code: private void readPageHeader() throws IOException {
          int bitOffset = sasFileProperties.isU64() ? PAGE_BIT_OFFSET_X64 : PAGE_BIT_OFFSET_X86;
          Long[] offset = {bitOffset + PAGE_TYPE_OFFSET, bitOffset + BLOCK_COUNT_OFFSET, bitOffset
                  + SUBHEADER_COUNT_OFFSET};
          Integer[] length = {PAGE_TYPE_LENGTH, BLOCK_COUNT_LENGTH, SUBHEADER_COUNT_LENGTH};
          List<byte[]> vars = getBytesFromFile(offset, length);
  
          currentPageType = bytesToShort(vars.get(0));
          LOGGER.debug(PAGE_TYPE, currentPageType);
          currentPageBlockCount = bytesToShort(vars.get(1));
          LOGGER.debug(BLOCK_COUNT, currentPageBlockCount);
          currentPageSubheadersCount = bytesToShort(vars.get(2));
          LOGGER.debug(SUBHEADER_COUNT, currentPageSubheadersCount);
      }
docs: The method to read page metadata and store it in {@link SasFileParser#currentPageType},
  {@link SasFileParser#currentPageBlockCount} and {@link SasFileParser#currentPageSubheadersCount}.
  
  @throws IOException if reading from the {@link SasFileParser#sasFileStream} string is impossible.