code: function DBCSDecoder(options, codec) {
      // Decoder state
      this.nodeIdx = 0;
      this.prevBuf = Buffer.alloc(0);
  
      // Static data
      this.decodeTables = codec.decodeTables;
      this.decodeTableSeq = codec.decodeTableSeq;
      this.defaultCharUnicode = codec.defaultCharUnicode;
      this.gb18030 = codec.gb18030;
  }
docs: == Decoder ==================================================================