DPDK  17.02.1
rte_jhash.h
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33 
34 #ifndef _RTE_JHASH_H
35 #define _RTE_JHASH_H
36 
43 #ifdef __cplusplus
44 extern "C" {
45 #endif
46 
47 #include <stdint.h>
48 #include <string.h>
49 #include <limits.h>
50 
51 #include <rte_log.h>
52 #include <rte_byteorder.h>
53 
54 /* jhash.h: Jenkins hash support.
55  *
56  * Copyright (C) 2006 Bob Jenkins (bob_jenkins@burtleburtle.net)
57  *
58  * http://burtleburtle.net/bob/hash/
59  *
60  * These are the credits from Bob's sources:
61  *
62  * lookup3.c, by Bob Jenkins, May 2006, Public Domain.
63  *
64  * These are functions for producing 32-bit hashes for hash table lookup.
65  * hashword(), hashlittle(), hashlittle2(), hashbig(), mix(), and final()
66  * are externally useful functions. Routines to test the hash are included
67  * if SELF_TEST is defined. You can use this free for any purpose. It's in
68  * the public domain. It has no warranty.
69  *
70  * $FreeBSD$
71  */
72 
73 #define rot(x, k) (((x) << (k)) | ((x) >> (32-(k))))
74 
76 #define __rte_jhash_mix(a, b, c) do { \
77  a -= c; a ^= rot(c, 4); c += b; \
78  b -= a; b ^= rot(a, 6); a += c; \
79  c -= b; c ^= rot(b, 8); b += a; \
80  a -= c; a ^= rot(c, 16); c += b; \
81  b -= a; b ^= rot(a, 19); a += c; \
82  c -= b; c ^= rot(b, 4); b += a; \
83 } while (0)
84 
85 #define __rte_jhash_final(a, b, c) do { \
86  c ^= b; c -= rot(b, 14); \
87  a ^= c; a -= rot(c, 11); \
88  b ^= a; b -= rot(a, 25); \
89  c ^= b; c -= rot(b, 16); \
90  a ^= c; a -= rot(c, 4); \
91  b ^= a; b -= rot(a, 14); \
92  c ^= b; c -= rot(b, 24); \
93 } while (0)
94 
96 #define RTE_JHASH_GOLDEN_RATIO 0xdeadbeef
97 
98 #if RTE_BYTE_ORDER == RTE_LITTLE_ENDIAN
99 #define BIT_SHIFT(x, y, k) (((x) >> (k)) | ((uint64_t)(y) << (32-(k))))
100 #else
101 #define BIT_SHIFT(x, y, k) (((uint64_t)(x) << (k)) | ((y) >> (32-(k))))
102 #endif
103 
104 #define LOWER8b_MASK rte_le_to_cpu_32(0xff)
105 #define LOWER16b_MASK rte_le_to_cpu_32(0xffff)
106 #define LOWER24b_MASK rte_le_to_cpu_32(0xffffff)
107 
108 static inline void
109 __rte_jhash_2hashes(const void *key, uint32_t length, uint32_t *pc,
110  uint32_t *pb, unsigned check_align)
111 {
112  uint32_t a, b, c;
113 
114  /* Set up the internal state */
115  a = b = c = RTE_JHASH_GOLDEN_RATIO + ((uint32_t)length) + *pc;
116  c += *pb;
117 
118  /*
119  * Check key alignment. For x86 architecture, first case is always optimal
120  * If check_align is not set, first case will be used
121  */
122 #if defined(RTE_ARCH_X86_64) || defined(RTE_ARCH_I686) || defined(RTE_ARCH_X86_X32)
123  const uint32_t *k = (const uint32_t *)key;
124  const uint32_t s = 0;
125 #else
126  const uint32_t *k = (uint32_t *)((uintptr_t)key & (uintptr_t)~3);
127  const uint32_t s = ((uintptr_t)key & 3) * CHAR_BIT;
128 #endif
129  if (!check_align || s == 0) {
130  while (length > 12) {
131  a += k[0];
132  b += k[1];
133  c += k[2];
134 
135  __rte_jhash_mix(a, b, c);
136 
137  k += 3;
138  length -= 12;
139  }
140 
141  switch (length) {
142  case 12:
143  c += k[2]; b += k[1]; a += k[0]; break;
144  case 11:
145  c += k[2] & LOWER24b_MASK; b += k[1]; a += k[0]; break;
146  case 10:
147  c += k[2] & LOWER16b_MASK; b += k[1]; a += k[0]; break;
148  case 9:
149  c += k[2] & LOWER8b_MASK; b += k[1]; a += k[0]; break;
150  case 8:
151  b += k[1]; a += k[0]; break;
152  case 7:
153  b += k[1] & LOWER24b_MASK; a += k[0]; break;
154  case 6:
155  b += k[1] & LOWER16b_MASK; a += k[0]; break;
156  case 5:
157  b += k[1] & LOWER8b_MASK; a += k[0]; break;
158  case 4:
159  a += k[0]; break;
160  case 3:
161  a += k[0] & LOWER24b_MASK; break;
162  case 2:
163  a += k[0] & LOWER16b_MASK; break;
164  case 1:
165  a += k[0] & LOWER8b_MASK; break;
166  /* zero length strings require no mixing */
167  case 0:
168  *pc = c;
169  *pb = b;
170  return;
171  };
172  } else {
173  /* all but the last block: affect some 32 bits of (a, b, c) */
174  while (length > 12) {
175  a += BIT_SHIFT(k[0], k[1], s);
176  b += BIT_SHIFT(k[1], k[2], s);
177  c += BIT_SHIFT(k[2], k[3], s);
178  __rte_jhash_mix(a, b, c);
179 
180  k += 3;
181  length -= 12;
182  }
183 
184  /* last block: affect all 32 bits of (c) */
185  switch (length) {
186  case 12:
187  a += BIT_SHIFT(k[0], k[1], s);
188  b += BIT_SHIFT(k[1], k[2], s);
189  c += BIT_SHIFT(k[2], k[3], s);
190  break;
191  case 11:
192  a += BIT_SHIFT(k[0], k[1], s);
193  b += BIT_SHIFT(k[1], k[2], s);
194  c += BIT_SHIFT(k[2], k[3], s) & LOWER24b_MASK;
195  break;
196  case 10:
197  a += BIT_SHIFT(k[0], k[1], s);
198  b += BIT_SHIFT(k[1], k[2], s);
199  c += BIT_SHIFT(k[2], k[3], s) & LOWER16b_MASK;
200  break;
201  case 9:
202  a += BIT_SHIFT(k[0], k[1], s);
203  b += BIT_SHIFT(k[1], k[2], s);
204  c += BIT_SHIFT(k[2], k[3], s) & LOWER8b_MASK;
205  break;
206  case 8:
207  a += BIT_SHIFT(k[0], k[1], s);
208  b += BIT_SHIFT(k[1], k[2], s);
209  break;
210  case 7:
211  a += BIT_SHIFT(k[0], k[1], s);
212  b += BIT_SHIFT(k[1], k[2], s) & LOWER24b_MASK;
213  break;
214  case 6:
215  a += BIT_SHIFT(k[0], k[1], s);
216  b += BIT_SHIFT(k[1], k[2], s) & LOWER16b_MASK;
217  break;
218  case 5:
219  a += BIT_SHIFT(k[0], k[1], s);
220  b += BIT_SHIFT(k[1], k[2], s) & LOWER8b_MASK;
221  break;
222  case 4:
223  a += BIT_SHIFT(k[0], k[1], s);
224  break;
225  case 3:
226  a += BIT_SHIFT(k[0], k[1], s) & LOWER24b_MASK;
227  break;
228  case 2:
229  a += BIT_SHIFT(k[0], k[1], s) & LOWER16b_MASK;
230  break;
231  case 1:
232  a += BIT_SHIFT(k[0], k[1], s) & LOWER8b_MASK;
233  break;
234  /* zero length strings require no mixing */
235  case 0:
236  *pc = c;
237  *pb = b;
238  return;
239  }
240  }
241 
242  __rte_jhash_final(a, b, c);
243 
244  *pc = c;
245  *pb = b;
246 }
247 
263 static inline void
264 rte_jhash_2hashes(const void *key, uint32_t length, uint32_t *pc, uint32_t *pb)
265 {
266  __rte_jhash_2hashes(key, length, pc, pb, 1);
267 }
268 
284 static inline void
285 rte_jhash_32b_2hashes(const uint32_t *k, uint32_t length, uint32_t *pc, uint32_t *pb)
286 {
287  __rte_jhash_2hashes((const void *) k, (length << 2), pc, pb, 0);
288 }
289 
304 static inline uint32_t
305 rte_jhash(const void *key, uint32_t length, uint32_t initval)
306 {
307  uint32_t initval2 = 0;
308 
309  rte_jhash_2hashes(key, length, &initval, &initval2);
310 
311  return initval;
312 }
313 
327 static inline uint32_t
328 rte_jhash_32b(const uint32_t *k, uint32_t length, uint32_t initval)
329 {
330  uint32_t initval2 = 0;
331 
332  rte_jhash_32b_2hashes(k, length, &initval, &initval2);
333 
334  return initval;
335 }
336 
337 static inline uint32_t
338 __rte_jhash_3words(uint32_t a, uint32_t b, uint32_t c, uint32_t initval)
339 {
340  a += RTE_JHASH_GOLDEN_RATIO + initval;
341  b += RTE_JHASH_GOLDEN_RATIO + initval;
342  c += RTE_JHASH_GOLDEN_RATIO + initval;
343 
344  __rte_jhash_final(a, b, c);
345 
346  return c;
347 }
348 
364 static inline uint32_t
365 rte_jhash_3words(uint32_t a, uint32_t b, uint32_t c, uint32_t initval)
366 {
367  return __rte_jhash_3words(a + 12, b + 12, c + 12, initval);
368 }
369 
383 static inline uint32_t
384 rte_jhash_2words(uint32_t a, uint32_t b, uint32_t initval)
385 {
386  return __rte_jhash_3words(a + 8, b + 8, 8, initval);
387 }
388 
400 static inline uint32_t
401 rte_jhash_1word(uint32_t a, uint32_t initval)
402 {
403  return __rte_jhash_3words(a + 4, 4, 4, initval);
404 }
405 
406 #ifdef __cplusplus
407 }
408 #endif
409 
410 #endif /* _RTE_JHASH_H */
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