Function AdjustRun

cpp/src/arrow/util/bit_run_reader.h:285–291

  }

  SetBitRun AdjustRun(SetBitRun run) {
    if (Reverse) {
      assert(run.position >= run.length);
      run.position -= run.length;
    }
    return run;
  }

  uint64_t LoadFullWord() {
    uint64_t word;