+/* By Paul Hsieh (C) 2004, 2005. Covered under the Paul Hsieh
+ * derivative license.
+ * See: http://www.azillionmonkeys.com/qed/weblicense.html for license
+ * details.
+ * http://www.azillionmonkeys.com/qed/hash.html
+*/
+
+#include "common.h"
+
+#undef get16bits
+#if (defined(__GNUC__) && defined(__i386__))
+#define get16bits(d) (*((const uint16_t *) (d)))
+#endif
+
+#if !defined (get16bits)
+#define get16bits(d) ((((uint32_t)(((const uint8_t *)(d))[1])) << 8)\
+ +(uint32_t)(((const uint8_t *)(d))[0]) )
+#endif
+
+uint32_t hsieh_hash(char *key, size_t key_length)
+{
+ uint32_t hash = 0, tmp;
+ int rem;
+
+ if (key_length <= 0 || key == NULL) return 0;
+
+ rem = key_length & 3;
+ key_length >>= 2;
+
+ /* Main loop */
+ for (;key_length > 0; key_length--) {
+ hash += get16bits (key);
+ tmp = (get16bits (key+2) << 11) ^ hash;
+ hash = (hash << 16) ^ tmp;
+ key += 2*sizeof (uint16_t);
+ hash += hash >> 11;
+ }
+
+ /* Handle end cases */
+ switch (rem) {
+ case 3: hash += get16bits (key);
+ hash ^= hash << 16;
+ hash ^= key[sizeof (uint16_t)] << 18;
+ hash += hash >> 11;
+ break;
+ case 2: hash += get16bits (key);
+ hash ^= hash << 11;
+ hash += hash >> 17;
+ break;
+ case 1: hash += *key;
+ hash ^= hash << 10;
+ hash += hash >> 1;
+ }
+
+ /* Force "avalanching" of final 127 bits */
+ hash ^= hash << 3;
+ hash += hash >> 5;
+ hash ^= hash << 4;
+ hash += hash >> 17;
+ hash ^= hash << 25;
+ hash += hash >> 6;
+
+ return hash;
+}
+