_fill_window();
}
}
function zip_deflate_better() {
/* Process the input block. */
while (zip_lookahead != 0 && zip_qhead == null) {
/* Insert the string window[strstart .. strstart+2] in the
* dictionary, and set hash_head to the head of the hash chain:
*/
zip_INSERT_STRING();
/* Find the longest match, discarding those <= prev_length.
*/
zip_prev_length = zip_match_length;
zip_prev_match = zip_match_start;
zip_match_length = zip_MIN_MATCH - 1;
if (zip_hash_head != zip_NIL &&
zip_prev_length < zip_max_lazy_match &&
zip_strstart - zip_hash_head <= zip_MAX_DIST) {
/* To simplify the code, we prevent matches with the string
* of window index 0 (in particular we have to avoid a match
* of the string with itself at the start of the input file).
*/
zip_match_length = zip_longest_match(zip_hash_head);
/* longest_match() sets match_start */
if (zip_match_length > zip_lookahead)
zip_match_length = zip_lookahead;
/* Ignore a length 3 match if it is too distant: */
if (zip_match_length == zip_MIN_MATCH &&
zip_strstart - zip_match_start > zip_TOO_FAR) {
/* If prev_match is also MIN_MATCH, match_start is garbage
* but we will ignore the current match anyway.
*/
zip_match_length--;
}
}
/* If there was a match at the previous step and the current
* match is not better, output the previous match:
*/
if (zip_prev_length >= zip_MIN_MATCH &&
zip_match_length <= zip_prev_length) {
var flush; // set if current block must be flushed
// check_match(strstart - 1, prev_match, prev_length);
flush = zip_ct_tally(zip_strstart - 1 - zip_prev_match,
zip_prev_length - zip_MIN_MATCH);
/* Insert in hash table all strings up to the end of the match.
* strstart-1 and strstart are already inserted.
*/
zip_lookahead -= zip_prev_length - 1;
zip_prev_length -= 2;
do {
zip_strstart++;
zip_INSERT_STRING();
/* strstart never exceeds WSIZE-MAX_MATCH, so there are
* always MIN_MATCH bytes ahead. If lookahead < MIN_MATCH
* these bytes are garbage, but it does not matter since the
* next lookahead bytes will always be emitted as literals.
*/
} while (--zip_prev_length != 0);
zip_match_available = 0;
zip_match_length = zip_MIN_MATCH - 1;
zip_strstart++;
if (flush) {
zip_flush_block(0);
zip_block_start = zip_strstart;
}
} else if (zip_match_available != 0) {
/* If there was no match at the previous position, output a
* single literal. If there was a match but the current match
* is longer, truncate the previous match to a single literal.
*/
if (zip_ct_tally(0, zip_window[zip_strstart - 1] & 0xff)) {
zip_flush_block(0);
zip_block_start = zip_strstart;
}
zip_strstart++;
zip_lookahead--;
} else {
/* There is no previous match to compare with, wait for
* the next step to decide.
*/
zip_match_available = 1;
zip_strstart++;
zip_lookahead--;
}
/* Make sure that we always have enough lookahead, except
* at the end of the input file. We need MAX_MATCH bytes
* for the next match, plus MIN_MATCH bytes to insert the
* string following the next match.
*/
while (zip_lookahead < zip_MIN_LOOKAHEAD && !zip_eofile)
zip_fill_window();
}
}
function zip_init_deflate() {
if (zip_eofile)
return;
zip_bi_buf = 0;
zip_bi_valid = 0;
zip_ct_init();
zip_lm_init();
zip_qhead = null;
zip_outcnt = 0;
zip_outoff = 0;
if (zip_compr_level <= 3) {
zip_prev_length = zip_MIN_MATCH - 1;
zip_match_length = 0;
}
else {
zip_match_length = zip_MIN_MATCH - 1;
zip_match_available = 0;
}
zip_complete = false;
}
/* ==========================================================================
* Same as above, but achieves better compression. We use a lazy
* evaluation for matches: a match is finally adopted only if there is
* no better match at the next window position.
*/
function zip_deflate_internal(buff, off, buff_size) {
var n;
if (!zip_initflag) {
zip_init_deflate();
zip_initflag = true;
if (zip_lookahead == 0) { // empty
zip_complete = true;
return 0;
}
}
if ((n = zip_qcopy(buff, off, buff_size)) == buff_size)
return buff_size;
if (zip_complete)
return n;
if (zip_compr_level <= 3) // optimized for speed
zip_deflate_fast();
else
zip_deflate_better();
if (zip_lookahead == 0) {
if (zip_match_available != 0)
zip_ct_tally(0, zip_window[zip_strstart - 1] & 0xff);
zip_flush_block(1);
zip_complete = true;
}
return n + zip_qcopy(buff, n + off, buff_size - n);
}
function zip_qcopy(buff, off, buff_size) {
var n, i, j;
n = 0;
while (zip_qhead != null && n < buff_size) {
i = buff_size - n;
if (i > zip_qhead.len)
i = zip_qhead.len;
// System.arraycopy(qhead.ptr, qhead.off, buff, off + n, i);
for (j = 0; j < i; j++)
buff[off + n + j] = zip_qhead.ptr[zip_qhead.off + j];
zip_qhead.off += i;
zip_qhead.len -= i;
n += i;
if (zip_qhead.len == 0) {
var p;
p = zip_qhead;
zip_qhead = zip_qhead.next;
zip_reuse_queue(p);
}
}
if (n == buff_size)
return n;
if (zip_outoff < zip_outcnt) {
i = buff_size - n;
if (i > zip_outcnt - zip_outoff)
i = zip_outcnt - zip_outoff;
// System.arraycopy(outbuf, outoff, buff, off + n, i);
for (j = 0; j < i; j++)
buff[off + n + j] = zip_outbuf[zip_outoff + j];
zip_outoff += i;
n += i;
if (zip_outcnt == zip_outoff)
zip_outcnt = zip_outoff = 0;
}
return n;
}
/* ==========================================================================
* Allocate the match buffer, initialize the various tables and save the
* location of the internal file attribute (ascii/binary) and method
* (DEFLATE/STORE).
*/
function zip_ct_init() {
var n; // iterates over tree elements
var bits; // bit counter
var length; // length value
var code; // code value
var dist; // distance index
if (zip_static_dtree[0].dl != 0) return; // ct_init already called
zip_l_desc.dyn_tree = zip_dyn_ltree;
zip_l_desc.static_tree = zip_static_ltree;
zip_l_desc.extra_bits = zip_extra_lbits;
zip_l_desc.extra_base = zip_LITERALS + 1;
zip_l_desc.elems = zip_L_CODES;
zip_l_desc.max_length = zip_MAX_BITS;
zip_l_desc.max_code = 0;
zip_d_desc.dyn_tree = zip_dyn_dtree;
zip_d_desc.static_tree = zip_static_dtree;
zip_d_desc.extra_bits = zip_extra_dbits;
zip_d_desc.extra_base = 0;
zip_d_desc.elems = zip_D_CODES;
zip_d_desc.max_length = zip_MAX_BITS;
zip_d_desc.max_code = 0;
zip_bl_desc.dyn_tree = zip_bl_tree;
zip_bl_desc.static_tree = null;
zip_bl_desc.extra_bits = zip_extra_blbits;
zip_bl_desc.extra_base = 0;
zip_bl_desc.elems = zip_BL_CODES;
zip_bl_desc.max_length = zip_MAX_BL_BITS;
zip_bl_desc.max_code = 0;
// Initialize the mapping length (0..255) -> length code (0..28)
length = 0;
for (code = 0; code < zip_LENGTH_CODES - 1; code++) {
zip_base_length[code] = length;
for (n = 0; n < (1 << zip_extra_lbits[code]); n++)
zip_length_code[length++] = code;
}
// Assert (length == 256, "ct_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:
*/
zip_length_code[length - 1] = code;
/* Initialize the mapping dist (0..32K) -> dist code (0..29) */
dist = 0;
for (code = 0; code < 16; code++) {
zip_base_dist[code] = dist;
for (n = 0; n < (1 << zip_extra_dbits[code]); n++) {
zip_dist_code[dist++] = code;
}
}
// Assert (dist == 256, "ct_init: dist != 256");
dist >>= 7; // from now on, all distances are divided by 128
for (; code < zip_D_CODES; code++) {
zip_base_dist[code] = dist << 7;
for (n = 0; n < (1 << (zip_extra_dbits[code] - 7)); n++)
zip_dist_code[256 + dist++] = code;
}
// Assert (dist == 256, "ct_init: 256+dist != 512");
// Construct the codes of the static literal tree
for (bits = 0; bits <= zip_MAX_BITS; bits++)
zip_bl_count[bits] = 0;
n = 0;
while (n <= 143) { zip_static_ltree[n++].dl = 8; zip_bl_count[8]++; }
while (n <= 255) { zip_static_ltree[n++].dl = 9; zip_bl_count[9]++; }
while (n <= 279) { zip_static_ltree[n++].dl = 7; zip_bl_count[7]++; }
while (n <= 287) { zip_static_ltree[n++].dl = 8; zip_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)
*/
zip_gen_codes(zip_static_ltree, zip_L_CODES + 1);
/* The static distance tree is trivial: */
for (n = 0; n < zip_D_CODES; n++) {
zip_static_dtree[n].dl = 5;
zip_static_dtree[n].fc = zip_bi_reverse(n, 5);
}
// Initialize the first block of the first file:
zip_init_block();
}
/* ==========================================================================
* Initialize a new block.
*/
function zip_init_block() {
var n; // iterates over tree elements
// Initialize the trees.
for (n = 0; n < zip_L_CODES; n++) zip_dyn_ltree[n].fc = 0;
for (n = 0; n < zip_D_CODES; n++) zip_dyn_dtree[n].fc = 0;
for (n = 0; n < zip_BL_CODES; n++) zip_bl_tree[n].fc = 0;
zip_dyn_ltree[zip_END_BLOCK].fc = 1;
zip_opt_len = zip_static_len = 0;
zip_last_lit = zip_last_dist = zip_last_flags = 0;
zip_flags = 0;
zip_flag_bit = 1;
}
/* ==========================================================================
* Restore the heap property by moving down the tree starting at node k,
* exchanging a node with the smallest of its two sons if necessary, stopping
* when the heap property is re-established (each father smaller than its
* two sons).
*/
function zip_pqdownheap(
tree, // the tree to restore
k) { // node to move down
var v = zip_heap[k];
var j = k << 1; // left son of k
while (j <= zip_heap_len) {
// Set j to the smallest of the two sons:
if (j < zip_heap_len &&
zip_SMALLER(tree, zip_heap[j + 1], zip_heap[j]))
j++;
// Exit if v is smaller than both sons
if (zip_SMALLER(tree, v, zip_heap[j]))
break;
// Exchange v with the smallest son
zip_heap[k] = zip_heap[j];
k = j;
// And continue down the tree, setting j to the left son of k
j <<= 1;
}
zip_heap[k] = v;
}
/* ==========================================================================
* 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 zip_gen_bitlen(desc) { // the tree descriptor
var tree = desc.dyn_tree;
var extra = desc.extra_bits;
var base = desc.extra_base;
var max_code = desc.max_code;
var max_length = desc.max_length;
var stree = desc.static_tree;
var h; // heap index
var n, m; // iterate over the tree elements
var bits; // bit length
var xbits; // extra bits
var f; // frequency
var overflow = 0; // number of elements with bit length too large
for (bits = 0; bits <= zip_MAX_BITS; bits++)
zip_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[zip_heap[zip_heap_max]].dl = 0; // root of the heap
for (h = zip_heap_max + 1; h < zip_HEAP_SIZE; h++) {
n = zip_heap[h];
bits = tree[tree[n].dl].dl + 1;
if (bits > max_length) {
bits = max_length;
overflow++;
}
tree[n].dl = bits;
// We overwrite tree[n].dl which is no longer needed
if (n > max_code)
continue; // not a leaf node
zip_bl_count[bits]++;
xbits = 0;
if (n >= base)
xbits = extra[n - base];
f = tree[n].fc;
zip_opt_len += f * (bits + xbits);
if (stree != null)
zip_static_len += f * (stree[n].dl + 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 (zip_bl_count[bits] == 0)
bits--;
zip_bl_count[bits]--; // move one leaf down the tree
zip_bl_count[bits + 1] += 2; // move one overflow item as its brother
zip_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 = zip_bl_count[bits];
while (n != 0) {
m = zip_heap[--h];
if (m > max_code)
continue;
if (tree[m].dl != bits) {
zip_opt_len += (bits - tree[m].dl) * tree[m].fc;
tree[m].fc = bits;
}
n--;
}
}
}
/* ==========================================================================
* Generate the codes for a given tree and bit counts (which need not be
* optimal).
* IN assertion: the array bl_count contains the bit length statistics for
* the given tree and the field len is set for all tree elements.
* OUT assertion: the field code is set for all tree elements of non
* zero code length.
*/
function zip_gen_codes(tree, // the tree to decorate
max_code) { // largest code with non zero frequency
var next_code = new Array(zip_MAX_BITS + 1); // next code value for each bit length
var code = 0; // running code value
var bits; // bit index
var n; // code index
/* The distribution counts are first used to generate the code values
* without bit reversal.
*/
for (bits = 1; bits <= zip_MAX_BITS; bits++) {
code = ((code + zip_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 + encoder->bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1,
// "inconsistent bit counts");
// Tracev((stderr,"\ngen_codes: max_code %d ", max_code));
for (n = 0; n <= max_code; n++) {
var len = tree[n].dl;
if (len == 0)
continue;
// Now reverse the bits
tree[n].fc = zip_bi_reverse(next_code[len]++, len);
// Tracec(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ",
// n, (isgraph(n) ? n : ' '), len, tree[n].fc, next_code[len]-1));
}
}
/* ==========================================================================
* Construct one Huffman tree and assigns the code bit strings and lengths.
* Update the total bit length for the current block.
* IN assertion: the field freq is set for all tree elements.
* OUT assertions: the fields len and code are set to the optimal bit length
* and corresponding code. The length opt_len is updated; static_len is
* also updated if stree is not null. The field max_code is set.
*/
function zip_build_tree(desc) { // the tree descriptor
var tree = desc.dyn_tree;
var stree = desc.static_tree;
var elems = desc.elems;
var n, m; // iterate over heap elements
var max_code = -1; // largest code with non zero frequency
var node = elems; // next internal node of the tree
/* 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.
*/
zip_heap_len = 0;
zip_heap_max = zip_HEAP_SIZE;
for (n = 0; n < elems; n++) {
if (tree[n].fc != 0) {
zip_heap[++zip_heap_len] = max_code = n;
zip_depth[n] = 0;
} else
tree[n].dl = 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 (zip_heap_len < 2) {
var xnew = zip_heap[++zip_heap_len] = (max_code < 2 ? ++max_code : 0);
tree[xnew].fc = 1;
zip_depth[xnew] = 0;
zip_opt_len--;
if (stree != null)
zip_static_len -= stree[xnew].dl;
// new 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 = zip_heap_len >> 1; n >= 1; n--)
zip_pqdownheap(tree, n);
/* Construct the Huffman tree by repeatedly combining the least two
* frequent nodes.
*/
do {
n = zip_heap[zip_SMALLEST];
zip_heap[zip_SMALLEST] = zip_heap[zip_heap_len--];
zip_pqdownheap(tree, zip_SMALLEST);
m = zip_heap[zip_SMALLEST]; // m = node of next least frequency
// keep the nodes sorted by frequency
zip_heap[--zip_heap_max] = n;
zip_heap[--zip_heap_max] = m;
// Create a new node father of n and m
tree[node].fc = tree[n].fc + tree[m].fc;
// depth[node] = (char)(MAX(depth[n], depth[m]) + 1);
if (zip_depth[n] > zip_depth[m] + 1)
zip_depth[node] = zip_depth[n];
else
zip_depth[node] = zip_depth[m] + 1;
tree[n].dl = tree[m].dl = node;
// and insert the new node in the heap
zip_heap[zip_SMALLEST] = node++;
zip_pqdownheap(tree, zip_SMALLEST);
} while (zip_heap_len >= 2);
zip_heap[--zip_heap_max] = zip_heap[zip_SMALLEST];
/* At this point, the fields freq and dad are set. We can now
* generate the bit lengths.
*/
zip_gen_bitlen(desc);
// The field len is now set, we can generate the bit codes
zip_gen_codes(tree, max_code);
}
/* ==========================================================================
* Scan a literal or distance tree to determine the frequencies of the codes
* in the bit length tree. Updates opt_len to take into account the repeat
* counts. (The contribution of the bit length codes will be added later
* during the construction of bl_tree.)
*/
function zip_scan_tree(tree,// the tree to be scanned
max_code) { // and its largest code of non zero frequency
var n; // iterates over all tree elements
var prevlen = -1; // last emitted length
var curlen; // length of current code
var nextlen = tree[0].dl; // length of next code
var count = 0; // repeat count of the current code
var max_count = 7; // max repeat count
var min_count = 4; // min repeat count
if (nextlen == 0) {
max_count = 138;
min_count = 3;
}
tree[max_code + 1].dl = 0xffff; // guard
for (n = 0; n <= max_code; n++) {
curlen = nextlen;
nextlen = tree[n + 1].dl;
if (++count < max_count && curlen == nextlen)
continue;
else if (count < min_count)
zip_bl_tree[curlen].fc += count;
else if (curlen != 0) {
if (curlen != prevlen)
zip_bl_tree[curlen].fc++;
zip_bl_tree[zip_REP_3_6].fc++;
} else if (count <= 10)
zip_bl_tree[zip_REPZ_3_10].fc++;
else
zip_bl_tree[zip_REPZ_11_138].fc++;
count = 0; prevlen = curlen;
if (nextlen == 0) {
max_count = 138;
min_count = 3;
} else if (curlen == nextlen) {
max_count = 6;
min_count = 3;
} else {
max_count = 7;
min_count = 4;
}
}
}
/* ==========================================================================
* Send a literal or distance tree in compressed form, using the codes in
* bl_tree.
*/
function zip_send_tree(tree, // the tree to be scanned
max_code) { // and its largest code of non zero frequency
var n; // iterates over all tree elements
var prevlen = -1; // last emitted length
var curlen; // length of current code
var nextlen = tree[0].dl; // length of next code
var count = 0; // repeat count of the current code
var max_count = 7; // max repeat count
var min_count = 4; // min repeat count
/* tree[max_code+1].dl = -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].dl;
if (++count < max_count && curlen == nextlen) {
continue;
} else if (count < min_count) {
do { zip_SEND_CODE(curlen, zip_bl_tree); } while (--count != 0);
} else if (curlen != 0) {
if (curlen != prevlen) {
zip_SEND_CODE(curlen, zip_bl_tree);
count--;
}
// Assert(count >= 3 && count <= 6, " 3_6?");
zip_SEND_CODE(zip_REP_3_6, zip_bl_tree);
zip_send_bits(count - 3, 2);
} else if (count <= 10) {
zip_SEND_CODE(zip_REPZ_3_10, zip_bl_tree);
zip_send_bits(count - 3, 3);
} else {
zip_SEND_CODE(zip_REPZ_11_138, zip_bl_tree);
zip_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;
}
}
}
/* ==========================================================================
* Construct the Huffman tree for the bit lengths and return the index in
* bl_order of the last bit length code to send.
*/
function zip_build_bl_tree() {
var max_blindex; // index of last bit length code of non zero freq
// Determine the bit length frequencies for literal and distance trees
zip_scan_tree(zip_dyn_ltree, zip_l_desc.max_code);
zip_scan_tree(zip_dyn_dtree, zip_d_desc.max_code);
// Build the bit length tree:
zip_build_tree(zip_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 = zip_BL_CODES - 1; max_blindex >= 3; max_blindex--) {
if (zip_bl_tree[zip_bl_order[max_blindex]].dl != 0) break;
}
/* Update opt_len to include the bit length tree and counts */
zip_opt_len += 3 * (max_blindex + 1) + 5 + 5 + 4;
// Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld",
// encoder->opt_len, encoder->static_len));
return max_blindex;
}
/* ==========================================================================
* Send the header for a block using dynamic Huffman trees: the counts, the
* lengths of the bit length codes, the literal tree and the distance tree.
* IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
*/
function zip_send_all_trees(lcodes, dcodes, blcodes) { // number of codes for each tree
var rank; // index in bl_order
// Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");
// Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES,
// "too many codes");
// Tracev((stderr, "\nbl counts: "));
zip_send_bits(lcodes - 257, 5); // not +255 as stated in appnote.txt
zip_send_bits(dcodes - 1, 5);
zip_send_bits(blcodes - 4, 4); // not -3 as stated in appnote.txt
for (rank = 0; rank < blcodes; rank++) {
// Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
zip_send_bits(zip_bl_tree[zip_bl_order[rank]].dl, 3);
}
// send the literal tree
zip_send_tree(zip_dyn_ltree, lcodes - 1);
// send the distance tree
zip_send_tree(zip_dyn_dtree, dcodes - 1);
}
/* ==========================================================================
* Determine the best encoding for the current block: dynamic trees, static
* trees or store, and output the encoded block to the zip file.
*/
function zip_flush_block(eof) { // true if this is the last block for a file
var opt_lenb, static_lenb; // opt_len and static_len in bytes
var max_blindex; // index of last bit length code of non zero freq
var stored_len; // length of input block
stored_len = zip_strstart - zip_block_start;
zip_flag_buf[zip_last_flags] = zip_flags; // Save the flags for the last 8 items
// Construct the literal and distance trees
zip_build_tree(zip_l_desc);
// Tracev((stderr, "\nlit data: dyn %ld, stat %ld",
// encoder->opt_len, encoder->static_len));
zip_build_tree(zip_d_desc);
// Tracev((stderr, "\ndist data: dyn %ld, stat %ld",
// encoder->opt_len, encoder->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 = zip_build_bl_tree();
// Determine the best encoding. Compute first the block length in bytes
opt_lenb = (zip_opt_len + 3 + 7) >> 3;
static_lenb = (zip_static_len + 3 + 7) >> 3;
// Trace((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u dist %u ",
// opt_lenb, encoder->opt_len,
// static_lenb, encoder->static_len, stored_len,
// encoder->last_lit, encoder->last_dist));
if (static_lenb <= opt_lenb)
opt_lenb = static_lenb;
if (stored_len + 4 <= opt_lenb // 4: two words for the lengths
&& zip_block_start >= 0) {
var i;
/* 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.
*/
zip_send_bits((zip_STORED_BLOCK << 1) + eof, 3); /* send block type */
zip_bi_windup(); /* align on byte boundary */
zip_put_short(stored_len);
zip_put_short(~stored_len);
// copy block
/*
p = &window[block_start];
for(i = 0; i < stored_len; i++)
put_byte(p[i]);
*/
for (i = 0; i < stored_len; i++)
zip_put_byte(zip_window[zip_block_start + i]);
} else if (static_lenb == opt_lenb) {
zip_send_bits((zip_STATIC_TREES << 1) + eof, 3);
zip_compress_block(zip_static_ltree, zip_static_dtree);
} else {
zip_send_bits((zip_DYN_TREES << 1) + eof, 3);
zip_send_all_trees(zip_l_desc.max_code + 1,
zip_d_desc.max_code + 1,
max_blindex + 1);
zip_compress_block(zip_dyn_ltree, zip_dyn_dtree);
}
zip_init_block();
if (eof != 0)
zip_bi_windup();
}
/* ==========================================================================
* Save the match info and tally the frequency counts. Return true if
* the current block must be flushed.
*/
function zip_ct_tally(
dist, // distance of matched string
lc) { // match length-MIN_MATCH or unmatched char (if dist==0)
zip_l_buf[zip_last_lit++] = lc;
if (dist == 0) {
// lc is the unmatched char
zip_dyn_ltree[lc].fc++;
} else {
// Here, lc is the match length - MIN_MATCH
dist--; // dist = match distance - 1
// Assert((ush)dist < (ush)MAX_DIST &&
// (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) &&
// (ush)D_CODE(dist) < (ush)D_CODES, "ct_tally: bad match");
zip_dyn_ltree[zip_length_code[lc] + zip_LITERALS + 1].fc++;
zip_dyn_dtree[zip_D_CODE(dist)].fc++;
zip_d_buf[zip_last_dist++] = dist;
zip_flags |= zip_flag_bit;
}
zip_flag_bit <<= 1;
// Output the flags if they fill a byte
if ((zip_last_lit & 7) == 0) {
zip_flag_buf[zip_last_flags++] = zip_flags;
zip_flags = 0;
zip_flag_bit = 1;
}
// Try to guess if it is profitable to stop the current block here
if (zip_compr_level > 2 && (zip_last_lit & 0xfff) == 0) {
// Compute an upper bound for the compressed length
var out_length = zip_last_lit * 8;
var in_length = zip_strstart - zip_block_start;
var dcode;
for (dcode = 0; dcode < zip_D_CODES; dcode++) {
out_length += zip_dyn_dtree[dcode].fc * (5 + zip_extra_dbits[dcode]);
}
out_length >>= 3;
// Trace((stderr,"\nlast_lit %u, last_dist %u, in %ld, out ~%ld(%ld%%) ",
// encoder->last_lit, encoder->last_dist, in_length, out_length,
// 100L - out_length*100L/in_length));
if (zip_last_dist < parseInt(zip_last_lit / 2) &&
out_length < parseInt(in_length / 2))
return true;
}
return (zip_last_lit == zip_LIT_BUFSIZE - 1 ||
zip_last_dist == zip_DIST_BUFSIZE);
/* 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 zip_compress_block(
ltree, // literal tree
dtree) { // distance tree
var dist; // distance of matched string
var lc; // match length or unmatched char (if dist == 0)
var lx = 0; // running index in l_buf
var dx = 0; // running index in d_buf
var fx = 0; // running index in flag_buf
var flag = 0; // current flags
var code; // the code to send
var extra; // number of extra bits to send
if (zip_last_lit != 0) do {
if ((lx & 7) == 0)
flag = zip_flag_buf[fx++];
lc = zip_l_buf[lx++] & 0xff;
if ((flag & 1) == 0) {
zip_SEND_CODE(lc, ltree); /* send a literal byte */
// Tracecv(isgraph(lc), (stderr," '%c' ", lc));
} else {
// Here, lc is the match length - MIN_MATCH
code = zip_length_code[lc];
zip_SEND_CODE(code + zip_LITERALS + 1, ltree); // send the length code
extra = zip_extra_lbits[code];
if (extra != 0) {
lc -= zip_base_length[code];
zip_send_bits(lc, extra); // send the extra length bits
}
dist = zip_d_buf[dx++];
// Here, dist is the match distance - 1
code = zip_D_CODE(dist);
// Assert (code < D_CODES, "bad d_code");
zip_SEND_CODE(code, dtree); // send the distance code
extra = zip_extra_dbits[code];
if (extra != 0) {
dist -= zip_base_dist[code];
zip_send_bits(dist, extra); // send the extra distance bits
}
} // literal or match pair ?
flag >>= 1;
} while (lx < zip_last_lit);
zip_SEND_CODE(zip_END_BLOCK, ltree);
}
/* ==========================================================================
* Send a value on a given number of bits.
* IN assertion: length <= 16 and value fits in length bits.
*/
var zip_Buf_size = 16; // bit size of bi_buf
function zip_send_bits(
value, // value to send
length) { // number of bits
/* If not enough room in bi_buf, use (valid) bits from bi_buf and
* (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))
* unused bits in value.
*/
if (zip_bi_valid > zip_Buf_size - length) {
zip_bi_buf |= (value << zip_bi_valid);
zip_put_short(zip_bi_buf);
zip_bi_buf = (value >> (zip_Buf_size - zip_bi_valid));
zip_bi_valid += length - zip_Buf_size;
} else {
zip_bi_buf |= value << zip_bi_valid;
zip_bi_valid += length;
}
}
/* ==========================================================================
* Reverse the first len bits of a code, using straightforward code (a faster
* method would use a table)
* IN assertion: 1 <= len <= 15
*/
function zip_bi_reverse(
code, // the value to invert
len) { // its bit length
var res = 0;
do {
res |= code & 1;
code >>= 1;
res <<= 1;
} while (--len > 0);
return res >> 1;
}
/* ==========================================================================
* Write out any remaining bits in an incomplete byte.
*/
function zip_bi_windup() {
if (zip_bi_valid > 8) {
zip_put_short(zip_bi_buf);
} else if (zip_bi_valid > 0) {
zip_put_byte(zip_bi_buf);
}
zip_bi_buf = 0;
zip_bi_valid = 0;
}
function zip_qoutbuf() {
if (zip_outcnt != 0) {
var q, i;
q = zip_new_queue();
if (zip_qhead == null)
zip_qhead = zip_qtail = q;
else
zip_qtail = zip_qtail.next = q;
q.len = zip_outcnt - zip_outoff;
// System.arraycopy(zip_outbuf, zip_outoff, q.ptr, 0, q.len);
for (i = 0; i < q.len; i++)
q.ptr[i] = zip_outbuf[zip_outoff + i];
zip_outcnt = zip_outoff = 0;
}
}
return function deflate(str, level) {
var i, j;
zip_deflate_data = str;
zip_deflate_pos = 0;
if (typeof level == "undefined")
level = zip_DEFAULT_LEVEL;
zip_deflate_start(level);
var buff = new Array(1024);
var aout = [];
while ((i = zip_deflate_internal(buff, 0, buff.length)) > 0) {
var cbuf = new Array(i);
for (j = 0; j < i; j++) {
cbuf[j] = String.fromCharCode(buff[j]);
}
aout[aout.length] = cbuf.join("");
}
zip_deflate_data = null; // G.C.
return aout.join("");
};
})();
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