Re: djbdns-1.05-epoll + speedup patch

["Matthew R. Dempsky" <mrd@alkemio.org>]

On Sun, Mar 04, 2007 at 06:16:57PM +0200, Sami Farin wrote:
> +static inline void dns_sortip(char *s,unsigned int n)
> +{
> +  int i;
> +  unsigned int rnd;
> +  char tmp[4];
> +
> +  n >>= 2;
> +  for (i = n - 1; i > 0; i--) {
> +    rnd = dns_random() % n;
> +    byte_copy(tmp,4,s + (i << 2));
> +    byte_copy(s + (i << 2),4,s + (rnd << 2));
> +    byte_copy(s + (rnd << 2),4,tmp);
> +  }
> +}

Beware this does not generate the same distribution as:

> -void dns_sortip(char *s,unsigned int n)
> -{
> -  unsigned int i;
> -  char tmp[4];
> -
> -  n >>= 2;
> -  while (n > 1) {
> -    i = dns_random(n);
> -    --n;
> -    byte_copy(tmp,4,s + (i << 2));
> -    byte_copy(s + (i << 2),4,s + (n << 2));
> -    byte_copy(s + (n << 2),4,tmp);
> -  }
> -}