[PATCH] zlib_inflate: Upgrade library code to a recent version

Upgrade the zlib_inflate implementation in the kernel from a patched
version 1.1.3/4 to a patched 1.2.3.

The code in the kernel is about seven years old and I noticed that the
external zlib library's inflate performance was significantly faster (~50%)
than the code in the kernel on ARM (and faster again on x86_32).

For comparison the newer deflate code is 20% slower on ARM and 50% slower
on x86_32 but gives an approx 1% compression ratio improvement.  I don't
consider this to be an improvement for kernel use so have no plans to
change the zlib_deflate code.

Various changes have been made to the zlib code in the kernel, the most
significant being the extra functions/flush option used by ppp_deflate.
This update reimplements the features PPP needs to ensure it continues to
work.

This code has been tested on ARM under both JFFS2 (with zlib compression
enabled) and ppp_deflate and on x86_32.  JFFS2 sees an approx.  10% real
world file read speed improvement.

This patch also removes ZLIB_VERSION as it no longer has a correct value.
We don't need version checks anyway as the kernel's module handling will
take care of that for us.  This removal is also more in keeping with the
zlib author's wishes (http://www.zlib.net/zlib_faq.html#faq24) and I've
added something to the zlib.h header to note its a modified version.

Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
Acked-by: Joern Engel <joern@wh.fh-wedel.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 300 insertions, 383 deletions

diff --git a/lib/zlib_inflate/inftrees.c b/lib/zlib_inflate/inftrees.c
index 874950e..62343c5 100644
--- a/lib/zlib_inflate/inftrees.c
+++ b/lib/zlib_inflate/inftrees.c
@@ -1,412 +1,329 @@
 /* inftrees.c -- generate Huffman trees for efficient decoding
- * Copyright (C) 1995-1998 Mark Adler
- * For conditions of distribution and use, see copyright notice in zlib.h 
+ * Copyright (C) 1995-2005 Mark Adler
+ * For conditions of distribution and use, see copyright notice in zlib.h
  */
 
 #include <linux/zutil.h>
 #include "inftrees.h"
-#include "infutil.h"
 
-static const char inflate_copyright[] __attribute_used__ =
-   " inflate 1.1.3 Copyright 1995-1998 Mark Adler ";
+#define MAXBITS 15
+
+const char inflate_copyright[] =
+   " inflate 1.2.3 Copyright 1995-2005 Mark Adler ";
 /*
   If you use the zlib library in a product, an acknowledgment is welcome
   in the documentation of your product. If for some reason you cannot
   include such an acknowledgment, I would appreciate that you keep this
   copyright string in the executable of your product.
  */
-struct internal_state;
-
-/* simplify the use of the inflate_huft type with some defines */
-#define exop word.what.Exop
-#define bits word.what.Bits
-
-
-static int huft_build (
-    uInt *,             /* code lengths in bits */
-    uInt,               /* number of codes */
-    uInt,               /* number of "simple" codes */
-    const uInt *,       /* list of base values for non-simple codes */
-    const uInt *,       /* list of extra bits for non-simple codes */
-    inflate_huft **,    /* result: starting table */
-    uInt *,             /* maximum lookup bits (returns actual) */
-    inflate_huft *,     /* space for trees */
-    uInt *,             /* hufts used in space */
-    uInt * );           /* space for values */
-
-/* Tables for deflate from PKZIP's appnote.txt. */
-static const uInt cplens[31] = { /* 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};
-        /* see note #13 above about 258 */
-static const uInt cplext[31] = { /* 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, 112, 112}; /* 112==invalid */
-static const uInt cpdist[30] = { /* 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};
-static const uInt cpdext[30] = { /* 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};
 
 /*
-   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.
+   Build a set of tables to decode the provided canonical Huffman code.
+   The code lengths are lens[0..codes-1].  The result starts at *table,
+   whose indices are 0..2^bits-1.  work is a writable array of at least
+   lens shorts, which is used as a work area.  type is the type of code
+   to be generated, CODES, LENS, or DISTS.  On return, zero is success,
+   -1 is an invalid code, and +1 means that ENOUGH isn't enough.  table
+   on return points to the next available entry's address.  bits is the
+   requested root table index bits, and on return it is the actual root
+   table index bits.  It will differ if the request is greater than the
+   longest code or if it is less than the shortest code.
  */
-
-
-/* If BMAX needs to be larger than 16, then h and x[] should be uLong. */
-#define BMAX 15         /* maximum bit length of any code */
-
-static int huft_build(
-	uInt *b,               /* code lengths in bits (all assumed <= BMAX) */
-	uInt n,                /* number of codes (assumed <= 288) */
-	uInt s,                /* number of simple-valued codes (0..s-1) */
-	const uInt *d,         /* list of base values for non-simple codes */
-	const uInt *e,         /* list of extra bits for non-simple codes */
-	inflate_huft **t,      /* result: starting table */
-	uInt *m,               /* maximum lookup bits, returns actual */
-	inflate_huft *hp,      /* space for trees */
-	uInt *hn,              /* hufts used in space */
-	uInt *v                /* working area: values in order of bit length */
-)
-/* Given a list of code lengths and a maximum table size, make a set of
-   tables to decode that set of codes.  Return Z_OK on success, Z_BUF_ERROR
-   if the given code set is incomplete (the tables are still built in this
-   case), Z_DATA_ERROR if the input is invalid (an over-subscribed set of
-   lengths), or Z_MEM_ERROR if not enough memory. */
+int zlib_inflate_table(type, lens, codes, table, bits, work)
+codetype type;
+unsigned short *lens;
+unsigned codes;
+code **table;
+unsigned *bits;
+unsigned short *work;
 {
+    unsigned len;               /* a code's length in bits */
+    unsigned sym;               /* index of code symbols */
+    unsigned min, max;          /* minimum and maximum code lengths */
+    unsigned root;              /* number of index bits for root table */
+    unsigned curr;              /* number of index bits for current table */
+    unsigned drop;              /* code bits to drop for sub-table */
+    int left;                   /* number of prefix codes available */
+    unsigned used;              /* code entries in table used */
+    unsigned huff;              /* Huffman code */
+    unsigned incr;              /* for incrementing code, index */
+    unsigned fill;              /* index for replicating entries */
+    unsigned low;               /* low bits for current root entry */
+    unsigned mask;              /* mask for low root bits */
+    code this;                  /* table entry for duplication */
+    code *next;             /* next available space in table */
+    const unsigned short *base;     /* base value table to use */
+    const unsigned short *extra;    /* extra bits table to use */
+    int end;                    /* use base and extra for symbol > end */
+    unsigned short count[MAXBITS+1];    /* number of codes of each length */
+    unsigned short offs[MAXBITS+1];     /* offsets in table for each length */
+    static const unsigned short lbase[31] = { /* Length codes 257..285 base */
+        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};
+    static const unsigned short lext[31] = { /* Length codes 257..285 extra */
+        16, 16, 16, 16, 16, 16, 16, 16, 17, 17, 17, 17, 18, 18, 18, 18,
+        19, 19, 19, 19, 20, 20, 20, 20, 21, 21, 21, 21, 16, 201, 196};
+    static const unsigned short dbase[32] = { /* Distance codes 0..29 base */
+        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, 0, 0};
+    static const unsigned short dext[32] = { /* Distance codes 0..29 extra */
+        16, 16, 16, 16, 17, 17, 18, 18, 19, 19, 20, 20, 21, 21, 22, 22,
+        23, 23, 24, 24, 25, 25, 26, 26, 27, 27,
+        28, 28, 29, 29, 64, 64};
+
+    /*
+       Process a set of code lengths to create a canonical Huffman code.  The
+       code lengths are lens[0..codes-1].  Each length corresponds to the
+       symbols 0..codes-1.  The Huffman code is generated by first sorting the
+       symbols by length from short to long, and retaining the symbol order
+       for codes with equal lengths.  Then the code starts with all zero bits
+       for the first code of the shortest length, and the codes are integer
+       increments for the same length, and zeros are appended as the length
+       increases.  For the deflate format, these bits are stored backwards
+       from their more natural integer increment ordering, and so when the
+       decoding tables are built in the large loop below, the integer codes
+       are incremented backwards.
+
+       This routine assumes, but does not check, that all of the entries in
+       lens[] are in the range 0..MAXBITS.  The caller must assure this.
+       1..MAXBITS is interpreted as that code length.  zero means that that
+       symbol does not occur in this code.
+
+       The codes are sorted by computing a count of codes for each length,
+       creating from that a table of starting indices for each length in the
+       sorted table, and then entering the symbols in order in the sorted
+       table.  The sorted table is work[], with that space being provided by
+       the caller.
+
+       The length counts are used for other purposes as well, i.e. finding
+       the minimum and maximum length codes, determining if there are any
+       codes at all, checking for a valid set of lengths, and looking ahead
+       at length counts to determine sub-table sizes when building the
+       decoding tables.
+     */
+
+    /* accumulate lengths for codes (assumes lens[] all in 0..MAXBITS) */
+    for (len = 0; len <= MAXBITS; len++)
+        count[len] = 0;
+    for (sym = 0; sym < codes; sym++)
+        count[lens[sym]]++;
+
+    /* bound code lengths, force root to be within code lengths */
+    root = *bits;
+    for (max = MAXBITS; max >= 1; max--)
+        if (count[max] != 0) break;
+    if (root > max) root = max;
+    if (max == 0) {                     /* no symbols to code at all */
+        this.op = (unsigned char)64;    /* invalid code marker */
+        this.bits = (unsigned char)1;
+        this.val = (unsigned short)0;
+        *(*table)++ = this;             /* make a table to force an error */
+        *(*table)++ = this;
+        *bits = 1;
+        return 0;     /* no symbols, but wait for decoding to report error */
+    }
+    for (min = 1; min <= MAXBITS; min++)
+        if (count[min] != 0) break;
+    if (root < min) root = min;
+
+    /* check for an over-subscribed or incomplete set of lengths */
+    left = 1;
+    for (len = 1; len <= MAXBITS; len++) {
+        left <<= 1;
+        left -= count[len];
+        if (left < 0) return -1;        /* over-subscribed */
+    }
+    if (left > 0 && (type == CODES || max != 1))
+        return -1;                      /* incomplete set */
+
+    /* generate offsets into symbol table for each length for sorting */
+    offs[1] = 0;
+    for (len = 1; len < MAXBITS; len++)
+        offs[len + 1] = offs[len] + count[len];
+
+    /* sort symbols by length, by symbol order within each length */
+    for (sym = 0; sym < codes; sym++)
+        if (lens[sym] != 0) work[offs[lens[sym]]++] = (unsigned short)sym;
+
+    /*
+       Create and fill in decoding tables.  In this loop, the table being
+       filled is at next and has curr index bits.  The code being used is huff
+       with length len.  That code is converted to an index by dropping drop
+       bits off of the bottom.  For codes where len is less than drop + curr,
+       those top drop + curr - len bits are incremented through all values to
+       fill the table with replicated entries.
+
+       root is the number of index bits for the root table.  When len exceeds
+       root, sub-tables are created pointed to by the root entry with an index
+       of the low root bits of huff.  This is saved in low to check for when a
+       new sub-table should be started.  drop is zero when the root table is
+       being filled, and drop is root when sub-tables are being filled.
+
+       When a new sub-table is needed, it is necessary to look ahead in the
+       code lengths to determine what size sub-table is needed.  The length
+       counts are used for this, and so count[] is decremented as codes are
+       entered in the tables.
+
+       used keeps track of how many table entries have been allocated from the
+       provided *table space.  It is checked when a LENS table is being made
+       against the space in *table, ENOUGH, minus the maximum space needed by
+       the worst case distance code, MAXD.  This should never happen, but the
+       sufficiency of ENOUGH has not been proven exhaustively, hence the check.
+       This assumes that when type == LENS, bits == 9.
+
+       sym increments through all symbols, and the loop terminates when
+       all codes of length max, i.e. all codes, have been processed.  This
+       routine permits incomplete codes, so another loop after this one fills
+       in the rest of the decoding tables with invalid code markers.
+     */
+
+    /* set up for code type */
+    switch (type) {
+    case CODES:
+        base = extra = work;    /* dummy value--not used */
+        end = 19;
+        break;
+    case LENS:
+        base = lbase;
+        base -= 257;
+        extra = lext;
+        extra -= 257;
+        end = 256;
+        break;
+    default:            /* DISTS */
+        base = dbase;
+        extra = dext;
+        end = -1;
+    }
 
-  uInt a;                       /* counter for codes of length k */
-  uInt c[BMAX+1];               /* bit length count table */
-  uInt f;                       /* i repeats in table every f entries */
-  int g;                        /* maximum code length */
-  int h;                        /* table level */
-  register uInt i;              /* counter, current code */
-  register uInt j;              /* counter */
-  register int k;               /* number of bits in current code */
-  int l;                        /* bits per table (returned in m) */
-  uInt mask;                    /* (1 << w) - 1, to avoid cc -O bug on HP */
-  register uInt *p;             /* pointer into c[], b[], or v[] */
-  inflate_huft *q;              /* points to current table */
-  struct inflate_huft_s r;      /* table entry for structure assignment */
-  inflate_huft *u[BMAX];        /* table stack */
-  register int w;               /* bits before this table == (l * h) */
-  uInt x[BMAX+1];               /* bit offsets, then code stack */
-  uInt *xp;                     /* pointer into x */
-  int y;                        /* number of dummy codes added */
-  uInt z;                       /* number of entries in current table */
-
-
-  /* Generate counts for each bit length */
-  p = c;
-#define C0 *p++ = 0;
-#define C2 C0 C0 C0 C0
-#define C4 C2 C2 C2 C2
-  C4                            /* clear c[]--assume BMAX+1 is 16 */
-  p = b;  i = n;
-  do {
-    c[*p++]++;                  /* assume all entries <= BMAX */
-  } while (--i);
-  if (c[0] == n)                /* null input--all zero length codes */
-  {
-    *t = NULL;
-    *m = 0;
-    return Z_OK;
-  }
-
-
-  /* Find minimum and maximum length, bound *m by those */
-  l = *m;
-  for (j = 1; j <= BMAX; j++)
-    if (c[j])
-      break;
-  k = j;                        /* minimum code length */
-  if ((uInt)l < j)
-    l = j;
-  for (i = BMAX; i; i--)
-    if (c[i])
-      break;
-  g = i;                        /* maximum code length */
-  if ((uInt)l > i)
-    l = i;
-  *m = l;
-
-
-  /* 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 Z_DATA_ERROR;
-  if ((y -= c[i]) < 0)
-    return Z_DATA_ERROR;
-  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 */
-  p = 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;                       /* bits decoded == (l * h) */
-  u[0] = NULL;                  /* just to keep compilers happy */
-  q = 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;                 /* previous table always l bits */
-
-        /* compute minimum size table less than or equal to l bits */
-        z = g - w;
-        z = z > (uInt)l ? l : z;        /* table size 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;
-          if (j < z)
-            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 */
-            }
+    /* initialize state for loop */
+    huff = 0;                   /* starting code */
+    sym = 0;                    /* starting code symbol */
+    len = min;                  /* starting code length */
+    next = *table;              /* current table to fill in */
+    curr = root;                /* current table index bits */
+    drop = 0;                   /* current bits to drop from code for index */
+    low = (unsigned)(-1);       /* trigger new sub-table when len > root */
+    used = 1U << root;          /* use root table entries */
+    mask = used - 1;            /* mask for comparing low */
+
+    /* check available table space */
+    if (type == LENS && used >= ENOUGH - MAXD)
+        return 1;
+
+    /* process all codes and make table entries */
+    for (;;) {
+        /* create table entry */
+        this.bits = (unsigned char)(len - drop);
+        if ((int)(work[sym]) < end) {
+            this.op = (unsigned char)0;
+            this.val = work[sym];
         }
-        z = 1 << j;             /* table entries for j-bit table */
-
-        /* allocate new table */
-        if (*hn + z > MANY)     /* (note: doesn't matter for fixed) */
-          return Z_DATA_ERROR;  /* overflow of MANY */
-        u[h] = q = hp + *hn;
-        *hn += z;
-
-        /* connect to last table, if there is one */
-        if (h)
-        {
-          x[h] = i;             /* save pattern for backing up */
-          r.bits = (Byte)l;     /* bits to dump before this table */
-          r.exop = (Byte)j;     /* bits in this table */
-          j = i >> (w - l);
-          r.base = (uInt)(q - u[h-1] - j);   /* offset to this table */
-          u[h-1][j] = r;        /* connect to last table */
+        else if ((int)(work[sym]) > end) {
+            this.op = (unsigned char)(extra[work[sym]]);
+            this.val = base[work[sym]];
+        }
+        else {
+            this.op = (unsigned char)(32 + 64);         /* end of block */
+            this.val = 0;
         }
-        else
-          *t = q;               /* first table is returned result */
-      }
-
-      /* set up table entry in r */
-      r.bits = (Byte)(k - w);
-      if (p >= v + n)
-        r.exop = 128 + 64;      /* out of values--invalid code */
-      else if (*p < s)
-      {
-        r.exop = (Byte)(*p < 256 ? 0 : 32 + 64);     /* 256 is end-of-block */
-        r.base = *p++;          /* simple code is just the value */
-      }
-      else
-      {
-        r.exop = (Byte)(e[*p - s] + 16 + 64);/* non-simple--look up in lists */
-        r.base = 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 */
-      mask = (1 << w) - 1;      /* needed on HP, cc -O bug */
-      while ((i & mask) != x[h])
-      {
-        h--;                    /* don't need to update q */
-        w -= l;
-        mask = (1 << w) - 1;
-      }
-    }
-  }
 
+        /* replicate for those indices with low len bits equal to huff */
+        incr = 1U << (len - drop);
+        fill = 1U << curr;
+        min = fill;                 /* save offset to next table */
+        do {
+            fill -= incr;
+            next[(huff >> drop) + fill] = this;
+        } while (fill != 0);
+
+        /* backwards increment the len-bit code huff */
+        incr = 1U << (len - 1);
+        while (huff & incr)
+            incr >>= 1;
+        if (incr != 0) {
+            huff &= incr - 1;
+            huff += incr;
+        }
+        else
+            huff = 0;
 
-  /* Return Z_BUF_ERROR if we were given an incomplete table */
-  return y != 0 && g != 1 ? Z_BUF_ERROR : Z_OK;
-}
+        /* go to next symbol, update count, len */
+        sym++;
+        if (--(count[len]) == 0) {
+            if (len == max) break;
+            len = lens[work[sym]];
+        }
 
+        /* create new sub-table if needed */
+        if (len > root && (huff & mask) != low) {
+            /* if first time, transition to sub-tables */
+            if (drop == 0)
+                drop = root;
+
+            /* increment past last table */
+            next += min;            /* here min is 1 << curr */
+
+            /* determine length of next table */
+            curr = len - drop;
+            left = (int)(1 << curr);
+            while (curr + drop < max) {
+                left -= count[curr + drop];
+                if (left <= 0) break;
+                curr++;
+                left <<= 1;
+            }
 
-int zlib_inflate_trees_bits(
-	uInt *c,                /* 19 code lengths */
-	uInt *bb,               /* bits tree desired/actual depth */
-	inflate_huft **tb,      /* bits tree result */
-	inflate_huft *hp,       /* space for trees */
-	z_streamp z             /* for messages */
-)
-{
-  int r;
-  uInt hn = 0;          /* hufts used in space */
-  uInt *v;              /* work area for huft_build */
-  
-  v = WS(z)->tree_work_area_1;
-  r = huft_build(c, 19, 19, NULL, NULL, tb, bb, hp, &hn, v);
-  if (r == Z_DATA_ERROR)
-    z->msg = (char*)"oversubscribed dynamic bit lengths tree";
-  else if (r == Z_BUF_ERROR || *bb == 0)
-  {
-    z->msg = (char*)"incomplete dynamic bit lengths tree";
-    r = Z_DATA_ERROR;
-  }
-  return r;
-}
+            /* check for enough space */
+            used += 1U << curr;
+            if (type == LENS && used >= ENOUGH - MAXD)
+                return 1;
 
-int zlib_inflate_trees_dynamic(
-	uInt nl,                /* number of literal/length codes */
-	uInt nd,                /* number of distance codes */
-	uInt *c,                /* that many (total) code lengths */
-	uInt *bl,               /* literal desired/actual bit depth */
-	uInt *bd,               /* distance desired/actual bit depth */
-	inflate_huft **tl,      /* literal/length tree result */
-	inflate_huft **td,      /* distance tree result */
-	inflate_huft *hp,       /* space for trees */
-	z_streamp z             /* for messages */
-)
-{
-  int r;
-  uInt hn = 0;          /* hufts used in space */
-  uInt *v;              /* work area for huft_build */
-
-  /* allocate work area */
-  v = WS(z)->tree_work_area_2;
-
-  /* build literal/length tree */
-  r = huft_build(c, nl, 257, cplens, cplext, tl, bl, hp, &hn, v);
-  if (r != Z_OK || *bl == 0)
-  {
-    if (r == Z_DATA_ERROR)
-      z->msg = (char*)"oversubscribed literal/length tree";
-    else if (r != Z_MEM_ERROR)
-    {
-      z->msg = (char*)"incomplete literal/length tree";
-      r = Z_DATA_ERROR;
-    }
-    return r;
-  }
-
-  /* build distance tree */
-  r = huft_build(c + nl, nd, 0, cpdist, cpdext, td, bd, hp, &hn, v);
-  if (r != Z_OK || (*bd == 0 && nl > 257))
-  {
-    if (r == Z_DATA_ERROR)
-      z->msg = (char*)"oversubscribed distance tree";
-    else if (r == Z_BUF_ERROR) {
-#ifdef PKZIP_BUG_WORKAROUND
-      r = Z_OK;
-    }
-#else
-      z->msg = (char*)"incomplete distance tree";
-      r = Z_DATA_ERROR;
-    }
-    else if (r != Z_MEM_ERROR)
-    {
-      z->msg = (char*)"empty distance tree with lengths";
-      r = Z_DATA_ERROR;
+            /* point entry in root table to sub-table */
+            low = huff & mask;
+            (*table)[low].op = (unsigned char)curr;
+            (*table)[low].bits = (unsigned char)root;
+            (*table)[low].val = (unsigned short)(next - *table);
+        }
     }
-    return r;
-#endif
-  }
 
-  /* done */
-  return Z_OK;
-}
+    /*
+       Fill in rest of table for incomplete codes.  This loop is similar to the
+       loop above in incrementing huff for table indices.  It is assumed that
+       len is equal to curr + drop, so there is no loop needed to increment
+       through high index bits.  When the current sub-table is filled, the loop
+       drops back to the root table to fill in any remaining entries there.
+     */
+    this.op = (unsigned char)64;                /* invalid code marker */
+    this.bits = (unsigned char)(len - drop);
+    this.val = (unsigned short)0;
+    while (huff != 0) {
+        /* when done with sub-table, drop back to root table */
+        if (drop != 0 && (huff & mask) != low) {
+            drop = 0;
+            len = root;
+            next = *table;
+            this.bits = (unsigned char)len;
+        }
 
+        /* put invalid code marker in table */
+        next[huff >> drop] = this;
 
-int zlib_inflate_trees_fixed(
-	uInt *bl,                /* literal desired/actual bit depth */
-	uInt *bd,                /* distance desired/actual bit depth */
-	inflate_huft **tl,       /* literal/length tree result */
-	inflate_huft **td,       /* distance tree result */
-	inflate_huft *hp,       /* space for trees */
-	z_streamp z              /* for memory allocation */
-)
-{
-  int i;                /* temporary variable */
-  unsigned l[288];      /* length list for huft_build */
-  uInt *v;              /* work area 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 = 9;
-  v = WS(z)->tree_work_area_1;
-  if ((i = huft_build(l, 288, 257, cplens, cplext, tl, bl, hp,  &i, v)) != 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, hp, &i, v)) > 1)
-    return i;
-
-  return Z_OK;
+        /* backwards increment the len-bit code huff */
+        incr = 1U << (len - 1);
+        while (huff & incr)
+            incr >>= 1;
+        if (incr != 0) {
+            huff &= incr - 1;
+            huff += incr;
+        }
+        else
+            huff = 0;
+    }
+
+    /* set return parameters */
+    *table += used;
+    *bits = root;
+    return 0;
 }