Re: ntohs/ntohl and bitops

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



From: Ulrich Drepper <[email protected]>
Date: Tue, 10 Jan 2006 14:02:52 -0800

> I just saw this in a patch:
> 
> +               if (ntohs(ih->frag_off) & IP_OFFSET)
> +                       return EBT_NOMATCH;
> 
> This isn't optimal, it requires a byte switch little endian machines.
> The compiler isn't smart enough.  It would be better to use
> 
>      if (ih->frag_off & ntohs(IP_OFFSET))
> 
> where the byte-swap can be done at compile time.  This is kind of ugly,
> I guess, so maybe a dedicate macro
> 
>     net_host_bit_p(ih->frag_off, IP_OFFSET)

The first suggestion isn't considered ugly, and the best form is:

	if (ih->frag_off & __constant_htons(IP_OFFSET))

I'll fix that up when I get a chance, thanks for catching it Uli.
-
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/

[Index of Archives]     [Kernel Newbies]     [Netfilter]     [Bugtraq]     [Photo]     [Stuff]     [Gimp]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Video 4 Linux]     [Linux for the blind]     [Linux Resources]
  Powered by Linux