reactos/dll/zlib/inftrees.c

   1 /* inftrees.c -- generate Huffman trees for efficient decoding
   2  * Copyright (C) 1995-2002 Mark Adler
   3  * For conditions of distribution and use, see copyright notice in zlib.h
   4  */
   5
   6 #include "zutil.h"
   7 #include "inftrees.h"
   8
   9 #if !defined(BUILDFIXED) && !defined(STDC)
  10 #  define BUILDFIXED   /* non ANSI compilers may not accept inffixed.h */
  11 #endif
  12
  13 const char inflate_copyright[] =
  14    " inflate 1.1.4 Copyright 1995-2002 Mark Adler ";
  15 /*
  16   If you use the zlib library in a product, an acknowledgment is welcome
  17   in the documentation of your product. If for some reason you cannot
  18   include such an acknowledgment, I would appreciate that you keep this
  19   copyright string in the executable of your product.
  20  */
  21 struct internal_state  {int dummy;}; /* for buggy compilers */
  22
  23 /* simplify the use of the inflate_huft type with some defines */
  24 #define exop word.what.Exop
  25 #define bits word.what.Bits
  26
  27
  28 local int huft_build OF((
  29     uIntf *,            /* code lengths in bits */
  30     uInt,               /* number of codes */
  31     uInt,               /* number of "simple" codes */
  32     const uIntf *,      /* list of base values for non-simple codes */
  33     const uIntf *,      /* list of extra bits for non-simple codes */
  34     inflate_huft * FAR*,/* result: starting table */
  35     uIntf *,            /* maximum lookup bits (returns actual) */
  36     inflate_huft *,     /* space for trees */
  37     uInt *,             /* hufts used in space */
  38     uIntf * ));         /* space for values */
  39
  40 /* Tables for deflate from PKZIP's appnote.txt. */
  41 local const uInt cplens[31] = { /* Copy lengths for literal codes 257..285 */
  42         3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31,
  43         35, 43, 51, 59, 67, 83, 99, 115, 131, 163, 195, 227, 258, 0, 0};
  44         /* see note #13 above about 258 */
  45 local const uInt cplext[31] = { /* Extra bits for literal codes 257..285 */
  46         0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2,
  47         3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 0, 112, 112}; /* 112==invalid */
  48 local const uInt cpdist[30] = { /* Copy offsets for distance codes 0..29 */
  49         1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193,
  50         257, 385, 513, 769, 1025, 1537, 2049, 3073, 4097, 6145,
  51         8193, 12289, 16385, 24577};
  52 local const uInt cpdext[30] = { /* Extra bits for distance codes */
  53         0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6,
  54         7, 7, 8, 8, 9, 9, 10, 10, 11, 11,
  55         12, 12, 13, 13};
  56
  57 /*
  58    Huffman code decoding is performed using a multi-level table lookup.
  59    The fastest way to decode is to simply build a lookup table whose
  60    size is determined by the longest code.  However, the time it takes
  61    to build this table can also be a factor if the data being decoded
  62    is not very long.  The most common codes are necessarily the
  63    shortest codes, so those codes dominate the decoding time, and hence
  64    the speed.  The idea is you can have a shorter table that decodes the
  65    shorter, more probable codes, and then point to subsidiary tables for
  66    the longer codes.  The time it costs to decode the longer codes is
  67    then traded against the time it takes to make longer tables.
  68
  69    This results of this trade are in the variables lbits and dbits
  70    below.  lbits is the number of bits the first level table for literal/
  71    length codes can decode in one step, and dbits is the same thing for
  72    the distance codes.  Subsequent tables are also less than or equal to
  73    those sizes.  These values may be adjusted either when all of the
  74    codes are shorter than that, in which case the longest code length in
  75    bits is used, or when the shortest code is *longer* than the requested
  76    table size, in which case the length of the shortest code in bits is
  77    used.
  78
  79    There are two different values for the two tables, since they code a
  80    different number of possibilities each.  The literal/length table
  81    codes 286 possible values, or in a flat code, a little over eight
  82    bits.  The distance table codes 30 possible values, or a little less
  83    than five bits, flat.  The optimum values for speed end up being
  84    about one bit more than those, so lbits is 8+1 and dbits is 5+1.
  85    The optimum values may differ though from machine to machine, and
  86    possibly even between compilers.  Your mileage may vary.
  87  */
  88
  89
  90 /* If BMAX needs to be larger than 16, then h and x[] should be uLong. */
  91 #define BMAX 15         /* maximum bit length of any code */
  92
  93 local int huft_build(b, n, s, d, e, t, m, hp, hn, v)
  94 uIntf *b;               /* code lengths in bits (all assumed <= BMAX) */
  95 uInt n;                 /* number of codes (assumed <= 288) */
  96 uInt s;                 /* number of simple-valued codes (0..s-1) */
  97 const uIntf *d;         /* list of base values for non-simple codes */
  98 const uIntf *e;         /* list of extra bits for non-simple codes */
  99 inflate_huft * FAR *t;  /* result: starting table */
 100 uIntf *m;               /* maximum lookup bits, returns actual */
 101 inflate_huft *hp;       /* space for trees */
 102 uInt *hn;               /* hufts used in space */
 103 uIntf *v;               /* working area: values in order of bit length */
 104 /* Given a list of code lengths and a maximum table size, make a set of
 105    tables to decode that set of codes.  Return Z_OK on success, Z_BUF_ERROR
 106    if the given code set is incomplete (the tables are still built in this
 107    case), or Z_DATA_ERROR if the input is invalid. */
 108 {
 109
 110   uInt a;                       /* counter for codes of length k */
 111   uInt c[BMAX+1];               /* bit length count table */
 112   uInt f;                       /* i repeats in table every f entries */
 113   int g;                        /* maximum code length */
 114   int h;                        /* table level */
 115   register uInt i;              /* counter, current code */
 116   register uInt j;              /* counter */
 117   register int k;               /* number of bits in current code */
 118   int l;                        /* bits per table (returned in m) */
 119   uInt mask;                    /* (1 << w) - 1, to avoid cc -O bug on HP */
 120   register uIntf *p;            /* pointer into c[], b[], or v[] */
 121   inflate_huft *q;              /* points to current table */
 122   struct inflate_huft_s r;      /* table entry for structure assignment */
 123   inflate_huft *u[BMAX];        /* table stack */
 124   register int w;               /* bits before this table == (l * h) */
 125   uInt x[BMAX+1];               /* bit offsets, then code stack */
 126   uIntf *xp;                    /* pointer into x */
 127   int y;                        /* number of dummy codes added */
 128   uInt z;                       /* number of entries in current table */
 129
 130   /* Make GCC 4.0 happy. */
 131   r.base = 0;
 132
 133   /* Generate counts for each bit length */
 134   p = c;
 135 #define C0 *p++ = 0;
 136 #define C2 C0 C0 C0 C0
 137 #define C4 C2 C2 C2 C2
 138   C4                            /* clear c[]--assume BMAX+1 is 16 */
 139   p = b;  i = n;
 140   do {
 141     c[*p++]++;                  /* assume all entries <= BMAX */
 142   } while (--i);
 143   if (c[0] == n)                /* null input--all zero length codes */
 144   {
 145     *t = (inflate_huft *)Z_NULL;
 146     *m = 0;
 147     return Z_OK;
 148   }
 149
 150
 151   /* Find minimum and maximum length, bound *m by those */
 152   l = *m;
 153   for (j = 1; j <= BMAX; j++)
 154     if (c[j])
 155       break;
 156   k = j;                        /* minimum code length */
 157   if ((uInt)l < j)
 158     l = j;
 159   for (i = BMAX; i; i--)
 160     if (c[i])
 161       break;
 162   g = i;                        /* maximum code length */
 163   if ((uInt)l > i)
 164     l = i;
 165   *m = l;
 166
 167
 168   /* Adjust last length count to fill out codes, if needed */
 169   for (y = 1 << j; j < i; j++, y <<= 1)
 170     if ((y -= c[j]) < 0)
 171       return Z_DATA_ERROR;
 172   if ((y -= c[i]) < 0)
 173     return Z_DATA_ERROR;
 174   c[i] += y;
 175
 176
 177   /* Generate starting offsets into the value table for each length */
 178   x[1] = j = 0;
 179   p = c + 1;  xp = x + 2;
 180   while (--i) {                 /* note that i == g from above */
 181     *xp++ = (j += *p++);
 182   }
 183
 184
 185   /* Make a table of values in order of bit lengths */
 186   p = b;  i = 0;
 187   do {
 188     if ((j = *p++) != 0)
 189       v[x[j]++] = i;
 190   } while (++i < n);
 191   n = x[g];                     /* set n to length of v */
 192
 193
 194   /* Generate the Huffman codes and for each, make the table entries */
 195   x[0] = i = 0;                 /* first Huffman code is zero */
 196   p = v;                        /* grab values in bit order */
 197   h = -1;                       /* no tables yet--level -1 */
 198   w = -l;                       /* bits decoded == (l * h) */
 199   u[0] = (inflate_huft *)Z_NULL;        /* just to keep compilers happy */
 200   q = (inflate_huft *)Z_NULL;   /* ditto */
 201   z = 0;                        /* ditto */
 202
 203   /* go through the bit lengths (k already is bits in shortest code) */
 204   for (; k <= g; k++)
 205   {
 206     a = c[k];
 207     while (a--)
 208     {
 209       /* here i is the Huffman code of length k bits for value *p */
 210       /* make tables up to required level */
 211       while (k > w + l)
 212       {
 213         h++;
 214         w += l;                 /* previous table always l bits */
 215
 216         /* compute minimum size table less than or equal to l bits */
 217         z = g - w;
 218         z = z > (uInt)l ? l : z;        /* table size upper limit */
 219         if ((f = 1 << (j = k - w)) > a + 1)     /* try a k-w bit table */
 220         {                       /* too few codes for k-w bit table */
 221           f -= a + 1;           /* deduct codes from patterns left */
 222           xp = c + k;
 223           if (j < z)
 224             while (++j < z)     /* try smaller tables up to z bits */
 225             {
 226               if ((f <<= 1) <= *++xp)
 227                 break;          /* enough codes to use up j bits */
 228               f -= *xp;         /* else deduct codes from patterns */
 229             }
 230         }
 231         z = 1 << j;             /* table entries for j-bit table */
 232
 233         /* allocate new table */
 234         if (*hn + z > MANY)     /* (note: doesn't matter for fixed) */
 235           return Z_DATA_ERROR;  /* overflow of MANY */
 236         u[h] = q = hp + *hn;
 237         *hn += z;
 238
 239         /* connect to last table, if there is one */
 240         if (h)
 241         {
 242           x[h] = i;             /* save pattern for backing up */
 243           r.bits = (Byte)l;     /* bits to dump before this table */
 244           r.exop = (Byte)j;     /* bits in this table */
 245           j = i >> (w - l);
 246           r.base = (uInt)(q - u[h-1] - j);   /* offset to this table */
 247           u[h-1][j] = r;        /* connect to last table */
 248         }
 249         else
 250           *t = q;               /* first table is returned result */
 251       }
 252
 253       /* set up table entry in r */
 254       r.bits = (Byte)(k - w);
 255       if (p >= v + n)
 256         r.exop = 128 + 64;      /* out of values--invalid code */
 257       else if (*p < s)
 258       {
 259         r.exop = (Byte)(*p < 256 ? 0 : 32 + 64);     /* 256 is end-of-block */
 260         r.base = *p++;          /* simple code is just the value */
 261       }
 262       else
 263       {
 264         r.exop = (Byte)(e[*p - s] + 16 + 64);/* non-simple--look up in lists */
 265         r.base = d[*p++ - s];
 266       }
 267
 268       /* fill code-like entries with r */
 269       f = 1 << (k - w);
 270       for (j = i >> w; j < z; j += f)
 271         q[j] = r;
 272
 273       /* backwards increment the k-bit code i */
 274       for (j = 1 << (k - 1); i & j; j >>= 1)
 275         i ^= j;
 276       i ^= j;
 277
 278       /* backup over finished tables */
 279       mask = (1 << w) - 1;      /* needed on HP, cc -O bug */
 280       while ((i & mask) != x[h])
 281       {
 282         h--;                    /* don't need to update q */
 283         w -= l;
 284         mask = (1 << w) - 1;
 285       }
 286     }
 287   }
 288
 289
 290   /* Return Z_BUF_ERROR if we were given an incomplete table */
 291   return y != 0 && g != 1 ? Z_BUF_ERROR : Z_OK;
 292 }
 293
 294
 295 int inflate_trees_bits(c, bb, tb, hp, z)
 296 uIntf *c;               /* 19 code lengths */
 297 uIntf *bb;              /* bits tree desired/actual depth */
 298 inflate_huft * FAR *tb; /* bits tree result */
 299 inflate_huft *hp;       /* space for trees */
 300 z_streamp z;            /* for messages */
 301 {
 302   int r;
 303   uInt hn = 0;          /* hufts used in space */
 304   uIntf *v;             /* work area for huft_build */
 305
 306   if ((v = (uIntf*)ZALLOC(z, 19, sizeof(uInt))) == Z_NULL)
 307     return Z_MEM_ERROR;
 308   r = huft_build(c, 19, 19, (uIntf*)Z_NULL, (uIntf*)Z_NULL,
 309                  tb, bb, hp, &hn, v);
 310   if (r == Z_DATA_ERROR)
 311     z->msg = (char*)"oversubscribed dynamic bit lengths tree";
 312   else if (r == Z_BUF_ERROR || *bb == 0)
 313   {
 314     z->msg = (char*)"incomplete dynamic bit lengths tree";
 315     r = Z_DATA_ERROR;
 316   }
 317   ZFREE(z, v);
 318   return r;
 319 }
 320
 321
 322 int inflate_trees_dynamic(nl, nd, c, bl, bd, tl, td, hp, z)
 323 uInt nl;                /* number of literal/length codes */
 324 uInt nd;                /* number of distance codes */
 325 uIntf *c;               /* that many (total) code lengths */
 326 uIntf *bl;              /* literal desired/actual bit depth */
 327 uIntf *bd;              /* distance desired/actual bit depth */
 328 inflate_huft * FAR *tl; /* literal/length tree result */
 329 inflate_huft * FAR *td; /* distance tree result */
 330 inflate_huft *hp;       /* space for trees */
 331 z_streamp z;            /* for messages */
 332 {
 333   int r;
 334   uInt hn = 0;          /* hufts used in space */
 335   uIntf *v;             /* work area for huft_build */
 336
 337   /* allocate work area */
 338   if ((v = (uIntf*)ZALLOC(z, 288, sizeof(uInt))) == Z_NULL)
 339     return Z_MEM_ERROR;
 340
 341   /* build literal/length tree */
 342   r = huft_build(c, nl, 257, cplens, cplext, tl, bl, hp, &hn, v);
 343   if (r != Z_OK || *bl == 0)
 344   {
 345     if (r == Z_DATA_ERROR)
 346       z->msg = (char*)"oversubscribed literal/length tree";
 347     else if (r != Z_MEM_ERROR)
 348     {
 349       z->msg = (char*)"incomplete literal/length tree";
 350       r = Z_DATA_ERROR;
 351     }
 352     ZFREE(z, v);
 353     return r;
 354   }
 355
 356   /* build distance tree */
 357   r = huft_build(c + nl, nd, 0, cpdist, cpdext, td, bd, hp, &hn, v);
 358   if (r != Z_OK || (*bd == 0 && nl > 257))
 359   {
 360     if (r == Z_DATA_ERROR)
 361       z->msg = (char*)"oversubscribed distance tree";
 362     else if (r == Z_BUF_ERROR) {
 363 #ifdef PKZIP_BUG_WORKAROUND
 364       r = Z_OK;
 365     }
 366 #else
 367       z->msg = (char*)"incomplete distance tree";
 368       r = Z_DATA_ERROR;
 369     }
 370     else if (r != Z_MEM_ERROR)
 371     {
 372       z->msg = (char*)"empty distance tree with lengths";
 373       r = Z_DATA_ERROR;
 374     }
 375     ZFREE(z, v);
 376     return r;
 377 #endif
 378   }
 379
 380   /* done */
 381   ZFREE(z, v);
 382   return Z_OK;
 383 }
 384
 385
 386 /* build fixed tables only once--keep them here */
 387 #ifdef BUILDFIXED
 388 local int fixed_built = 0;
 389 #define FIXEDH 544      /* number of hufts used by fixed tables */
 390 local inflate_huft fixed_mem[FIXEDH];
 391 local uInt fixed_bl;
 392 local uInt fixed_bd;
 393 local inflate_huft *fixed_tl;
 394 local inflate_huft *fixed_td;
 395 #else
 396 #include "inffixed.h"
 397 #endif
 398
 399
 400 int inflate_trees_fixed(bl, bd, tl, td, z)
 401 uIntf *bl;               /* literal desired/actual bit depth */
 402 uIntf *bd;               /* distance desired/actual bit depth */
 403 inflate_huft * FAR *tl;  /* literal/length tree result */
 404 inflate_huft * FAR *td;  /* distance tree result */
 405 z_streamp z;             /* for memory allocation */
 406 {
 407 #ifdef BUILDFIXED
 408   /* build fixed tables if not already */
 409   if (!fixed_built)
 410   {
 411     int k;              /* temporary variable */
 412     uInt f = 0;         /* number of hufts used in fixed_mem */
 413     uIntf *c;           /* length list for huft_build */
 414     uIntf *v;           /* work area for huft_build */
 415
 416     /* allocate memory */
 417     if ((c = (uIntf*)ZALLOC(z, 288, sizeof(uInt))) == Z_NULL)
 418       return Z_MEM_ERROR;
 419     if ((v = (uIntf*)ZALLOC(z, 288, sizeof(uInt))) == Z_NULL)
 420     {
 421       ZFREE(z, c);
 422       return Z_MEM_ERROR;
 423     }
 424
 425     /* literal table */
 426     for (k = 0; k < 144; k++)
 427       c[k] = 8;
 428     for (; k < 256; k++)
 429       c[k] = 9;
 430     for (; k < 280; k++)
 431       c[k] = 7;
 432     for (; k < 288; k++)
 433       c[k] = 8;
 434     fixed_bl = 9;
 435     huft_build(c, 288, 257, cplens, cplext, &fixed_tl, &fixed_bl,
 436                fixed_mem, &f, v);
 437
 438     /* distance table */
 439     for (k = 0; k < 30; k++)
 440       c[k] = 5;
 441     fixed_bd = 5;
 442     huft_build(c, 30, 0, cpdist, cpdext, &fixed_td, &fixed_bd,
 443                fixed_mem, &f, v);
 444
 445     /* done */
 446     ZFREE(z, v);
 447     ZFREE(z, c);
 448     fixed_built = 1;
 449   }
 450 #endif
 451   *bl = fixed_bl;
 452   *bd = fixed_bd;
 453   *tl = fixed_tl;
 454   *td = fixed_td;
 455   return Z_OK;
 456 }