1 #include "Platform.h"
2 #include <stdio.h> // for NULL
3
4 /* By Paul Hsieh (C) 2004, 2005. Covered under the Paul Hsieh derivative
5 license. See:
6 http://www.azillionmonkeys.com/qed/weblicense.html for license details.
7
8 http://www.azillionmonkeys.com/qed/hash.html */
9
10 /*
11 #undef get16bits
12 #if (defined(__GNUC__) && defined(__i386__)) || defined(__WATCOMC__) \
13 || defined(_MSC_VER) || defined (__BORLANDC__) || defined (__TURBOC__)
14 #define get16bits(d) (*((const uint16_t *) (d)))
15 #endif
16
17 #if !defined (get16bits)
18 #define get16bits(d) ((((uint32_t)(((const uint8_t *)(d))[1])) << 8)\
19 +(uint32_t)(((const uint8_t *)(d))[0]) )
20 #endif
21 */
22
get16bits(const void * p)23 FORCE_INLINE uint16_t get16bits ( const void * p )
24 {
25 return *(const uint16_t*)p;
26 }
27
SuperFastHash(const signed char * data,int len)28 uint32_t SuperFastHash (const signed char * data, int len) {
29 uint32_t hash = 0, tmp;
30 int rem;
31
32 if (len <= 0 || data == NULL) return 0;
33
34 rem = len & 3;
35 len >>= 2;
36
37 /* Main loop */
38 for (;len > 0; len--) {
39 hash += get16bits (data);
40 tmp = (get16bits (data+2) << 11) ^ hash;
41 hash = (hash << 16) ^ tmp;
42 data += 2*sizeof (uint16_t);
43 hash += hash >> 11;
44 }
45
46 /* Handle end cases */
47 switch (rem) {
48 case 3: hash += get16bits (data);
49 hash ^= hash << 16;
50 hash ^= data[sizeof (uint16_t)] << 18;
51 hash += hash >> 11;
52 break;
53 case 2: hash += get16bits (data);
54 hash ^= hash << 11;
55 hash += hash >> 17;
56 break;
57 case 1: hash += *data;
58 hash ^= hash << 10;
59 hash += hash >> 1;
60 }
61
62 /* Force "avalanching" of final 127 bits */
63 hash ^= hash << 3;
64 hash += hash >> 5;
65 hash ^= hash << 4;
66 hash += hash >> 17;
67 hash ^= hash << 25;
68 hash += hash >> 6;
69
70 return hash;
71 }
72
SuperFastHash(const void * key,int len,uint32_t,void * out)73 void SuperFastHash ( const void * key, int len, uint32_t /*seed*/, void * out )
74 {
75 *(uint32_t*)out = SuperFastHash((const signed char*)key,len);
76 }
77