--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/app/src/main/java/com/jcraft/jzlib/Tree.java	Thu Dec 03 11:23:55 2015 -0800
@@ -0,0 +1,367 @@
+/* -*-mode:java; c-basic-offset:2; -*- */
+/*
+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.
+ */
+
+package com.jcraft.jzlib;
+
+final class Tree{
+  static final private int MAX_BITS=15;
+  static final private int BL_CODES=19;
+  static final private int D_CODES=30;
+  static final private int LITERALS=256;
+  static final private int LENGTH_CODES=29;
+  static final private int L_CODES=(LITERALS+1+LENGTH_CODES);
+  static final private int HEAP_SIZE=(2*L_CODES+1);
+
+  // Bit length codes must not exceed MAX_BL_BITS bits
+  static final int MAX_BL_BITS=7; 
+
+  // end of block literal code
+  static final int END_BLOCK=256; 
+
+  // repeat previous bit length 3-6 times (2 bits of repeat count)
+  static final int REP_3_6=16; 
+
+  // repeat a zero length 3-10 times  (3 bits of repeat count)
+  static final int REPZ_3_10=17; 
+
+  // repeat a zero length 11-138 times  (7 bits of repeat count)
+  static final int REPZ_11_138=18; 
+
+  // extra bits for each length code
+  static final int[] extra_lbits={
+    0,0,0,0,0,0,0,0,1,1,1,1,2,2,2,2,3,3,3,3,4,4,4,4,5,5,5,5,0
+  };
+
+  // extra bits for each distance code
+  static final int[] extra_dbits={
+    0,0,0,0,1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,13,13
+  };
+
+  // extra bits for each bit length code
+  static final int[] extra_blbits={
+    0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7
+  };
+
+  static final byte[] bl_order={
+    16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15};
+
+
+  // The lengths of the bit length codes are sent in order of decreasing
+  // probability, to avoid transmitting the lengths for unused bit
+  // length codes.
+
+  static final int Buf_size=8*2;
+
+  // see definition of array dist_code below
+  static final int DIST_CODE_LEN=512;
+
+  static final byte[] _dist_code = {
+    0,  1,  2,  3,  4,  4,  5,  5,  6,  6,  6,  6,  7,  7,  7,  7,  8,  8,  8,  8,
+    8,  8,  8,  8,  9,  9,  9,  9,  9,  9,  9,  9, 10, 10, 10, 10, 10, 10, 10, 10,
+    10, 10, 10, 10, 10, 10, 10, 10, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11,
+    11, 11, 11, 11, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12,
+    12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 13, 13, 13, 13,
+    13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13,
+    13, 13, 13, 13, 13, 13, 13, 13, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14,
+    14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14,
+    14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14,
+    14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 15, 15, 15, 15, 15, 15, 15, 15,
+    15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15,
+    15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15,
+    15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15,  0,  0, 16, 17,
+    18, 18, 19, 19, 20, 20, 20, 20, 21, 21, 21, 21, 22, 22, 22, 22, 22, 22, 22, 22,
+    23, 23, 23, 23, 23, 23, 23, 23, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
+    24, 24, 24, 24, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25,
+    26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26,
+    26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 27, 27, 27, 27, 27, 27, 27, 27,
+    27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27,
+    27, 27, 27, 27, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28,
+    28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28,
+    28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28,
+    28, 28, 28, 28, 28, 28, 28, 28, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29,
+    29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29,
+    29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29,
+    29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29
+  };
+
+  static final byte[] _length_code={
+    0,  1,  2,  3,  4,  5,  6,  7,  8,  8,  9,  9, 10, 10, 11, 11, 12, 12, 12, 12,
+    13, 13, 13, 13, 14, 14, 14, 14, 15, 15, 15, 15, 16, 16, 16, 16, 16, 16, 16, 16,
+    17, 17, 17, 17, 17, 17, 17, 17, 18, 18, 18, 18, 18, 18, 18, 18, 19, 19, 19, 19,
+    19, 19, 19, 19, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20,
+    21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 22, 22, 22, 22,
+    22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 23, 23, 23, 23, 23, 23, 23, 23,
+    23, 23, 23, 23, 23, 23, 23, 23, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
+    24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
+    25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25,
+    25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 26, 26, 26, 26, 26, 26, 26, 26,
+    26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26, 26,
+    26, 26, 26, 26, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27,
+    27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 28
+  };
+
+  static final int[] base_length = {
+    0, 1, 2, 3, 4, 5, 6, 7, 8, 10, 12, 14, 16, 20, 24, 28, 32, 40, 48, 56,
+    64, 80, 96, 112, 128, 160, 192, 224, 0
+  };
+
+  static final int[] base_dist = {
+       0,   1,      2,     3,     4,    6,     8,    12,    16,     24,
+      32,  48,     64,    96,   128,  192,   256,   384,   512,    768,
+    1024, 1536,  2048,  3072,  4096,  6144,  8192, 12288, 16384, 24576
+  };
+
+  // Mapping from a distance to a distance code. dist is the distance - 1 and
+  // must not have side effects. _dist_code[256] and _dist_code[257] are never
+  // used.
+  static int d_code(int dist){
+    return ((dist) < 256 ? _dist_code[dist] : _dist_code[256+((dist)>>>7)]);
+  }
+
+  short[] dyn_tree;      // the dynamic tree
+  int     max_code;      // largest code with non zero frequency
+  StaticTree stat_desc;  // the corresponding static tree
+
+  // 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.
+  void gen_bitlen(Deflate s){
+    short[] tree = dyn_tree;
+    short[] stree = stat_desc.static_tree;
+    int[] extra = stat_desc.extra_bits;
+    int base = stat_desc.extra_base;
+    int max_length = stat_desc.max_length;
+    int h;              // heap index
+    int n, m;           // iterate over the tree elements
+    int bits;           // bit length
+    int xbits;          // extra bits
+    short f;            // frequency
+    int overflow = 0;   // number of elements with bit length too large
+
+    for (bits = 0; bits <= MAX_BITS; bits++) s.bl_count[bits] = 0;
+
+    // In a first pass, compute the optimal bit lengths (which may
+    // overflow in the case of the bit length tree).
+    tree[s.heap[s.heap_max]*2+1] = 0; // root of the heap
+
+    for(h=s.heap_max+1; h<HEAP_SIZE; h++){
+      n = s.heap[h];
+      bits = tree[tree[n*2+1]*2+1] + 1;
+      if (bits > max_length){ bits = max_length; overflow++; }
+      tree[n*2+1] = (short)bits;
+      // We overwrite tree[n*2+1] which is no longer needed
+
+      if (n > max_code) continue;  // not a leaf node
+
+      s.bl_count[bits]++;
+      xbits = 0;
+      if (n >= base) xbits = extra[n-base];
+      f = tree[n*2];
+      s.opt_len += f * (bits + xbits);
+      if (stree!=null) s.static_len += f * (stree[n*2+1] + 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(s.bl_count[bits]==0) bits--;
+      s.bl_count[bits]--;      // move one leaf down the tree
+      s.bl_count[bits+1]+=2;   // move one overflow item as its brother
+      s.bl_count[max_length]--;
+      // The brother of the overflow item also moves one step up,
+      // but this does not affect bl_count[max_length]
+      overflow -= 2;
+    }
+    while (overflow > 0);
+
+    for (bits = max_length; bits != 0; bits--) {
+      n = s.bl_count[bits];
+      while (n != 0) {
+	m = s.heap[--h];
+	if (m > max_code) continue;
+	if (tree[m*2+1] != bits) {
+	  s.opt_len += ((long)bits - (long)tree[m*2+1])*(long)tree[m*2];
+	  tree[m*2+1] = (short)bits;
+	}
+	n--;
+      }
+    }
+  }
+
+  // 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.
+  void build_tree(Deflate s){
+    short[] tree=dyn_tree;
+    short[] stree=stat_desc.static_tree;
+    int elems=stat_desc.elems;
+    int n, m;          // iterate over heap elements
+    int max_code=-1;   // largest code with non zero frequency
+    int node;          // new node being created
+
+    // Construct the initial heap, with least frequent element in
+    // heap[1]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
+    // heap[0] is not used.
+    s.heap_len = 0;
+    s.heap_max = HEAP_SIZE;
+
+    for(n=0; n<elems; n++) {
+      if(tree[n*2] != 0) {
+	s.heap[++s.heap_len] = max_code = n;
+	s.depth[n] = 0;
+      }
+      else{
+	tree[n*2+1] = 0;
+      }
+    }
+
+    // The pkzip format requires that at least one distance code exists,
+    // and that at least one bit should be sent even if there is only one
+    // possible code. So to avoid special checks later on we force at least
+    // two codes of non zero frequency.
+    while (s.heap_len < 2) {
+      node = s.heap[++s.heap_len] = (max_code < 2 ? ++max_code : 0);
+      tree[node*2] = 1;
+      s.depth[node] = 0;
+      s.opt_len--; if (stree!=null) s.static_len -= stree[node*2+1];
+      // node is 0 or 1 so it does not have extra bits
+    }
+    this.max_code = max_code;
+
+    // The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
+    // establish sub-heaps of increasing lengths:
+
+    for(n=s.heap_len/2;n>=1; n--)
+      s.pqdownheap(tree, n);
+
+    // Construct the Huffman tree by repeatedly combining the least two
+    // frequent nodes.
+
+    node=elems;                 // next internal node of the tree
+    do{
+      // n = node of least frequency
+      n=s.heap[1];
+      s.heap[1]=s.heap[s.heap_len--];
+      s.pqdownheap(tree, 1);
+      m=s.heap[1];                // m = node of next least frequency
+
+      s.heap[--s.heap_max] = n; // keep the nodes sorted by frequency
+      s.heap[--s.heap_max] = m;
+
+      // Create a new node father of n and m
+      tree[node*2] = (short)(tree[n*2] + tree[m*2]);
+      s.depth[node] = (byte)(Math.max(s.depth[n],s.depth[m])+1);
+      tree[n*2+1] = tree[m*2+1] = (short)node;
+
+      // and insert the new node in the heap
+      s.heap[1] = node++;
+      s.pqdownheap(tree, 1);
+    }
+    while(s.heap_len>=2);
+
+    s.heap[--s.heap_max] = s.heap[1];
+
+    // At this point, the fields freq and dad are set. We can now
+    // generate the bit lengths.
+
+    gen_bitlen(s);
+
+    // The field len is now set, we can generate the bit codes
+    gen_codes(tree, max_code, s.bl_count, s.next_code);
+  }
+
+  // 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.
+  private final static void gen_codes(
+                        short[] tree, // the tree to decorate
+                        int max_code, // largest code with non zero frequency
+                        short[] bl_count, // number of codes at each bit length
+                        short[] next_code){
+    short code = 0;            // running code value
+    int bits;                  // bit index
+    int n;                     // code index
+
+    // The distribution counts are first used to generate the code values
+    // without bit reversal.
+    next_code[0]=0;
+    for (bits = 1; bits <= MAX_BITS; bits++) {
+      next_code[bits] = code = (short)((code + bl_count[bits-1]) << 1);
+    }
+
+    // Check that the bit counts in bl_count are consistent. The last code
+    // must be all ones.
+    //Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1,
+    //        "inconsistent bit counts");
+    //Tracev((stderr,"\ngen_codes: max_code %d ", max_code));
+
+    for (n = 0;  n <= max_code; n++) {
+      int len = tree[n*2+1];
+      if (len == 0) continue;
+      // Now reverse the bits
+      tree[n*2] = (short)(bi_reverse(next_code[len]++, len));
+    }
+  }
+
+  // Reverse the first len bits of a code, using straightforward code (a faster
+  // method would use a table)
+  // IN assertion: 1 <= len <= 15
+  private final static int bi_reverse(
+                        int code, // the value to invert
+			int len   // its bit length
+			){
+    int res = 0;
+    do{
+      res|=code&1;
+      code>>>=1;
+      res<<=1;
+    } 
+    while(--len>0);
+    return res>>>1;
+  }
+}
+