code: private void dataBufferAppend(char[] ch, int start, int length) {
          dataBuffer = (char[]) extendArray(dataBuffer, dataBuffer.length,
                  dataBufferPos + length);
  
          System.arraycopy(ch, start, dataBuffer, dataBufferPos, length);
          dataBufferPos += length;
      }
docs: Append (part of) a character array to the data buffer.