Hello.

On 11/18/2015 1:33 AM, Alexander Aring wrote:

This patch adds a static inline function ipv6_addr_prefix_cpy which

   I suggest not to reduce "copy".

copies a ipv6 address prefix(argument pfx) into the ipv6 address prefix.
The prefix len is given by plen as bits. This function mainly based on
ipv6_addr_prefix which copies one address prefix from address into a new
ipv6 address destination and zero all other address bits.

The difference is that ipv6_addr_prefix_cpy don't get a prefix from an
ipv6 address, it sets a prefix to an ipv6 address with keeping other
address bits. The use case is for context based address compression
inside 6LoWPAN IPHC header which keeping ipv6 prefixes inside a context
table to lookup address-bits without sending them.

Cc: David S. Miller <da...@davemloft.net>
Cc: Alexey Kuznetsov <kuz...@ms2.inr.ac.ru>
Cc: James Morris <jmor...@namei.org>
Cc: Hideaki YOSHIFUJI <yoshf...@linux-ipv6.org>
Cc: Patrick McHardy <ka...@trash.net>
Signed-off-by: Alexander Aring <alex.ar...@gmail.com>
---
  include/net/ipv6.h | 15 +++++++++++++++
  1 file changed, 15 insertions(+)

diff --git a/include/net/ipv6.h b/include/net/ipv6.h
index e1a10b0..9d38fc2 100644
--- a/include/net/ipv6.h
+++ b/include/net/ipv6.h
@@ -382,6 +382,21 @@ static inline void ipv6_addr_prefix(struct in6_addr *pfx,
                pfx->s6_addr[o] = addr->s6_addr[o] & (0xff00 >> b);
  }

+static inline void ipv6_addr_prefix_cpy(struct in6_addr *addr,
+                                       const struct in6_addr *pfx,
+                                       int plen)
+{
+       /* caller must guarantee 0 <= plen <= 128 */
+       int o = plen >> 3,
+           b = plen & 0x7;

   Unusual declaration style, why not just have *int* on both lines?

[...]

MBR, Sergei

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