Answer by bugs king for How to check if a number is a power of 2

bool isPowerOfTwo(int x_){  register int bitpos, bitpos2;  asm ("bsrl %1,%0": "+r" (bitpos):"rm" (x_));  asm ("bsfl %1,%0": "+r" (bitpos2):"rm" (x_));  return bitpos > 0 && bitpos == bitpos2;}