text: // zinflate.cpp - modified by Wei Dai from Mark Adler's inflate.c
  
  // This file originally came from MIT's PGP source distribution.
  // I've retrofitted it with bug fixes made in inflate.c versions c11, c15, 
  // and c15b. The latest inflate.c and change log is distributed with 
  // the unzip source. -- Wei Dai 11/4/1999
  
  /* inflate.c -- Not copyrighted 1992 by Mark Adler
     version c10p1, 10 January 1993 */
  
  /* You can do whatever you like with this source file, though I would
     prefer that if you modify it and redistribute it that you include
     comments to that effect with your name and the date.  Thank you.
     [The history has been moved to the file ChangeLog.]
   */
  
  /*
     Inflate deflated (PKZIP's method 8 compressed) data.  The compression
     method searches for as much of the current string of bytes (up to a
     length of 258) in the previous 32K bytes.  If it doesn't find any
     matches (of at least length 3), it codes the next byte.  Otherwise, it
     codes the length of the matched string and its distance backwards from
     the current position.  There is a single Huffman code that codes both
     single bytes (called "literals") and match lengths.  A second Huffman
     code codes the distance information, which follows a length code.  Each
     length or distance code actually represents a base value and a number
     of "extra" (sometimes zero) bits to get to add to the base value.  At
     the end of each deflated block is a special end-of-block (EOB) literal/
     length code.  The decoding process is basically: get a literal/length
     code; if EOB then done; if a literal, emit the decoded byte; if a
     length then get the distance and emit the referred-to bytes from the
     sliding window of previously emitted data.
  
     There are (currently) three kinds of inflate blocks: stored, fixed, and
     dynamic.  The compressor deals with some chunk of data at a time, and
     decides which method to use on a chunk-by-chunk basis.  A chunk might
     typically be 32K or 64K.  If the chunk is uncompressible, then the
     "stored" method is used.  In this case, the bytes are simply stored as
     is, eight bits per byte, with none of the above coding.  The bytes are
     preceded by a count, since there is no longer an EOB code.
  
     If the data is compressible, then either the fixed or dynamic methods
     are used.  In the dynamic method, the compressed data is preceded by
     an encoding of the literal/length and distance Huffman codes that are
     to be used to decode this block.  The representation is itself Huffman
     coded, and so is preceded by a description of that code.  These code
     descriptions take up a little space, and so for small blocks, there is
     a predefined set of codes, called the fixed codes.  The fixed method is
     used if the block codes up smaller that way (usually for quite small
     chunks), otherwise the dynamic method is used.  In the latter case, the
     codes are customized to the probabilities in the current block, and so
     can code it much better than the pre-determined fixed codes.
  
     The Huffman codes themselves are decoded using a mutli-level table
     lookup, in order to maximize the speed of decoding plus the speed of
     building the decoding tables.  See the comments below that precede the
     lbits and dbits tuning parameters.
   */
  
  #include "pch.h"
  #include "zinflate.h"
  #include <stddef.h>     // for NULL
  
  NAMESPACE_BEGIN(CryptoPP)
  
  const unsigned int WSIZE = 0x8000;
  const unsigned long MAX_CHUNKSIZE = 0x10000L;
  
  Inflator::Inflator(BufferedTransformation *output, BufferedTransformation *bypassed)
  	: Fork(output, bypassed), slide(WSIZE)
  {
  	wp = 0;
  	bb = 0;
  	bk = 0;
  	afterEnd = false;
  }
  
  void Inflator::Put(const byte *inString, unsigned int length)
  {
  	if (afterEnd)
  		AccessPort(1).Put(inString, length);
  	else
  	{
  		inQueue.Put(inString, length);
  
  		while(!afterEnd && inQueue.CurrentSize() >= MAX_CHUNKSIZE)
  			inflate_block(afterEnd);
  
  		if (afterEnd)
  		{
  			flush_output(wp);
  			if (bk>=8)  // undo too much lookahead
  				AccessPort(1).Put(byte(bb>>(bk-=8)));
  
  			inQueue.TransferTo(AccessPort(1));
  		}
  	}
  }
  
  void Inflator::InputFinished()
  {
  	while(!afterEnd && inQueue.CurrentSize())
  		inflate_block(afterEnd);
  
  	flush_output(wp);
  
  	if (bk>=8)  // undo too much lookahead
  		AccessPort(1).Put(byte(bb>>(bk-=8)));
  
  	inQueue.TransferTo(AccessPort(1));
  }
  
  void Inflator::flush_output(unsigned int w)
  {
  	AccessPort(0).Put(slide, w);
  	wp = 0;
  }
  
  #define memzero(x, y) memset(x, 0, y)
  
  #  define Assert(cond,msg) assert(cond)
  #  define Trace(x)
  #  define Tracev(x)
  #  define Tracevv(x)
  #  define Tracec(c,x)
  #  define Tracecv(c,x)
  
  
  /* Tables for deflate from PKZIP's appnote.txt. */
  const word16 Inflator::border[] = {    /* Order of the bit length code lengths */
  		16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15};
  const word16 Inflator::cplens[] = {         /* Copy lengths for literal codes 257..285 */
  		3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31,
  		35, 43, 51, 59, 67, 83, 99, 115, 131, 163, 195, 227, 258, 0, 0};
  		/* note: see note #13 above about the 258 in this list. */
  const word16 Inflator::cplext[] = {         /* Extra bits for literal codes 257..285 */
  		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, 99, 99}; /* 99==invalid */
  const word16 Inflator::cpdist[] = {         /* Copy offsets for distance codes 0..29 */
  		1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193,
  		257, 385, 513, 769, 1025, 1537, 2049, 3073, 4097, 6145,
  		8193, 12289, 16385, 24577};
  const word16 Inflator::cpdext[] = {         /* Extra bits for distance codes */
  		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};
  
  
  
  /* Macros for inflate() bit peeking and grabbing.
     The usage is:
  
  		NEEDBITS(j)
  		x = b & mask_bits[j];
  		DUMPBITS(j)
  
     where NEEDBITS makes sure that b has at least j bits in it, and
     DUMPBITS removes the bits from b.  The macros use the variable k
     for the number of bits in b.  Normally, b and k are register
     variables for speed, and are initialized at the beginning of a
     routine that uses these macros from a global bit buffer and count.
  
     If we assume that EOB will be the longest code, then we will never
     ask for bits with NEEDBITS that are beyond the end of the stream.
     So, NEEDBITS should not read any more bytes than are needed to
     meet the request.  Then no bytes need to be "returned" to the buffer
     at the end of the last block.
  
     However, this assumption is not true for fixed blocks--the EOB code
     is 7 bits, but the other literal/length codes can be 8 or 9 bits.
     (The EOB code is shorter than other codes because fixed blocks are
     generally short.  So, while a block always has an EOB, many other
     literal/length codes have a significantly lower probability of
     showing up at all.)  However, by making the first table have a
     lookup of seven bits, the EOB code will be found in that first
     lookup, and so will not require that too many bits be pulled from
     the stream.
   */
  
  
  const word16 Inflator::mask_bits[] = {
  	0x0000,
  	0x0001, 0x0003, 0x0007, 0x000f, 0x001f, 0x003f, 0x007f, 0x00ff,
  	0x01ff, 0x03ff, 0x07ff, 0x0fff, 0x1fff, 0x3fff, 0x7fff, 0xffff
  };
  
  byte Inflator::NEXTBYTE()
  {
  	byte b;
  	if (!inQueue.Get(b))
  		throw UnexpectedEndErr();
  	return b;
  }
  
  #define NEEDBITS(n) {while(k<(n)){b|=((word32)NEXTBYTE())<<k;k+=8;}}
  #define DUMPBITS(n) {b>>=(n);k-=(n);}
  
  
  /*
     Huffman code decoding is performed using a multi-level table lookup.
     The fastest way to decode is to simply build a lookup table whose
     size is determined by the longest code.  However, the time it takes
     to build this table can also be a factor if the data being decoded
     is not very long.  The most common codes are necessarily the
     shortest codes, so those codes dominate the decoding time, and hence
     the speed.  The idea is you can have a shorter table that decodes the
     shorter, more probable codes, and then point to subsidiary tables for
     the longer codes.  The time it costs to decode the longer codes is
     then traded against the time it takes to make longer tables.
  
     This results of this trade are in the variables lbits and dbits
     below.  lbits is the number of bits the first level table for literal/
     length codes can decode in one step, and dbits is the same thing for
     the distance codes.  Subsequent tables are also less than or equal to
     those sizes.  These values may be adjusted either when all of the
     codes are shorter than that, in which case the longest code length in
     bits is used, or when the shortest code is *longer* than the requested
     table size, in which case the length of the shortest code in bits is
     used.
  
     There are two different values for the two tables, since they code a
     different number of possibilities each.  The literal/length table
     codes 286 possible values, or in a flat code, a little over eight
     bits.  The distance table codes 30 possible values, or a little less
     than five bits, flat.  The optimum values for speed end up being
     about one bit more than those, so lbits is 8+1 and dbits is 5+1.
     The optimum values may differ though from machine to machine, and
     possibly even between compilers.  Your mileage may vary.
   */
  
  
  const int lbits = 9;          /* bits in base literal/length lookup table */
  const int dbits = 6;          /* bits in base distance lookup table */
  
  
  /* If BMAX needs to be larger than 16, then h and x[] should be word32. */
  #define BMAX 16         /* maximum bit length of any code (16 for explode) */
  #define N_MAX 288       /* maximum number of codes in any set */
  
  int Inflator::huft_build(unsigned *b, unsigned n, unsigned s, const word16 *d, const word16 *e, huft **t, int *m)
  /* Given a list of code lengths and a maximum table size, make a set of
     tables to decode that set of codes.  Return zero on success, one if
     the given code set is incomplete (the tables are still built in this
     case), two if the input is invalid (all zero length codes or an
     oversubscribed set of lengths), and three if not enough memory. */
  {
    unsigned a;                   /* counter for codes of length k */
    unsigned c[BMAX+1];           /* bit length count table */
    unsigned el;                  /* length of EOB code (value 256) */
    unsigned f;                   /* i repeats in table every f entries */
    int g;                        /* maximum code length */
    int h;                        /* table level */
    register unsigned i;          /* counter, current code */
    register unsigned j;          /* counter */
    register int k;               /* number of bits in current code */
    int lx[BMAX+1];               /* memory for l[-1..BMAX-1] */
    int *l = lx+1;                /* stack of bits per table */
    register unsigned *p;         /* pointer into c[], b[], or v[] */
    register struct huft *q;      /* points to current table */
    struct huft r;                /* table entry for structure assignment */
    struct huft *u[BMAX];         /* table stack */
    unsigned v[N_MAX];            /* values in order of bit length */
    register int w;               /* bits before this table == (l * h) */
    unsigned x[BMAX+1];           /* bit offsets, then code stack */
    unsigned *xp;                 /* pointer into x */
    int y;                        /* number of dummy codes added */
    unsigned z;                   /* number of entries in current table */
  
  
    /* Generate counts for each bit length */
    el = n > 256 ? b[256] : BMAX; /* set length of EOB code, if any */
    memzero((char *)c, sizeof(c));
    p = (unsigned *)b;  i = n;
    do {
      c[*p]++; p++;               /* assume all entries <= BMAX */
    } while (--i);
    if (c[0] == n)                /* null input--all zero length codes */
    {
      *t = (struct huft *)NULL;
      *m = 0;
      return 0;
    }
  
  
    /* Find minimum and maximum length, bound *m by those */
    for (j = 1; j <= BMAX; j++)
      if (c[j])
        break;
    k = j;                        /* minimum code length */
    if ((unsigned)*m < j)
      *m = j;
    for (i = BMAX; i; i--)
      if (c[i])
        break;
    g = i;                        /* maximum code length */
    if ((unsigned)*m > i)
      *m = i;
  
  
    /* Adjust last length count to fill out codes, if needed */
    for (y = 1 << j; j < i; j++, y <<= 1)
      if ((y -= c[j]) < 0)
        return 2;                 /* bad input: more codes than bits */
    if ((y -= c[i]) < 0)
      return 2;
    c[i] += y;
  
  
    /* Generate starting offsets into the value table for each length */
    x[1] = j = 0;
    p = c + 1;  xp = x + 2;
    while (--i) {                 /* note that i == g from above */
      *xp++ = (j += *p++);
    }
  
  
    /* Make a table of values in order of bit lengths */
    memzero((char *)v, sizeof(v));
    p = (unsigned *)b;  i = 0;
    do {
      if ((j = *p++) != 0)
        v[x[j]++] = i;
    } while (++i < n);
    n = x[g];                     /* set n to length of v */
  
  
    /* Generate the Huffman codes and for each, make the table entries */
    x[0] = i = 0;                 /* first Huffman code is zero */
    p = v;                        /* grab values in bit order */
    h = -1;                       /* no tables yet--level -1 */
    w = l[-1] = 0;                /* no bits decoded yet */
    u[0] = (struct huft *)NULL;   /* just to keep compilers happy */
    q = (struct huft *)NULL;      /* ditto */
    z = 0;                        /* ditto */
  
    /* go through the bit lengths (k already is bits in shortest code) */
    for (; k <= g; k++)
    {
      a = c[k];
      while (a--)
      {
        /* here i is the Huffman code of length k bits for value *p */
        /* make tables up to required level */
        while (k > w + l[h])
        {
          w += l[h++];            /* add bits already decoded */
  
          /* compute minimum size table less than or equal to *m bits */
          z = (z = g - w) > (unsigned)*m ? *m : z;        /* upper limit */
          if ((f = 1 << (j = k - w)) > a + 1)     /* try a k-w bit table */
          {                       /* too few codes for k-w bit table */
            f -= a + 1;           /* deduct codes from patterns left */
            xp = c + k;
            while (++j < z)       /* try smaller tables up to z bits */
            {
              if ((f <<= 1) <= *++xp)
                break;            /* enough codes to use up j bits */
              f -= *xp;           /* else deduct codes from patterns */
            }
          }
          if ((unsigned)w + j > el && (unsigned)w < el)
            j = el - w;           /* make EOB code end at table */
          z = 1 << j;             /* table entries for j-bit table */
          l[h] = j;               /* set table size in stack */
  
          /* allocate and link in new table */
  		try
  		{
  			q = SecAlloc(huft, z+2);
  		}
  		catch (...)
  		{
            if (h)
              huft_free(u[0]);
            return 3;             /* not enough memory */
  		}
          *t = q + 2;             /* link to list for huft_free() */
          *(t = &(q->v.t)) = (struct huft *)NULL;
  		q[1].v.n = z;
          u[h] = (q+=2);             /* table starts after link */
  
          /* connect to last table, if there is one */
          if (h)
          {
            x[h] = i;             /* save pattern for backing up */
            r.b = (byte)l[h-1];    /* bits to dump before this table */
            r.e = (byte)(16 + j);  /* bits in this table */
            r.v.t = q;            /* pointer to this table */
            j = (i & ((1 << w) - 1)) >> (w - l[h-1]);
            u[h-1][j] = r;        /* connect to last table */
          }
        }
  
        /* set up table entry in r */
        r.b = (byte)(k - w);
        if (p >= v + n)
          r.e = 99;               /* out of values--invalid code */
        else if (*p < s)
        {
          r.e = (byte)(*p < 256 ? 16 : 15);  /* 256 is end-of-block code */
          r.v.n = (word16)*p++;                /* simple code is just the value */
        }
        else
        {
          r.e = (byte)e[*p - s];   /* non-simple--look up in lists */
          r.v.n = d[*p++ - s];
        }
  
        /* fill code-like entries with r */
        f = 1 << (k - w);
        for (j = i >> w; j < z; j += f)
          q[j] = r;
  
        /* backwards increment the k-bit code i */
        for (j = 1 << (k - 1); i & j; j >>= 1)
          i ^= j;
        i ^= j;
  
        /* backup over finished tables */
        while ((i & ((1 << w) - 1)) != x[h])
          w -= l[--h];            /* don't need to update q */
      }
    }
  
  
    /* return actual size of base table */
    *m = l[0];
  
  
    /* Return true (1) if we were given an incomplete table */
    return y != 0 && g != 1;
  }
  
  
  int Inflator::huft_free(huft *t)
  /* Free the malloc'ed tables built by huft_build(), which makes a linked
     list of the tables it made, with the links in a dummy first entry of
     each table. */
  {
    register huft *p, *q;
  
    /* Go through linked list, freeing from the malloced (t[-1]) address. */
    p = t;
    while (p != (huft *)NULL)
    {
  	q = (p-=2)->v.t;
  	SecFree(p, p[1].v.n + 2);
  	p = q;
    }
    return 0;
  }
  
  
  int Inflator::inflate_codes(huft *tl, huft *td, int bl, int bd)
  /* inflate (decompress) the codes in a deflated (compressed) block.
     Return an error code or zero if it all goes ok. */
  {
    register unsigned e;  /* table entry flag/number of extra bits */
    unsigned n, d;        /* length and index for copy */
    unsigned w;           /* current window position */
    huft *t;       /* pointer to table entry */
    unsigned ml, md;      /* masks for bl and bd bits */
    register word32 b;       /* bit buffer */
    register unsigned k;  /* number of bits in bit buffer */
  
  
    /* make local copies of globals */
    b = bb;                       /* initialize bit buffer */
    k = bk;
    w = wp;                       /* initialize window position */
  
    /* inflate the coded data */
    ml = mask_bits[bl];           /* precompute masks for speed */
    md = mask_bits[bd];
    for (;;)                      /* do until end of block */
    {
  	NEEDBITS((unsigned)bl)
  	if ((e = (t = tl + ((unsigned)b & ml))->e) > 16)
  	  do {
  		if (e == 99)
  		  return 1;
  		DUMPBITS(t->b)
  		e -= 16;
  		NEEDBITS(e)
  	  } while ((e = (t = t->v.t + ((unsigned)b & mask_bits[e]))->e) > 16);
  	DUMPBITS(t->b)
  	if (e == 16)                /* then it's a literal */
  	{
  	  slide[w++] = (byte)t->v.n;
  	  Tracevv((stderr, "%c", slide[w-1]));
  	  if (w == WSIZE)
  	  {
  		flush_output(w);
  		w = 0;
  	  }
  	}
  	else                        /* it's an EOB or a length */
  	{
  	  /* exit if end of block */
  	  if (e == 15)
  		break;
  
  	  /* get length of block to copy */
  	  NEEDBITS(e)
  	  n = t->v.n + ((unsigned)b & mask_bits[e]);
  	  DUMPBITS(e);
  
  	  /* decode distance of block to copy */
  	  NEEDBITS((unsigned)bd)
  	  if ((e = (t = td + ((unsigned)b & md))->e) > 16)
  		do {
  		  if (e == 99)
  			return 1;
  		  DUMPBITS(t->b)
  		  e -= 16;
  		  NEEDBITS(e)
  		} while ((e = (t = t->v.t + ((unsigned)b & mask_bits[e]))->e) > 16);
  	  DUMPBITS(t->b)
  	  NEEDBITS(e)
  	  d = w - t->v.n - ((unsigned)b & mask_bits[e]);
  	  DUMPBITS(e)
  	  Tracevv((stderr,"\\[%d,%d]", w-d, n));
  
  	  /* do the copy */
  	  do {
  		n -= (e = (e = WSIZE - ((d &= WSIZE-1) > w ? d : w)) > n ? n : e);
  #if !defined(NOMEMCPY) && !defined(DEBUG)
  		if (w - d >= e)         /* (this test assumes unsigned comparison) */
  		{
  		  memcpy(slide + w, slide + d, e);
  		  w += e;
  		  d += e;
  		}
  		else                      /* do it slow to avoid memcpy() overlap */
  #endif /* !NOMEMCPY */
  		  do {
  			slide[w++] = slide[d++];
  		Tracevv((stderr, "%c", slide[w-1]));
  		  } while (--e);
  		if (w == WSIZE)
  		{
  		  flush_output(w);
  		  w = 0;
  		}
  	  } while (n);
  	}
    }
  
  
    /* restore the globals from the locals */
    wp = w;                       /* restore global window pointer */
    bb = b;                       /* restore global bit buffer */
    bk = k;
  
    /* done */
    return 0;
  }
  
  
  
  int Inflator::inflate_stored()
  /* "decompress" an inflated type 0 (stored) block. */
  {
    unsigned n;           /* number of bytes in block */
    unsigned w;           /* current window position */
    register word32 b;       /* bit buffer */
    register unsigned k;  /* number of bits in bit buffer */
  
  
    /* make local copies of globals */
    b = bb;                       /* initialize bit buffer */
    k = bk;
    w = wp;                       /* initialize window position */
  
  
    /* go to byte boundary */
    n = k & 7;
    DUMPBITS(n);
  
  
    /* get the length and its complement */
    NEEDBITS(16)
    n = ((unsigned)b & 0xffff);
    DUMPBITS(16)
    NEEDBITS(16)
    if (n != (unsigned)((~b) & 0xffff))
  	return 1;                   /* error in compressed data */
    DUMPBITS(16)
  
  
    /* read and output the compressed data */
    while (n--)
    {
  	NEEDBITS(8)
  	slide[w++] = (byte)b;
  	if (w == WSIZE)
  	{
  	  flush_output(w);
  	  w = 0;
  	}
  	DUMPBITS(8)
    }
  
  
    /* restore the globals from the locals */
    wp = w;                       /* restore global window pointer */
    bb = b;                       /* restore global bit buffer */
    bk = k;
    return 0;
  }
  
  
  
  int Inflator::inflate_fixed()
  /* decompress an inflated type 1 (fixed Huffman codes) block.  We should
     either replace this with a custom decoder, or at least precompute the
     Huffman tables. */
  {
    int i;                /* temporary variable */
    huft *tl;      /* literal/length code table */
    huft *td;      /* distance code table */
    int bl;               /* lookup bits for tl */
    int bd;               /* lookup bits for td */
    unsigned l[288];      /* length list for huft_build */
  
  
    /* set up literal table */
    for (i = 0; i < 144; i++)
  	l[i] = 8;
    for (; i < 256; i++)
  	l[i] = 9;
    for (; i < 280; i++)
  	l[i] = 7;
    for (; i < 288; i++)          /* make a complete, but wrong code set */
  	l[i] = 8;
    bl = 7;
    if ((i = huft_build(l, 288, 257, cplens, cplext, &tl, &bl)) != 0)
  	return i;
  
  
    /* set up distance table */
    for (i = 0; i < 30; i++)      /* make an incomplete code set */
  	l[i] = 5;
    bd = 5;
    if ((i = huft_build(l, 30, 0, cpdist, cpdext, &td, &bd)) > 1)
    {
  	huft_free(tl);
  	return i;
    }
  
  
    /* decompress until an end-of-block code */
    if (inflate_codes(tl, td, bl, bd))
  	return 1;
  
  
    /* free the decoding tables, return */
    huft_free(tl);
    huft_free(td);
    return 0;
  }
  
  
  
  int Inflator::inflate_dynamic()
  /* decompress an inflated type 2 (dynamic Huffman codes) block. */
  {
    int i;                /* temporary variables */
    unsigned j;
    unsigned l;           /* last length */
    unsigned m;           /* mask for bit lengths table */
    unsigned n;           /* number of lengths to get */
    huft *tl;      /* literal/length code table */
    huft *td;      /* distance code table */
    int bl;               /* lookup bits for tl */
    int bd;               /* lookup bits for td */
    unsigned nb;          /* number of bit length codes */
    unsigned nl;          /* number of literal/length codes */
    unsigned nd;          /* number of distance codes */
  #ifdef PKZIP_BUG_WORKAROUND
    unsigned ll[288+32];  /* literal/length and distance code lengths */
  #else
    unsigned ll[286+30];  /* literal/length and distance code lengths */
  #endif
    register word32 b;       /* bit buffer */
    register unsigned k;  /* number of bits in bit buffer */
  
  
    /* make local bit buffer */
    b = bb;
    k = bk;
  
  
    /* read in table lengths */
    NEEDBITS(5)
    nl = 257 + ((unsigned)b & 0x1f);      /* number of literal/length codes */
    DUMPBITS(5)
    NEEDBITS(5)
    nd = 1 + ((unsigned)b & 0x1f);        /* number of distance codes */
    DUMPBITS(5)
    NEEDBITS(4)
    nb = 4 + ((unsigned)b & 0xf);         /* number of bit length codes */
    DUMPBITS(4)
  #ifdef PKZIP_BUG_WORKAROUND
    if (nl > 288 || nd > 32)
  #else
    if (nl > 286 || nd > 30)
  #endif
  	return 1;                   /* bad lengths */
  
  
    /* read in bit-length-code lengths */
    for (j = 0; j < nb; j++)
    {
  	NEEDBITS(3)
  	ll[border[j]] = (unsigned)b & 7;
  	DUMPBITS(3)
    }
    for (; j < 19; j++)
  	ll[border[j]] = 0;
  
  
    /* build decoding table for trees--single level, 7 bit lookup */
    bl = 7;
    i = huft_build(ll, 19, 19, NULL, NULL, &tl, &bl);
    if (bl == 0)                        /* no bit lengths */
      i = 1;
    if (i)
    {
      if (i == 1)
        huft_free(tl);
      return i;                   /* incomplete code set */
    }
  
  
    /* read in literal and distance code lengths */
    n = nl + nd;
    m = mask_bits[bl];
    i = l = 0;
    while ((unsigned)i < n)
    {
  	NEEDBITS((unsigned)bl)
  	j = (td = tl + ((unsigned)b & m))->b;
  	DUMPBITS(j)
  	j = td->v.n;
  	if (j < 16)                 /* length of code in bits (0..15) */
  	  ll[i++] = l = j;          /* save last length in l */
  	else if (j == 16)           /* repeat last length 3 to 6 times */
  	{
  	  NEEDBITS(2)
  	  j = 3 + ((unsigned)b & 3);
  	  DUMPBITS(2)
  	  if ((unsigned)i + j > n)
  		return 1;
  	  while (j--)
  		ll[i++] = l;
  	}
  	else if (j == 17)           /* 3 to 10 zero length codes */
  	{
  	  NEEDBITS(3)
  	  j = 3 + ((unsigned)b & 7);
  	  DUMPBITS(3)
  	  if ((unsigned)i + j > n)
  		return 1;
  	  while (j--)
  		ll[i++] = 0;
  	  l = 0;
  	}
  	else                        /* j == 18: 11 to 138 zero length codes */
  	{
  	  NEEDBITS(7)
  	  j = 11 + ((unsigned)b & 0x7f);
  	  DUMPBITS(7)
  	  if ((unsigned)i + j > n)
  		return 1;
  	  while (j--)
  		ll[i++] = 0;
  	  l = 0;
  	}
    }
  
  
    /* free decoding table for trees */
    huft_free(tl);
  
  
    /* restore the global bit buffer */
    bb = b;
    bk = k;
  
  
    /* build the decoding tables for literal/length and distance codes */
    bl = lbits;
    i = huft_build(ll, nl, 257, cplens, cplext, &tl, &bl);
    if (bl == 0)                        /* no literals or lengths */
      i = 1;
    if (i)
    {
      if (i == 1) {
        huft_free(tl);
      }
      return i;                   /* incomplete code set */
    }
    bd = dbits;
    i = huft_build(ll + nl, nd, 0, cpdist, cpdext, &td, &bd);
    if (bd == 0 && nl > 257)    /* lengths but no distances */
    {
      huft_free(tl);
      return 1;
    }
    if (i == 1) {
  #ifdef PKZIP_BUG_WORKAROUND
      i = 0;
  #else
      huft_free(td);
  #endif
    }
    if (i)
    {
      huft_free(tl);
      return i;
    }
  
  
    /* decompress until an end-of-block code */
    if (inflate_codes(tl, td, bl, bd))
  	return 1;
  
  
    /* free the decoding tables, return */
    huft_free(tl);
    huft_free(td);
    return 0;
  }
  
  
  
  int Inflator::inflate_block(bool &e)
  /* decompress an inflated block */
  {
    unsigned t;           /* block type */
    register word32 b;       /* bit buffer */
    register unsigned k;  /* number of bits in bit buffer */
  
  
    /* make local bit buffer */
    b = bb;
    k = bk;
  
  
    /* read in last block bit */
    NEEDBITS(1)
    e = (int)b & 1;
    DUMPBITS(1)
  
  
    /* read in block type */
    NEEDBITS(2)
    t = (unsigned)b & 3;
    DUMPBITS(2)
  
  
    /* restore the global bit buffer */
    bb = b;
    bk = k;
  
  
    int status;
  
    /* inflate that block type */
    switch (t)
    {
  	case 0:
  		status = inflate_stored();
  		break;
  	case 1:
  		status = inflate_fixed();
  		break;
  	case 2:
  		status = inflate_dynamic();
  		break;
  	default:
  		status = 2;
    }
  	if (status)
  		throw Err("Inflator: error decompressing block");
  	return status;
  }
  
  NAMESPACE_END
  