1 files changed, 471 insertions, 0 deletions

diff --git a/inftrees.c b/inftrees.c
new file mode 100644
index 0000000..4b00e3c
--- /dev/null
+++ b/inftrees.c
@@ -0,0 +1,471 @@
+/* inftrees.c -- generate Huffman trees for efficient decoding
+ * Copyright (C) 1995 Mark Adler
+ * For conditions of distribution and use, see copyright notice in zlib.h 
+ */
+
+#include "zutil.h"
+#include "inftrees.h"
+
+struct internal_state  {int dummy;}; /* for buggy compilers */
+
+/* simplify the use of the inflate_huft type with some defines */
+#define base more.Base
+#define next more.Next
+#define exop word.what.Exop
+#define bits word.what.Bits
+
+
+local int huft_build __P((
+    uInt *,             /* code lengths in bits */
+    uInt,               /* number of codes */
+    uInt,               /* number of "simple" codes */
+    uInt *,             /* list of base values for non-simple codes */
+    uInt *,             /* list of extra bits for non-simple codes */
+    inflate_huft **,    /* result: starting table */
+    uInt *,             /* maximum lookup bits (returns actual) */
+    z_stream *));       /* for zalloc function */
+
+local voidp falloc __P((
+    voidp,              /* opaque pointer (not used) */
+    uInt,               /* number of items */
+    uInt));             /* size of item */
+
+local void ffree __P((
+    voidp q,            /* opaque pointer (not used) */
+    voidp p));          /* what to free (not used) */
+
+/* Tables for deflate from PKZIP's appnote.txt. */
+local uInt 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};
+        /* actually lengths - 2; also see note #13 above about 258 */
+local uInt 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, 128, 128}; /* 128==invalid */
+local uInt 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};
+local uInt 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};
+
+/*
+   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.
+ */
+
+
+/* If BMAX needs to be larger than 16, then h and x[] should be uLong. */
+#define BMAX 15         /* maximum bit length of any code */
+#define N_MAX 288       /* maximum number of codes in any set */
+
+#ifdef DEBUG
+  uInt inflate_hufts;
+#endif
+
+local int huft_build(b, n, s, d, e, t, m, zs)
+uInt *b;                /* code lengths in bits (all assumed <= BMAX) */
+uInt n;                 /* number of codes (assumed <= N_MAX) */
+uInt s;                 /* number of simple-valued codes (0..s-1) */
+uInt *d;                /* list of base values for non-simple codes */
+uInt *e;                /* list of extra bits for non-simple codes */
+inflate_huft **t;       /* result: starting table */
+uInt *m;                /* maximum lookup bits, returns actual */
+z_stream *zs;           /* for zalloc function */
+/* 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 (all zero length codes or an
+   over-subscribed set of lengths), or Z_MEM_ERROR if not enough memory. */
+{
+  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) */
+  register uInt *p;             /* pointer into c[], b[], or v[] */
+  register inflate_huft *q;     /* points to current table */
+  inflate_huft r;               /* table entry for structure assignment */
+  inflate_huft *u[BMAX];        /* table stack */
+  uInt v[N_MAX];                /* values in order of bit length */
+  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 = (inflate_huft *)Z_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);
+
+
+  /* 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] = (inflate_huft *)Z_NULL;        /* just to keep compilers happy */
+  q = (inflate_huft *)Z_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 = (z = g - w) > (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 */
+            }
+        }
+        z = 1 << j;             /* table entries for j-bit table */
+
+        /* allocate and link in new table */
+        if ((q = (inflate_huft *)ZALLOC
+             (zs,z + 1,sizeof(inflate_huft))) == Z_NULL)
+        {
+          if (h)
+            inflate_trees_free(u[0], zs);
+          return Z_MEM_ERROR;   /* not enough memory */
+        }
+#ifdef DEBUG
+        inflate_hufts += z + 1;
+#endif
+        *t = q + 1;             /* link to list for huft_free() */
+        *(t = &(q->next)) = (inflate_huft *)Z_NULL;
+        u[h] = ++q;             /* table starts after link */
+
+        /* connect to last table, if there is one */
+        if (h)
+        {
+          x[h] = i;             /* save pattern for backing up */
+          r.bits = (char)l;     /* bits to dump before this table */
+          r.exop = (char)(-j);  /* bits in this table */
+          r.next = q;           /* pointer to this table */
+          j = i >> (w - l);     /* (get around Turbo C bug) */
+          u[h-1][j] = r;        /* connect to last table */
+        }
+      }
+
+      /* set up table entry in r */
+      r.bits = (char)(k - w);
+      if (p >= v + n)
+        r.exop = -128;          /* out of values--invalid code */
+      else if (*p < s)
+      {
+        r.exop = (char)(*p < 256 ? 16 : -64);   /* 256 is end-of-block code */
+        r.base = *p++;          /* simple code is just the value */
+      }
+      else
+      {
+        r.exop = (char)e[*p - s];       /* 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 */
+      while ((i & ((1 << w) - 1)) != x[h])
+      {
+        h--;                    /* don't need to update q */
+        w -= l;
+      }
+    }
+  }
+
+
+  /* Return Z_BUF_ERROR if we were given an incomplete table */
+  return y != 0 && g != 1 ? Z_BUF_ERROR : Z_OK;
+}
+
+
+int inflate_trees_bits(c, bb, tb, z)
+uInt *c;                /* 19 code lengths */
+uInt *bb;               /* bits tree desired/actual depth */
+inflate_huft **tb;      /* bits tree result */
+z_stream *z;            /* for zfree function */
+{
+  int r;
+
+  r = huft_build(c, 19, 19, (uInt*)Z_NULL, (uInt*)Z_NULL, tb, bb, z);
+  if (r == Z_DATA_ERROR)
+    z->msg = "oversubscribed dynamic bit lengths tree";
+  else if (r == Z_BUF_ERROR)
+  {
+    inflate_trees_free(*tb, z);
+    z->msg = "incomplete dynamic bit lengths tree";
+    r = Z_DATA_ERROR;
+  }
+  return r;
+}
+
+
+int inflate_trees_dynamic(nl, nd, c, bl, bd, tl, td, z)
+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 */
+z_stream *z;            /* for zfree function */
+{
+  int r;
+
+  /* build literal/length tree */
+  if ((r = huft_build(c, nl, 257, cplens, cplext, tl, bl, z)) != Z_OK)
+  {
+    if (r == Z_DATA_ERROR)
+      z->msg = "oversubscribed literal/length tree";
+    else if (r == Z_BUF_ERROR)
+    {
+      inflate_trees_free(*tl, z);
+      z->msg = "incomplete literal/length tree";
+      r = Z_DATA_ERROR;
+    }
+    return r;
+  }
+
+  /* build distance tree */
+  if ((r = huft_build(c + nl, nd, 0, cpdist, cpdext, td, bd, z)) != Z_OK)
+  {
+    if (r == Z_DATA_ERROR)
+      z->msg = "oversubscribed literal/length tree";
+    else if (r == Z_BUF_ERROR) {
+#ifdef PKZIP_BUG_WORKAROUND
+      r = Z_OK;
+    }
+#else
+      inflate_trees_free(*td, z);
+      z->msg = "incomplete literal/length tree";
+      r = Z_DATA_ERROR;
+    }
+    inflate_trees_free(*tl, z);
+    return r;
+#endif
+  }
+
+  /* done */
+  return Z_OK;
+}
+
+
+/* build fixed tables only once--keep them here */
+local int fixed_lock = 0;
+local int fixed_built = 0;
+#define FIXEDH 530      /* number of hufts used by fixed tables */
+local uInt fixed_left = FIXEDH;
+local inflate_huft fixed_mem[FIXEDH];
+local uInt fixed_bl;
+local uInt fixed_bd;
+local inflate_huft *fixed_tl;
+local inflate_huft *fixed_td;
+
+
+local voidp falloc(q, n, s)
+voidp q;        /* opaque pointer (not used) */
+uInt n;         /* number of items */
+uInt s;         /* size of item */
+{
+  Assert(s == sizeof(inflate_huft) && n <= fixed_left,
+         "inflate_trees falloc overflow");
+  fixed_left -= n;
+  return (voidp)(fixed_mem + fixed_left);
+}
+
+
+local void ffree(q, p)
+voidp q;
+voidp p;
+{
+  Assert(0, "inflate_trees ffree called!");
+}
+
+
+int inflate_trees_fixed(bl, bd, tl, td)
+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 */
+{
+  /* build fixed tables if not built already--lock out other instances */
+  while (++fixed_lock > 1)
+    fixed_lock--;
+  if (!fixed_built)
+  {
+    int k;              /* temporary variable */
+    unsigned c[288];    /* length list for huft_build */
+    z_stream z;         /* for falloc function */
+
+    /* set up fake z_stream for memory routines */
+    z.zalloc = falloc;
+    z.zfree = ffree;
+    z.opaque = Z_NULL;
+
+    /* literal table */
+    for (k = 0; k < 144; k++)
+      c[k] = 8;
+    for (; k < 256; k++)
+      c[k] = 9;
+    for (; k < 280; k++)
+      c[k] = 7;
+    for (; k < 288; k++)
+      c[k] = 8;
+    fixed_bl = 7;
+    huft_build(c, 288, 257, cplens, cplext, &fixed_tl, &fixed_bl, &z);
+
+    /* distance table */
+    for (k = 0; k < 30; k++)
+      c[k] = 5;
+    fixed_bd = 5;
+    huft_build(c, 30, 0, cpdist, cpdext, &fixed_td, &fixed_bd, &z);
+
+    /* done */
+    fixed_built = 1;
+  }
+  fixed_lock--;
+  *bl = fixed_bl;
+  *bd = fixed_bd;
+  *tl = fixed_tl;
+  *td = fixed_td;
+  return Z_OK;
+}
+
+
+int inflate_trees_free(t, z)
+inflate_huft *t;        /* table to free */
+z_stream *z;            /* for zfree function */
+/* 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 inflate_huft *p, *q;
+
+  /* Don't free fixed trees */
+  if (t >= fixed_mem && t <= fixed_mem + FIXEDH)
+    return Z_OK;
+
+  /* Go through linked list, freeing from the malloced (t[-1]) address. */
+  p = t;
+  while (p != Z_NULL)
+  {
+    q = (--p)->next;
+    ZFREE(z,p);
+    p = q;
+  } 
+  return Z_OK;
+}