#include <limits.h>

static unsigned next_power_of_2(unsigned n)
{
	--n;
	n |= n >> 1;
	n |= n >> 2;
	n |= n >> 4;
	n |= n >> 8;
#if (UINT_MAX > (1 << 16))
	n |= n >> 16;
#endif
#if (UINT_MAX > (1L << 32))
	n |= n >> 32;
#endif
	return n+1;
}