inflate.c

gzip解压缩算法在tic64x核上的移植。在dm642上测试过。工程中含测试源码

    }
    DUMPBITS(8)
  }


  /* restore the globals from the locals */
  wp = w;                       /* restore global window pointer */
  bb = b;                       /* restore global bit buffer */
  bk = k;
  return 0;
}



int inflate_fixed()
/* decompress an inflated type 1 (fixed Huffman codes) block.  We should
   either replace this with a custom decoder, or at least precompute the
   Huffman tables. */
{
  int i;                /* temporary variable */
  struct huft *tl;      /* literal/length code table */
  struct huft *td;      /* distance code table */
  int bl;               /* lookup bits for tl */
  int bd;               /* lookup bits for td */
  unsigned l[288];      /* length list for huft_build */


  /* set up literal table */
  for (i = 0; i < 144; i++)
    l[i] = 8;
  for (; i < 256; i++)
    l[i] = 9;
  for (; i < 280; i++)
    l[i] = 7;
  for (; i < 288; i++)          /* make a complete, but wrong code set */
    l[i] = 8;
  bl = 7;
  if ((i = huft_build(l, 288, 257, cplens, cplext, &tl, &bl)) != 0)
    return i;


  /* set up distance table */
  for (i = 0; i < 30; i++)      /* make an incomplete code set */
    l[i] = 5;
  bd = 5;
  if ((i = huft_build(l, 30, 0, cpdist, cpdext, &td, &bd)) > 1)
  {
    huft_free(tl);
    return i;
  }


  /* decompress until an end-of-block code */
  if (inflate_codes(tl, td, bl, bd))
    return 1;


  /* free the decoding tables, return */
  huft_free(tl);
  huft_free(td);
  return 0;
}



int inflate_dynamic()
/* decompress an inflated type 2 (dynamic Huffman codes) block. */
{
  int i;                /* temporary variables */
  unsigned j;
  unsigned l;           /* last length */
  unsigned m;           /* mask for bit lengths table */
  unsigned n;           /* number of lengths to get */
  struct huft *tl;      /* literal/length code table */
  struct huft *td;      /* distance code table */
  int bl;               /* lookup bits for tl */
  int bd;               /* lookup bits for td */
  unsigned nb;          /* number of bit length codes */
  unsigned nl;          /* number of literal/length codes */
  unsigned nd;          /* number of distance codes */

  unsigned ll[286+30];  /* literal/length and distance code lengths */

  register ulg b;       /* bit buffer */
  register unsigned k;  /* number of bits in bit buffer */


  /* make local bit buffer */
  b = bb;
  k = bk;
  
  //memset(ll,0xff,316*4);

  /* read in table lengths */
  NEEDBITS(5)
  nl = 257 + ((unsigned)b & 0x1f);      /* number of literal/length codes */
  DUMPBITS(5)
  NEEDBITS(5)
  nd = 1 + ((unsigned)b & 0x1f);        /* number of distance codes */
  DUMPBITS(5)
  NEEDBITS(4)
  nb = 4 + ((unsigned)b & 0xf);         /* number of bit length codes */
  DUMPBITS(4)
#ifdef PKZIP_BUG_WORKAROUND
  if (nl > 288 || nd > 32)
#else
  if (nl > 286 || nd > 30)
#endif
    return 1;                   /* bad lengths */


  /* read in bit-length-code lengths */
  for (j = 0; j < nb; j++)
  {
    NEEDBITS(3)
    ll[border[j]] = (unsigned)b & 7;
    DUMPBITS(3)
  }
  for (; j < 19; j++)
    ll[border[j]] = 0;


  /* build decoding table for trees--single level, 7 bit lookup */
  bl = 7;
  if ((i = huft_build(ll, 19, 19, NULL, NULL, &tl, &bl)) != 0)
  {
    if (i == 1)
      huft_free(tl);
    return i;                   /* incomplete code set */
  }


  /* read in literal and distance code lengths */
  n = nl + nd;
  m = mask_bits[bl];
  i = l = 0;
  while ((unsigned)i < n)
  {
    NEEDBITS((unsigned)bl)
    j = (td = tl + ((unsigned)b & m))->b;
    DUMPBITS(j)
    j = td->v.n;
    if (j < 16)                 /* length of code in bits (0..15) */
      ll[i++] = l = j;          /* save last length in l */
    else if (j == 16)           /* repeat last length 3 to 6 times */
    {
      NEEDBITS(2)
      j = 3 + ((unsigned)b & 3);
      DUMPBITS(2)
      if ((unsigned)i + j > n)
        return 1;
      while (j--)
        ll[i++] = l;
    }
    else if (j == 17)           /* 3 to 10 zero length codes */
    {
      NEEDBITS(3)
      j = 3 + ((unsigned)b & 7);
      DUMPBITS(3)
      if ((unsigned)i + j > n)
        return 1;
      while (j--)
        ll[i++] = 0;
      l = 0;
    }
    else                        /* j == 18: 11 to 138 zero length codes */
    {
      NEEDBITS(7)
      j = 11 + ((unsigned)b & 0x7f);
      DUMPBITS(7)
      if ((unsigned)i + j > n)
        return 1;
      while (j--)
        ll[i++] = 0;
      l = 0;
    }
  }


  /* free decoding table for trees */
  huft_free(tl);


  /* restore the global bit buffer */
  bb = b;
  bk = k;


  /* build the decoding tables for literal/length and distance codes */
  bl = lbits;
  if ((i = huft_build(ll, nl, 257, cplens, cplext, &tl, &bl)) != 0)
  {
    if (i == 1) {
      fprintf(stderr, " incomplete literal tree\n");
      huft_free(tl);
    }
    return i;                   /* incomplete code set */
  }
  bd = dbits;
  if ((i = huft_build(ll + nl, nd, 0, cpdist, cpdext, &td, &bd)) != 0)
  {
    if (i == 1) {
      fprintf(stderr, " incomplete distance tree\n");
#ifdef PKZIP_BUG_WORKAROUND
      i = 0;
    }
#else
      huft_free(td);
    }
    huft_free(tl);
    return i;                   /* incomplete code set */
#endif
  }


  /* decompress until an end-of-block code */
  if (inflate_codes(tl, td, bl, bd))
    return 1;


  /* free the decoding tables, return */
  huft_free(tl);
  huft_free(td);
  return 0;
}



int inflate_block(e)
int *e;                 /* last block flag */
/* decompress an inflated block */
{
  unsigned t;           /* block type */
  register ulg b;       /* bit buffer */
  register unsigned k;  /* number of bits in bit buffer */


  /* make local bit buffer */
  b = bb;
  k = bk;


  /* read in last block bit */
  NEEDBITS(1)
  *e = (int)b & 1;
  DUMPBITS(1)


  /* read in block type */
  NEEDBITS(2)
  t = (unsigned)b & 3;
  DUMPBITS(2)


  /* restore the global bit buffer */
  bb = b;
  bk = k;


  /* inflate that block type */
  if (t == 2)
    return inflate_dynamic();
  if (t == 0)
    return inflate_stored();
  if (t == 1)
    return inflate_fixed();


  /* bad block type */
  return 2;
}



int inflate()
/* decompress an inflated entry */
{
  int e;                /* last block flag */
  int r;                /* result code */
  unsigned h;           /* maximum struct huft's malloc'ed */


  /* initialize window, bit buffer */
  wp = 0;
  bk = 0;
  bb = 0;

  /* decompress until the last block */
  h = 0;
  do {
    hufts = 0;
    if ((r = inflate_block(&e)) != 0)
      return r;
    if (hufts > h)
      h = hufts;
  } while (!e);

  /* Undo too much lookahead. The next read will be byte aligned so we
   * can discard unused bits in the last meaningful byte.
   */
  while (bk >= 8) {
    bk -= 8;
    inptr--;
  }

  /* flush out slide */
  flush_output(wp);


  /* return success */
#ifdef DEBUG
  fprintf(stderr, "<%u> ", h);
#endif /* DEBUG */
  return 0;
}