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view jenkinsHash_lookup3.c @ 31:1d42a512f482
Renamed VMS to PR, in new branch
| author | Sean Halle <seanhalle@yahoo.com> |
|---|---|
| date | Fri, 08 Mar 2013 05:44:24 -0800 |
| parents | |
| children | f82bd67d93fa |
line source
1 /*
2 -------------------------------------------------------------------------------
3 lookup3.c, by Bob Jenkins, May 2006, Public Domain.
5 These are functions for producing 32-bit hashes for hash table lookup.
6 hashword(), hashlittle(), hashlittle2(), hashbig(), mix(), and final()
7 are externally useful functions. Routines to test the hash are included
8 if SELF_TEST is defined. You can use this free for any purpose. It's in
9 the public domain. It has no warranty.
11 You probably want to use hashlittle(). hashlittle() and hashbig()
12 hash byte arrays. hashlittle() is is faster than hashbig() on
13 little-endian machines. Intel and AMD are little-endian machines.
14 On second thought, you probably want hashlittle2(), which is identical to
15 hashlittle() except it returns two 32-bit hashes for the price of one.
16 You could implement hashbig2() if you wanted but I haven't bothered here.
18 If you want to find a hash of, say, exactly 7 integers, do
19 a = i1; b = i2; c = i3;
20 mix(a,b,c);
21 a += i4; b += i5; c += i6;
22 mix(a,b,c);
23 a += i7;
24 final(a,b,c);
25 then use c as the hash value. If you have a variable length array of
26 4-byte integers to hash, use hashword(). If you have a byte array (like
27 a character string), use hashlittle(). If you have several byte arrays, or
28 a mix of things, see the comments above hashlittle().
30 Why is this so big? I read 12 bytes at a time into 3 4-byte integers,
31 then mix those integers. This is fast (you can do a lot more thorough
32 mixing with 12*3 instructions on 3 integers than you can with 3 instructions
33 on 1 byte), but shoehorning those bytes into integers efficiently is messy.
34 -------------------------------------------------------------------------------
35 */
36 //#define SELF_TEST 1
38 #include <stdio.h> /* defines printf for tests */
39 #include <time.h> /* defines time_t for timings in the test */
40 #include <stdint.h> /* defines uint32_t etc */
41 #include <sys/param.h> /* attempt to define endianness */
42 #ifdef linux
43 # include <endian.h> /* attempt to define endianness */
44 #endif
46 /*
47 * My best guess at if you are big-endian or little-endian. This may
48 * need adjustment.
49 */
50 #if (defined(__BYTE_ORDER) && defined(__LITTLE_ENDIAN) && \
51 __BYTE_ORDER == __LITTLE_ENDIAN) || \
52 (defined(i386) || defined(__i386__) || defined(__i486__) || \
53 defined(__i586__) || defined(__i686__) || defined(vax) || defined(MIPSEL))
54 # define HASH_LITTLE_ENDIAN 1
55 # define HASH_BIG_ENDIAN 0
56 #elif (defined(__BYTE_ORDER) && defined(__BIG_ENDIAN) && \
57 __BYTE_ORDER == __BIG_ENDIAN) || \
58 (defined(sparc) || defined(POWERPC) || defined(mc68000) || defined(sel))
59 # define HASH_LITTLE_ENDIAN 0
60 # define HASH_BIG_ENDIAN 1
61 #else
62 # define HASH_LITTLE_ENDIAN 0
63 # define HASH_BIG_ENDIAN 0
64 #endif
66 #define hashsize(n) ((uint32_t)1<<(n))
67 #define hashmask(n) (hashsize(n)-1)
68 #define rot(x,k) (((x)<<(k)) | ((x)>>(32-(k))))
70 /*
71 -------------------------------------------------------------------------------
72 mix -- mix 3 32-bit values reversibly.
74 This is reversible, so any information in (a,b,c) before mix() is
75 still in (a,b,c) after mix().
77 If four pairs of (a,b,c) inputs are run through mix(), or through
78 mix() in reverse, there are at least 32 bits of the output that
79 are sometimes the same for one pair and different for another pair.
80 This was tested for:
81 * pairs that differed by one bit, by two bits, in any combination
82 of top bits of (a,b,c), or in any combination of bottom bits of
83 (a,b,c).
84 * "differ" is defined as +, -, ^, or ~^. For + and -, I transformed
85 the output delta to a Gray code (a^(a>>1)) so a string of 1's (as
86 is commonly produced by subtraction) look like a single 1-bit
87 difference.
88 * the base values were pseudorandom, all zero but one bit set, or
89 all zero plus a counter that starts at zero.
91 Some k values for my "a-=c; a^=rot(c,k); c+=b;" arrangement that
92 satisfy this are
93 4 6 8 16 19 4
94 9 15 3 18 27 15
95 14 9 3 7 17 3
96 Well, "9 15 3 18 27 15" didn't quite get 32 bits diffing
97 for "differ" defined as + with a one-bit base and a two-bit delta. I
98 used http://burtleburtle.net/bob/hash/avalanche.html to choose
99 the operations, constants, and arrangements of the variables.
101 This does not achieve avalanche. There are input bits of (a,b,c)
102 that fail to affect some output bits of (a,b,c), especially of a. The
103 most thoroughly mixed value is c, but it doesn't really even achieve
104 avalanche in c.
106 This allows some parallelism. Read-after-writes are good at doubling
107 the number of bits affected, so the goal of mixing pulls in the opposite
108 direction as the goal of parallelism. I did what I could. Rotates
109 seem to cost as much as shifts on every machine I could lay my hands
110 on, and rotates are much kinder to the top and bottom bits, so I used
111 rotates.
112 -------------------------------------------------------------------------------
113 */
114 #define mix(a,b,c) \
115 { \
116 a -= c; a ^= rot(c, 4); c += b; \
117 b -= a; b ^= rot(a, 6); a += c; \
118 c -= b; c ^= rot(b, 8); b += a; \
119 a -= c; a ^= rot(c,16); c += b; \
120 b -= a; b ^= rot(a,19); a += c; \
121 c -= b; c ^= rot(b, 4); b += a; \
122 }
124 /*
125 -------------------------------------------------------------------------------
126 final -- final mixing of 3 32-bit values (a,b,c) into c
128 Pairs of (a,b,c) values differing in only a few bits will usually
129 produce values of c that look totally different. This was tested for
130 * pairs that differed by one bit, by two bits, in any combination
131 of top bits of (a,b,c), or in any combination of bottom bits of
132 (a,b,c).
133 * "differ" is defined as +, -, ^, or ~^. For + and -, I transformed
134 the output delta to a Gray code (a^(a>>1)) so a string of 1's (as
135 is commonly produced by subtraction) look like a single 1-bit
136 difference.
137 * the base values were pseudorandom, all zero but one bit set, or
138 all zero plus a counter that starts at zero.
140 These constants passed:
141 14 11 25 16 4 14 24
142 12 14 25 16 4 14 24
143 and these came close:
144 4 8 15 26 3 22 24
145 10 8 15 26 3 22 24
146 11 8 15 26 3 22 24
147 -------------------------------------------------------------------------------
148 */
149 #define final(a,b,c) \
150 { \
151 c ^= b; c -= rot(b,14); \
152 a ^= c; a -= rot(c,11); \
153 b ^= a; b -= rot(a,25); \
154 c ^= b; c -= rot(b,16); \
155 a ^= c; a -= rot(c,4); \
156 b ^= a; b -= rot(a,14); \
157 c ^= b; c -= rot(b,24); \
158 }
160 /*
161 --------------------------------------------------------------------
162 This works on all machines. To be useful, it requires
163 -- that the key be an array of uint32_t's, and
164 -- that the length be the number of uint32_t's in the key
166 The function hashword() is identical to hashlittle() on little-endian
167 machines, and identical to hashbig() on big-endian machines,
168 except that the length has to be measured in uint32_ts rather than in
169 bytes. hashlittle() is more complicated than hashword() only because
170 hashlittle() has to dance around fitting the key bytes into registers.
171 --------------------------------------------------------------------
172 */
173 inline uint32_t
174 jenkHash32(
175 const uint32_t *k, /* the key, an array of uint32_t values */
176 size_t length) /* the length of the key, in uint32_ts */
177 {
178 uint32_t a,b,c;
180 /* Set up the internal state */
181 a = b = c = 0xdeadbeef + (((uint32_t)length)<<2) + 0x7291f8a3;//arbitrary
183 /*------------------------------------------------- handle most of the key */
184 while (length > 3)
185 {
186 a += k[0];
187 b += k[1];
188 c += k[2];
189 mix(a,b,c);
190 length -= 3;
191 k += 3;
192 }
194 /*------------------------------------------- handle the last 3 uint32_t's */
195 switch(length) /* all the case statements fall through */
196 {
197 case 3 : c+=k[2];
198 case 2 : b+=k[1];
199 case 1 : a+=k[0];
200 final(a,b,c);
201 case 0: /* case 0: nothing left to add */
202 break;
203 }
204 /*------------------------------------------------------ report the result */
205 return c;
206 }
209 /*
210 --------------------------------------------------------------------
211 hashword2() -- same as hashword(), but take two seeds and return two
212 32-bit values. pc and pb must both be nonnull, and *pc and *pb must
213 both be initialized with seeds. If you pass in (*pb)==0, the output
214 (*pc) will be the same as the return value from hashword().
215 --------------------------------------------------------------------
216 */
217 void hashword2 (
218 const uint32_t *k, /* the key, an array of uint32_t values */
219 size_t length, /* the length of the key, in uint32_ts */
220 uint32_t *pc, /* IN: seed OUT: primary hash value */
221 uint32_t *pb) /* IN: more seed OUT: secondary hash value */
222 {
223 uint32_t a,b,c;
225 /* Set up the internal state */
226 a = b = c = 0xdeadbeef + ((uint32_t)(length<<2)) + *pc;
227 c += *pb;
229 /*------------------------------------------------- handle most of the key */
230 while (length > 3)
231 {
232 a += k[0];
233 b += k[1];
234 c += k[2];
235 mix(a,b,c);
236 length -= 3;
237 k += 3;
238 }
240 /*------------------------------------------- handle the last 3 uint32_t's */
241 switch(length) /* all the case statements fall through */
242 {
243 case 3 : c+=k[2];
244 case 2 : b+=k[1];
245 case 1 : a+=k[0];
246 final(a,b,c);
247 case 0: /* case 0: nothing left to add */
248 break;
249 }
250 /*------------------------------------------------------ report the result */
251 *pc=c; *pb=b;
252 }
255 /*
256 -------------------------------------------------------------------------------
257 hashlittle() -- hash a variable-length key into a 32-bit value
258 k : the key (the unaligned variable-length array of bytes)
259 length : the length of the key, counting by bytes
260 initval : can be any 4-byte value
261 Returns a 32-bit value. Every bit of the key affects every bit of
262 the return value. Two keys differing by one or two bits will have
263 totally different hash values.
265 The best hash table sizes are powers of 2. There is no need to do
266 mod a prime (mod is sooo slow!). If you need less than 32 bits,
267 use a bitmask. For example, if you need only 10 bits, do
268 h = (h & hashmask(10));
269 In which case, the hash table should have hashsize(10) elements.
271 If you are hashing n strings (uint8_t **)k, do it like this:
272 for (i=0, h=0; i<n; ++i) h = hashlittle( k[i], len[i], h);
274 By Bob Jenkins, 2006. bob_jenkins@burtleburtle.net. You may use this
275 code any way you wish, private, educational, or commercial. It's free.
277 Use for hash table lookup, or anything where one collision in 2^^32 is
278 acceptable. Do NOT use for cryptographic purposes.
279 -------------------------------------------------------------------------------
280 */
282 uint32_t hashlittle( const void *key, size_t length, uint32_t initval)
283 {
284 uint32_t a,b,c; /* internal state */
285 union { const void *ptr; size_t i; } u; /* needed for Mac Powerbook G4 */
287 /* Set up the internal state */
288 a = b = c = 0xdeadbeef + ((uint32_t)length) + initval;
290 u.ptr = key;
291 if (HASH_LITTLE_ENDIAN && ((u.i & 0x3) == 0)) {
292 const uint32_t *k = (const uint32_t *)key; /* read 32-bit chunks */
293 const uint8_t *k8;
295 /*------ all but last block: aligned reads and affect 32 bits of (a,b,c) */
296 while (length > 12)
297 {
298 a += k[0];
299 b += k[1];
300 c += k[2];
301 mix(a,b,c);
302 length -= 12;
303 k += 3;
304 }
306 /*----------------------------- handle the last (probably partial) block */
307 /*
308 * "k[2]&0xffffff" actually reads beyond the end of the string, but
309 * then masks off the part it's not allowed to read. Because the
310 * string is aligned, the masked-off tail is in the same word as the
311 * rest of the string. Every machine with memory protection I've seen
312 * does it on word boundaries, so is OK with this. But VALGRIND will
313 * still catch it and complain. The masking trick does make the hash
314 * noticably faster for short strings (like English words).
315 */
316 #ifndef VALGRIND
318 switch(length)
319 {
320 case 12: c+=k[2]; b+=k[1]; a+=k[0]; break;
321 case 11: c+=k[2]&0xffffff; b+=k[1]; a+=k[0]; break;
322 case 10: c+=k[2]&0xffff; b+=k[1]; a+=k[0]; break;
323 case 9 : c+=k[2]&0xff; b+=k[1]; a+=k[0]; break;
324 case 8 : b+=k[1]; a+=k[0]; break;
325 case 7 : b+=k[1]&0xffffff; a+=k[0]; break;
326 case 6 : b+=k[1]&0xffff; a+=k[0]; break;
327 case 5 : b+=k[1]&0xff; a+=k[0]; break;
328 case 4 : a+=k[0]; break;
329 case 3 : a+=k[0]&0xffffff; break;
330 case 2 : a+=k[0]&0xffff; break;
331 case 1 : a+=k[0]&0xff; break;
332 case 0 : return c; /* zero length strings require no mixing */
333 }
335 #else /* make valgrind happy */
337 k8 = (const uint8_t *)k;
338 switch(length)
339 {
340 case 12: c+=k[2]; b+=k[1]; a+=k[0]; break;
341 case 11: c+=((uint32_t)k8[10])<<16; /* fall through */
342 case 10: c+=((uint32_t)k8[9])<<8; /* fall through */
343 case 9 : c+=k8[8]; /* fall through */
344 case 8 : b+=k[1]; a+=k[0]; break;
345 case 7 : b+=((uint32_t)k8[6])<<16; /* fall through */
346 case 6 : b+=((uint32_t)k8[5])<<8; /* fall through */
347 case 5 : b+=k8[4]; /* fall through */
348 case 4 : a+=k[0]; break;
349 case 3 : a+=((uint32_t)k8[2])<<16; /* fall through */
350 case 2 : a+=((uint32_t)k8[1])<<8; /* fall through */
351 case 1 : a+=k8[0]; break;
352 case 0 : return c;
353 }
355 #endif /* !valgrind */
357 } else if (HASH_LITTLE_ENDIAN && ((u.i & 0x1) == 0)) {
358 const uint16_t *k = (const uint16_t *)key; /* read 16-bit chunks */
359 const uint8_t *k8;
361 /*--------------- all but last block: aligned reads and different mixing */
362 while (length > 12)
363 {
364 a += k[0] + (((uint32_t)k[1])<<16);
365 b += k[2] + (((uint32_t)k[3])<<16);
366 c += k[4] + (((uint32_t)k[5])<<16);
367 mix(a,b,c);
368 length -= 12;
369 k += 6;
370 }
372 /*----------------------------- handle the last (probably partial) block */
373 k8 = (const uint8_t *)k;
374 switch(length)
375 {
376 case 12: c+=k[4]+(((uint32_t)k[5])<<16);
377 b+=k[2]+(((uint32_t)k[3])<<16);
378 a+=k[0]+(((uint32_t)k[1])<<16);
379 break;
380 case 11: c+=((uint32_t)k8[10])<<16; /* fall through */
381 case 10: c+=k[4];
382 b+=k[2]+(((uint32_t)k[3])<<16);
383 a+=k[0]+(((uint32_t)k[1])<<16);
384 break;
385 case 9 : c+=k8[8]; /* fall through */
386 case 8 : b+=k[2]+(((uint32_t)k[3])<<16);
387 a+=k[0]+(((uint32_t)k[1])<<16);
388 break;
389 case 7 : b+=((uint32_t)k8[6])<<16; /* fall through */
390 case 6 : b+=k[2];
391 a+=k[0]+(((uint32_t)k[1])<<16);
392 break;
393 case 5 : b+=k8[4]; /* fall through */
394 case 4 : a+=k[0]+(((uint32_t)k[1])<<16);
395 break;
396 case 3 : a+=((uint32_t)k8[2])<<16; /* fall through */
397 case 2 : a+=k[0];
398 break;
399 case 1 : a+=k8[0];
400 break;
401 case 0 : return c; /* zero length requires no mixing */
402 }
404 } else { /* need to read the key one byte at a time */
405 const uint8_t *k = (const uint8_t *)key;
407 /*--------------- all but the last block: affect some 32 bits of (a,b,c) */
408 while (length > 12)
409 {
410 a += k[0];
411 a += ((uint32_t)k[1])<<8;
412 a += ((uint32_t)k[2])<<16;
413 a += ((uint32_t)k[3])<<24;
414 b += k[4];
415 b += ((uint32_t)k[5])<<8;
416 b += ((uint32_t)k[6])<<16;
417 b += ((uint32_t)k[7])<<24;
418 c += k[8];
419 c += ((uint32_t)k[9])<<8;
420 c += ((uint32_t)k[10])<<16;
421 c += ((uint32_t)k[11])<<24;
422 mix(a,b,c);
423 length -= 12;
424 k += 12;
425 }
427 /*-------------------------------- last block: affect all 32 bits of (c) */
428 switch(length) /* all the case statements fall through */
429 {
430 case 12: c+=((uint32_t)k[11])<<24;
431 case 11: c+=((uint32_t)k[10])<<16;
432 case 10: c+=((uint32_t)k[9])<<8;
433 case 9 : c+=k[8];
434 case 8 : b+=((uint32_t)k[7])<<24;
435 case 7 : b+=((uint32_t)k[6])<<16;
436 case 6 : b+=((uint32_t)k[5])<<8;
437 case 5 : b+=k[4];
438 case 4 : a+=((uint32_t)k[3])<<24;
439 case 3 : a+=((uint32_t)k[2])<<16;
440 case 2 : a+=((uint32_t)k[1])<<8;
441 case 1 : a+=k[0];
442 break;
443 case 0 : return c;
444 }
445 }
447 final(a,b,c);
448 return c;
449 }
452 /*
453 * hashlittle2: return 2 32-bit hash values
454 *
455 * This is identical to hashlittle(), except it returns two 32-bit hash
456 * values instead of just one. This is good enough for hash table
457 * lookup with 2^^64 buckets, or if you want a second hash if you're not
458 * happy with the first, or if you want a probably-unique 64-bit ID for
459 * the key. *pc is better mixed than *pb, so use *pc first. If you want
460 * a 64-bit value do something like "*pc + (((uint64_t)*pb)<<32)".
461 */
462 void hashlittle2(
463 const void *key, /* the key to hash */
464 size_t length, /* length of the key */
465 uint32_t *pc, /* IN: primary initval, OUT: primary hash */
466 uint32_t *pb) /* IN: secondary initval, OUT: secondary hash */
467 {
468 uint32_t a,b,c; /* internal state */
469 union { const void *ptr; size_t i; } u; /* needed for Mac Powerbook G4 */
471 /* Set up the internal state */
472 a = b = c = 0xdeadbeef + ((uint32_t)length) + *pc;
473 c += *pb;
475 u.ptr = key;
476 if (HASH_LITTLE_ENDIAN && ((u.i & 0x3) == 0)) {
477 const uint32_t *k = (const uint32_t *)key; /* read 32-bit chunks */
478 const uint8_t *k8;
480 /*------ all but last block: aligned reads and affect 32 bits of (a,b,c) */
481 while (length > 12)
482 {
483 a += k[0];
484 b += k[1];
485 c += k[2];
486 mix(a,b,c);
487 length -= 12;
488 k += 3;
489 }
491 /*----------------------------- handle the last (probably partial) block */
492 /*
493 * "k[2]&0xffffff" actually reads beyond the end of the string, but
494 * then masks off the part it's not allowed to read. Because the
495 * string is aligned, the masked-off tail is in the same word as the
496 * rest of the string. Every machine with memory protection I've seen
497 * does it on word boundaries, so is OK with this. But VALGRIND will
498 * still catch it and complain. The masking trick does make the hash
499 * noticably faster for short strings (like English words).
500 */
501 #ifndef VALGRIND
503 switch(length)
504 {
505 case 12: c+=k[2]; b+=k[1]; a+=k[0]; break;
506 case 11: c+=k[2]&0xffffff; b+=k[1]; a+=k[0]; break;
507 case 10: c+=k[2]&0xffff; b+=k[1]; a+=k[0]; break;
508 case 9 : c+=k[2]&0xff; b+=k[1]; a+=k[0]; break;
509 case 8 : b+=k[1]; a+=k[0]; break;
510 case 7 : b+=k[1]&0xffffff; a+=k[0]; break;
511 case 6 : b+=k[1]&0xffff; a+=k[0]; break;
512 case 5 : b+=k[1]&0xff; a+=k[0]; break;
513 case 4 : a+=k[0]; break;
514 case 3 : a+=k[0]&0xffffff; break;
515 case 2 : a+=k[0]&0xffff; break;
516 case 1 : a+=k[0]&0xff; break;
517 case 0 : *pc=c; *pb=b; return; /* zero length strings require no mixing */
518 }
520 #else /* make valgrind happy */
522 k8 = (const uint8_t *)k;
523 switch(length)
524 {
525 case 12: c+=k[2]; b+=k[1]; a+=k[0]; break;
526 case 11: c+=((uint32_t)k8[10])<<16; /* fall through */
527 case 10: c+=((uint32_t)k8[9])<<8; /* fall through */
528 case 9 : c+=k8[8]; /* fall through */
529 case 8 : b+=k[1]; a+=k[0]; break;
530 case 7 : b+=((uint32_t)k8[6])<<16; /* fall through */
531 case 6 : b+=((uint32_t)k8[5])<<8; /* fall through */
532 case 5 : b+=k8[4]; /* fall through */
533 case 4 : a+=k[0]; break;
534 case 3 : a+=((uint32_t)k8[2])<<16; /* fall through */
535 case 2 : a+=((uint32_t)k8[1])<<8; /* fall through */
536 case 1 : a+=k8[0]; break;
537 case 0 : *pc=c; *pb=b; return; /* zero length strings require no mixing */
538 }
540 #endif /* !valgrind */
542 } else if (HASH_LITTLE_ENDIAN && ((u.i & 0x1) == 0)) {
543 const uint16_t *k = (const uint16_t *)key; /* read 16-bit chunks */
544 const uint8_t *k8;
546 /*--------------- all but last block: aligned reads and different mixing */
547 while (length > 12)
548 {
549 a += k[0] + (((uint32_t)k[1])<<16);
550 b += k[2] + (((uint32_t)k[3])<<16);
551 c += k[4] + (((uint32_t)k[5])<<16);
552 mix(a,b,c);
553 length -= 12;
554 k += 6;
555 }
557 /*----------------------------- handle the last (probably partial) block */
558 k8 = (const uint8_t *)k;
559 switch(length)
560 {
561 case 12: c+=k[4]+(((uint32_t)k[5])<<16);
562 b+=k[2]+(((uint32_t)k[3])<<16);
563 a+=k[0]+(((uint32_t)k[1])<<16);
564 break;
565 case 11: c+=((uint32_t)k8[10])<<16; /* fall through */
566 case 10: c+=k[4];
567 b+=k[2]+(((uint32_t)k[3])<<16);
568 a+=k[0]+(((uint32_t)k[1])<<16);
569 break;
570 case 9 : c+=k8[8]; /* fall through */
571 case 8 : b+=k[2]+(((uint32_t)k[3])<<16);
572 a+=k[0]+(((uint32_t)k[1])<<16);
573 break;
574 case 7 : b+=((uint32_t)k8[6])<<16; /* fall through */
575 case 6 : b+=k[2];
576 a+=k[0]+(((uint32_t)k[1])<<16);
577 break;
578 case 5 : b+=k8[4]; /* fall through */
579 case 4 : a+=k[0]+(((uint32_t)k[1])<<16);
580 break;
581 case 3 : a+=((uint32_t)k8[2])<<16; /* fall through */
582 case 2 : a+=k[0];
583 break;
584 case 1 : a+=k8[0];
585 break;
586 case 0 : *pc=c; *pb=b; return; /* zero length strings require no mixing */
587 }
589 } else { /* need to read the key one byte at a time */
590 const uint8_t *k = (const uint8_t *)key;
592 /*--------------- all but the last block: affect some 32 bits of (a,b,c) */
593 while (length > 12)
594 {
595 a += k[0];
596 a += ((uint32_t)k[1])<<8;
597 a += ((uint32_t)k[2])<<16;
598 a += ((uint32_t)k[3])<<24;
599 b += k[4];
600 b += ((uint32_t)k[5])<<8;
601 b += ((uint32_t)k[6])<<16;
602 b += ((uint32_t)k[7])<<24;
603 c += k[8];
604 c += ((uint32_t)k[9])<<8;
605 c += ((uint32_t)k[10])<<16;
606 c += ((uint32_t)k[11])<<24;
607 mix(a,b,c);
608 length -= 12;
609 k += 12;
610 }
612 /*-------------------------------- last block: affect all 32 bits of (c) */
613 switch(length) /* all the case statements fall through */
614 {
615 case 12: c+=((uint32_t)k[11])<<24;
616 case 11: c+=((uint32_t)k[10])<<16;
617 case 10: c+=((uint32_t)k[9])<<8;
618 case 9 : c+=k[8];
619 case 8 : b+=((uint32_t)k[7])<<24;
620 case 7 : b+=((uint32_t)k[6])<<16;
621 case 6 : b+=((uint32_t)k[5])<<8;
622 case 5 : b+=k[4];
623 case 4 : a+=((uint32_t)k[3])<<24;
624 case 3 : a+=((uint32_t)k[2])<<16;
625 case 2 : a+=((uint32_t)k[1])<<8;
626 case 1 : a+=k[0];
627 break;
628 case 0 : *pc=c; *pb=b; return; /* zero length strings require no mixing */
629 }
630 }
632 final(a,b,c);
633 *pc=c; *pb=b;
634 }
638 /*
639 * hashbig():
640 * This is the same as hashword() on big-endian machines. It is different
641 * from hashlittle() on all machines. hashbig() takes advantage of
642 * big-endian byte ordering.
643 */
644 uint32_t hashbig( const void *key, size_t length, uint32_t initval)
645 {
646 uint32_t a,b,c;
647 union { const void *ptr; size_t i; } u; /* to cast key to (size_t) happily */
649 /* Set up the internal state */
650 a = b = c = 0xdeadbeef + ((uint32_t)length) + initval;
652 u.ptr = key;
653 if (HASH_BIG_ENDIAN && ((u.i & 0x3) == 0)) {
654 const uint32_t *k = (const uint32_t *)key; /* read 32-bit chunks */
655 const uint8_t *k8;
657 /*------ all but last block: aligned reads and affect 32 bits of (a,b,c) */
658 while (length > 12)
659 {
660 a += k[0];
661 b += k[1];
662 c += k[2];
663 mix(a,b,c);
664 length -= 12;
665 k += 3;
666 }
668 /*----------------------------- handle the last (probably partial) block */
669 /*
670 * "k[2]<<8" actually reads beyond the end of the string, but
671 * then shifts out the part it's not allowed to read. Because the
672 * string is aligned, the illegal read is in the same word as the
673 * rest of the string. Every machine with memory protection I've seen
674 * does it on word boundaries, so is OK with this. But VALGRIND will
675 * still catch it and complain. The masking trick does make the hash
676 * noticably faster for short strings (like English words).
677 */
678 #ifndef VALGRIND
680 switch(length)
681 {
682 case 12: c+=k[2]; b+=k[1]; a+=k[0]; break;
683 case 11: c+=k[2]&0xffffff00; b+=k[1]; a+=k[0]; break;
684 case 10: c+=k[2]&0xffff0000; b+=k[1]; a+=k[0]; break;
685 case 9 : c+=k[2]&0xff000000; b+=k[1]; a+=k[0]; break;
686 case 8 : b+=k[1]; a+=k[0]; break;
687 case 7 : b+=k[1]&0xffffff00; a+=k[0]; break;
688 case 6 : b+=k[1]&0xffff0000; a+=k[0]; break;
689 case 5 : b+=k[1]&0xff000000; a+=k[0]; break;
690 case 4 : a+=k[0]; break;
691 case 3 : a+=k[0]&0xffffff00; break;
692 case 2 : a+=k[0]&0xffff0000; break;
693 case 1 : a+=k[0]&0xff000000; break;
694 case 0 : return c; /* zero length strings require no mixing */
695 }
697 #else /* make valgrind happy */
699 k8 = (const uint8_t *)k;
700 switch(length) /* all the case statements fall through */
701 {
702 case 12: c+=k[2]; b+=k[1]; a+=k[0]; break;
703 case 11: c+=((uint32_t)k8[10])<<8; /* fall through */
704 case 10: c+=((uint32_t)k8[9])<<16; /* fall through */
705 case 9 : c+=((uint32_t)k8[8])<<24; /* fall through */
706 case 8 : b+=k[1]; a+=k[0]; break;
707 case 7 : b+=((uint32_t)k8[6])<<8; /* fall through */
708 case 6 : b+=((uint32_t)k8[5])<<16; /* fall through */
709 case 5 : b+=((uint32_t)k8[4])<<24; /* fall through */
710 case 4 : a+=k[0]; break;
711 case 3 : a+=((uint32_t)k8[2])<<8; /* fall through */
712 case 2 : a+=((uint32_t)k8[1])<<16; /* fall through */
713 case 1 : a+=((uint32_t)k8[0])<<24; break;
714 case 0 : return c;
715 }
717 #endif /* !VALGRIND */
719 } else { /* need to read the key one byte at a time */
720 const uint8_t *k = (const uint8_t *)key;
722 /*--------------- all but the last block: affect some 32 bits of (a,b,c) */
723 while (length > 12)
724 {
725 a += ((uint32_t)k[0])<<24;
726 a += ((uint32_t)k[1])<<16;
727 a += ((uint32_t)k[2])<<8;
728 a += ((uint32_t)k[3]);
729 b += ((uint32_t)k[4])<<24;
730 b += ((uint32_t)k[5])<<16;
731 b += ((uint32_t)k[6])<<8;
732 b += ((uint32_t)k[7]);
733 c += ((uint32_t)k[8])<<24;
734 c += ((uint32_t)k[9])<<16;
735 c += ((uint32_t)k[10])<<8;
736 c += ((uint32_t)k[11]);
737 mix(a,b,c);
738 length -= 12;
739 k += 12;
740 }
742 /*-------------------------------- last block: affect all 32 bits of (c) */
743 switch(length) /* all the case statements fall through */
744 {
745 case 12: c+=k[11];
746 case 11: c+=((uint32_t)k[10])<<8;
747 case 10: c+=((uint32_t)k[9])<<16;
748 case 9 : c+=((uint32_t)k[8])<<24;
749 case 8 : b+=k[7];
750 case 7 : b+=((uint32_t)k[6])<<8;
751 case 6 : b+=((uint32_t)k[5])<<16;
752 case 5 : b+=((uint32_t)k[4])<<24;
753 case 4 : a+=k[3];
754 case 3 : a+=((uint32_t)k[2])<<8;
755 case 2 : a+=((uint32_t)k[1])<<16;
756 case 1 : a+=((uint32_t)k[0])<<24;
757 break;
758 case 0 : return c;
759 }
760 }
762 final(a,b,c);
763 return c;
764 }
767 #ifdef SELF_TEST
769 /* used for timings */
770 void driver1()
771 {
772 uint8_t buf[256];
773 uint32_t i;
774 uint32_t h=0;
775 time_t a,z;
777 time(&a);
778 for (i=0; i<256; ++i) buf[i] = 'x';
779 for (i=0; i<1; ++i)
780 {
781 h = hashlittle(&buf[0],1,h);
782 }
783 time(&z);
785 if (z-a > 0) printf("time %d %.8x\n", z-a, h);
787 }
789 /* check that every input bit changes every output bit half the time */
790 #define HASHSTATE 1
791 #define HASHLEN 1
792 #define MAXPAIR 60
793 #define MAXLEN 70
794 void driver2()
795 {
796 uint8_t qa[MAXLEN+1], qb[MAXLEN+2], *a = &qa[0], *b = &qb[1];
797 uint32_t c[HASHSTATE], d[HASHSTATE], i=0, j=0, k, l, m=0, z;
798 uint32_t e[HASHSTATE],f[HASHSTATE],g[HASHSTATE],h[HASHSTATE];
799 uint32_t x[HASHSTATE],y[HASHSTATE];
800 uint32_t hlen;
802 printf("No more than %d trials should ever be needed \n",MAXPAIR/2);
803 for (hlen=0; hlen < MAXLEN; ++hlen)
804 {
805 z=0;
806 for (i=0; i<hlen; ++i) /*----------------------- for each input byte, */
807 {
808 for (j=0; j<8; ++j) /*------------------------ for each input bit, */
809 {
810 for (m=1; m<8; ++m) /*------------ for serveral possible initvals, */
811 {
812 for (l=0; l<HASHSTATE; ++l)
813 e[l]=f[l]=g[l]=h[l]=x[l]=y[l]=~((uint32_t)0);
815 /*---- check that every output bit is affected by that input bit */
816 for (k=0; k<MAXPAIR; k+=2)
817 {
818 uint32_t finished=1;
819 /* keys have one bit different */
820 for (l=0; l<hlen+1; ++l) {a[l] = b[l] = (uint8_t)0;}
821 /* have a and b be two keys differing in only one bit */
822 a[i] ^= (k<<j);
823 a[i] ^= (k>>(8-j));
824 c[0] = hashlittle(a, hlen, m);
825 b[i] ^= ((k+1)<<j);
826 b[i] ^= ((k+1)>>(8-j));
827 d[0] = hashlittle(b, hlen, m);
828 /* check every bit is 1, 0, set, and not set at least once */
829 for (l=0; l<HASHSTATE; ++l)
830 {
831 e[l] &= (c[l]^d[l]);
832 f[l] &= ~(c[l]^d[l]);
833 g[l] &= c[l];
834 h[l] &= ~c[l];
835 x[l] &= d[l];
836 y[l] &= ~d[l];
837 if (e[l]|f[l]|g[l]|h[l]|x[l]|y[l]) finished=0;
838 }
839 if (finished) break;
840 }
841 if (k>z) z=k;
842 if (k==MAXPAIR)
843 {
844 printf("Some bit didn't change: ");
845 printf("%.8x %.8x %.8x %.8x %.8x %.8x ",
846 e[0],f[0],g[0],h[0],x[0],y[0]);
847 printf("i %d j %d m %d len %d\n", i, j, m, hlen);
848 }
849 if (z==MAXPAIR) goto done;
850 }
851 }
852 }
853 done:
854 if (z < MAXPAIR)
855 {
856 printf("Mix success %2d bytes %2d initvals ",i,m);
857 printf("required %d trials\n", z/2);
858 }
859 }
860 printf("\n");
861 }
863 /* Check for reading beyond the end of the buffer and alignment problems */
864 void driver3()
865 {
866 uint8_t buf[MAXLEN+20], *b;
867 uint32_t len;
868 uint8_t q[] = "This is the time for all good men to come to the aid of their country...";
869 uint32_t h;
870 uint8_t qq[] = "xThis is the time for all good men to come to the aid of their country...";
871 uint32_t i;
872 uint8_t qqq[] = "xxThis is the time for all good men to come to the aid of their country...";
873 uint32_t j;
874 uint8_t qqqq[] = "xxxThis is the time for all good men to come to the aid of their country...";
875 uint32_t ref,x,y;
876 uint8_t *p;
878 printf("Endianness. These lines should all be the same (for values filled in):\n");
879 printf("%.8x %.8x %.8x\n",
880 jenkHash32((const uint32_t *)q, (sizeof(q)-1)/4, 13),
881 jenkHash32((const uint32_t *)q, (sizeof(q)-5)/4, 13),
882 jenkHash32((const uint32_t *)q, (sizeof(q)-9)/4, 13));
883 p = q;
884 printf("%.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x\n",
885 hashlittle(p, sizeof(q)-1, 13), hashlittle(p, sizeof(q)-2, 13),
886 hashlittle(p, sizeof(q)-3, 13), hashlittle(p, sizeof(q)-4, 13),
887 hashlittle(p, sizeof(q)-5, 13), hashlittle(p, sizeof(q)-6, 13),
888 hashlittle(p, sizeof(q)-7, 13), hashlittle(p, sizeof(q)-8, 13),
889 hashlittle(p, sizeof(q)-9, 13), hashlittle(p, sizeof(q)-10, 13),
890 hashlittle(p, sizeof(q)-11, 13), hashlittle(p, sizeof(q)-12, 13));
891 p = &qq[1];
892 printf("%.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x\n",
893 hashlittle(p, sizeof(q)-1, 13), hashlittle(p, sizeof(q)-2, 13),
894 hashlittle(p, sizeof(q)-3, 13), hashlittle(p, sizeof(q)-4, 13),
895 hashlittle(p, sizeof(q)-5, 13), hashlittle(p, sizeof(q)-6, 13),
896 hashlittle(p, sizeof(q)-7, 13), hashlittle(p, sizeof(q)-8, 13),
897 hashlittle(p, sizeof(q)-9, 13), hashlittle(p, sizeof(q)-10, 13),
898 hashlittle(p, sizeof(q)-11, 13), hashlittle(p, sizeof(q)-12, 13));
899 p = &qqq[2];
900 printf("%.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x\n",
901 hashlittle(p, sizeof(q)-1, 13), hashlittle(p, sizeof(q)-2, 13),
902 hashlittle(p, sizeof(q)-3, 13), hashlittle(p, sizeof(q)-4, 13),
903 hashlittle(p, sizeof(q)-5, 13), hashlittle(p, sizeof(q)-6, 13),
904 hashlittle(p, sizeof(q)-7, 13), hashlittle(p, sizeof(q)-8, 13),
905 hashlittle(p, sizeof(q)-9, 13), hashlittle(p, sizeof(q)-10, 13),
906 hashlittle(p, sizeof(q)-11, 13), hashlittle(p, sizeof(q)-12, 13));
907 p = &qqqq[3];
908 printf("%.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x\n",
909 hashlittle(p, sizeof(q)-1, 13), hashlittle(p, sizeof(q)-2, 13),
910 hashlittle(p, sizeof(q)-3, 13), hashlittle(p, sizeof(q)-4, 13),
911 hashlittle(p, sizeof(q)-5, 13), hashlittle(p, sizeof(q)-6, 13),
912 hashlittle(p, sizeof(q)-7, 13), hashlittle(p, sizeof(q)-8, 13),
913 hashlittle(p, sizeof(q)-9, 13), hashlittle(p, sizeof(q)-10, 13),
914 hashlittle(p, sizeof(q)-11, 13), hashlittle(p, sizeof(q)-12, 13));
915 printf("\n");
917 /* check that hashlittle2 and hashlittle produce the same results */
918 i=47; j=0;
919 hashlittle2(q, sizeof(q), &i, &j);
920 if (hashlittle(q, sizeof(q), 47) != i)
921 printf("hashlittle2 and hashlittle mismatch\n");
923 /* check that hashword2 and hashword produce the same results */
924 len = 0xdeadbeef;
925 i=47, j=0;
926 hashword2(&len, 1, &i, &j);
927 if (jenkHash32(&len, 1, 47) != i)
928 printf("hashword2 and hashword mismatch %x %x\n",
929 i, jenkHash32(&len, 1, 47));
931 /* check hashlittle doesn't read before or after the ends of the string */
932 for (h=0, b=buf+1; h<8; ++h, ++b)
933 {
934 for (i=0; i<MAXLEN; ++i)
935 {
936 len = i;
937 for (j=0; j<i; ++j) *(b+j)=0;
939 /* these should all be equal */
940 ref = hashlittle(b, len, (uint32_t)1);
941 *(b+i)=(uint8_t)~0;
942 *(b-1)=(uint8_t)~0;
943 x = hashlittle(b, len, (uint32_t)1);
944 y = hashlittle(b, len, (uint32_t)1);
945 if ((ref != x) || (ref != y))
946 {
947 printf("alignment error: %.8x %.8x %.8x %d %d\n",ref,x,y,
948 h, i);
949 }
950 }
951 }
952 }
954 /* check for problems with nulls */
955 void driver4()
956 {
957 uint8_t buf[1];
958 uint32_t h,i,state[HASHSTATE];
961 buf[0] = ~0;
962 for (i=0; i<HASHSTATE; ++i) state[i] = 1;
963 printf("These should all be different\n");
964 for (i=0, h=0; i<8; ++i)
965 {
966 h = hashlittle(buf, 0, h);
968 printf("%2ld 0-byte strings, hash is %.8x\n", i, h);
970 }
971 }
973 void driver5()
974 {
976 uint32_t b,c;
977 b=0, c=0, hashlittle2("", 0, &c, &b);
978 printf("hash is %.8lx %.8lx\n", c, b); /* deadbeef deadbeef */
979 b=0xdeadbeef, c=0, hashlittle2("", 0, &c, &b);
980 printf("hash is %.8lx %.8lx\n", c, b); /* bd5b7dde deadbeef */
981 b=0xdeadbeef, c=0xdeadbeef, hashlittle2("", 0, &c, &b);
982 printf("hash is %.8lx %.8lx\n", c, b); /* 9c093ccd bd5b7dde */
983 b=0, c=0, hashlittle2("Four score and seven years ago", 30, &c, &b);
984 printf("hash is %.8lx %.8lx\n", c, b); /* 17770551 ce7226e6 */
985 b=1, c=0, hashlittle2("Four score and seven years ago", 30, &c, &b);
986 printf("hash is %.8lx %.8lx\n", c, b); /* e3607cae bd371de4 */
987 b=0, c=1, hashlittle2("Four score and seven years ago", 30, &c, &b);
988 printf("hash is %.8lx %.8lx\n", c, b); /* cd628161 6cbea4b3 */
989 c = hashlittle("Four score and seven years ago", 30, 0);
990 printf("hash is %.8lx\n", c); /* 17770551 */
991 c = hashlittle("Four score and seven years ago", 30, 1);
992 printf("hash is %.8lx\n", c); /* cd628161 */
994 }
997 int test_lookup3()
998 {
999 driver1(); /* test that the key is hashed: used for timings */
1000 driver2(); /* test that whole key is hashed thoroughly */
1001 driver3(); /* test that nothing but the key is hashed */
1002 driver4(); /* test hashing multiple buffers (all buffers are null) */
1003 driver5(); /* test the hash against known vectors */
1004 return 1;
1005 }
1007 #endif /* SELF_TEST */