1 // From http://www.azillionmonkeys.com/qed/hash.html
5 typedef uint32 uint32_t;
6 typedef uint16 uint16_t;
11 #if (defined(__GNUC__) && defined(__i386__)) || defined(__WATCOMC__) \
12 || defined(_MSC_VER) || defined (__BORLANDC__) || defined (__TURBOC__)
13 #define get16bits(d) (*((const uint16_t *) (d)))
16 #if !defined (get16bits)
17 #define get16bits(d) ((((uint32_t)(((const uint8_t *)(d))[1])) << 8)\
18 +(uint32_t)(((const uint8_t *)(d))[0]) )
21 uint32 SuperFastHash(const char * data, int len) {
22 uint32_t hash = len, tmp;
25 if (len <= 0 || data == NULL)
32 for (; len > 0; len--) {
33 hash += get16bits(data);
34 tmp = (get16bits(data + 2) << 11) ^ hash;
35 hash = (hash << 16) ^ tmp;
36 data += 2 * sizeof(uint16_t);
40 /* Handle end cases */
43 hash += get16bits(data);
46 // Treat the final character as signed. This ensures all platforms behave
47 // consistently with the original x86 code.
48 hash ^= static_cast<signed char>(data[sizeof(uint16_t)]) << 18;
52 hash += get16bits(data);
57 hash += static_cast<signed char>(*data);
62 /* Force "avalanching" of final 127 bits */