| tanjent@gmail.com | 7e5c363 | 2010-11-02 00:50:04 +0000 | [diff] [blame^] | 1 | #include "Hashes.h"
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| 2 |
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| 3 | #include "Random.h"
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| 4 |
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| 5 | //----------------------------------------------------------------------------
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| 6 | // fake / bad hashes
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| 7 |
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| 8 | void randhash ( const void *, int, uint32_t, void * out )
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| 9 | {
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| 10 | *(uint32_t*)out = rand_u32();
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| 11 | }
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| 12 |
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| 13 | void BadHash ( const void * key, int len, uint32_t seed, void * out )
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| 14 | {
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| 15 | uint32_t h = seed;
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| 16 |
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| 17 | const uint8_t * data = (const uint8_t*)key;
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| 18 |
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| 19 | for(int i = 0; i < len; i++)
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| 20 | {
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| 21 | h ^= h >> 3;
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| 22 | h ^= h << 5;
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| 23 | h ^= data[i];
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| 24 | }
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| 25 |
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| 26 | *(uint32_t*)out = h;
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| 27 | }
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| 28 |
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| 29 | void sumhash ( const void * key, int len, uint32_t seed, void * out )
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| 30 | {
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| 31 | uint32_t h = seed;
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| 32 |
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| 33 | const uint8_t * data = (const uint8_t*)key;
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| 34 |
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| 35 | for(int i = 0; i < len; i++)
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| 36 | {
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| 37 | h += data[i];
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| 38 | }
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| 39 |
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| 40 | *(uint32_t*)out = h;
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| 41 | }
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| 42 |
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| 43 | void DoNothingHash ( const void *, int, uint32_t, void * )
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| 44 | {
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| 45 | return;
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| 46 | }
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| 47 |
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| 48 | //-----------------------------------------------------------------------------
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| 49 | // One-byte-at-a-time hash based on Murmur's mix
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| 50 |
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| 51 | uint32_t MurmurOAAT ( const void * key, int len, uint32_t h )
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| 52 | {
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| 53 | const uint8_t * data = (const uint8_t*)key;
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| 54 |
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| 55 | h ^= len;
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| 56 |
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| 57 | for(int i = 0; i < len; i++)
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| 58 | {
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| 59 | h ^= data[i];
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| 60 | h *= 0x5bd1e995;
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| 61 | h ^= h >> 16;
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| 62 | }
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| 63 |
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| 64 | return h;
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| 65 | }
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| 66 |
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| 67 | //----------------------------------------------------------------------------
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| 68 |
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| 69 | void FNV ( const void * key, int len, uint32_t seed, void * out )
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| 70 | {
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| 71 | unsigned int h = seed;
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| 72 |
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| 73 | const uint8_t * data = (const uint8_t*)key;
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| 74 |
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| 75 | h ^= 2166136261;
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| 76 |
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| 77 | for(int i = 0; i < len; i++)
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| 78 | {
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| 79 | h ^= data[i];
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| 80 | h *= 16777619;
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| 81 | }
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| 82 |
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| 83 | *(uint32_t*)out = h;
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| 84 | }
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| 85 |
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| 86 | //-----------------------------------------------------------------------------
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| 87 |
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| 88 | uint32_t x17 ( const void * key, int len, uint32_t h )
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| 89 | {
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| 90 | const uint8_t * data = (const uint8_t*)key;
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| 91 |
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| 92 | for(int i = 0; i < len; ++i)
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| 93 | {
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| 94 | h = 17 * h + (data[i] - ' ');
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| 95 | }
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| 96 |
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| 97 | return h ^ (h >> 16);
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| 98 | }
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| 99 |
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| 100 | //-----------------------------------------------------------------------------
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| 101 |
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| 102 | uint32_t Bernstein ( const void * key, int len, uint32_t h )
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| 103 | {
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| 104 | const uint8_t * data = (const uint8_t*)key;
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| 105 |
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| 106 | for(int i = 0; i < len; ++i)
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| 107 | {
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| 108 | h = 33 * h + data[i];
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| 109 | }
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| 110 |
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| 111 | return h;
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| 112 | }
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| 113 |
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| 114 | //-----------------------------------------------------------------------------
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