Re: [PATCH] Update jhash.h with the new version of Jenkins' hash

On Wed, Feb 11, 2009 at 11:50:38PM +0100, Jozsef Kadlecsik wrote:

On Wed, 11 Feb 2009, Micha? Miros?aw wrote:

quoted

On Wed, Feb 11, 2009 at 11:19:20AM +0100, Jozsef Kadlecsik wrote:

quoted

 /* The golden ration: an arbitrary value */
-#define JHASH_GOLDEN_RATIO	0x9e3779b9
+#define JHASH_GOLDEN_RATIO	0xdeadbeef

I have a stupid question: if this is arbitrary value, then why not
just get rid of it (IOW use zero as it's used in addition)?

lookup3() is a quite generic hash function and it supports 0-byte strings 
as input keys too. If the input key is a 0-byte string and the arbitrary 
value is zero, then the hash value simply equal to the initval. In order 
to avoid that case, the arbitrary value must be nonzero.

Double-hashing, of course! I really need more sleep. Sorry for the noise. :>

Best Regards,
Michał Mirosław