thirdparty/freetype-2.3.12/src/gzip/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
  14 #if 0
  15 local const char inflate_copyright[] =
  16    " inflate 1.1.4 Copyright 1995-2002 Mark Adler ";
  17 #endif
  18 /*
  19   If you use the zlib library in a product, an acknowledgment is welcome
  20   in the documentation of your product. If for some reason you cannot
  21   include such an acknowledgment, I would appreciate that you keep this
  22   copyright string in the executable of your product.
  23  */
  24
  25 /* simplify the use of the inflate_huft type with some defines */
  26 #define exop word.what.Exop
  27 #define bits word.what.Bits
  28
  29
  30 local int huft_build OF((
  31     uIntf *,            /* code lengths in bits */
  32     uInt,               /* number of codes */
  33     uInt,               /* number of "simple" codes */
  34     const uIntf *,      /* list of base values for non-simple codes */
  35     const uIntf *,      /* list of extra bits for non-simple codes */
  36     inflate_huft * FAR*,/* result: starting table */
  37     uIntf *,            /* maximum lookup bits (returns actual) */
  38     inflate_huft *,     /* space for trees */
  39     uInt *,             /* hufts used in space */
  40     uIntf * ));         /* space for values */
  41
  42 /* Tables for deflate from PKZIP's appnote.txt. */
  43 local const uInt cplens[31] = { /* Copy lengths for literal codes 257..285 */
  44         3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31,
  45         35, 43, 51, 59, 67, 83, 99, 115, 131, 163, 195, 227, 258, 0, 0};
  46         /* see note #13 above about 258 */
  47 local const uInt cplext[31] = { /* Extra bits for literal codes 257..285 */
  48         0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2,
  49         3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 0, 112, 112}; /* 112==invalid */
  50 local const uInt cpdist[30] = { /* Copy offsets for distance codes 0..29 */
  51         1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193,
  52         257, 385, 513, 769, 1025, 1537, 2049, 3073, 4097, 6145,
  53         8193, 12289, 16385, 24577};
  54 local const uInt cpdext[30] = { /* Extra bits for distance codes */
  55         0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6,
  56         7, 7, 8, 8, 9, 9, 10, 10, 11, 11,
  57         12, 12, 13, 13};
  58
  59 /*
  60    Huffman code decoding is performed using a multi-level table lookup.
  61    The fastest way to decode is to simply build a lookup table whose
  62    size is determined by the longest code.  However, the time it takes
  63    to build this table can also be a factor if the data being decoded
  64    is not very long.  The most common codes are necessarily the
  65    shortest codes, so those codes dominate the decoding time, and hence
  66    the speed.  The idea is you can have a shorter table that decodes the
  67    shorter, more probable codes, and then point to subsidiary tables for
  68    the longer codes.  The time it costs to decode the longer codes is
  69    then traded against the time it takes to make longer tables.
  70
  71    This results of this trade are in the variables lbits and dbits
  72    below.  lbits is the number of bits the first level table for literal/
  73    length codes can decode in one step, and dbits is the same thing for
  74    the distance codes.  Subsequent tables are also less than or equal to
  75    those sizes.  These values may be adjusted either when all of the
  76    codes are shorter than that, in which case the longest code length in
  77    bits is used, or when the shortest code is *longer* than the requested
  78    table size, in which case the length of the shortest code in bits is
  79    used.
  80
  81    There are two different values for the two tables, since they code a
  82    different number of possibilities each.  The literal/length table
  83    codes 286 possible values, or in a flat code, a little over eight
  84    bits.  The distance table codes 30 possible values, or a little less
  85    than five bits, flat.  The optimum values for speed end up being
  86    about one bit more than those, so lbits is 8+1 and dbits is 5+1.
  87    The optimum values may differ though from machine to machine, and
  88    possibly even between compilers.  Your mileage may vary.
  89  */
  90
  91
  92 /* If BMAX needs to be larger than 16, then h and x[] should be uLong. */
  93 #define BMAX 15         /* maximum bit length of any code */
  94
  95 local int huft_build( /* b, n, s, d, e, t, m, hp, hn, v) */
  96 uIntf *b,               /* code lengths in bits (all assumed <= BMAX) */
  97 uInt n,                 /* number of codes (assumed <= 288) */
  98 uInt s,                 /* number of simple-valued codes (0..s-1) */
  99 const uIntf *d,         /* list of base values for non-simple codes */
 100 const uIntf *e,         /* list of extra bits for non-simple codes */
 101 inflate_huft * FAR *t,  /* result: starting table */
 102 uIntf *m,               /* maximum lookup bits, returns actual */
 103 inflate_huft *hp,       /* space for trees */
 104 uInt *hn,               /* hufts used in space */
 105 uIntf *v                /* working area: values in order of bit length */
 106 /* Given a list of code lengths and a maximum table size, make a set of
 107    tables to decode that set of codes.  Return Z_OK on success, Z_BUF_ERROR
 108    if the given code set is incomplete (the tables are still built in this
 109    case), or Z_DATA_ERROR if the input is invalid. */
 110 )
 111 {
 112
 113   uInt a;                       /* counter for codes of length k */
 114   uInt c[BMAX+1];               /* bit length count table */
 115   uInt f;                       /* i repeats in table every f entries */
 116   int g;                        /* maximum code length */
 117   int h;                        /* table level */
 118   register uInt i;              /* counter, current code */
 119   register uInt j;              /* counter */
 120   register int k;               /* number of bits in current code */
 121   int l;                        /* bits per table (returned in m) */
 122   uInt mask;                    /* (1 << w) - 1, to avoid cc -O bug on HP */
 123   register uIntf *p;            /* pointer into c[], b[], or v[] */
 124   inflate_huft *q;              /* points to current table */
 125   struct inflate_huft_s r;      /* table entry for structure assignment */
 126   inflate_huft *u[BMAX];        /* table stack */
 127   register int w;               /* bits before this table == (l * h) */
 128   uInt x[BMAX+1];               /* bit offsets, then code stack */
 129   uIntf *xp;                    /* pointer into x */
 130   int y;                        /* number of dummy codes added */
 131   uInt z;                       /* number of entries in current table */
 132
 133
 134   /* Make compiler happy */
 135   r.base = 0;
 136
 137   /* Generate counts for each bit length */
 138   p = c;
 139 #define C0 *p++ = 0;
 140 #define C2 C0 C0 C0 C0
 141 #define C4 C2 C2 C2 C2
 142   C4                            /* clear c[]--assume BMAX+1 is 16 */
 143   p = b;  i = n;
 144   do {
 145     c[*p++]++;                  /* assume all entries <= BMAX */
 146   } while (--i);
 147   if (c[0] == n)                /* null input--all zero length codes */
 148   {
 149     *t = (inflate_huft *)Z_NULL;
 150     *m = 0;
 151     return Z_OK;
 152   }
 153
 154
 155   /* Find minimum and maximum length, bound *m by those */
 156   l = *m;
 157   for (j = 1; j <= BMAX; j++)
 158     if (c[j])
 159       break;
 160   k = j;                        /* minimum code length */
 161   if ((uInt)l < j)
 162     l = j;
 163   for (i = BMAX; i; i--)
 164     if (c[i])
 165       break;
 166   g = i;                        /* maximum code length */
 167   if ((uInt)l > i)
 168     l = i;
 169   *m = l;
 170
 171
 172   /* Adjust last length count to fill out codes, if needed */
 173   for (y = 1 << j; j < i; j++, y <<= 1)
 174     if ((y -= c[j]) < 0)
 175       return Z_DATA_ERROR;
 176   if ((y -= c[i]) < 0)
 177     return Z_DATA_ERROR;
 178   c[i] += y;
 179
 180
 181   /* Generate starting offsets into the value table for each length */
 182   x[1] = j = 0;
 183   p = c + 1;  xp = x + 2;
 184   while (--i) {                 /* note that i == g from above */
 185     *xp++ = (j += *p++);
 186   }
 187
 188
 189   /* Make a table of values in order of bit lengths */
 190   p = b;  i = 0;
 191   do {
 192     if ((j = *p++) != 0)
 193       v[x[j]++] = i;
 194   } while (++i < n);
 195   n = x[g];                     /* set n to length of v */
 196
 197
 198   /* Generate the Huffman codes and for each, make the table entries */
 199   x[0] = i = 0;                 /* first Huffman code is zero */
 200   p = v;                        /* grab values in bit order */
 201   h = -1;                       /* no tables yet--level -1 */
 202   w = -l;                       /* bits decoded == (l * h) */
 203   u[0] = (inflate_huft *)Z_NULL;        /* just to keep compilers happy */
 204   q = (inflate_huft *)Z_NULL;   /* ditto */
 205   z = 0;                        /* ditto */
 206
 207   /* go through the bit lengths (k already is bits in shortest code) */
 208   for (; k <= g; k++)
 209   {
 210     a = c[k];
 211     while (a--)
 212     {
 213       /* here i is the Huffman code of length k bits for value *p */
 214       /* make tables up to required level */
 215       while (k > w + l)
 216       {
 217         h++;
 218         w += l;                 /* previous table always l bits */
 219
 220         /* compute minimum size table less than or equal to l bits */
 221         z = g - w;
 222         z = z > (uInt)l ? (uInt)l : z;        /* table size upper limit */
 223         if ((f = 1 << (j = k - w)) > a + 1)     /* try a k-w bit table */
 224         {                       /* too few codes for k-w bit table */
 225           f -= a + 1;           /* deduct codes from patterns left */
 226           xp = c + k;
 227           if (j < z)
 228             while (++j < z)     /* try smaller tables up to z bits */
 229             {
 230               if ((f <<= 1) <= *++xp)
 231                 break;          /* enough codes to use up j bits */
 232               f -= *xp;         /* else deduct codes from patterns */
 233             }
 234         }
 235         z = 1 << j;             /* table entries for j-bit table */
 236
 237         /* allocate new table */
 238         if (*hn + z > MANY)     /* (note: doesn't matter for fixed) */
 239           return Z_DATA_ERROR;  /* overflow of MANY */
 240         u[h] = q = hp + *hn;
 241         *hn += z;
 242
 243         /* connect to last table, if there is one */
 244         if (h)
 245         {
 246           x[h] = i;             /* save pattern for backing up */
 247           r.bits = (Byte)l;     /* bits to dump before this table */
 248           r.exop = (Byte)j;     /* bits in this table */
 249           j = i >> (w - l);
 250           r.base = (uInt)(q - u[h-1] - j);   /* offset to this table */
 251           u[h-1][j] = r;        /* connect to last table */
 252         }
 253         else
 254           *t = q;               /* first table is returned result */
 255       }
 256
 257       /* set up table entry in r */
 258       r.bits = (Byte)(k - w);
 259       if (p >= v + n)
 260         r.exop = 128 + 64;      /* out of values--invalid code */
 261       else if (*p < s)
 262       {
 263         r.exop = (Byte)(*p < 256 ? 0 : 32 + 64);     /* 256 is end-of-block */
 264         r.base = *p++;          /* simple code is just the value */
 265       }
 266       else
 267       {
 268         r.exop = (Byte)(e[*p - s] + 16 + 64);/* non-simple--look up in lists */
 269         r.base = d[*p++ - s];
 270       }
 271
 272       /* fill code-like entries with r */
 273       f = 1 << (k - w);
 274       for (j = i >> w; j < z; j += f)
 275         q[j] = r;
 276
 277       /* backwards increment the k-bit code i */
 278       for (j = 1 << (k - 1); i & j; j >>= 1)
 279         i ^= j;
 280       i ^= j;
 281
 282       /* backup over finished tables */
 283       mask = (1 << w) - 1;      /* needed on HP, cc -O bug */
 284       while ((i & mask) != x[h])
 285       {
 286         h--;                    /* don't need to update q */
 287         w -= l;
 288         mask = (1 << w) - 1;
 289       }
 290     }
 291   }
 292
 293
 294   /* Return Z_BUF_ERROR if we were given an incomplete table */
 295   return y != 0 && g != 1 ? Z_BUF_ERROR : Z_OK;
 296 }
 297
 298
 299 local int inflate_trees_bits( /* c, bb, tb, hp, z) */
 300 uIntf *c,               /* 19 code lengths */
 301 uIntf *bb,              /* bits tree desired/actual depth */
 302 inflate_huft * FAR *tb, /* bits tree result */
 303 inflate_huft *hp,       /* space for trees */
 304 z_streamp z             /* for messages */
 305 )
 306 {
 307   int r;
 308   uInt hn = 0;          /* hufts used in space */
 309   uIntf *v;             /* work area for huft_build */
 310
 311   if ((v = (uIntf*)ZALLOC(z, 19, sizeof(uInt))) == Z_NULL)
 312     return Z_MEM_ERROR;
 313   r = huft_build(c, 19, 19, (uIntf*)Z_NULL, (uIntf*)Z_NULL,
 314                  tb, bb, hp, &hn, v);
 315   if (r == Z_DATA_ERROR)
 316     z->msg = (char*)"oversubscribed dynamic bit lengths tree";
 317   else if (r == Z_BUF_ERROR || *bb == 0)
 318   {
 319     z->msg = (char*)"incomplete dynamic bit lengths tree";
 320     r = Z_DATA_ERROR;
 321   }
 322   ZFREE(z, v);
 323   return r;
 324 }
 325
 326
 327 local int inflate_trees_dynamic( /* nl, nd, c, bl, bd, tl, td, hp, z) */
 328 uInt nl,                /* number of literal/length codes */
 329 uInt nd,                /* number of distance codes */
 330 uIntf *c,               /* that many (total) code lengths */
 331 uIntf *bl,              /* literal desired/actual bit depth */
 332 uIntf *bd,              /* distance desired/actual bit depth */
 333 inflate_huft * FAR *tl, /* literal/length tree result */
 334 inflate_huft * FAR *td, /* distance tree result */
 335 inflate_huft *hp,       /* space for trees */
 336 z_streamp z             /* for messages */
 337 )
 338 {
 339   int r;
 340   uInt hn = 0;          /* hufts used in space */
 341   uIntf *v;             /* work area for huft_build */
 342
 343   /* allocate work area */
 344   if ((v = (uIntf*)ZALLOC(z, 288, sizeof(uInt))) == Z_NULL)
 345     return Z_MEM_ERROR;
 346
 347   /* build literal/length tree */
 348   r = huft_build(c, nl, 257, cplens, cplext, tl, bl, hp, &hn, v);
 349   if (r != Z_OK || *bl == 0)
 350   {
 351     if (r == Z_DATA_ERROR)
 352       z->msg = (char*)"oversubscribed literal/length tree";
 353     else if (r != Z_MEM_ERROR)
 354     {
 355       z->msg = (char*)"incomplete literal/length tree";
 356       r = Z_DATA_ERROR;
 357     }
 358     ZFREE(z, v);
 359     return r;
 360   }
 361
 362   /* build distance tree */
 363   r = huft_build(c + nl, nd, 0, cpdist, cpdext, td, bd, hp, &hn, v);
 364   if (r != Z_OK || (*bd == 0 && nl > 257))
 365   {
 366     if (r == Z_DATA_ERROR)
 367       z->msg = (char*)"oversubscribed distance tree";
 368     else if (r == Z_BUF_ERROR) {
 369 #if 0
 370     {
 371 #endif
 372 #ifdef PKZIP_BUG_WORKAROUND
 373       r = Z_OK;
 374     }
 375 #else
 376       z->msg = (char*)"incomplete distance tree";
 377       r = Z_DATA_ERROR;
 378     }
 379     else if (r != Z_MEM_ERROR)
 380     {
 381       z->msg = (char*)"empty distance tree with lengths";
 382       r = Z_DATA_ERROR;
 383     }
 384     ZFREE(z, v);
 385     return r;
 386 #endif
 387   }
 388
 389   /* done */
 390   ZFREE(z, v);
 391   return Z_OK;
 392 }
 393
 394
 395 /* build fixed tables only once--keep them here */
 396 #ifdef BUILDFIXED
 397 local int fixed_built = 0;
 398 #define FIXEDH 544      /* number of hufts used by fixed tables */
 399 local inflate_huft fixed_mem[FIXEDH];
 400 local uInt fixed_bl;
 401 local uInt fixed_bd;
 402 local inflate_huft *fixed_tl;
 403 local inflate_huft *fixed_td;
 404 #else
 405 #include "inffixed.h"
 406 #endif
 407
 408
 409 local int inflate_trees_fixed( /* bl, bd, tl, td, z) */
 410 uIntf *bl,                      /* literal desired/actual bit depth */
 411 uIntf *bd,                      /* distance desired/actual bit depth */
 412 const inflate_huft * FAR *tl,   /* literal/length tree result */
 413 const inflate_huft * FAR *td,   /* distance tree result */
 414 z_streamp z                     /* for memory allocation */
 415 )
 416 {
 417 #ifdef BUILDFIXED
 418   /* build fixed tables if not already */
 419   if (!fixed_built)
 420   {
 421     int k;              /* temporary variable */
 422     uInt f = 0;         /* number of hufts used in fixed_mem */
 423     uIntf *c;           /* length list for huft_build */
 424     uIntf *v;           /* work area for huft_build */
 425
 426     /* allocate memory */
 427     if ((c = (uIntf*)ZALLOC(z, 288, sizeof(uInt))) == Z_NULL)
 428       return Z_MEM_ERROR;
 429     if ((v = (uIntf*)ZALLOC(z, 288, sizeof(uInt))) == Z_NULL)
 430     {
 431       ZFREE(z, c);
 432       return Z_MEM_ERROR;
 433     }
 434
 435     /* literal table */
 436     for (k = 0; k < 144; k++)
 437       c[k] = 8;
 438     for (; k < 256; k++)
 439       c[k] = 9;
 440     for (; k < 280; k++)
 441       c[k] = 7;
 442     for (; k < 288; k++)
 443       c[k] = 8;
 444     fixed_bl = 9;
 445     huft_build(c, 288, 257, cplens, cplext, &fixed_tl, &fixed_bl,
 446                fixed_mem, &f, v);
 447
 448     /* distance table */
 449     for (k = 0; k < 30; k++)
 450       c[k] = 5;
 451     fixed_bd = 5;
 452     huft_build(c, 30, 0, cpdist, cpdext, &fixed_td, &fixed_bd,
 453                fixed_mem, &f, v);
 454
 455     /* done */
 456     ZFREE(z, v);
 457     ZFREE(z, c);
 458     fixed_built = 1;
 459   }
 460 #else
 461   FT_UNUSED(z);
 462 #endif
 463   *bl = fixed_bl;
 464   *bd = fixed_bd;
 465   *tl = fixed_tl;
 466   *td = fixed_td;
 467   return Z_OK;
 468 }