Initial import of old CVS repository

1 files changed, 1640 insertions, 0 deletions

diff --git a/crypto/src/util/zlib/Deflate.cs b/crypto/src/util/zlib/Deflate.cs
new file mode 100644
index 000000000..ca0430939
--- /dev/null
+++ b/crypto/src/util/zlib/Deflate.cs
@@ -0,0 +1,1640 @@
+using System;
+/*
+ * $Id: Deflate.cs,v 1.2 2008-05-10 09:35:40 bouncy Exp $
+ *
+Copyright (c) 2000,2001,2002,2003 ymnk, JCraft,Inc. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+  1. Redistributions of source code must retain the above copyright notice,
+     this list of conditions and the following disclaimer.
+
+  2. Redistributions in binary form must reproduce the above copyright 
+     notice, this list of conditions and the following disclaimer in 
+     the documentation and/or other materials provided with the distribution.
+
+  3. The names of the authors may not be used to endorse or promote products
+     derived from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES,
+INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL JCRAFT,
+INC. OR ANY CONTRIBUTORS TO THIS SOFTWARE BE LIABLE FOR ANY DIRECT, INDIRECT,
+INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
+OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
+EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+/*
+ * This program is based on zlib-1.1.3, so all credit should go authors
+ * Jean-loup Gailly(jloup@gzip.org) and Mark Adler(madler@alumni.caltech.edu)
+ * and contributors of zlib.
+ */
+
+namespace Org.BouncyCastle.Utilities.Zlib {
+
+    public sealed class Deflate{
+
+        private const int MAX_MEM_LEVEL=9;
+
+        private const int Z_DEFAULT_COMPRESSION=-1;
+
+        private const int MAX_WBITS=15;            // 32K LZ77 window
+        private const int DEF_MEM_LEVEL=8;
+
+        internal class Config{
+            internal int good_length; // reduce lazy search above this match length
+            internal int max_lazy;    // do not perform lazy search above this match length
+            internal int nice_length; // quit search above this match length
+            internal int max_chain;
+            internal int func;
+            internal Config(int good_length, int max_lazy, 
+                int nice_length, int max_chain, int func){
+                this.good_length=good_length;
+                this.max_lazy=max_lazy;
+                this.nice_length=nice_length;
+                this.max_chain=max_chain;
+                this.func=func;
+            }
+        }
+  
+        private const int STORED=0;
+        private const int FAST=1;
+        private const int SLOW=2;
+        private static readonly Config[] config_table;
+
+		static Deflate(){
+            config_table=new Config[10];
+            //                         good  lazy  nice  chain
+            config_table[0]=new Config(0,    0,    0,    0, STORED);
+            config_table[1]=new Config(4,    4,    8,    4, FAST);
+            config_table[2]=new Config(4,    5,   16,    8, FAST);
+            config_table[3]=new Config(4,    6,   32,   32, FAST);
+
+            config_table[4]=new Config(4,    4,   16,   16, SLOW);
+            config_table[5]=new Config(8,   16,   32,   32, SLOW);
+            config_table[6]=new Config(8,   16,  128,  128, SLOW);
+            config_table[7]=new Config(8,   32,  128,  256, SLOW);
+            config_table[8]=new Config(32, 128,  258, 1024, SLOW);
+            config_table[9]=new Config(32, 258,  258, 4096, SLOW);
+        }
+
+        private static readonly String[] z_errmsg = {
+                                               "need dictionary",     // Z_NEED_DICT       2
+                                               "stream end",          // Z_STREAM_END      1
+                                               "",                    // Z_OK              0
+                                               "file error",          // Z_ERRNO         (-1)
+                                               "stream error",        // Z_STREAM_ERROR  (-2)
+                                               "data error",          // Z_DATA_ERROR    (-3)
+                                               "insufficient memory", // Z_MEM_ERROR     (-4)
+                                               "buffer error",        // Z_BUF_ERROR     (-5)
+                                               "incompatible version",// Z_VERSION_ERROR (-6)
+                                               ""
+                                           };
+
+        // block not completed, need more input or more output
+        private const int NeedMore=0; 
+
+        // block flush performed
+        private const int BlockDone=1; 
+
+        // finish started, need only more output at next deflate
+        private const int FinishStarted=2;
+
+        // finish done, accept no more input or output
+        private const int FinishDone=3;
+
+        // preset dictionary flag in zlib header
+        private const int PRESET_DICT=0x20;
+
+        private const int Z_FILTERED=1;
+        private const int Z_HUFFMAN_ONLY=2;
+        private const int Z_DEFAULT_STRATEGY=0;
+
+        private const int Z_NO_FLUSH=0;
+        private const int Z_PARTIAL_FLUSH=1;
+        private const int Z_SYNC_FLUSH=2;
+        private const int Z_FULL_FLUSH=3;
+        private const int Z_FINISH=4;
+
+        private const int Z_OK=0;
+        private const int Z_STREAM_END=1;
+        private const int Z_NEED_DICT=2;
+        private const int Z_ERRNO=-1;
+        private const int Z_STREAM_ERROR=-2;
+        private const int Z_DATA_ERROR=-3;
+        private const int Z_MEM_ERROR=-4;
+        private const int Z_BUF_ERROR=-5;
+        private const int Z_VERSION_ERROR=-6;
+
+        private const int INIT_STATE=42;
+        private const int BUSY_STATE=113;
+        private const int FINISH_STATE=666;
+
+        // The deflate compression method
+        private const int Z_DEFLATED=8;
+
+        private const int STORED_BLOCK=0;
+        private const int STATIC_TREES=1;
+        private const int DYN_TREES=2;
+
+        // The three kinds of block type
+        private const int Z_BINARY=0;
+        private const int Z_ASCII=1;
+        private const int Z_UNKNOWN=2;
+
+        private const int Buf_size=8*2;
+
+        // repeat previous bit length 3-6 times (2 bits of repeat count)
+        private const int REP_3_6=16; 
+
+        // repeat a zero length 3-10 times  (3 bits of repeat count)
+        private const int REPZ_3_10=17; 
+
+        // repeat a zero length 11-138 times  (7 bits of repeat count)
+        private const int REPZ_11_138=18; 
+
+        private const int MIN_MATCH=3;
+        private const int MAX_MATCH=258;
+        private const int MIN_LOOKAHEAD=(MAX_MATCH+MIN_MATCH+1);
+
+        private const int MAX_BITS=15;
+        private const int D_CODES=30;
+        private const int BL_CODES=19;
+        private const int LENGTH_CODES=29;
+        private const int LITERALS=256;
+        private const int L_CODES=(LITERALS+1+LENGTH_CODES);
+        private const int HEAP_SIZE=(2*L_CODES+1);
+
+        private const int END_BLOCK=256;
+
+        internal ZStream strm;         // pointer back to this zlib stream
+        internal int status;           // as the name implies
+        internal byte[] pending_buf;   // output still pending
+        internal int pending_buf_size; // size of pending_buf
+        internal int pending_out;      // next pending byte to output to the stream
+        internal int pending;          // nb of bytes in the pending buffer
+        internal int noheader;         // suppress zlib header and adler32
+        internal byte data_type;       // UNKNOWN, BINARY or ASCII
+        internal byte method;          // STORED (for zip only) or DEFLATED
+        internal int last_flush;       // value of flush param for previous deflate call
+
+        internal int w_size;           // LZ77 window size (32K by default)
+        internal int w_bits;           // log2(w_size)  (8..16)
+        internal int w_mask;           // w_size - 1
+
+        internal byte[] window;
+        // Sliding window. Input bytes are read into the second half of the window,
+        // and move to the first half later to keep a dictionary of at least wSize
+        // bytes. With this organization, matches are limited to a distance of
+        // wSize-MAX_MATCH bytes, but this ensures that IO is always
+        // performed with a length multiple of the block size. Also, it limits
+        // the window size to 64K, which is quite useful on MSDOS.
+        // To do: use the user input buffer as sliding window.
+
+        internal int window_size;
+        // Actual size of window: 2*wSize, except when the user input buffer
+        // is directly used as sliding window.
+
+        internal short[] prev;
+        // Link to older string with same hash index. To limit the size of this
+        // array to 64K, this link is maintained only for the last 32K strings.
+        // An index in this array is thus a window index modulo 32K.
+
+        internal short[] head; // Heads of the hash chains or NIL.
+
+        internal int ins_h;          // hash index of string to be inserted
+        internal int hash_size;      // number of elements in hash table
+        internal int hash_bits;      // log2(hash_size)
+        internal int hash_mask;      // hash_size-1
+
+        // Number of bits by which ins_h must be shifted at each input
+        // step. It must be such that after MIN_MATCH steps, the oldest
+        // byte no longer takes part in the hash key, that is:
+        // hash_shift * MIN_MATCH >= hash_bits
+        internal int hash_shift;
+
+        // Window position at the beginning of the current output block. Gets
+        // negative when the window is moved backwards.
+
+        internal int block_start;
+
+        internal int match_length;           // length of best match
+        internal int prev_match;             // previous match
+        internal int match_available;        // set if previous match exists
+        internal int strstart;               // start of string to insert
+        internal int match_start;            // start of matching string
+        internal int lookahead;              // number of valid bytes ahead in window
+
+        // Length of the best match at previous step. Matches not greater than this
+        // are discarded. This is used in the lazy match evaluation.
+        internal int prev_length;
+
+        // To speed up deflation, hash chains are never searched beyond this
+        // length.  A higher limit improves compression ratio but degrades the speed.
+        internal int max_chain_length;
+
+        // Attempt to find a better match only when the current match is strictly
+        // smaller than this value. This mechanism is used only for compression
+        // levels >= 4.
+        internal int max_lazy_match;
+
+        // Insert new strings in the hash table only if the match length is not
+        // greater than this length. This saves time but degrades compression.
+        // max_insert_length is used only for compression levels <= 3.
+
+        internal int level;    // compression level (1..9)
+        internal int strategy; // favor or force Huffman coding
+
+        // Use a faster search when the previous match is longer than this
+        internal int good_match;
+
+        // Stop searching when current match exceeds this
+        internal int nice_match;
+
+        internal short[] dyn_ltree;       // literal and length tree
+        internal short[] dyn_dtree;       // distance tree
+        internal short[] bl_tree;         // Huffman tree for bit lengths
+
+        internal Tree l_desc=new Tree();  // desc for literal tree
+        internal Tree d_desc=new Tree();  // desc for distance tree
+        internal Tree bl_desc=new Tree(); // desc for bit length tree
+
+        // number of codes at each bit length for an optimal tree
+        internal short[] bl_count=new short[MAX_BITS+1];
+
+        // heap used to build the Huffman trees
+        internal int[] heap=new int[2*L_CODES+1];
+
+        internal int heap_len;               // number of elements in the heap
+        internal int heap_max;               // element of largest frequency
+        // The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used.
+        // The same heap array is used to build all trees.
+
+        // Depth of each subtree used as tie breaker for trees of equal frequency
+        internal byte[] depth=new byte[2*L_CODES+1];
+
+        internal int l_buf;               // index for literals or lengths */
+
+        // Size of match buffer for literals/lengths.  There are 4 reasons for
+        // limiting lit_bufsize to 64K:
+        //   - frequencies can be kept in 16 bit counters
+        //   - if compression is not successful for the first block, all input
+        //     data is still in the window so we can still emit a stored block even
+        //     when input comes from standard input.  (This can also be done for
+        //     all blocks if lit_bufsize is not greater than 32K.)
+        //   - if compression is not successful for a file smaller than 64K, we can
+        //     even emit a stored file instead of a stored block (saving 5 bytes).
+        //     This is applicable only for zip (not gzip or zlib).
+        //   - creating new Huffman trees less frequently may not provide fast
+        //     adaptation to changes in the input data statistics. (Take for
+        //     example a binary file with poorly compressible code followed by
+        //     a highly compressible string table.) Smaller buffer sizes give
+        //     fast adaptation but have of course the overhead of transmitting
+        //     trees more frequently.
+        //   - I can't count above 4
+        internal int lit_bufsize;
+
+        internal int last_lit;      // running index in l_buf
+
+        // Buffer for distances. To simplify the code, d_buf and l_buf have
+        // the same number of elements. To use different lengths, an extra flag
+        // array would be necessary.
+
+        internal int d_buf;         // index of pendig_buf
+
+        internal int opt_len;        // bit length of current block with optimal trees
+        internal int static_len;     // bit length of current block with static trees
+        internal int matches;        // number of string matches in current block
+        internal int last_eob_len;   // bit length of EOB code for last block
+
+        // Output buffer. bits are inserted starting at the bottom (least
+        // significant bits).
+        internal uint bi_buf;
+
+        // Number of valid bits in bi_buf.  All bits above the last valid bit
+        // are always zero.
+        internal int bi_valid;
+
+        internal Deflate(){
+            dyn_ltree=new short[HEAP_SIZE*2];
+            dyn_dtree=new short[(2*D_CODES+1)*2]; // distance tree
+            bl_tree=new short[(2*BL_CODES+1)*2];  // Huffman tree for bit lengths
+        }
+
+        internal void lm_init() {
+            window_size=2*w_size;
+
+            head[hash_size-1]=0;
+            for(int i=0; i<hash_size-1; i++){
+                head[i]=0;
+            }
+
+            // Set the default configuration parameters:
+            max_lazy_match   = Deflate.config_table[level].max_lazy;
+            good_match       = Deflate.config_table[level].good_length;
+            nice_match       = Deflate.config_table[level].nice_length;
+            max_chain_length = Deflate.config_table[level].max_chain;
+
+            strstart = 0;
+            block_start = 0;
+            lookahead = 0;
+            match_length = prev_length = MIN_MATCH-1;
+            match_available = 0;
+            ins_h = 0;
+        }
+
+        // Initialize the tree data structures for a new zlib stream.
+        internal void tr_init(){
+
+            l_desc.dyn_tree = dyn_ltree;
+            l_desc.stat_desc = StaticTree.static_l_desc;
+
+            d_desc.dyn_tree = dyn_dtree;
+            d_desc.stat_desc = StaticTree.static_d_desc;
+
+            bl_desc.dyn_tree = bl_tree;
+            bl_desc.stat_desc = StaticTree.static_bl_desc;
+
+            bi_buf = 0;
+            bi_valid = 0;
+            last_eob_len = 8; // enough lookahead for inflate
+
+            // Initialize the first block of the first file:
+            init_block();
+        }
+
+        internal void init_block(){
+            // Initialize the trees.
+            for(int i = 0; i < L_CODES; i++) dyn_ltree[i*2] = 0;
+            for(int i= 0; i < D_CODES; i++) dyn_dtree[i*2] = 0;
+            for(int i= 0; i < BL_CODES; i++) bl_tree[i*2] = 0;
+
+            dyn_ltree[END_BLOCK*2] = 1;
+            opt_len = static_len = 0;
+            last_lit = matches = 0;
+        }
+
+        // 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).
+        internal void pqdownheap(short[] tree,  // the tree to restore
+            int k          // node to move down
+            ){
+            int v = heap[k];
+            int j = k << 1;  // left son of k
+            while (j <= heap_len) {
+                // Set j to the smallest of the two sons:
+                if (j < heap_len &&
+                    smaller(tree, heap[j+1], heap[j], depth)){
+                    j++;
+                }
+                // Exit if v is smaller than both sons
+                if(smaller(tree, v, heap[j], depth)) break;
+
+                // Exchange v with the smallest son
+                heap[k]=heap[j];  k = j;
+                // And continue down the tree, setting j to the left son of k
+                j <<= 1;
+            }
+            heap[k] = v;
+        }
+
+        internal static bool smaller(short[] tree, int n, int m, byte[] depth){
+            short tn2=tree[n*2];
+            short tm2=tree[m*2];
+            return (tn2<tm2 ||
+                (tn2==tm2 && depth[n] <= depth[m]));
+        }
+
+        // Scan a literal or distance tree to determine the frequencies of the codes
+        // in the bit length tree.
+        internal void scan_tree (short[] tree,// the tree to be scanned
+            int max_code // and its largest code of non zero frequency
+            ){
+            int n;                     // iterates over all tree elements
+            int prevlen = -1;          // last emitted length
+            int curlen;                // length of current code
+            int nextlen = tree[0*2+1]; // length of next code
+            int count = 0;             // repeat count of the current code
+            int max_count = 7;         // max repeat count
+            int min_count = 4;         // min repeat count
+
+            if (nextlen == 0){ max_count = 138; min_count = 3; }
+            tree[(max_code+1)*2+1] = -1; // guard
+
+            for(n = 0; n <= max_code; n++) {
+                curlen = nextlen; nextlen = tree[(n+1)*2+1];
+                if(++count < max_count && curlen == nextlen) {
+                    continue;
+                }
+                else if(count < min_count) {
+                    bl_tree[curlen*2] += (short)count;
+                }
+                else if(curlen != 0) {
+                    if(curlen != prevlen) bl_tree[curlen*2]++;
+                    bl_tree[REP_3_6*2]++;
+                }
+                else if(count <= 10) {
+                    bl_tree[REPZ_3_10*2]++;
+                }
+                else{
+                    bl_tree[REPZ_11_138*2]++;
+                }
+                count = 0; prevlen = curlen;
+                if(nextlen == 0) {
+                    max_count = 138; min_count = 3;
+                }
+                else if(curlen == nextlen) {
+                    max_count = 6; min_count = 3;
+                }
+                else{
+                    max_count = 7; min_count = 4;
+                }
+            }
+        }
+
+        // Construct the Huffman tree for the bit lengths and return the index in
+        // bl_order of the last bit length code to send.
+        internal int build_bl_tree(){
+            int max_blindex;  // index of last bit length code of non zero freq
+
+            // Determine the bit length frequencies for literal and distance trees
+            scan_tree(dyn_ltree, l_desc.max_code);
+            scan_tree(dyn_dtree, d_desc.max_code);
+
+            // Build the bit length tree:
+            bl_desc.build_tree(this);
+            // opt_len now includes the length of the tree representations, except
+            // the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
+
+            // Determine the number of bit length codes to send. The pkzip format
+            // requires that at least 4 bit length codes be sent. (appnote.txt says
+            // 3 but the actual value used is 4.)
+            for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) {
+                if (bl_tree[Tree.bl_order[max_blindex]*2+1] != 0) break;
+            }
+            // Update opt_len to include the bit length tree and counts
+            opt_len += 3*(max_blindex+1) + 5+5+4;
+
+            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.
+        internal void send_all_trees(int lcodes, int dcodes, int blcodes){
+            int rank;                    // index in bl_order
+
+            send_bits(lcodes-257, 5); // not +255 as stated in appnote.txt
+            send_bits(dcodes-1,   5);
+            send_bits(blcodes-4,  4); // not -3 as stated in appnote.txt
+            for (rank = 0; rank < blcodes; rank++) {
+                send_bits(bl_tree[Tree.bl_order[rank]*2+1], 3);
+            }
+            send_tree(dyn_ltree, lcodes-1); // literal tree
+            send_tree(dyn_dtree, dcodes-1); // distance tree
+        }
+
+        // Send a literal or distance tree in compressed form, using the codes in
+        // bl_tree.
+        internal void send_tree (short[] tree,// the tree to be sent
+            int max_code // and its largest code of non zero frequency
+            ){
+            int n;                     // iterates over all tree elements
+            int prevlen = -1;          // last emitted length
+            int curlen;                // length of current code
+            int nextlen = tree[0*2+1]; // length of next code
+            int count = 0;             // repeat count of the current code
+            int max_count = 7;         // max repeat count
+            int min_count = 4;         // min repeat count
+
+            if (nextlen == 0){ max_count = 138; min_count = 3; }
+
+            for (n = 0; n <= max_code; n++) {
+                curlen = nextlen; nextlen = tree[(n+1)*2+1];
+                if(++count < max_count && curlen == nextlen) {
+                    continue;
+                }
+                else if(count < min_count) {
+                    do { send_code(curlen, bl_tree); } while (--count != 0);
+                }
+                else if(curlen != 0){
+                    if(curlen != prevlen){
+                        send_code(curlen, bl_tree); count--;
+                    }
+                    send_code(REP_3_6, bl_tree); 
+                    send_bits(count-3, 2);
+                }
+                else if(count <= 10){
+                    send_code(REPZ_3_10, bl_tree); 
+                    send_bits(count-3, 3);
+                }
+                else{
+                    send_code(REPZ_11_138, bl_tree);
+                    send_bits(count-11, 7);
+                }
+                count = 0; prevlen = curlen;
+                if(nextlen == 0){
+                    max_count = 138; min_count = 3;
+                }
+                else if(curlen == nextlen){
+                    max_count = 6; min_count = 3;
+                }
+                else{
+                    max_count = 7; min_count = 4;
+                }
+            }
+        }
+
+        // Output a byte on the stream.
+        // IN assertion: there is enough room in pending_buf.
+        internal void put_byte(byte[] p, int start, int len){
+            System.Array.Copy(p, start, pending_buf, pending, len);
+            pending+=len;
+        }
+
+        internal void put_byte(byte c){
+            pending_buf[pending++]=c;
+        }
+        internal void put_short(int w) {
+            pending_buf[pending++]=(byte)(w/*&0xff*/);
+            pending_buf[pending++]=(byte)(w>>8);
+        }
+        internal void putShortMSB(int b){
+            pending_buf[pending++]=(byte)(b>>8);
+            pending_buf[pending++]=(byte)(b/*&0xff*/);
+        }   
+
+        internal void send_code(int c, short[] tree){
+            int c2=c*2;
+            send_bits((tree[c2]&0xffff), (tree[c2+1]&0xffff));
+        }
+
+        internal void send_bits(int val, int length){
+            if (bi_valid > Buf_size - length) {
+                bi_buf |= (uint)(val << bi_valid);
+                pending_buf[pending++]=(byte)(bi_buf/*&0xff*/);
+                pending_buf[pending++]=(byte)(bi_buf>>8);
+                bi_buf = ((uint)val) >> (Buf_size - bi_valid);
+                bi_valid += length - Buf_size;
+            } else {
+                bi_buf |= (uint)(val << bi_valid);
+                bi_valid += length;
+            }
+//            int len = length;
+//            if (bi_valid > (int)Buf_size - len) {
+//                int val = value;
+//                //      bi_buf |= (val << bi_valid);
+//                bi_buf = (short)((ushort)bi_buf | (ushort)((val << bi_valid)&0xffff));
+//                put_short(bi_buf);
+//                bi_buf = (short)(((uint)val) >> (Buf_size - bi_valid));
+//                bi_valid += len - Buf_size;
+//            } else {
+//                //      bi_buf |= (value) << bi_valid;
+//                bi_buf = (short)((ushort)bi_buf | (ushort)(((value) << bi_valid)&0xffff));
+//                bi_valid += 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.
+        // The current inflate code requires 9 bits of lookahead. If the
+        // last two codes for the previous block (real code plus EOB) were coded
+        // on 5 bits or less, inflate may have only 5+3 bits of lookahead to decode
+        // the last real code. In this case we send two empty static blocks instead
+        // of one. (There are no problems if the previous block is stored or fixed.)
+        // To simplify the code, we assume the worst case of last real code encoded
+        // on one bit only.
+        internal void _tr_align(){
+            send_bits(STATIC_TREES<<1, 3);
+            send_code(END_BLOCK, StaticTree.static_ltree);
+
+            bi_flush();
+
+            // Of the 10 bits for the empty block, we have already sent
+            // (10 - bi_valid) bits. The lookahead for the last real code (before
+            // the EOB of the previous block) was thus at least one plus the length
+            // of the EOB plus what we have just sent of the empty static block.
+            if (1 + last_eob_len + 10 - bi_valid < 9) {
+                send_bits(STATIC_TREES<<1, 3);
+                send_code(END_BLOCK, StaticTree.static_ltree);
+                bi_flush();
+            }
+            last_eob_len = 7;
+        }
+
+
+        // Save the match info and tally the frequency counts. Return true if
+        // the current block must be flushed.
+        internal bool _tr_tally (int dist, // distance of matched string
+            int lc // match length-MIN_MATCH or unmatched char (if dist==0)
+            ){
+
+            pending_buf[d_buf+last_lit*2] = (byte)(dist>>8);
+            pending_buf[d_buf+last_lit*2+1] = (byte)dist;
+
+            pending_buf[l_buf+last_lit] = (byte)lc; last_lit++;
+
+            if (dist == 0) {
+                // lc is the unmatched char
+                dyn_ltree[lc*2]++;
+            } 
+            else {
+                matches++;
+                // Here, lc is the match length - MIN_MATCH
+                dist--;             // dist = match distance - 1
+                dyn_ltree[(Tree._length_code[lc]+LITERALS+1)*2]++;
+                dyn_dtree[Tree.d_code(dist)*2]++;
+            }
+
+            if ((last_lit & 0x1fff) == 0 && level > 2) {
+                // Compute an upper bound for the compressed length
+                int out_length = last_lit*8;
+                int in_length = strstart - block_start;
+                int dcode;
+                for (dcode = 0; dcode < D_CODES; dcode++) {
+                    out_length += (int)((int)dyn_dtree[dcode*2] *
+                        (5L+Tree.extra_dbits[dcode]));
+                }
+                out_length >>= 3;
+                if ((matches < (last_lit/2)) && out_length < in_length/2) return true;
+            }
+
+            return (last_lit == lit_bufsize-1);
+            // We avoid equality with lit_bufsize because of wraparound at 64K
+            // on 16 bit machines and because stored blocks are restricted to
+            // 64K-1 bytes.
+        }
+
+        // Send the block data compressed using the given Huffman trees
+        internal void compress_block(short[] ltree, short[] dtree){
+            int  dist;      // distance of matched string
+            int lc;         // match length or unmatched char (if dist == 0)
+            int lx = 0;     // running index in l_buf
+            int code;       // the code to send
+            int extra;      // number of extra bits to send
+
+            if (last_lit != 0){
+                do{
+                    dist=((pending_buf[d_buf+lx*2]<<8)&0xff00)|
+                        (pending_buf[d_buf+lx*2+1]&0xff);
+                    lc=(pending_buf[l_buf+lx])&0xff; lx++;
+
+                    if(dist == 0){
+                        send_code(lc, ltree); // send a literal byte
+                    } 
+                    else{
+                        // Here, lc is the match length - MIN_MATCH
+                        code = Tree._length_code[lc];
+
+                        send_code(code+LITERALS+1, ltree); // send the length code
+                        extra = Tree.extra_lbits[code];
+                        if(extra != 0){
+                            lc -= Tree.base_length[code];
+                            send_bits(lc, extra);       // send the extra length bits
+                        }
+                        dist--; // dist is now the match distance - 1
+                        code = Tree.d_code(dist);
+
+                        send_code(code, dtree);       // send the distance code
+                        extra = Tree.extra_dbits[code];
+                        if (extra != 0) {
+                            dist -= Tree.base_dist[code];
+                            send_bits(dist, extra);   // send the extra distance bits
+                        }
+                    } // literal or match pair ?
+
+                    // Check that the overlay between pending_buf and d_buf+l_buf is ok:
+                }
+                while (lx < last_lit);
+            }
+
+            send_code(END_BLOCK, ltree);
+            last_eob_len = ltree[END_BLOCK*2+1];
+        }
+
+        // Set the data type to ASCII or BINARY, using a crude approximation:
+        // binary if more than 20% of the bytes are <= 6 or >= 128, ascii otherwise.
+        // IN assertion: the fields freq of dyn_ltree are set and the total of all
+        // frequencies does not exceed 64K (to fit in an int on 16 bit machines).
+        internal void set_data_type(){
+            int n = 0;
+            int  ascii_freq = 0;
+            int  bin_freq = 0;
+            while(n<7){ bin_freq += dyn_ltree[n*2]; n++;}
+            while(n<128){ ascii_freq += dyn_ltree[n*2]; n++;}
+            while(n<LITERALS){ bin_freq += dyn_ltree[n*2]; n++;}
+            data_type=(byte)(bin_freq > (ascii_freq >> 2) ? Z_BINARY : Z_ASCII);
+        }
+
+        // Flush the bit buffer, keeping at most 7 bits in it.
+        internal void bi_flush(){
+            if (bi_valid == 16) {
+                pending_buf[pending++]=(byte)(bi_buf/*&0xff*/);
+                pending_buf[pending++]=(byte)(bi_buf>>8);
+                bi_buf=0;
+                bi_valid=0;
+            }
+            else if (bi_valid >= 8) {
+                pending_buf[pending++]=(byte)(bi_buf);
+                bi_buf>>=8;
+                bi_buf &= 0x00ff;
+                bi_valid-=8;
+            }
+        }
+
+        // Flush the bit buffer and align the output on a byte boundary
+        internal void bi_windup(){
+            if (bi_valid > 8) {
+                pending_buf[pending++]=(byte)(bi_buf);
+                pending_buf[pending++]=(byte)(bi_buf>>8);
+            } else if (bi_valid > 0) {
+                pending_buf[pending++]=(byte)(bi_buf);
+            }
+            bi_buf = 0;
+            bi_valid = 0;
+        }
+
+        // Copy a stored block, storing first the length and its
+        // one's complement if requested.
+        internal void copy_block(int buf,         // the input data
+            int len,         // its length
+            bool header   // true if block header must be written
+            ){
+            //int index=0;
+            bi_windup();      // align on byte boundary
+            last_eob_len = 8; // enough lookahead for inflate
+
+            if (header) {
+                put_short((short)len);   
+                put_short((short)~len);
+            }
+
+            //  while(len--!=0) {
+            //    put_byte(window[buf+index]);
+            //    index++;
+            //  }
+            put_byte(window, buf, len);
+        }
+
+        internal void flush_block_only(bool eof){
+            _tr_flush_block(block_start>=0 ? block_start : -1,
+                strstart-block_start,
+                eof);
+            block_start=strstart;
+            strm.flush_pending();
+        }
+
+        // Copy without compression as much as possible from the input stream, return
+        // the current block state.
+        // This function does not insert new strings in the dictionary since
+        // uncompressible data is probably not useful. This function is used
+        // only for the level=0 compression option.
+        // NOTE: this function should be optimized to avoid extra copying from
+        // window to pending_buf.
+        internal int deflate_stored(int flush){
+            // Stored blocks are limited to 0xffff bytes, pending_buf is limited
+            // to pending_buf_size, and each stored block has a 5 byte header:
+
+            int max_block_size = 0xffff;
+            int max_start;
+
+            if(max_block_size > pending_buf_size - 5) {
+                max_block_size = pending_buf_size - 5;
+            }
+
+            // Copy as much as possible from input to output:
+            while(true){
+                // Fill the window as much as possible:
+                if(lookahead<=1){
+                    fill_window();
+                    if(lookahead==0 && flush==Z_NO_FLUSH) return NeedMore;
+                    if(lookahead==0) break; // flush the current block
+                }
+
+                strstart+=lookahead;
+                lookahead=0;
+
+                // Emit a stored block if pending_buf will be full:
+                max_start=block_start+max_block_size;
+                if(strstart==0|| strstart>=max_start) {
+                    // strstart == 0 is possible when wraparound on 16-bit machine
+                    lookahead = (int)(strstart-max_start);
+                    strstart = (int)max_start;
+      
+                    flush_block_only(false);
+                    if(strm.avail_out==0) return NeedMore;
+
+                }
+
+                // Flush if we may have to slide, otherwise block_start may become
+                // negative and the data will be gone:
+                if(strstart-block_start >= w_size-MIN_LOOKAHEAD) {
+                    flush_block_only(false);
+                    if(strm.avail_out==0) return NeedMore;
+                }
+            }
+
+            flush_block_only(flush == Z_FINISH);
+            if(strm.avail_out==0)
+                return (flush == Z_FINISH) ? FinishStarted : NeedMore;
+
+            return flush == Z_FINISH ? FinishDone : BlockDone;
+        }
+
+        // Send a stored block
+        internal void _tr_stored_block(int buf,        // input block
+            int stored_len, // length of input block
+            bool eof     // true if this is the last block for a file
+            ){
+            send_bits((STORED_BLOCK<<1)+(eof?1:0), 3);  // send block type
+            copy_block(buf, stored_len, true);          // with header
+        }
+
+        // Determine the best encoding for the current block: dynamic trees, static
+        // trees or store, and output the encoded block to the zip file.
+        internal void _tr_flush_block(int buf,        // input block, or NULL if too old
+            int stored_len, // length of input block
+            bool eof     // true if this is the last block for a file
+            ) {
+            int opt_lenb, static_lenb;// opt_len and static_len in bytes
+            int max_blindex = 0;      // index of last bit length code of non zero freq
+
+            // Build the Huffman trees unless a stored block is forced
+            if(level > 0) {
+                // Check if the file is ascii or binary
+                if(data_type == Z_UNKNOWN) set_data_type();
+
+                // Construct the literal and distance trees
+                l_desc.build_tree(this);
+
+                d_desc.build_tree(this);
+
+                // 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();
+
+                // Determine the best encoding. Compute first the block length in bytes
+                opt_lenb=(opt_len+3+7)>>3;
+                static_lenb=(static_len+3+7)>>3;
+
+                if(static_lenb<=opt_lenb) opt_lenb=static_lenb;
+            }
+            else {
+                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(buf, stored_len, eof);
+            }
+            else if(static_lenb == opt_lenb){
+                send_bits((STATIC_TREES<<1)+(eof?1:0), 3);
+                compress_block(StaticTree.static_ltree, StaticTree.static_dtree);
+            }
+            else{
+                send_bits((DYN_TREES<<1)+(eof?1:0), 3);
+                send_all_trees(l_desc.max_code+1, d_desc.max_code+1, max_blindex+1);
+                compress_block(dyn_ltree, dyn_dtree);
+            }
+
+            // The above check is made mod 2^32, for files larger than 512 MB
+            // and uLong implemented on 32 bits.
+
+            init_block();
+
+            if(eof){
+                bi_windup();
+            }
+        }
+
+        // Fill the window when the lookahead becomes insufficient.
+        // Updates strstart and lookahead.
+        //
+        // IN assertion: lookahead < MIN_LOOKAHEAD
+        // OUT assertions: strstart <= window_size-MIN_LOOKAHEAD
+        //    At least one byte has been read, or avail_in == 0; reads are
+        //    performed for at least two bytes (required for the zip translate_eol
+        //    option -- not supported here).
+        internal void fill_window(){
+            int n, m;
+            int p;
+            int more;    // Amount of free space at the end of the window.
+
+            do{
+                more = (window_size-lookahead-strstart);
+
+                // Deal with !@#$% 64K limit:
+                if(more==0 && strstart==0 && lookahead==0){
+                    more = w_size;
+                } 
+                else if(more==-1) {
+                    // Very unlikely, but possible on 16 bit machine if strstart == 0
+                    // and lookahead == 1 (input done one byte at time)
+                    more--;
+
+                    // 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.
+                }
+                else if(strstart >= w_size+ w_size-MIN_LOOKAHEAD) {
+                    System.Array.Copy(window, w_size, window, 0, w_size);
+                    match_start-=w_size;
+                    strstart-=w_size; // we now have strstart >= MAX_DIST
+                    block_start-=w_size;
+
+                    // Slide the hash table (could be avoided with 32 bit values
+                    // at the expense of memory usage). We slide even when level == 0
+                    // to keep the hash table consistent if we switch back to level > 0
+                    // later. (Using level 0 permanently is not an optimal usage of
+                    // zlib, so we don't care about this pathological case.)
+
+                    n = hash_size;
+                    p=n;
+                    do {
+                        m = (head[--p]&0xffff);
+                        head[p]=(short)(m>=w_size ? (m-w_size) : 0);
+                    }
+                    while (--n != 0);
+
+                    n = w_size;
+                    p = n;
+                    do {
+                        m = (prev[--p]&0xffff);
+                        prev[p] = (short)(m >= w_size ? (m-w_size) : 0);
+                        // If n is not on any hash chain, prev[n] is garbage but
+                        // its value will never be used.
+                    }
+                    while (--n!=0);
+                    more += w_size;
+                }
+
+                if (strm.avail_in == 0) return;
+
+                // If there was no sliding:
+                //    strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 &&
+                //    more == window_size - lookahead - strstart
+                // => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1)
+                // => more >= window_size - 2*WSIZE + 2
+                // In the BIG_MEM or MMAP case (not yet supported),
+                //   window_size == input_size + MIN_LOOKAHEAD  &&
+                //   strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD.
+                // Otherwise, window_size == 2*WSIZE so more >= 2.
+                // If there was sliding, more >= WSIZE. So in all cases, more >= 2.
+
+                n = strm.read_buf(window, strstart + lookahead, more);
+                lookahead += n;
+
+                // Initialize the hash value now that we have some input:
+                if(lookahead >= MIN_MATCH) {
+                    ins_h = window[strstart]&0xff;
+                    ins_h=(((ins_h)<<hash_shift)^(window[strstart+1]&0xff))&hash_mask;
+                }
+                // If the whole input has less than MIN_MATCH bytes, ins_h is garbage,
+                // but this is not important since only literal bytes will be emitted.
+            }
+            while (lookahead < MIN_LOOKAHEAD && strm.avail_in != 0);
+        }
+
+        // Compress as much as possible from the input stream, return the current
+        // block state.
+        // This function does not perform lazy evaluation of 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.
+        internal int deflate_fast(int flush){
+            //    short hash_head = 0; // head of the hash chain
+            int hash_head = 0; // head of the hash chain
+            bool bflush;      // set if current block must be flushed
+
+            while(true){
+                // 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.
+                if(lookahead < MIN_LOOKAHEAD){
+                    fill_window();
+                    if(lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH){
+                        return NeedMore;
+                    }
+                    if(lookahead == 0) break; // flush the current block
+                }
+
+                // Insert the string window[strstart .. strstart+2] in the
+                // dictionary, and set hash_head to the head of the hash chain:
+                if(lookahead >= MIN_MATCH){
+                    ins_h=(((ins_h)<<hash_shift)^(window[(strstart)+(MIN_MATCH-1)]&0xff))&hash_mask;
+
+                    //  prev[strstart&w_mask]=hash_head=head[ins_h];
+                    hash_head=(head[ins_h]&0xffff);
+                    prev[strstart&w_mask]=head[ins_h];
+                    head[ins_h]=(short)strstart;
+                }
+
+                // Find the longest match, discarding those <= prev_length.
+                // At this point we have always match_length < MIN_MATCH
+
+                if(hash_head!=0L && 
+                    ((strstart-hash_head)&0xffff) <= w_size-MIN_LOOKAHEAD
+                    ){
+                    // 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).
+                    if(strategy != Z_HUFFMAN_ONLY){
+                        match_length=longest_match (hash_head);
+                    }
+                    // longest_match() sets match_start
+                }
+                if(match_length>=MIN_MATCH){
+                    //        check_match(strstart, match_start, match_length);
+
+                    bflush=_tr_tally(strstart-match_start, match_length-MIN_MATCH);
+
+                    lookahead -= 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(match_length <= max_lazy_match &&
+                        lookahead >= MIN_MATCH) {
+                        match_length--; // string at strstart already in hash table
+                        do{
+                            strstart++;
+
+                            ins_h=((ins_h<<hash_shift)^(window[(strstart)+(MIN_MATCH-1)]&0xff))&hash_mask;
+                            //      prev[strstart&w_mask]=hash_head=head[ins_h];
+                            hash_head=(head[ins_h]&0xffff);
+                            prev[strstart&w_mask]=head[ins_h];
+                            head[ins_h]=(short)strstart;
+
+                            // strstart never exceeds WSIZE-MAX_MATCH, so there are
+                            // always MIN_MATCH bytes ahead.
+                        }
+                        while (--match_length != 0);
+                        strstart++; 
+                    }
+                    else{
+                        strstart += match_length;
+                        match_length = 0;
+                        ins_h = window[strstart]&0xff;
+
+                        ins_h=(((ins_h)<<hash_shift)^(window[strstart+1]&0xff))&hash_mask;
+                        // If lookahead < MIN_MATCH, ins_h is garbage, but it does not
+                        // matter since it will be recomputed at next deflate call.
+                    }
+                }
+                else {
+                    // No match, output a literal byte
+
+                    bflush=_tr_tally(0, window[strstart]&0xff);
+                    lookahead--;
+                    strstart++; 
+                }
+                if (bflush){
+
+                    flush_block_only(false);
+                    if(strm.avail_out==0) return NeedMore;
+                }
+            }
+
+            flush_block_only(flush == Z_FINISH);
+            if(strm.avail_out==0){
+                if(flush == Z_FINISH) return FinishStarted;
+                else return NeedMore;
+            }
+            return flush==Z_FINISH ? FinishDone : BlockDone;
+        }
+
+        // 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.
+        internal int deflate_slow(int flush){
+            //    short hash_head = 0;    // head of hash chain
+            int hash_head = 0;    // head of hash chain
+            bool bflush;         // set if current block must be flushed
+
+            // Process the input block.
+            while(true){
+                // 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.
+
+                if (lookahead < MIN_LOOKAHEAD) {
+                    fill_window();
+                    if(lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
+                        return NeedMore;
+                    }
+                    if(lookahead == 0) break; // flush the current block
+                }
+
+                // Insert the string window[strstart .. strstart+2] in the
+                // dictionary, and set hash_head to the head of the hash chain:
+
+                if(lookahead >= MIN_MATCH) {
+                    ins_h=(((ins_h)<<hash_shift)^(window[(strstart)+(MIN_MATCH-1)]&0xff)) & hash_mask;
+                    //  prev[strstart&w_mask]=hash_head=head[ins_h];
+                    hash_head=(head[ins_h]&0xffff);
+                    prev[strstart&w_mask]=head[ins_h];
+                    head[ins_h]=(short)strstart;
+                }
+
+                // Find the longest match, discarding those <= prev_length.
+                prev_length = match_length; prev_match = match_start;
+                match_length = MIN_MATCH-1;
+
+                if (hash_head != 0 && prev_length < max_lazy_match &&
+                    ((strstart-hash_head)&0xffff) <= w_size-MIN_LOOKAHEAD
+                    ){
+                    // 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).
+
+                    if(strategy != Z_HUFFMAN_ONLY) {
+                        match_length = longest_match(hash_head);
+                    }
+                    // longest_match() sets match_start
+
+                    if (match_length <= 5 && (strategy == Z_FILTERED ||
+                        (match_length == MIN_MATCH &&
+                        strstart - match_start > 4096))) {
+
+                        // If prev_match is also MIN_MATCH, match_start is garbage
+                        // but we will ignore the current match anyway.
+                        match_length = MIN_MATCH-1;
+                    }
+                }
+
+                // If there was a match at the previous step and the current
+                // match is not better, output the previous match:
+                if(prev_length >= MIN_MATCH && match_length <= prev_length) {
+                    int max_insert = strstart + lookahead - MIN_MATCH;
+                    // Do not insert strings in hash table beyond this.
+
+                    //          check_match(strstart-1, prev_match, prev_length);
+
+                    bflush=_tr_tally(strstart-1-prev_match, prev_length - MIN_MATCH);
+
+                    // Insert in hash table all strings up to the end of the match.
+                    // strstart-1 and strstart are already inserted. If there is not
+                    // enough lookahead, the last two strings are not inserted in
+                    // the hash table.
+                    lookahead -= prev_length-1;
+                    prev_length -= 2;
+                    do{
+                        if(++strstart <= max_insert) {
+                            ins_h=(((ins_h)<<hash_shift)^(window[(strstart)+(MIN_MATCH-1)]&0xff))&hash_mask;
+                            //prev[strstart&w_mask]=hash_head=head[ins_h];
+                            hash_head=(head[ins_h]&0xffff);
+                            prev[strstart&w_mask]=head[ins_h];
+                            head[ins_h]=(short)strstart;
+                        }
+                    }
+                    while(--prev_length != 0);
+                    match_available = 0;
+                    match_length = MIN_MATCH-1;
+                    strstart++;
+
+                    if (bflush){
+                        flush_block_only(false);
+                        if(strm.avail_out==0) return NeedMore;
+                    }
+                } else if (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.
+
+                    bflush=_tr_tally(0, window[strstart-1]&0xff);
+
+                    if (bflush) {
+                        flush_block_only(false);
+                    }
+                    strstart++;
+                    lookahead--;
+                    if(strm.avail_out == 0) return NeedMore;
+                } else {
+                    // There is no previous match to compare with, wait for
+                    // the next step to decide.
+
+                    match_available = 1;
+                    strstart++;
+                    lookahead--;
+                }
+            }
+
+            if(match_available!=0) {
+                bflush=_tr_tally(0, window[strstart-1]&0xff);
+                match_available = 0;
+            }
+            flush_block_only(flush == Z_FINISH);
+
+            if(strm.avail_out==0){
+                if(flush == Z_FINISH) return FinishStarted;
+                else return NeedMore;
+            }
+
+            return flush == Z_FINISH ? FinishDone : BlockDone;
+        }
+
+        internal int longest_match(int cur_match){
+            int chain_length = max_chain_length; // max hash chain length
+            int scan = strstart;                 // current string
+            int match;                           // matched string
+            int len;                             // length of current match
+            int best_len = prev_length;          // best match length so far
+            int limit = strstart>(w_size-MIN_LOOKAHEAD) ?
+                strstart-(w_size-MIN_LOOKAHEAD) : 0;
+            int nice_match=this.nice_match;
+
+            // Stop when cur_match becomes <= limit. To simplify the code,
+            // we prevent matches with the string of window index 0.
+
+            int wmask = w_mask;
+
+            int strend = strstart + MAX_MATCH;
+            byte scan_end1 = window[scan+best_len-1];
+            byte scan_end = window[scan+best_len];
+
+            // The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
+            // It is easy to get rid of this optimization if necessary.
+
+            // Do not waste too much time if we already have a good match:
+            if (prev_length >= good_match) {
+                chain_length >>= 2;
+            }
+
+            // Do not look for matches beyond the end of the input. This is necessary
+            // to make deflate deterministic.
+            if (nice_match > lookahead) nice_match = lookahead;
+
+            do {
+                match = cur_match;
+
+                // Skip to next match if the match length cannot increase
+                // or if the match length is less than 2:
+                if (window[match+best_len]   != scan_end  ||
+                    window[match+best_len-1] != scan_end1 ||
+                    window[match]       != window[scan]     ||
+                    window[++match]     != window[scan+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.
+                scan += 2; match++;
+
+                // We check for insufficient lookahead only every 8th comparison;
+                // the 256th check will be made at strstart+258.
+                do {
+                } while (window[++scan] == window[++match] &&
+                    window[++scan] == window[++match] &&
+                    window[++scan] == window[++match] &&
+                    window[++scan] == window[++match] &&
+                    window[++scan] == window[++match] &&
+                    window[++scan] == window[++match] &&
+                    window[++scan] == window[++match] &&
+                    window[++scan] == window[++match] &&
+                    scan < strend);
+
+                len = MAX_MATCH - (int)(strend - scan);
+                scan = strend - MAX_MATCH;
+
+                if(len>best_len) {
+                    match_start = cur_match;
+                    best_len = len;
+                    if (len >= nice_match) break;
+                    scan_end1  = window[scan+best_len-1];
+                    scan_end   = window[scan+best_len];
+                }
+
+            } while ((cur_match = (prev[cur_match & wmask]&0xffff)) > limit
+                && --chain_length != 0);
+
+            if (best_len <= lookahead) return best_len;
+            return lookahead;
+        }
+    
+        internal int deflateInit(ZStream strm, int level, int bits){
+            return deflateInit2(strm, level, Z_DEFLATED, bits, DEF_MEM_LEVEL,
+                Z_DEFAULT_STRATEGY);
+        }
+        internal int deflateInit(ZStream strm, int level){
+            return deflateInit(strm, level, MAX_WBITS);
+        }
+        internal int deflateInit2(ZStream strm, int level, int method,  int windowBits,
+            int memLevel, int strategy){
+            int noheader = 0;
+            //    byte[] my_version=ZLIB_VERSION;
+
+            //
+            //  if (version == null || version[0] != my_version[0]
+            //  || stream_size != sizeof(z_stream)) {
+            //  return Z_VERSION_ERROR;
+            //  }
+
+            strm.msg = null;
+
+            if (level == Z_DEFAULT_COMPRESSION) level = 6;
+
+            if (windowBits < 0) { // undocumented feature: suppress zlib header
+                noheader = 1;
+                windowBits = -windowBits;
+            }
+
+            if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || 
+                method != Z_DEFLATED ||
+                windowBits < 9 || windowBits > 15 || level < 0 || level > 9 ||
+                strategy < 0 || strategy > Z_HUFFMAN_ONLY) {
+                return Z_STREAM_ERROR;
+            }
+
+            strm.dstate = (Deflate)this;
+
+            this.noheader = noheader;
+            w_bits = windowBits;
+            w_size = 1 << w_bits;
+            w_mask = w_size - 1;
+
+            hash_bits = memLevel + 7;
+            hash_size = 1 << hash_bits;
+            hash_mask = hash_size - 1;
+            hash_shift = ((hash_bits+MIN_MATCH-1)/MIN_MATCH);
+
+            window = new byte[w_size*2];
+            prev = new short[w_size];
+            head = new short[hash_size];
+
+            lit_bufsize = 1 << (memLevel + 6); // 16K elements by default
+
+            // We overlay pending_buf and d_buf+l_buf. This works since the average
+            // output size for (length,distance) codes is <= 24 bits.
+            pending_buf = new byte[lit_bufsize*4];
+            pending_buf_size = lit_bufsize*4;
+
+            d_buf = lit_bufsize/2;
+            l_buf = (1+2)*lit_bufsize;
+
+            this.level = level;
+
+            //System.out.println("level="+level);
+
+            this.strategy = strategy;
+            this.method = (byte)method;
+
+            return deflateReset(strm);
+        }
+
+        internal int deflateReset(ZStream strm){
+            strm.total_in = strm.total_out = 0;
+            strm.msg = null; //
+            strm.data_type = Z_UNKNOWN;
+
+            pending = 0;
+            pending_out = 0;
+
+            if(noheader < 0) {
+                noheader = 0; // was set to -1 by deflate(..., Z_FINISH);
+            }
+            status = (noheader!=0) ? BUSY_STATE : INIT_STATE;
+            strm.adler=strm._adler.adler32(0, null, 0, 0);
+
+            last_flush = Z_NO_FLUSH;
+
+            tr_init();
+            lm_init();
+            return Z_OK;
+        }
+
+        internal int deflateEnd(){
+            if(status!=INIT_STATE && status!=BUSY_STATE && status!=FINISH_STATE){
+                return Z_STREAM_ERROR;
+            }
+            // Deallocate in reverse order of allocations:
+            pending_buf=null;
+            head=null;
+            prev=null;
+            window=null;
+            // free
+            // dstate=null;
+            return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK;
+        }
+
+        internal int deflateParams(ZStream strm, int _level, int _strategy){
+            int err=Z_OK;
+
+            if(_level == Z_DEFAULT_COMPRESSION){
+                _level = 6;
+            }
+            if(_level < 0 || _level > 9 || 
+                _strategy < 0 || _strategy > Z_HUFFMAN_ONLY) {
+                return Z_STREAM_ERROR;
+            }
+
+            if(config_table[level].func!=config_table[_level].func &&
+                strm.total_in != 0) {
+                // Flush the last buffer:
+                err = strm.deflate(Z_PARTIAL_FLUSH);
+            }
+
+            if(level != _level) {
+                level = _level;
+                max_lazy_match   = config_table[level].max_lazy;
+                good_match       = config_table[level].good_length;
+                nice_match       = config_table[level].nice_length;
+                max_chain_length = config_table[level].max_chain;
+            }
+            strategy = _strategy;
+            return err;
+        }
+
+        internal int deflateSetDictionary (ZStream strm, byte[] dictionary, int dictLength){
+            int length = dictLength;
+            int index=0;
+
+            if(dictionary == null || status != INIT_STATE)
+                return Z_STREAM_ERROR;
+
+            strm.adler=strm._adler.adler32(strm.adler, dictionary, 0, dictLength);
+
+            if(length < MIN_MATCH) return Z_OK;
+            if(length > w_size-MIN_LOOKAHEAD){
+                length = w_size-MIN_LOOKAHEAD;
+                index=dictLength-length; // use the tail of the dictionary
+            }
+            System.Array.Copy(dictionary, index, window, 0, length);
+            strstart = length;
+            block_start = length;
+
+            // Insert all strings in the hash table (except for the last two bytes).
+            // s->lookahead stays null, so s->ins_h will be recomputed at the next
+            // call of fill_window.
+
+            ins_h = window[0]&0xff;
+            ins_h=(((ins_h)<<hash_shift)^(window[1]&0xff))&hash_mask;
+
+            for(int n=0; n<=length-MIN_MATCH; n++){
+                ins_h=(((ins_h)<<hash_shift)^(window[(n)+(MIN_MATCH-1)]&0xff))&hash_mask;
+                prev[n&w_mask]=head[ins_h];
+                head[ins_h]=(short)n;
+            }
+            return Z_OK;
+        }
+
+        internal int deflate(ZStream strm, int flush){
+            int old_flush;
+
+            if(flush>Z_FINISH || flush<0){
+                return Z_STREAM_ERROR;
+            }
+
+            if(strm.next_out == null ||
+                (strm.next_in == null && strm.avail_in != 0) ||
+                (status == FINISH_STATE && flush != Z_FINISH)) {
+                strm.msg=z_errmsg[Z_NEED_DICT-(Z_STREAM_ERROR)];
+                return Z_STREAM_ERROR;
+            }
+            if(strm.avail_out == 0){
+                strm.msg=z_errmsg[Z_NEED_DICT-(Z_BUF_ERROR)];
+                return Z_BUF_ERROR;
+            }
+
+            this.strm = strm; // just in case
+            old_flush = last_flush;
+            last_flush = flush;
+
+            // Write the zlib header
+            if(status == INIT_STATE) {
+                int header = (Z_DEFLATED+((w_bits-8)<<4))<<8;
+                int level_flags=((level-1)&0xff)>>1;
+
+                if(level_flags>3) level_flags=3;
+                header |= (level_flags<<6);
+                if(strstart!=0) header |= PRESET_DICT;
+                header+=31-(header % 31);
+
+                status=BUSY_STATE;
+                putShortMSB(header);
+
+
+                // Save the adler32 of the preset dictionary:
+                if(strstart!=0){
+                    putShortMSB((int)(strm.adler>>16));
+                    putShortMSB((int)(strm.adler&0xffff));
+                }
+                strm.adler=strm._adler.adler32(0, null, 0, 0);
+            }
+
+            // Flush as much pending output as possible
+            if(pending != 0) {
+                strm.flush_pending();
+                if(strm.avail_out == 0) {
+                    //System.out.println("  avail_out==0");
+                    // Since avail_out is 0, deflate will be called again with
+                    // more output space, but possibly with both pending and
+                    // avail_in equal to zero. There won't be anything to do,
+                    // but this is not an error situation so make sure we
+                    // return OK instead of BUF_ERROR at next call of deflate:
+                    last_flush = -1;
+                    return Z_OK;
+                }
+
+                // Make sure there is something to do and avoid duplicate consecutive
+                // flushes. For repeated and useless calls with Z_FINISH, we keep
+                // returning Z_STREAM_END instead of Z_BUFF_ERROR.
+            }
+            else if(strm.avail_in==0 && flush <= old_flush &&
+                flush != Z_FINISH) {
+                strm.msg=z_errmsg[Z_NEED_DICT-(Z_BUF_ERROR)];
+                return Z_BUF_ERROR;
+            }
+
+            // User must not provide more input after the first FINISH:
+            if(status == FINISH_STATE && strm.avail_in != 0) {
+                strm.msg=z_errmsg[Z_NEED_DICT-(Z_BUF_ERROR)];
+                return Z_BUF_ERROR;
+            }
+
+            // Start a new block or continue the current one.
+            if(strm.avail_in!=0 || lookahead!=0 ||
+                (flush != Z_NO_FLUSH && status != FINISH_STATE)) {
+                int bstate=-1;
+                switch(config_table[level].func){
+                    case STORED: 
+                        bstate = deflate_stored(flush);
+                        break;
+                    case FAST: 
+                        bstate = deflate_fast(flush);
+                        break;
+                    case SLOW: 
+                        bstate = deflate_slow(flush);
+                        break;
+                    default:
+                        break;
+                }
+
+                if (bstate==FinishStarted || bstate==FinishDone) {
+                    status = FINISH_STATE;
+                }
+                if (bstate==NeedMore || bstate==FinishStarted) {
+                    if(strm.avail_out == 0) {
+                        last_flush = -1; // avoid BUF_ERROR next call, see above
+                    }
+                    return Z_OK;
+                    // If flush != Z_NO_FLUSH && avail_out == 0, the next call
+                    // of deflate should use the same flush parameter to make sure
+                    // that the flush is complete. So we don't have to output an
+                    // empty block here, this will be done at next call. This also
+                    // ensures that for a very small output buffer, we emit at most
+                    // one empty block.
+                }
+
+                if (bstate==BlockDone) {
+                    if(flush == Z_PARTIAL_FLUSH) {
+                        _tr_align();
+                    } 
+                    else { // FULL_FLUSH or SYNC_FLUSH
+                        _tr_stored_block(0, 0, false);
+                        // For a full flush, this empty block will be recognized
+                        // as a special marker by inflate_sync().
+                        if(flush == Z_FULL_FLUSH) {
+                            //state.head[s.hash_size-1]=0;
+                            for(int i=0; i<hash_size/*-1*/; i++)  // forget history
+                                head[i]=0;
+                        }
+                    }
+                    strm.flush_pending();
+                    if(strm.avail_out == 0) {
+                        last_flush = -1; // avoid BUF_ERROR at next call, see above
+                        return Z_OK;
+                    }
+                }
+            }
+
+            if(flush!=Z_FINISH) return Z_OK;
+            if(noheader!=0) return Z_STREAM_END;
+
+            // Write the zlib trailer (adler32)
+            putShortMSB((int)(strm.adler>>16));
+            putShortMSB((int)(strm.adler&0xffff));
+            strm.flush_pending();
+
+            // If avail_out is zero, the application will call deflate again
+            // to flush the rest.
+            noheader = -1; // write the trailer only once!
+            return pending != 0 ? Z_OK : Z_STREAM_END;
+        }
+    }
+}
\ No newline at end of file