Function gen_codes

Picviewer CE+/dist.user.js:10724–10756

(tree, max_code, bl_count)

 *     zero code length.
 */
function gen_codes(tree, max_code, bl_count)
//    ct_data *tree;             /* the tree to decorate */
//    int max_code;              /* largest code with non zero frequency */
//    ushf *bl_count;            /* number of codes at each bit length */
{
  var next_code = new Array(MAX_BITS + 1); /* next code value for each bit length */
  var code = 0;              /* running code value */
  var bits;                  /* bit index */
  var n;                     /* code index */

  /* The distribution counts are first used to generate the code values
   * without bit reversal.
   */
  for (bits = 1; bits <= MAX_BITS; bits++) {
    next_code[bits] = code = (code + bl_count[bits - 1]) << 1;
  }
  /* Check that the bit counts in bl_count are consistent. The last code
   * must be all ones.
   */
  //Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1,
  //        "inconsistent bit counts");
  //Tracev((stderr,"\ngen_codes: max_code %d ", max_code));

  for (n = 0;  n <= max_code; n++) {
    var len = tree[n * 2 + 1]/*.Len*/;
    if (len === 0) { continue; }
    /* Now reverse the bits */
    tree[n * 2]/*.Code*/ = bi_reverse(next_code[len]++, len);

    //Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ",
    //     n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1));
  }
}


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