Method PutValue

be/src/util/bit-stream-utils.inline.h:28–57

namespace impala {

inline bool BitWriter::PutValue(uint64_t v, int num_bits) {
  DCHECK_LE(num_bits, MAX_BITWIDTH);
  DCHECK(num_bits == MAX_BITWIDTH || v >> num_bits == 0)
      << "v = " << v << ", num_bits = " << num_bits;

  if (UNLIKELY(byte_offset_ * 8 + bit_offset_ + num_bits > max_bytes_ * 8)) return false;

  buffered_values_ |= v << bit_offset_;
  bit_offset_ += num_bits;

  if (UNLIKELY(bit_offset_ >= 64)) {
    // Flush buffered_values_ and write out bits of v that did not fit
    memcpy(buffer_ + byte_offset_, &buffered_values_, 8);
    byte_offset_ += 8;
    bit_offset_ -= 64;

    // Shifting with the same or greater amount than the number of bits in the number is
    // undefined behaviour.
    int shift = num_bits - bit_offset_;

    if (LIKELY(shift < 64)) {
      buffered_values_ = v >> shift;
    } else {
      buffered_values_ = 0;
    }
  }

  DCHECK_LT(bit_offset_, 64);
  return true;
}

inline void BitWriter::Flush(bool align) {
  int num_bytes = BitUtil::Ceil(bit_offset_, 8);