PageRenderTime 66ms CodeModel.GetById 13ms app.highlight 47ms RepoModel.GetById 1ms app.codeStats 0ms

/src/freetype/src/gzip/inftrees.c

https://bitbucket.org/cabalistic/ogredeps/
C | 468 lines | 338 code | 53 blank | 77 comment | 79 complexity | cc23afce692bd5f66ec6e0b6597cedef MD5 | raw file
  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
 15local 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
 30local 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. */
 43local 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 */
 47local 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 */
 50local 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};
 54local 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
 95local int huft_build( /* b, n, s, d, e, t, m, hp, hn, v) */
 96uIntf *b,               /* code lengths in bits (all assumed <= BMAX) */
 97uInt n,                 /* number of codes (assumed <= 288) */
 98uInt s,                 /* number of simple-valued codes (0..s-1) */
 99const uIntf *d,         /* list of base values for non-simple codes */
100const uIntf *e,         /* list of extra bits for non-simple codes */
101inflate_huft * FAR *t,  /* result: starting table */
102uIntf *m,               /* maximum lookup bits, returns actual */
103inflate_huft *hp,       /* space for trees */
104uInt *hn,               /* hufts used in space */
105uIntf *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
299local int inflate_trees_bits( /* c, bb, tb, hp, z) */
300uIntf *c,               /* 19 code lengths */
301uIntf *bb,              /* bits tree desired/actual depth */
302inflate_huft * FAR *tb, /* bits tree result */
303inflate_huft *hp,       /* space for trees */
304z_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
327local int inflate_trees_dynamic( /* nl, nd, c, bl, bd, tl, td, hp, z) */
328uInt nl,                /* number of literal/length codes */
329uInt nd,                /* number of distance codes */
330uIntf *c,               /* that many (total) code lengths */
331uIntf *bl,              /* literal desired/actual bit depth */
332uIntf *bd,              /* distance desired/actual bit depth */
333inflate_huft * FAR *tl, /* literal/length tree result */
334inflate_huft * FAR *td, /* distance tree result */
335inflate_huft *hp,       /* space for trees */
336z_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
397local int fixed_built = 0;
398#define FIXEDH 544      /* number of hufts used by fixed tables */
399local inflate_huft fixed_mem[FIXEDH];
400local uInt fixed_bl;
401local uInt fixed_bd;
402local inflate_huft *fixed_tl;
403local inflate_huft *fixed_td;
404#else
405#include "inffixed.h"
406#endif
407
408
409local int inflate_trees_fixed( /* bl, bd, tl, td, z) */
410uIntf *bl,                      /* literal desired/actual bit depth */
411uIntf *bd,                      /* distance desired/actual bit depth */
412const inflate_huft * FAR *tl,   /* literal/length tree result */
413const inflate_huft * FAR *td,   /* distance tree result */
414z_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}