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unzip-6.0/explode.c  view on Meta::CPAN

#endif

/* routines here */
static int get_tree OF((__GPRO__ unsigned *l, unsigned n));
static int explode_lit OF((__GPRO__ struct huft *tb, struct huft *tl,
                           struct huft *td, unsigned bb, unsigned bl,
                           unsigned bd, unsigned bdl));
static int explode_nolit OF((__GPRO__ struct huft *tl, struct huft *td,
                             unsigned bl, unsigned bd, unsigned bdl));
int explode OF((__GPRO));


/* The implode algorithm uses a sliding 4K or 8K byte window on the
   uncompressed stream to find repeated byte strings.  This is implemented
   here as a circular buffer.  The index is updated simply by incrementing
   and then and'ing with 0x0fff (4K-1) or 0x1fff (8K-1).  Here, the 32K
   buffer of inflate is used, and it works just as well to always have
   a 32K circular buffer, so the index is anded with 0x7fff.  This is
   done to allow the window to also be used as the output buffer. */
/* This must be supplied in an external module useable like "uch slide[8192];"
   or "uch *slide;", where the latter would be malloc'ed.  In unzip, slide[]
   is actually a 32K area for use by inflate, which uses a 32K sliding window.
 */


#define INVALID_CODE 99
#define IS_INVALID_CODE(c)  ((c) == INVALID_CODE)

/* Tables for length and distance */
static ZCONST ush cplen2[] =
        {2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17,
        18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34,
        35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51,
        52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65};
static ZCONST ush cplen3[] =
        {3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18,
        19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35,
        36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52,
        53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66};
static ZCONST uch extra[] =
        {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
        8};
static ZCONST ush cpdist4[] =
        {1, 65, 129, 193, 257, 321, 385, 449, 513, 577, 641, 705,
        769, 833, 897, 961, 1025, 1089, 1153, 1217, 1281, 1345, 1409, 1473,
        1537, 1601, 1665, 1729, 1793, 1857, 1921, 1985, 2049, 2113, 2177,
        2241, 2305, 2369, 2433, 2497, 2561, 2625, 2689, 2753, 2817, 2881,
        2945, 3009, 3073, 3137, 3201, 3265, 3329, 3393, 3457, 3521, 3585,
        3649, 3713, 3777, 3841, 3905, 3969, 4033};
static ZCONST ush cpdist8[] =
        {1, 129, 257, 385, 513, 641, 769, 897, 1025, 1153, 1281,
        1409, 1537, 1665, 1793, 1921, 2049, 2177, 2305, 2433, 2561, 2689,
        2817, 2945, 3073, 3201, 3329, 3457, 3585, 3713, 3841, 3969, 4097,
        4225, 4353, 4481, 4609, 4737, 4865, 4993, 5121, 5249, 5377, 5505,
        5633, 5761, 5889, 6017, 6145, 6273, 6401, 6529, 6657, 6785, 6913,
        7041, 7169, 7297, 7425, 7553, 7681, 7809, 7937, 8065};


/* Macros for inflate() bit peeking and grabbing.
   The usage is:

        NEEDBITS(j)
        x = b & mask_bits[j];
        DUMPBITS(j)

   where NEEDBITS makes sure that b has at least j bits in it, and
   DUMPBITS removes the bits from b.  The macros use the variable k
   for the number of bits in b.  Normally, b and k are register
   variables for speed.
 */

#define NEEDBITS(n) {while(k<(n)){b|=((ulg)NEXTBYTE)<<k;k+=8;}}
#define DUMPBITS(n) {b>>=(n);k-=(n);}

#define DECODEHUFT(htab, bits, mask) {\
  NEEDBITS((unsigned)(bits))\
  t = (htab) + ((~(unsigned)b)&(mask));\
  while (1) {\
    DUMPBITS(t->b)\
    if ((e=t->e) <= 32) break;\
    if (IS_INVALID_CODE(e)) return 1;\
    e &= 31;\
    NEEDBITS(e)\
    t = t->v.t + ((~(unsigned)b)&mask_bits[e]);\
  }\
}


static int get_tree(__G__ l, n)
     __GDEF
unsigned *l;            /* bit lengths */
unsigned n;             /* number expected */
/* Get the bit lengths for a code representation from the compressed
   stream.  If get_tree() returns 4, then there is an error in the data.
   Otherwise zero is returned. */
{
  unsigned i;           /* bytes remaining in list */
  unsigned k;           /* lengths entered */
  unsigned j;           /* number of codes */
  unsigned b;           /* bit length for those codes */


  /* get bit lengths */
  i = NEXTBYTE + 1;                     /* length/count pairs to read */
  k = 0;                                /* next code */
  do {
    b = ((j = NEXTBYTE) & 0xf) + 1;     /* bits in code (1..16) */
    j = ((j & 0xf0) >> 4) + 1;          /* codes with those bits (1..16) */
    if (k + j > n)
      return 4;                         /* don't overflow l[] */
    do {
      l[k++] = b;
    } while (--j);
  } while (--i);
  return k != n ? 4 : 0;                /* should have read n of them */
}