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 23 FORCE_INLINE uint16_t get16bits ( const void * p ) 24 { 25 return *(const uint16_t*)p; 26 } 27 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 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
