On Fri, 15 Jun 2007 14:54:20 -0500 "David M. Lloyd" <[EMAIL PROTECTED]> wrote:
> On Fri, 15 Jun 2007 21:47:50 +0200 (CEST) > Jan Engelhardt <[EMAIL PROTECTED]> wrote: > > > On Jun 15 2007 18:56, Vegard Nossum wrote: > > > bool is_power_of_2(unsigned long n) > > > { > > >- return (n != 0 && ((n & (n - 1)) == 0)); > > >+ return n * !(n & (n - 1)); > > > } > > > > There is a third way which uses neither * nor &&, but []: > > I assume using something GCC-specific is right out? > > bool is_power_of_to(unsigned long n) > { > return __builtin_ffsl(n) == 1; Pretend I typed this instead: bool is_power_of_2(unsigned long n) { return __builtin_popcountl(n) == 1; } All I can say is, it's really hot here :P - DML - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/