static inline unsigned int __ffs(unsigned int x)
{
	unsigned int ret;
	asm("rep bsfl %1,%0"
		:"=r" (ret)
		:"rm" (x));
	return ret;
}
#define statically_true(x) (__builtin_constant_p(x) && (x))

static inline unsigned int do_variable_ffs(unsigned int x)
{
#if __SIZEOF_LONG__ == 4
	return __builtin_ffs(x);
#else
	unsigned int ret;
	asm("rep bsfl %1,%0"
		:"=r" (ret)
		:"rm" (x), "0" (-1));
	return ret+1;
#endif
}

#define variable_ffs(x) (statically_true((x)!=0) ? __ffs(x)+1 : do_variable_ffs(x))
#define constant_ffs(x) __builtin_ffs(x)

#define ffs(x) (__builtin_constant_p(x) ? constant_ffs(x) : variable_ffs(x))

unsigned int myffs(unsigned int x) { return ffs(x); }
unsigned int ffs5(void) { return ffs(5); }
unsigned int addffs(int x)
{
	unsigned int sum = 0;
	while (x) {
		sum += ffs(x);
		x--;
	}
	return sum;
}