context: // Copyright (c) 2009, Dino Chiesa.  
  // This code is licensed under the Microsoft internal license.  See the license.txt file in the source
  // distribution for details. 
  //
  // The zlib code is derived from the jzlib implementation, but significantly modified.
  // The object model is not the same, and many of the behaviors are different.
  // Nonetheless, in keeping with the license for jzlib, I am reproducing the copyright to that code here.
  // 
  // -----------------------------------------------------------------------
  // 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.
  */
  
  
  using System;
  namespace Ionic.Zlib
  {
      sealed class InflateBlocks
      {
          private const int MANY = 1440;
  
          // And'ing with mask[n] masks the lower n bits
          //UPGRADE_NOTE: Final was removed from the declaration of 'inflate_mask'. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1003'"
          private static readonly int[] inflate_mask = new int[] { 0x00000000, 0x00000001, 0x00000003, 0x00000007, 0x0000000f, 0x0000001f, 0x0000003f, 0x0000007f, 0x000000ff, 0x000001ff, 0x000003ff, 0x000007ff, 0x00000fff, 0x00001fff, 0x00003fff, 0x00007fff, 0x0000ffff };
  
          // Table for deflate from PKZIP's appnote.txt.
          //UPGRADE_NOTE: Final was removed from the declaration of 'border'. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1003'"
          internal static readonly int[] border = new int[] { 16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15 };
  
          private const int TYPE = 0; // get type bits (3, including end bit)
          private const int LENS = 1; // get lengths for stored
          private const int STORED = 2; // processing stored block
          private const int TABLE = 3; // get table lengths
          private const int BTREE = 4; // get bit lengths tree for a dynamic block
          private const int DTREE = 5; // get length, distance trees for a dynamic block
          private const int CODES = 6; // processing fixed or dynamic block
          private const int DRY = 7; // output remaining window bytes
          private const int DONE = 8; // finished last block, done
          private const int BAD = 9; // ot a data error--stuck here
  
          internal int mode; // current inflate_block mode 
  
          internal int left; // if STORED, bytes left to copy 
  
          internal int table; // table lengths (14 bits) 
          internal int index; // index into blens (or border) 
          internal int[] blens; // bit lengths of codes 
          internal int[] bb = new int[1]; // bit length tree depth 
          internal int[] tb = new int[1]; // bit length decoding tree 
  
          internal InflateCodes codes = new InflateCodes(); // if CODES, current state 
  
          internal int last; // true if this block is the last block 
  
          // mode independent information 
          internal int bitk; // bits in bit buffer 
          internal int bitb; // bit buffer 
          internal int[] hufts; // single malloc for tree space 
          internal byte[] window; // sliding window 
          internal int end; // one byte after sliding window 
          internal int read; // window read pointer 
          internal int write; // window write pointer 
          internal System.Object checkfn; // check function 
          internal long check; // check on output 
  
          internal InfTree inftree = new InfTree();
  
          internal InflateBlocks(ZlibCodec z, System.Object checkfn, int w)
          {
              hufts = new int[MANY * 3];
              window = new byte[w];
              end = w;
              this.checkfn = checkfn;
              mode = TYPE;
              Reset(z, null);
          }
  
          internal void Reset(ZlibCodec z, long[] c)
          {
              if (c != null)
                  c[0] = check;
              if (mode == BTREE || mode == DTREE)
              {
              }
              if (mode == CODES)
              {
              }
              mode = TYPE;
              bitk = 0;
              bitb = 0;
              read = write = 0;
  
              if (checkfn != null)
                  z._Adler32 = check = Adler.Adler32(0L, null, 0, 0);
          }
  
          internal int Process(ZlibCodec z, int r)
          {
              int t; // temporary storage
              int b; // bit buffer
              int k; // bits in bit buffer
              int p; // input data pointer
              int n; // bytes available there
              int q; // output window write pointer
              int m; // bytes to end of window or read pointer
  
              // copy input/output information to locals (UPDATE macro restores)
              {
                  p = z.NextIn; n = z.AvailableBytesIn; b = bitb; k = bitk;
              }
              {
                  q = write; m = (int)(q < read ? read - q - 1 : end - q);
              }
  
              // process input based on current state
              while (true)
              {
                  switch (mode)
                  {
  
                      case TYPE:
  
                          while (k < (3))
                          {
                              if (n != 0)
                              {
                                  r = ZlibConstants.Z_OK;
                              }
                              else
                              {
                                  bitb = b; bitk = k;
                                  z.AvailableBytesIn = n;
                                  z.TotalBytesIn += p - z.NextIn; z.NextIn = p;
                                  write = q;
                                  return Flush(z, r);
                              }
                              ;
                              n--;
                              b |= (z.InputBuffer[p++] & 0xff) << k;
                              k += 8;
                          }
                          t = (int)(b & 7);
                          last = t & 1;
  
                          switch (SharedUtils.URShift(t, 1))
                          {
  
                              case 0:  // stored 
                                  {
                                      b = SharedUtils.URShift(b, (3)); k -= (3);
                                  }
                                  t = k & 7; // go to byte boundary
                                  {
                                      b = SharedUtils.URShift(b, (t)); k -= (t);
                                  }
                                  mode = LENS; // get length of stored block
                                  break;
  
                              case 1:  // fixed
                                  {
                                      int[] bl = new int[1];
                                      int[] bd = new int[1];
                                      int[][] tl = new int[1][];
                                      int[][] td = new int[1][];
  
                                      InfTree.inflate_trees_fixed(bl, bd, tl, td, z);
                                      codes.Init(bl[0], bd[0], tl[0], 0, td[0], 0, z);
                                  }
                                  {
                                      b = SharedUtils.URShift(b, (3)); k -= (3);
                                  }
  
                                  mode = CODES;
                                  break;
  
                              case 2:  // dynamic
                                  {
                                      b = SharedUtils.URShift(b, (3)); k -= (3);
                                  }
  
                                  mode = TABLE;
                                  break;
  
                              case 3:  // illegal
                                  {
                                      b = SharedUtils.URShift(b, (3)); k -= (3);
                                  }
                                  mode = BAD;
                                  z.Message = "invalid block type";
                                  r = ZlibConstants.Z_DATA_ERROR;
  
                                  bitb = b; bitk = k;
                                  z.AvailableBytesIn = n; z.TotalBytesIn += p - z.NextIn; z.NextIn = p;
                                  write = q;
                                  return Flush(z, r);
                          }
                          break;
  
                      case LENS:
  
                          while (k < (32))
                          {
                              if (n != 0)
                              {
                                  r = ZlibConstants.Z_OK;
                              }
                              else
                              {
                                  bitb = b; bitk = k;
                                  z.AvailableBytesIn = n;
                                  z.TotalBytesIn += p - z.NextIn; z.NextIn = p;
                                  write = q;
                                  return Flush(z, r);
                              }
                              ;
                              n--;
                              b |= (z.InputBuffer[p++] & 0xff) << k;
                              k += 8;
                          }
  
                          if (((SharedUtils.URShift((~b), 16)) & 0xffff) != (b & 0xffff))
                          {
                              mode = BAD;
                              z.Message = "invalid stored block lengths";
                              r = ZlibConstants.Z_DATA_ERROR;
  
                              bitb = b; bitk = k;
                              z.AvailableBytesIn = n; z.TotalBytesIn += p - z.NextIn; z.NextIn = p;
                              write = q;
                              return Flush(z, r);
                          }
                          left = (b & 0xffff);
                          b = k = 0; // dump bits
                          mode = left != 0 ? STORED : (last != 0 ? DRY : TYPE);
                          break;
  
                      case STORED:
                          if (n == 0)
                          {
                              bitb = b; bitk = k;
                              z.AvailableBytesIn = n; z.TotalBytesIn += p - z.NextIn; z.NextIn = p;
                              write = q;
                              return Flush(z, r);
                          }
  
                          if (m == 0)
                          {
                              if (q == end && read != 0)
                              {
                                  q = 0; m = (int)(q < read ? read - q - 1 : end - q);
                              }
                              if (m == 0)
                              {
                                  write = q;
                                  r = Flush(z, r);
                                  q = write; m = (int)(q < read ? read - q - 1 : end - q);
                                  if (q == end && read != 0)
                                  {
                                      q = 0; m = (int)(q < read ? read - q - 1 : end - q);
                                  }
                                  if (m == 0)
                                  {
                                      bitb = b; bitk = k;
                                      z.AvailableBytesIn = n; z.TotalBytesIn += p - z.NextIn; z.NextIn = p;
                                      write = q;
                                      return Flush(z, r);
                                  }
                              }
                          }
                          r = ZlibConstants.Z_OK;
  
                          t = left;
                          if (t > n)
                              t = n;
                          if (t > m)
                              t = m;
                          Array.Copy(z.InputBuffer, p, window, q, t);
                          p += t; n -= t;
                          q += t; m -= t;
                          if ((left -= t) != 0)
                              break;
                          mode = last != 0 ? DRY : TYPE;
                          break;
  
                      case TABLE:
  
                          while (k < (14))
                          {
                              if (n != 0)
                              {
                                  r = ZlibConstants.Z_OK;
                              }
                              else
                              {
                                  bitb = b; bitk = k;
                                  z.AvailableBytesIn = n;
                                  z.TotalBytesIn += p - z.NextIn; z.NextIn = p;
                                  write = q;
                                  return Flush(z, r);
                              }
                              ;
                              n--;
                              b |= (z.InputBuffer[p++] & 0xff) << k;
                              k += 8;
                          }
  
                          table = t = (b & 0x3fff);
                          if ((t & 0x1f) > 29 || ((t >> 5) & 0x1f) > 29)
                          {
                              mode = BAD;
                              z.Message = "too many length or distance symbols";
                              r = ZlibConstants.Z_DATA_ERROR;
  
                              bitb = b; bitk = k;
                              z.AvailableBytesIn = n; z.TotalBytesIn += p - z.NextIn; z.NextIn = p;
                              write = q;
                              return Flush(z, r);
                          }
                          t = 258 + (t & 0x1f) + ((t >> 5) & 0x1f);
                          if (blens == null || blens.Length < t)
                          {
                              blens = new int[t];
                          }
                          else
                          {
                              for (int i = 0; i < t; i++)
                              {
                                  blens[i] = 0;
                              }
                          }
                          {
                              b = SharedUtils.URShift(b, (14)); k -= (14);
                          }
  
                          index = 0;
                          mode = BTREE;
                          goto case BTREE;
  
                      case BTREE:
                          while (index < 4 + (SharedUtils.URShift(table, 10)))
                          {
                              while (k < (3))
                              {
                                  if (n != 0)
                                  {
                                      r = ZlibConstants.Z_OK;
                                  }
                                  else
                                  {
                                      bitb = b; bitk = k;
                                      z.AvailableBytesIn = n;
                                      z.TotalBytesIn += p - z.NextIn; z.NextIn = p;
                                      write = q;
                                      return Flush(z, r);
                                  }
                                  ;
                                  n--;
                                  b |= (z.InputBuffer[p++] & 0xff) << k;
                                  k += 8;
                              }
  
                              blens[border[index++]] = b & 7;
  
                              {
                                  b = SharedUtils.URShift(b, (3)); k -= (3);
                              }
                          }
  
                          while (index < 19)
                          {
                              blens[border[index++]] = 0;
                          }
  
                          bb[0] = 7;
                          t = inftree.inflate_trees_bits(blens, bb, tb, hufts, z);
                          if (t != ZlibConstants.Z_OK)
                          {
                              r = t;
                              if (r == ZlibConstants.Z_DATA_ERROR)
                              {
                                  blens = null;
                                  mode = BAD;
                              }
  
                              bitb = b; bitk = k;
                              z.AvailableBytesIn = n; z.TotalBytesIn += p - z.NextIn; z.NextIn = p;
                              write = q;
                              return Flush(z, r);
                          }
  
                          index = 0;
                          mode = DTREE;
                          goto case DTREE;
  
                      case DTREE:
                          while (true)
                          {
                              t = table;
                              if (!(index < 258 + (t & 0x1f) + ((t >> 5) & 0x1f)))
                              {
                                  break;
                              }
  
                              int i, j, c;
  
                              t = bb[0];
  
                              while (k < (t))
                              {
                                  if (n != 0)
                                  {
                                      r = ZlibConstants.Z_OK;
                                  }
                                  else
                                  {
                                      bitb = b; bitk = k;
                                      z.AvailableBytesIn = n;
                                      z.TotalBytesIn += p - z.NextIn; z.NextIn = p;
                                      write = q;
                                      return Flush(z, r);
                                  }
                                  ;
                                  n--;
                                  b |= (z.InputBuffer[p++] & 0xff) << k;
                                  k += 8;
                              }
  
                              if (tb[0] == -1)
                              {
                                  //System.err.println("null...");
                              }
  
                              t = hufts[(tb[0] + (b & inflate_mask[t])) * 3 + 1];
                              c = hufts[(tb[0] + (b & inflate_mask[t])) * 3 + 2];
  
                              if (c < 16)
                              {
                                  b = SharedUtils.URShift(b, (t)); k -= (t);
                                  blens[index++] = c;
                              }
                              else
                              {
                                  // c == 16..18
                                  i = c == 18 ? 7 : c - 14;
                                  j = c == 18 ? 11 : 3;
  
                                  while (k < (t + i))
                                  {
                                      if (n != 0)
                                      {
                                          r = ZlibConstants.Z_OK;
                                      }
                                      else
                                      {
                                          bitb = b; bitk = k;
                                          z.AvailableBytesIn = n;
                                          z.TotalBytesIn += p - z.NextIn; z.NextIn = p;
                                          write = q;
                                          return Flush(z, r);
                                      }
                                      ;
                                      n--;
                                      b |= (z.InputBuffer[p++] & 0xff) << k;
                                      k += 8;
                                  }
  
                                  b = SharedUtils.URShift(b, (t)); k -= (t);
  
                                  j += (b & inflate_mask[i]);
  
                                  b = SharedUtils.URShift(b, (i)); k -= (i);
  
                                  i = index;
                                  t = table;
                                  if (i + j > 258 + (t & 0x1f) + ((t >> 5) & 0x1f) || (c == 16 && i < 1))
                                  {
                                      blens = null;
                                      mode = BAD;
                                      z.Message = "invalid bit length repeat";
                                      r = ZlibConstants.Z_DATA_ERROR;
  
                                      bitb = b; bitk = k;
                                      z.AvailableBytesIn = n; z.TotalBytesIn += p - z.NextIn; z.NextIn = p;
                                      write = q;
                                      return Flush(z, r);
                                  }
  
                                  c = c == 16 ? blens[i - 1] : 0;
                                  do
                                  {
                                      blens[i++] = c;
                                  }
                                  while (--j != 0);
                                  index = i;
                              }
                          }
  
                          tb[0] = -1;
                          {
                              int[] bl = new int[] { 9 };  // must be <= 9 for lookahead assumptions
                              int[] bd = new int[] { 6 }; // must be <= 9 for lookahead assumptions							
                              int[] tl = new int[1];
                              int[] td = new int[1];
  
                              t = table;
                              t = inftree.inflate_trees_dynamic(257 + (t & 0x1f), 1 + ((t >> 5) & 0x1f), blens, bl, bd, tl, td, hufts, z);
  
                              if (t != ZlibConstants.Z_OK)
                              {
                                  if (t == ZlibConstants.Z_DATA_ERROR)
                                  {
                                      blens = null;
                                      mode = BAD;
                                  }
                                  r = t;
  
                                  bitb = b; bitk = k;
                                  z.AvailableBytesIn = n; z.TotalBytesIn += p - z.NextIn; z.NextIn = p;
                                  write = q;
                                  return Flush(z, r);
                              }
                              codes.Init(bl[0], bd[0], hufts, tl[0], hufts, td[0], z);
                          }
                          mode = CODES;
                          goto case CODES;
  
                      case CODES:
                          bitb = b; bitk = k;
                          z.AvailableBytesIn = n; z.TotalBytesIn += p - z.NextIn; z.NextIn = p;
                          write = q;
  
                          if ((r = codes.Process(this, z, r)) != ZlibConstants.Z_STREAM_END)
                          {
                              return Flush(z, r);
                          }
                          r = ZlibConstants.Z_OK;
                          p = z.NextIn; n = z.AvailableBytesIn; b = bitb; k = bitk;
                          q = write; m = (int)(q < read ? read - q - 1 : end - q);
  
                          if (last == 0)
                          {
                              mode = TYPE;
                              break;
                          }
                          mode = DRY;
                          goto case DRY;
  
                      case DRY:
                          write = q;
                          r = Flush(z, r);
                          q = write; m = (int)(q < read ? read - q - 1 : end - q);
                          if (read != write)
                          {
                              bitb = b; bitk = k;
                              z.AvailableBytesIn = n; z.TotalBytesIn += p - z.NextIn; z.NextIn = p;
                              write = q;
                              return Flush(z, r);
                          }
                          mode = DONE;
                          goto case DONE;
  
                      case DONE:
                          r = ZlibConstants.Z_STREAM_END;
  
                          bitb = b; bitk = k;
                          z.AvailableBytesIn = n; z.TotalBytesIn += p - z.NextIn; z.NextIn = p;
                          write = q;
                          return Flush(z, r);
  
                      case BAD:
                          r = ZlibConstants.Z_DATA_ERROR;
  
                          bitb = b; bitk = k;
                          z.AvailableBytesIn = n; z.TotalBytesIn += p - z.NextIn; z.NextIn = p;
                          write = q;
                          return Flush(z, r);
  
  
                      default:
                          r = ZlibConstants.Z_STREAM_ERROR;
  
                          bitb = b; bitk = k;
                          z.AvailableBytesIn = n; z.TotalBytesIn += p - z.NextIn; z.NextIn = p;
                          write = q;
                          return Flush(z, r);
  
                  }
              }
          }
  
          internal void Free(ZlibCodec z)
          {
              Reset(z, null);
              window = null;
              hufts = null;
              //ZFREE(z, s);
          }
  
          internal void SetDictionary(byte[] d, int start, int n)
          {
              Array.Copy(d, start, window, 0, n);
              read = write = n;
          }
  
          // Returns true if inflate is currently at the end of a block generated
          // by Z_SYNC_FLUSH or Z_FULL_FLUSH. 
          internal int SyncPoint()
          {
              return mode == LENS ? 1 : 0;
          }
  
          // copy as much as possible from the sliding window to the output area
          internal int Flush(ZlibCodec z, int r)
          {
              int n;
              int p;
              int q;
  
              // local copies of source and destination pointers
              p = z.NextOut;
              q = read;
  
              // compute number of bytes to copy as far as end of window
              n = (int)((q <= write ? write : end) - q);
              if (n > z.AvailableBytesOut)
                  n = z.AvailableBytesOut;
              if (n != 0 && r == ZlibConstants.Z_BUF_ERROR)
                  r = ZlibConstants.Z_OK;
  
              // update counters
              z.AvailableBytesOut -= n;
              z.TotalBytesOut += n;
  
              // update check information
              if (checkfn != null)
                  z._Adler32 = check = Adler.Adler32(check, window, q, n);
  
              // copy as far as end of window
              Array.Copy(window, q, z.OutputBuffer, p, n);
              p += n;
              q += n;
  
              // see if more to copy at beginning of window
              if (q == end)
              {
                  // wrap pointers
                  q = 0;
                  if (write == end)
                      write = 0;
  
                  // compute bytes to copy
                  n = write - q;
                  if (n > z.AvailableBytesOut)
                      n = z.AvailableBytesOut;
                  if (n != 0 && r == ZlibConstants.Z_BUF_ERROR)
                      r = ZlibConstants.Z_OK;
  
                  // update counters
                  z.AvailableBytesOut -= n;
                  z.TotalBytesOut += n;
  
                  // update check information
                  if (checkfn != null)
                      z._Adler32 = check = Adler.Adler32(check, window, q, n);
  
                  // copy
                  Array.Copy(window, q, z.OutputBuffer, p, n);
                  p += n;
                  q += n;
              }
  
              // update pointers
              z.NextOut = p;
              read = q;
  
              // done
              return r;
          }
      }
  
      sealed class InflateCodes
      {
          //UPGRADE_NOTE: Final was removed from the declaration of 'inflate_mask'. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1003'"
          private static readonly int[] inflate_mask = new int[] { 0x00000000, 0x00000001, 0x00000003, 0x00000007, 0x0000000f, 0x0000001f, 0x0000003f, 0x0000007f, 0x000000ff, 0x000001ff, 0x000003ff, 0x000007ff, 0x00000fff, 0x00001fff, 0x00003fff, 0x00007fff, 0x0000ffff };
  
          // waiting for "i:"=input,
          //             "o:"=output,
          //             "x:"=nothing
          private const int START = 0; // x: set up for LEN
          private const int LEN = 1; // i: get length/literal/eob next
          private const int LENEXT = 2; // i: getting length extra (have base)
          private const int DIST = 3; // i: get distance next
          private const int DISTEXT = 4; // i: getting distance extra
          private const int COPY = 5; // o: copying bytes in window, waiting for space
          private const int LIT = 6; // o: got literal, waiting for output space
          private const int WASH = 7; // o: got eob, possibly still output waiting
          private const int END = 8; // x: got eob and all data flushed
          private const int BADCODE = 9; // x: got error
  
          internal int mode; // current inflate_codes mode
  
          // mode dependent information
          internal int len;
  
          internal int[] tree; // pointer into tree
          internal int tree_index = 0;
          internal int need; // bits needed
  
          internal int lit;
  
          // if EXT or COPY, where and how much
          internal int get_Renamed; // bits to get for extra
          internal int dist; // distance back to copy from
  
          internal byte lbits; // ltree bits decoded per branch
          internal byte dbits; // dtree bits decoder per branch
          internal int[] ltree; // literal/length/eob tree
          internal int ltree_index; // literal/length/eob tree
          internal int[] dtree; // distance tree
          internal int dtree_index; // distance tree
  
          internal InflateCodes()
          {
          }
  
          internal void Init(int bl, int bd, int[] tl, int tl_index, int[] td, int td_index, ZlibCodec z)
          {
              mode = START;
              lbits = (byte)bl;
              dbits = (byte)bd;
              ltree = tl;
              ltree_index = tl_index;
              dtree = td;
              dtree_index = td_index;
              tree = null;
          }
  
          internal int Process(InflateBlocks blocks, ZlibCodec z, int r)
          {
              int j; // temporary storage
              int tindex; // temporary pointer
              int e; // extra bits or operation
              int b = 0; // bit buffer
              int k = 0; // bits in bit buffer
              int p = 0; // input data pointer
              int n; // bytes available there
              int q; // output window write pointer
              int m; // bytes to end of window or read pointer
              int f; // pointer to copy strings from
  
              // copy input/output information to locals (UPDATE macro restores)
              p = z.NextIn; n = z.AvailableBytesIn; b = blocks.bitb; k = blocks.bitk;
              q = blocks.write; m = q < blocks.read ? blocks.read - q - 1 : blocks.end - q;
  
              // process input and output based on current state
              while (true)
              {
                  switch (mode)
                  {
                      // waiting for "i:"=input, "o:"=output, "x:"=nothing
                      case START:  // x: set up for LEN
                          if (m >= 258 && n >= 10)
                          {
  
                              blocks.bitb = b; blocks.bitk = k;
                              z.AvailableBytesIn = n; z.TotalBytesIn += p - z.NextIn; z.NextIn = p;
                              blocks.write = q;
                              r = InflateFast(lbits, dbits, ltree, ltree_index, dtree, dtree_index, blocks, z);
  
                              p = z.NextIn; n = z.AvailableBytesIn; b = blocks.bitb; k = blocks.bitk;
                              q = blocks.write; m = q < blocks.read ? blocks.read - q - 1 : blocks.end - q;
  
                              if (r != ZlibConstants.Z_OK)
                              {
                                  mode = (r == ZlibConstants.Z_STREAM_END) ? WASH : BADCODE;
                                  break;
                              }
                          }
                          need = lbits;
                          tree = ltree;
                          tree_index = ltree_index;
  
                          mode = LEN;
                          goto case LEN;
  
                      case LEN:  // i: get length/literal/eob next
                          j = need;
  
                          while (k < (j))
                          {
                              if (n != 0)
                                  r = ZlibConstants.Z_OK;
                              else
                              {
  
                                  blocks.bitb = b; blocks.bitk = k;
                                  z.AvailableBytesIn = n; z.TotalBytesIn += p - z.NextIn; z.NextIn = p;
                                  blocks.write = q;
                                  return blocks.Flush(z, r);
                              }
                              n--;
                              b |= (z.InputBuffer[p++] & 0xff) << k;
                              k += 8;
                          }
  
                          tindex = (tree_index + (b & inflate_mask[j])) * 3;
  
                          b = SharedUtils.URShift(b, (tree[tindex + 1]));
                          k -= (tree[tindex + 1]);
  
                          e = tree[tindex];
  
                          if (e == 0)
                          {
                              // literal
                              lit = tree[tindex + 2];
                              mode = LIT;
                              break;
                          }
                          if ((e & 16) != 0)
                          {
                              // length
                              get_Renamed = e & 15;
                              len = tree[tindex + 2];
                              mode = LENEXT;
                              break;
                          }
                          if ((e & 64) == 0)
                          {
                              // next table
                              need = e;
                              tree_index = tindex / 3 + tree[tindex + 2];
                              break;
                          }
                          if ((e & 32) != 0)
                          {
                              // end of block
                              mode = WASH;
                              break;
                          }
                          mode = BADCODE; // invalid code
                          z.Message = "invalid literal/length code";
                          r = ZlibConstants.Z_DATA_ERROR;
  
                          blocks.bitb = b; blocks.bitk = k;
                          z.AvailableBytesIn = n; z.TotalBytesIn += p - z.NextIn; z.NextIn = p;
                          blocks.write = q;
                          return blocks.Flush(z, r);
  
  
                      case LENEXT:  // i: getting length extra (have base)
                          j = get_Renamed;
  
                          while (k < (j))
                          {
                              if (n != 0)
                                  r = ZlibConstants.Z_OK;
                              else
                              {
  
                                  blocks.bitb = b; blocks.bitk = k;
                                  z.AvailableBytesIn = n; z.TotalBytesIn += p - z.NextIn; z.NextIn = p;
                                  blocks.write = q;
                                  return blocks.Flush(z, r);
                              }
                              n--; b |= (z.InputBuffer[p++] & 0xff) << k;
                              k += 8;
                          }
  
                          len += (b & inflate_mask[j]);
  
                          b >>= j;
                          k -= j;
  
                          need = dbits;
                          tree = dtree;
                          tree_index = dtree_index;
                          mode = DIST;
                          goto case DIST;
  
                      case DIST:  // i: get distance next
                          j = need;
  
                          while (k < (j))
                          {
                              if (n != 0)
                                  r = ZlibConstants.Z_OK;
                              else
                              {
  
                                  blocks.bitb = b; blocks.bitk = k;
                                  z.AvailableBytesIn = n; z.TotalBytesIn += p - z.NextIn; z.NextIn = p;
                                  blocks.write = q;
                                  return blocks.Flush(z, r);
                              }
                              n--; b |= (z.InputBuffer[p++] & 0xff) << k;
                              k += 8;
                          }
  
                          tindex = (tree_index + (b & inflate_mask[j])) * 3;
  
                          b >>= tree[tindex + 1];
                          k -= tree[tindex + 1];
  
                          e = (tree[tindex]);
                          if ((e & 16) != 0)
                          {
                              // distance
                              get_Renamed = e & 15;
                              dist = tree[tindex + 2];
                              mode = DISTEXT;
                              break;
                          }
                          if ((e & 64) == 0)
                          {
                              // next table
                              need = e;
                              tree_index = tindex / 3 + tree[tindex + 2];
                              break;
                          }
                          mode = BADCODE; // invalid code
                          z.Message = "invalid distance code";
                          r = ZlibConstants.Z_DATA_ERROR;
  
                          blocks.bitb = b; blocks.bitk = k;
                          z.AvailableBytesIn = n; z.TotalBytesIn += p - z.NextIn; z.NextIn = p;
                          blocks.write = q;
                          return blocks.Flush(z, r);
  
  
                      case DISTEXT:  // i: getting distance extra
                          j = get_Renamed;
  
                          while (k < (j))
                          {
                              if (n != 0)
                                  r = ZlibConstants.Z_OK;
                              else
                              {
  
                                  blocks.bitb = b; blocks.bitk = k;
                                  z.AvailableBytesIn = n; z.TotalBytesIn += p - z.NextIn; z.NextIn = p;
                                  blocks.write = q;
                                  return blocks.Flush(z, r);
                              }
                              n--; b |= (z.InputBuffer[p++] & 0xff) << k;
                              k += 8;
                          }
  
  
gt:                         dist += (b & inflate_mask[j]);