> On 18 Jun 2020, at 7:49 pm, Theo Buehler <[email protected]> wrote:
>
> The same trick as in the previous diff can be used a second time:
> widen the type, accumulate before folding.
>
> I've also shuffled things into an order where the introduction of
> a stoeplitz_hash_n32(scache, n32) suggests itself as a next step.
> It would just call stoeplitz_hash_n16(scache, n32 ^ (n32 >> 16));
> This trivializes the ip4 versions to one line:
>
> return (stoeplitz_hash_n32(faddr ^ laddr));
>
> and
>
> return (stoeplitz_hash_n32(faddr ^ laddr ^ fport ^ lport));
>
> respectively. At that point I will definitely be done since there
> will be no more code to remove... The ip6 versions are only slightly
> simplified by this.
>
> While I think this is rather neat, I don't want to push things too far.
> Should I do this?
i want a hash_n32 anyway (for feeding things like gre keys in). i think i would
like it more than the folding of the 32-bits into 16-bits at the end of these
functions too.
this diff is ok.
dlg
>
> Index: toeplitz.c
> ===================================================================
> RCS file: /var/cvs/src/sys/net/toeplitz.c,v
> retrieving revision 1.4
> diff -u -p -r1.4 toeplitz.c
> --- toeplitz.c 18 Jun 2020 05:33:17 -0000 1.4
> +++ toeplitz.c 18 Jun 2020 09:35:12 -0000
> @@ -116,30 +116,25 @@ uint16_t
> stoeplitz_hash_ip4(const struct stoeplitz_cache *scache,
> in_addr_t faddr, in_addr_t laddr)
> {
> - uint16_t lo;
> + uint32_t n32;
>
> - lo = faddr >> 0;
> - lo ^= faddr >> 16;
> - lo ^= laddr >> 0;
> - lo ^= laddr >> 16;
> + n32 = faddr ^ laddr;
> + n32 ^= n32 >> 16;
>
> - return (stoeplitz_hash_n16(scache, lo));
> + return (stoeplitz_hash_n16(scache, n32));
> }
>
> uint16_t
> stoeplitz_hash_ip4port(const struct stoeplitz_cache *scache,
> in_addr_t faddr, in_addr_t laddr, in_port_t fport, in_port_t lport)
> {
> - uint16_t lo;
> + uint32_t n32;
>
> - lo = faddr >> 0;
> - lo ^= faddr >> 16;
> - lo ^= laddr >> 0;
> - lo ^= laddr >> 16;
> - lo ^= fport >> 0;
> - lo ^= lport >> 0;
> + n32 = faddr ^ laddr;
> + n32 ^= fport ^ lport;
> + n32 ^= n32 >> 16;
>
> - return (stoeplitz_hash_n16(scache, lo));
> + return (stoeplitz_hash_n16(scache, n32));
> }
>
> #ifdef INET6
> @@ -147,44 +142,32 @@ uint16_t
> stoeplitz_hash_ip6(const struct stoeplitz_cache *scache,
> const struct in6_addr *faddr6, const struct in6_addr *laddr6)
> {
> - uint16_t lo = 0;
> + uint32_t n32 = 0;
> size_t i;
>
> - for (i = 0; i < nitems(faddr6->s6_addr32); i++) {
> - uint32_t faddr = faddr6->s6_addr32[i];
> - uint32_t laddr = laddr6->s6_addr32[i];
> -
> - lo ^= faddr >> 0;
> - lo ^= faddr >> 16;
> - lo ^= laddr >> 0;
> - lo ^= laddr >> 16;
> - }
> + for (i = 0; i < nitems(faddr6->s6_addr32); i++)
> + n32 ^= faddr6->s6_addr32[i] ^ laddr6->s6_addr32[i];
> +
> + n32 ^= n32 >> 16;
>
> - return (stoeplitz_hash_n16(scache, lo));
> + return (stoeplitz_hash_n16(scache, n32));
> }
>
> uint16_t
> stoeplitz_hash_ip6port(const struct stoeplitz_cache *scache,
> - const struct in6_addr *faddr6, const struct in6_addr * laddr6,
> + const struct in6_addr *faddr6, const struct in6_addr *laddr6,
> in_port_t fport, in_port_t lport)
> {
> - uint16_t lo = 0;
> + uint32_t n32 = 0;
> size_t i;
>
> - for (i = 0; i < nitems(faddr6->s6_addr32); i++) {
> - uint32_t faddr = faddr6->s6_addr32[i];
> - uint32_t laddr = laddr6->s6_addr32[i];
> -
> - lo ^= faddr >> 0;
> - lo ^= faddr >> 16;
> - lo ^= laddr >> 0;
> - lo ^= laddr >> 16;
> - }
> + for (i = 0; i < nitems(faddr6->s6_addr32); i++)
> + n32 ^= faddr6->s6_addr32[i] ^ laddr6->s6_addr32[i];
>
> - lo ^= fport >> 0;
> - lo ^= lport >> 0;
> + n32 ^= fport ^ lport;
> + n32 ^= n32 >> 16;
>
> - return (stoeplitz_hash_n16(scache, lo));
> + return (stoeplitz_hash_n16(scache, n32));
> }
> #endif /* INET6 */
>
>
