+
+/* Hash P as a null-terminated string.
+
+ Copied from gcc/hashtable.c. Zack had the following to say with respect
+ to applicability, though note that unlike hashtable.c, this hash table
+ implementation re-hashes rather than chain buckets.
+
+ http://gcc.gnu.org/ml/gcc-patches/2001-08/msg01021.html
+ From: Zack Weinberg <zackw@panix.com>
+ Date: Fri, 17 Aug 2001 02:15:56 -0400
+
+ I got it by extracting all the identifiers from all the source code
+ I had lying around in mid-1999, and testing many recurrences of
+ the form "H_n = H_{n-1} * K + c_n * L + M" where K, L, M were either
+ prime numbers or the appropriate identity. This was the best one.
+ I don't remember exactly what constituted "best", except I was
+ looking at bucket-length distributions mostly.
+
+ So it should be very good at hashing identifiers, but might not be
+ as good at arbitrary strings.
+
+ I'll add that it thoroughly trounces the hash functions recommended
+ for this use at http://burtleburtle.net/bob/hash/index.html, both
+ on speed and bucket distribution. I haven't tried it against the
+ function they just started using for Perl's hashes. */
+
+hashval_t
+htab_hash_string (p)
+ const PTR p;
+{
+ const unsigned char *str = (const unsigned char *) p;
+ hashval_t r = 0;
+ unsigned char c;
+
+ while ((c = *str++) != 0)
+ r = r * 67 + c - 113;
+
+ return r;
+}