changed hcl_hash_bytes() to sdbm hash

hcl/lib/utl.c

@@ -41,7 +41,13 @@ hcl_oow_t hcl_hash_bytes (const hcl_oob_t* ptr, hcl_oow_t len)
 	const hcl_uint8_t* bp, * be;
 
 	bp = ptr; be = bp + len;
-	while (bp < be) h = h * 31 + *bp++;
+
+	/* this hash doesn't produce good distribution */
+	/*while (bp < be) h = h * 31 + *bp++; */
+
+	/* SDBM hash is known to produce good overall distribution 
+	 * for many different data sets */
+	while (bp < be) h = (h << 6) + (h << 16) - h + *bp++;
 
 	/* constrain the hash value to be representable in a small integer
 	 * for convenience sake */