Function tr_static_init

Picviewer CE+/dist.user.js:10762–10860

()

 * Initialize the various 'constant' tables.
 */
function tr_static_init() {
  var n;        /* iterates over tree elements */
  var bits;     /* bit counter */
  var length;   /* length value */
  var code;     /* code value */
  var dist;     /* distance index */
  var bl_count = new Array(MAX_BITS + 1);
  /* number of codes at each bit length for an optimal tree */

  // do check in _tr_init()
  //if (static_init_done) return;

  /* For some embedded targets, global variables are not initialized: */
/*#ifdef NO_INIT_GLOBAL_POINTERS
  static_l_desc.static_tree = static_ltree;
  static_l_desc.extra_bits = extra_lbits;
  static_d_desc.static_tree = static_dtree;
  static_d_desc.extra_bits = extra_dbits;
  static_bl_desc.extra_bits = extra_blbits;
#endif*/

  /* Initialize the mapping length (0..255) -> length code (0..28) */
  length = 0;
  for (code = 0; code < LENGTH_CODES - 1; code++) {
    base_length[code] = length;
    for (n = 0; n < (1 << extra_lbits[code]); n++) {
      _length_code[length++] = code;
    }
  }
  //Assert (length == 256, "tr_static_init: length != 256");
  /* Note that the length 255 (match length 258) can be represented
   * in two different ways: code 284 + 5 bits or code 285, so we
   * overwrite length_code[255] to use the best encoding:
   */
  _length_code[length - 1] = code;

  /* Initialize the mapping dist (0..32K) -> dist code (0..29) */
  dist = 0;
  for (code = 0; code < 16; code++) {
    base_dist[code] = dist;
    for (n = 0; n < (1 << extra_dbits[code]); n++) {
      _dist_code[dist++] = code;
    }
  }
  //Assert (dist == 256, "tr_static_init: dist != 256");
  dist >>= 7; /* from now on, all distances are divided by 128 */
  for (; code < D_CODES; code++) {
    base_dist[code] = dist << 7;
    for (n = 0; n < (1 << (extra_dbits[code] - 7)); n++) {
      _dist_code[256 + dist++] = code;
    }
  }
  //Assert (dist == 256, "tr_static_init: 256+dist != 512");

  /* Construct the codes of the static literal tree */
  for (bits = 0; bits <= MAX_BITS; bits++) {
    bl_count[bits] = 0;
  }