From b2a52eedaa406bacfa53d2b2a3d4236e46042bcd Mon Sep 17 00:00:00 2001
From: Ben Pfaff <blp@nicira.com>
Date: Fri, 14 Dec 2012 13:43:54 -0800
Subject: [PATCH] hash: Correct implementation of mhash_finish().
With rotates instead of shifts, the upper and lower 16 bits of the returned
hash are always the same.
I noticed this while working on replacing Jenkins hash by murmurhash,
because some of the database unit tests started failing, e.g. "row
hashing (scalars)".
Signed-off-by: Ben Pfaff <blp@nicira.com>
Acked-by: Ethan Jackson <ethan@nicira.com>
---
lib/hash.h | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/lib/hash.h b/lib/hash.h
index 701e6866e..96866c42a 100644
--- a/lib/hash.h
+++ b/lib/hash.h
@@ -152,11 +152,11 @@ static inline uint32_t mhash_add(uint32_t hash, uint32_t data)
static inline uint32_t mhash_finish(uint32_t hash, size_t n)
{
hash ^= n * 4;
- hash ^= hash_rot(hash, 16);
+ hash ^= hash >> 16;
hash *= 0x85ebca6b;
- hash ^= hash_rot(hash, 13);
+ hash ^= hash >> 13;
hash *= 0xc2b2ae35;
- hash ^= hash_rot(hash, 16);
+ hash ^= hash >> 16;
return hash;
}
--
2.47.0