1 #include "jenkins_hash.h"
2 #include <stdlib.h>
3 #ifdef WIN32
4 #define _USE_MATH_DEFINES //For M_LOG2E
5 #endif
6 #include <math.h>
7 #include <limits.h>
8 #include <string.h>
9
10 //#define DEBUG
11 #include "debug.h"
12
13 #define hashsize(n) ((cmph_uint32)1<<(n))
14 #define hashmask(n) (hashsize(n)-1)
15
16
17
18 //#define NM2 /* Define this if you do not want power of 2 table sizes*/
19
20
21 /*
22 --------------------------------------------------------------------
23 mix -- mix 3 32-bit values reversibly.
24 For every delta with one or two bits set, and the deltas of all three
25 high bits or all three low bits, whether the original value of a,b,c
26 is almost all zero or is uniformly distributed,
27 * If mix() is run forward or backward, at least 32 bits in a,b,c
28 have at least 1/4 probability of changing.
29 * If mix() is run forward, every bit of c will change between 1/3 and
30 2/3 of the time. (Well, 22/100 and 78/100 for some 2-bit deltas.)
31 mix() was built out of 36 single-cycle latency instructions in a
32 structure that could supported 2x parallelism, like so:
33 a -= b;
34 a -= c; x = (c>>13);
35 b -= c; a ^= x;
36 b -= a; x = (a<<8);
37 c -= a; b ^= x;
38 c -= b; x = (b>>13);
39 ...
40 Unfortunately, superscalar Pentiums and Sparcs can't take advantage
41 of that parallelism. They've also turned some of those single-cycle
42 latency instructions into multi-cycle latency instructions. Still,
43 this is the fastest good hash I could find. There were about 2^^68
44 to choose from. I only looked at a billion or so.
45 --------------------------------------------------------------------
46 */
47 #define mix(a,b,c) \
48 { \
49 a -= b; a -= c; a ^= (c>>13); \
50 b -= c; b -= a; b ^= (a<<8); \
51 c -= a; c -= b; c ^= (b>>13); \
52 a -= b; a -= c; a ^= (c>>12); \
53 b -= c; b -= a; b ^= (a<<16); \
54 c -= a; c -= b; c ^= (b>>5); \
55 a -= b; a -= c; a ^= (c>>3); \
56 b -= c; b -= a; b ^= (a<<10); \
57 c -= a; c -= b; c ^= (b>>15); \
58 }
59
60 /*
61 --------------------------------------------------------------------
62 hash() -- hash a variable-length key into a 32-bit value
63 k : the key (the unaligned variable-length array of bytes)
64 len : the length of the key, counting by bytes
65 initval : can be any 4-byte value
66 Returns a 32-bit value. Every bit of the key affects every bit of
67 the return value. Every 1-bit and 2-bit delta achieves avalanche.
68 About 6*len+35 instructions.
69
70 The best hash table sizes are powers of 2. There is no need to do
71 mod a prime (mod is sooo slow!). If you need less than 32 bits,
72 use a bitmask. For example, if you need only 10 bits, do
73 h = (h & hashmask(10));
74 In which case, the hash table should have hashsize(10) elements.
75
76 If you are hashing n strings (cmph_uint8 **)k, do it like this:
77 for (i=0, h=0; i<n; ++i) h = hash( k[i], len[i], h);
78
79 By Bob Jenkins, 1996. bob_jenkins@burtleburtle.net. You may use this
80 code any way you wish, private, educational, or commercial. It's free.
81
82 See http://burtleburtle.net/bob/hash/evahash.html
83 Use for hash table lookup, or anything where one collision in 2^^32 is
84 acceptable. Do NOT use for cryptographic purposes.
85 --------------------------------------------------------------------
86 */
jenkins_state_new(cmph_uint32 size)87 jenkins_state_t *jenkins_state_new(cmph_uint32 size) //size of hash table
88 {
89 jenkins_state_t *state = (jenkins_state_t *)malloc(sizeof(jenkins_state_t));
90 if (!state) return NULL;
91 DEBUGP("Initializing jenkins hash\n");
92 state->seed = ((cmph_uint32)rand() % size);
93 return state;
94 }
jenkins_state_destroy(jenkins_state_t * state)95 void jenkins_state_destroy(jenkins_state_t *state)
96 {
97 free(state);
98 }
99
100
__jenkins_hash_vector(cmph_uint32 seed,const char * k,cmph_uint32 keylen,cmph_uint32 * hashes)101 static inline void __jenkins_hash_vector(cmph_uint32 seed, const char *k, cmph_uint32 keylen, cmph_uint32 * hashes)
102 {
103 register cmph_uint32 len, length;
104
105 /* Set up the internal state */
106 length = keylen;
107 len = length;
108 hashes[0] = hashes[1] = 0x9e3779b9; /* the golden ratio; an arbitrary value */
109 hashes[2] = seed; /* the previous hash value - seed in our case */
110
111 /*---------------------------------------- handle most of the key */
112 while (len >= 12)
113 {
114 hashes[0] += ((cmph_uint32)k[0] +((cmph_uint32)k[1]<<8) +((cmph_uint32)k[2]<<16) +((cmph_uint32)k[3]<<24));
115 hashes[1] += ((cmph_uint32)k[4] +((cmph_uint32)k[5]<<8) +((cmph_uint32)k[6]<<16) +((cmph_uint32)k[7]<<24));
116 hashes[2] += ((cmph_uint32)k[8] +((cmph_uint32)k[9]<<8) +((cmph_uint32)k[10]<<16)+((cmph_uint32)k[11]<<24));
117 mix(hashes[0],hashes[1],hashes[2]);
118 k += 12; len -= 12;
119 }
120
121 /*------------------------------------- handle the last 11 bytes */
122 hashes[2] += length;
123 switch(len) /* all the case statements fall through */
124 {
125 case 11:
126 hashes[2] +=((cmph_uint32)k[10]<<24);
127 case 10:
128 hashes[2] +=((cmph_uint32)k[9]<<16);
129 case 9 :
130 hashes[2] +=((cmph_uint32)k[8]<<8);
131 /* the first byte of hashes[2] is reserved for the length */
132 case 8 :
133 hashes[1] +=((cmph_uint32)k[7]<<24);
134 case 7 :
135 hashes[1] +=((cmph_uint32)k[6]<<16);
136 case 6 :
137 hashes[1] +=((cmph_uint32)k[5]<<8);
138 case 5 :
139 hashes[1] +=(cmph_uint8) k[4];
140 case 4 :
141 hashes[0] +=((cmph_uint32)k[3]<<24);
142 case 3 :
143 hashes[0] +=((cmph_uint32)k[2]<<16);
144 case 2 :
145 hashes[0] +=((cmph_uint32)k[1]<<8);
146 case 1 :
147 hashes[0] +=(cmph_uint8)k[0];
148 /* case 0: nothing left to add */
149 }
150
151 mix(hashes[0],hashes[1],hashes[2]);
152 }
153
jenkins_hash(jenkins_state_t * state,const char * k,cmph_uint32 keylen)154 cmph_uint32 jenkins_hash(jenkins_state_t *state, const char *k, cmph_uint32 keylen)
155 {
156 cmph_uint32 hashes[3];
157 __jenkins_hash_vector(state->seed, k, keylen, hashes);
158 return hashes[2];
159 /* cmph_uint32 a, b, c;
160 cmph_uint32 len, length;
161
162 // Set up the internal state
163 length = keylen;
164 len = length;
165 a = b = 0x9e3779b9; // the golden ratio; an arbitrary value
166 c = state->seed; // the previous hash value - seed in our case
167
168 // handle most of the key
169 while (len >= 12)
170 {
171 a += (k[0] +((cmph_uint32)k[1]<<8) +((cmph_uint32)k[2]<<16) +((cmph_uint32)k[3]<<24));
172 b += (k[4] +((cmph_uint32)k[5]<<8) +((cmph_uint32)k[6]<<16) +((cmph_uint32)k[7]<<24));
173 c += (k[8] +((cmph_uint32)k[9]<<8) +((cmph_uint32)k[10]<<16)+((cmph_uint32)k[11]<<24));
174 mix(a,b,c);
175 k += 12; len -= 12;
176 }
177
178 // handle the last 11 bytes
179 c += length;
180 switch(len) /// all the case statements fall through
181 {
182 case 11:
183 c +=((cmph_uint32)k[10]<<24);
184 case 10:
185 c +=((cmph_uint32)k[9]<<16);
186 case 9 :
187 c +=((cmph_uint32)k[8]<<8);
188 // the first byte of c is reserved for the length
189 case 8 :
190 b +=((cmph_uint32)k[7]<<24);
191 case 7 :
192 b +=((cmph_uint32)k[6]<<16);
193 case 6 :
194 b +=((cmph_uint32)k[5]<<8);
195 case 5 :
196 b +=k[4];
197 case 4 :
198 a +=((cmph_uint32)k[3]<<24);
199 case 3 :
200 a +=((cmph_uint32)k[2]<<16);
201 case 2 :
202 a +=((cmph_uint32)k[1]<<8);
203 case 1 :
204 a +=k[0];
205 // case 0: nothing left to add
206 }
207
208 mix(a,b,c);
209
210 /// report the result
211
212 return c;
213 */
214 }
215
jenkins_hash_vector_(jenkins_state_t * state,const char * k,cmph_uint32 keylen,cmph_uint32 * hashes)216 void jenkins_hash_vector_(jenkins_state_t *state, const char *k, cmph_uint32 keylen, cmph_uint32 * hashes)
217 {
218 __jenkins_hash_vector(state->seed, k, keylen, hashes);
219 }
220
jenkins_state_dump(jenkins_state_t * state,char ** buf,cmph_uint32 * buflen)221 void jenkins_state_dump(jenkins_state_t *state, char **buf, cmph_uint32 *buflen)
222 {
223 *buflen = sizeof(cmph_uint32);
224 *buf = (char *)malloc(sizeof(cmph_uint32));
225 if (!*buf)
226 {
227 *buflen = UINT_MAX;
228 return;
229 }
230 memcpy(*buf, &(state->seed), sizeof(cmph_uint32));
231 DEBUGP("Dumped jenkins state with seed %u\n", state->seed);
232 return;
233 }
234
jenkins_state_copy(jenkins_state_t * src_state)235 jenkins_state_t *jenkins_state_copy(jenkins_state_t *src_state)
236 {
237 jenkins_state_t *dest_state = (jenkins_state_t *)malloc(sizeof(jenkins_state_t));
238 dest_state->hashfunc = src_state->hashfunc;
239 dest_state->seed = src_state->seed;
240 return dest_state;
241 }
242
jenkins_state_load(const char * buf,cmph_uint32 buflen)243 jenkins_state_t *jenkins_state_load(const char *buf, cmph_uint32 buflen)
244 {
245 jenkins_state_t *state = (jenkins_state_t *)malloc(sizeof(jenkins_state_t));
246 state->seed = *(cmph_uint32 *)buf;
247 state->hashfunc = CMPH_HASH_JENKINS;
248 DEBUGP("Loaded jenkins state with seed %u\n", state->seed);
249 return state;
250 }
251
252
253 /** \fn void jenkins_state_pack(jenkins_state_t *state, void *jenkins_packed);
254 * \brief Support the ability to pack a jenkins function into a preallocated contiguous memory space pointed by jenkins_packed.
255 * \param state points to the jenkins function
256 * \param jenkins_packed pointer to the contiguous memory area used to store the jenkins function. The size of jenkins_packed must be at least jenkins_state_packed_size()
257 */
jenkins_state_pack(jenkins_state_t * state,void * jenkins_packed)258 void jenkins_state_pack(jenkins_state_t *state, void *jenkins_packed)
259 {
260 if (state && jenkins_packed)
261 {
262 memcpy(jenkins_packed, &(state->seed), sizeof(cmph_uint32));
263 }
264 }
265
266 /** \fn cmph_uint32 jenkins_state_packed_size(jenkins_state_t *state);
267 * \brief Return the amount of space needed to pack a jenkins function.
268 * \return the size of the packed function or zero for failures
269 */
jenkins_state_packed_size(void)270 cmph_uint32 jenkins_state_packed_size(void)
271 {
272 return sizeof(cmph_uint32);
273 }
274
275
276 /** \fn cmph_uint32 jenkins_hash_packed(void *jenkins_packed, const char *k, cmph_uint32 keylen);
277 * \param jenkins_packed is a pointer to a contiguous memory area
278 * \param key is a pointer to a key
279 * \param keylen is the key length
280 * \return an integer that represents a hash value of 32 bits.
281 */
jenkins_hash_packed(void * jenkins_packed,const char * k,cmph_uint32 keylen)282 cmph_uint32 jenkins_hash_packed(void *jenkins_packed, const char *k, cmph_uint32 keylen)
283 {
284 cmph_uint32 hashes[3];
285 __jenkins_hash_vector(*((cmph_uint32 *)jenkins_packed), k, keylen, hashes);
286 return hashes[2];
287 }
288
289 /** \fn jenkins_hash_vector_packed(void *jenkins_packed, const char *k, cmph_uint32 keylen, cmph_uint32 * hashes);
290 * \param jenkins_packed is a pointer to a contiguous memory area
291 * \param key is a pointer to a key
292 * \param keylen is the key length
293 * \param hashes is a pointer to a memory large enough to fit three 32-bit integers.
294 */
jenkins_hash_vector_packed(void * jenkins_packed,const char * k,cmph_uint32 keylen,cmph_uint32 * hashes)295 void jenkins_hash_vector_packed(void *jenkins_packed, const char *k, cmph_uint32 keylen, cmph_uint32 * hashes)
296 {
297 __jenkins_hash_vector(*((cmph_uint32 *)jenkins_packed), k, keylen, hashes);
298 }
299