docs: function getTagLength(tag) {
    var lenTag = 4;
    
    while(lenTag > 1) {
      var tmpTag = tag >>> ((lenTag - 1) * 8);
      
      if ((tmpTag & 0xFF) != 0x00) {
        break;
      } 
      
      lenTag--;
    }
    
    return lenTag;
  }