#pragma once
#include<algorithm>

namespace at {
namespace native {

// returns 2**floor(log2(n))
static int lastPow2(unsigned int n) {
  n |= (n >> 1);
  n |= (n >> 2);
  n |= (n >> 4);
  n |= (n >> 8);
  n |= (n >> 16);
  return std::max<int>(1, n - (n >> 1));
}

} // namespace native
} // namespace at