fanf 01/03/22 09:35:11
Modified: tables apr_hash.c
Log:
better hash function citation
Revision Changes Path
1.18 +13 -8 apr/tables/apr_hash.c
Index: apr_hash.c
===================================================================
RCS file: /home/cvs/apr/tables/apr_hash.c,v
retrieving revision 1.17
retrieving revision 1.18
diff -u -u -r1.17 -r1.18
--- apr_hash.c 2001/03/10 00:07:09 1.17
+++ apr_hash.c 2001/03/22 17:35:08 1.18
@@ -222,12 +222,18 @@
klen = strlen(key);
/*
- * This is Daniel J. Bernstein's popular `times 33' hash function
- * as posted by him years ago on comp.lang.c and used by perl.
- * This is one of the best known hash functions for strings
- * because it is both computed very fast and distributes very
- * well.
+ * This is the popular `times 33' hash algorithm which is used by
+ * perl and also appears in Berkeley DB. This is one of the best
+ * known hash functions for strings because it is both computed
+ * very fast and distributes very well.
*
+ * The originator may be Dan Bernstein but the code in Berkeley DB
+ * cites Chris Torek as the source. The best citation I have found
+ * is "Chris Torek, Hash function for text in C, Usenet message
+ * <[EMAIL PROTECTED]> in comp.lang.c , October, 1990." in Rich
+ * Salz's USENIX 1992 paper about INN which can be found at
+ * <http://citeseer.nj.nec.com/salz92internetnews.html>.
+ *
* The magic of number 33, i.e. why it works better than many other
* constants, prime or not, has never been adequately explained by
* anyone. So I try an explanation: if one experimentally tests all
@@ -248,9 +254,8 @@
* operation can be replaced by a faster operation based on just one
* shift plus either a single addition or subtraction operation. And
* because a hash function has to both distribute good _and_ has to
- * be very fast to compute, those few numbers should be preferred
- * and seems to be the reason why Daniel J. Bernstein also preferred
- * it.
+ * be very fast to compute, those few numbers should be preferred.
+ *
* -- Ralf S. Engelschall <[EMAIL PROTECTED]>
*/
hash = 0;
