Function ffs

freebsd/i386/include/cpufunc.h:200–210

#define	HAVE_INLINE_FFS

static __inline __pure2 int
ffs(int mask)
{
	/*
	 * Note that gcc-2's builtin ffs would be used if we didn't declare
	 * this inline or turn off the builtin.  The builtin is faster but
	 * broken in gcc-2.4.5 and slower but working in gcc-2.5 and later
	 * versions.
	 */
	 return (mask == 0 ? mask : (int)bsfl((u_int)mask) + 1);
}

#define	HAVE_INLINE_FFSL