jszip-deflate.js

	// 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.
 */
var zip_gen_bitlen = function(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.
   */
var zip_gen_codes = function(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.
 */
var zip_build_tree = function(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.)
 */
var zip_scan_tree = function(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.
   */
var zip_send_tree = function(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.
 */
var zip_build_bl_tree = function() {
    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.
 */
var zip_send_all_trees = function(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.
 */
var zip_flush_block = function(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.
 */
var zip_ct_tally = function(
	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
   */
var zip_compress_block = function(
	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
var zip_send_bits = function(
	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
 */
var zip_bi_reverse = function(
	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.
 */
var zip_bi_windup = function() {
    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;
}

var zip_qoutbuf = function() {
    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;
    }
}

var zip_deflate = function(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("");
}

//
// end of the script of Masanao Izumo.
//

// we add the compression method for JSZip
if(!JSZip.compressions["DEFLATE"]) {
  JSZip.compressions["DEFLATE"] = {
    magic : "\x08\x00",
    compress : zip_deflate
  }
} else {
  JSZip.compressions["DEFLATE"].compress = zip_deflate;
}

})();