From: Lennart Poettering <lennart@poettering.net>
Date: Fri, 7 Oct 2011 19:00:48 +0000 (+0200)
Subject: hashmap: use different version of DJB's hash algorithm that uses shifting instead... 
X-Git-Tag: v37~26
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=7dfe96eebc1cde5d6b23d7879087ea9102943d7d;p=systemd

hashmap: use different version of DJB's hash algorithm that uses shifting instead of multiplication
---

diff --git a/src/hashmap.c b/src/hashmap.c
index 0d89da46..95ea45da 100644
--- a/src/hashmap.c
+++ b/src/hashmap.c
@@ -124,11 +124,13 @@ __attribute__((destructor)) static void cleanup_pool(void) {
 #endif
 
 unsigned string_hash_func(const void *p) {
-        unsigned hash = 0;
-        const char *c;
+        unsigned hash = 5381;
+        const signed char *c;
+
+        /* DJB's hash function */
 
         for (c = p; *c; c++)
-                hash = 31 * hash + (unsigned) *c;
+                hash = (hash << 5) + hash + (unsigned) *c;
 
         return hash;
 }