inftrees.c

mp3 source code decoder & encoder

        {
          if (h)
            inflate_trees_free(u[0], zs);
          return Z_MEM_ERROR;   /* not enough memory */
        }
#ifdef DEBUG
        inflate_hufts += z + 1;
#endif
        *t = q + 1;             /* link to list for huft_free() */
        *(t = &(q->next)) = Z_NULL;
        u[h] = ++q;             /* table starts after link */

        /* connect to last table, if there is one */
        if (h)
        {
          x[h] = i;             /* save pattern for backing up */
          r.bits = (Byte)l;     /* bits to dump before this table */
          r.exop = (Byte)j;     /* bits in this table */
          r.next = q;           /* pointer to this table */
          j = i >> (w - l);     /* (get around Turbo C bug) */
          u[h-1][j] = r;        /* connect to last table */
        }
      }

      /* set up table entry in r */
      r.bits = (Byte)(k - w);
      if (p >= v + n)
        r.exop = 128 + 64;      /* out of values--invalid code */
      else if (*p < s)
      {
        r.exop = (Byte)(*p < 256 ? 0 : 32 + 64);     /* 256 is end-of-block */
        r.base = *p++;          /* simple code is just the value */
      }
      else
      {
        r.exop = (Byte)(e[*p - s] + 16 + 64);/* non-simple--look up in lists */
        r.base = d[*p++ - s];
      }

      /* fill code-like entries with r */
      f = 1 << (k - w);
      for (j = i >> w; j < z; j += f)
        q[j] = r;

      /* backwards increment the k-bit code i */
      for (j = 1 << (k - 1); i & j; j >>= 1)
        i ^= j;
      i ^= j;

      /* backup over finished tables */
      while ((i & ((1 << w) - 1)) != x[h])
      {
        h--;                    /* don't need to update q */
        w -= l;
      }
    }
  }


  /* Return Z_BUF_ERROR if we were given an incomplete table */
  return y != 0 && g != 1 ? Z_BUF_ERROR : Z_OK;
}


int inflate_trees_bits(uIntf *c, uIntf *bb, inflate_huft * FAR *tb, z_streamp z)
/* c      19 code lengths */
/* bb     bits tree desired/actual depth */
/* tb     bits tree result */
/* z      for zfree function */
{
  int r;

  r = huft_build(c, 19, 19, (uIntf*)Z_NULL, (uIntf*)Z_NULL, tb, bb, z);
  if (r == Z_DATA_ERROR)
    z->msg = (char*)"oversubscribed dynamic bit lengths tree";
  else if (r == Z_BUF_ERROR)
  {
    inflate_trees_free(*tb, z);
    z->msg = (char*)"incomplete dynamic bit lengths tree";
    r = Z_DATA_ERROR;
  }
  return r;
}


int inflate_trees_dynamic(uInt nl, uInt nd, uIntf *c, uIntf *bl, uIntf *bd, 
						  inflate_huft * FAR *tl, inflate_huft * FAR *td, z_streamp z)
/* nl      number of literal/length codes */
/* nd      number of distance codes */
/* c       that many (total) code lengths */
/* bl      literal desired/actual bit depth */
/* bd      distance desired/actual bit depth */
/* tl      literal/length tree result */
/* td      distance tree result */
/* z       for zfree function */
{
  int r;

  /* build literal/length tree */
  if ((r = huft_build(c, nl, 257, cplens, cplext, tl, bl, z)) != Z_OK)
  {
    if (r == Z_DATA_ERROR)
      z->msg = (char*)"oversubscribed literal/length tree";
    else if (r == Z_BUF_ERROR)
    {
      inflate_trees_free(*tl, z);
      z->msg = (char*)"incomplete literal/length tree";
      r = Z_DATA_ERROR;
    }
    return r;
  }

  /* build distance tree */
  if ((r = huft_build(c + nl, nd, 0, cpdist, cpdext, td, bd, z)) != Z_OK)
  {
    if (r == Z_DATA_ERROR)
      z->msg = (char*)"oversubscribed literal/length tree";
    else if (r == Z_BUF_ERROR) {
#ifdef PKZIP_BUG_WORKAROUND
      r = Z_OK;
    }
#else
      inflate_trees_free(*td, z);
      z->msg = (char*)"incomplete literal/length tree";
      r = Z_DATA_ERROR;
    }
    inflate_trees_free(*tl, z);
    return r;
#endif
  }

  /* done */
  return Z_OK;
}


/* build fixed tables only once--keep them here */
local int fixed_built = 0;
#define FIXEDH 530      /* number of hufts used by fixed tables */
local inflate_huft fixed_mem[FIXEDH];
local uInt fixed_bl;
local uInt fixed_bd;
local inflate_huft *fixed_tl;
local inflate_huft *fixed_td;


local voidpf falloc(voidpf q, uInt n, uInt s)
/* q     opaque pointer */
/* n     number of items */
/* s     size of item */
{
  Assert(s == sizeof(inflate_huft) && n <= *(intf *)q,
         "inflate_trees falloc overflow");
  *(intf *)q -= n+s-s; /* s-s to avoid warning */
  return (voidpf)(fixed_mem + *(intf *)q);
}


int inflate_trees_fixed(uIntf *bl, uIntf *bd, inflate_huft * FAR *tl, inflate_huft * FAR *td)
/* bl     literal desired/actual bit depth */
/* bd     distance desired/actual bit depth */
/* tl     literal/length tree result */
/* td     distance tree result */
{
  /* build fixed tables if not already (multiple overlapped executions ok) */
  if (!fixed_built)
  {
    int k;              /* temporary variable */
    unsigned c[288];    /* length list for huft_build */
    z_stream z;         /* for falloc function */
    int f = FIXEDH;     /* number of hufts left in fixed_mem */

    /* set up fake z_stream for memory routines */
    z.zalloc = falloc;
    z.zfree = Z_NULL;
    z.opaque = (voidpf)&f;

    /* literal table */
    for (k = 0; k < 144; k++)
      c[k] = 8;
    for (; k < 256; k++)
      c[k] = 9;
    for (; k < 280; k++)
      c[k] = 7;
    for (; k < 288; k++)
      c[k] = 8;
    fixed_bl = 7;
    huft_build(c, 288, 257, cplens, cplext, &fixed_tl, &fixed_bl, &z);

    /* distance table */
    for (k = 0; k < 30; k++)
      c[k] = 5;
    fixed_bd = 5;
    huft_build(c, 30, 0, cpdist, cpdext, &fixed_td, &fixed_bd, &z);

    /* done */
    Assert(f == 0, "invalid build of fixed tables");
    fixed_built = 1;
  }
  *bl = fixed_bl;
  *bd = fixed_bd;
  *tl = fixed_tl;
  *td = fixed_td;
  return Z_OK;
}


int inflate_trees_free(t, z)
inflate_huft *t;        /* table to free */
z_streamp z;            /* for zfree function */
/* Free the malloc'ed tables built by huft_build(), which makes a linked
   list of the tables it made, with the links in a dummy first entry of
   each table. */
{
  register inflate_huft *p, *q, *r;

  /* Reverse linked list */
  p = Z_NULL;
  q = t;
  while (q != Z_NULL)
  {
    r = (q - 1)->next;
    (q - 1)->next = p;
    p = q;
    q = r;
  }
  /* Go through linked list, freeing from the malloced (t[-1]) address. */
  while (p != Z_NULL)
  {
    q = (--p)->next;
    ZFREE(z,p);
    p = q;
  } 
  return Z_OK;
}