Function NextPower2

cpp/src/arrow/util/bit_util.h:56–68

Returns the smallest power of two that contains v. If v is already a power of two, it is returned as is.

// Returns the smallest power of two that contains v.  If v is already a
// power of two, it is returned as is.
static inline int64_t NextPower2(int64_t n) {
  // Taken from
  // http://graphics.stanford.edu/~seander/bithacks.html#RoundUpPowerOf2
  n--;
  n |= n >> 1;
  n |= n >> 2;
  n |= n >> 4;
  n |= n >> 8;
  n |= n >> 16;
  n |= n >> 32;
  n++;
  return n;
}

constexpr bool IsMultipleOf64(int64_t n) { return (n & 63) == 0; }