From: Alan T. DeKok <aland@freeradius.org>
Date: Mon, 28 May 2012 15:42:06 +0000 (+0200)
Subject: FNV-1a: xor then multiply, not multiply then xor
X-Git-Tag: release_2_2_0~125
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f46e77e5958bf27ea6d22aecb996ac1f464b0c94;p=thirdparty%2Ffreeradius-server.git

FNV-1a: xor then multiply, not multiply then xor

it has much better properties
---

diff --git a/src/lib/hash.c b/src/lib/hash.c
index b7bbf0988f7..5bcab6bc1d3 100644
--- a/src/lib/hash.c
+++ b/src/lib/hash.c
@@ -706,6 +706,12 @@ uint32_t fr_hash(const void *data, size_t size)
 	 *	FNV-1 hash each octet in the buffer
 	 */
 	while (p != q) {
+		/*
+		 *	XOR the 8-bit quantity into the bottom of
+		 *	the hash.
+		 */
+		hash ^= (uint32_t) (*p++);
+
 		/*
 		 *	Multiple by 32-bit magic FNV prime, mod 2^32
 		 */
@@ -716,11 +722,6 @@ uint32_t fr_hash(const void *data, size_t size)
 		 */
 		hash += (hash<<1) + (hash<<4) + (hash<<7) + (hash<<8) + (hash<<24);
 #endif
-		/*
-		 *	XOR the 8-bit quantity into the bottom of
-		 *	the hash.
-		 */
-		hash ^= (uint32_t) (*p++);
     }
 
     return hash;