DPDK  20.11.3
rte_jhash.h
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1 /* SPDX-License-Identifier: BSD-3-Clause
2  * Copyright(c) 2010-2015 Intel Corporation.
3  */
4 
5 #ifndef _RTE_JHASH_H
6 #define _RTE_JHASH_H
7 
14 #ifdef __cplusplus
15 extern "C" {
16 #endif
17 
18 #include <stdint.h>
19 #include <string.h>
20 #include <limits.h>
21 
22 #include <rte_config.h>
23 #include <rte_log.h>
24 #include <rte_byteorder.h>
25 
26 /* jhash.h: Jenkins hash support.
27  *
28  * Copyright (C) 2006 Bob Jenkins (bob_jenkins@burtleburtle.net)
29  *
30  * http://burtleburtle.net/bob/hash/
31  *
32  * These are the credits from Bob's sources:
33  *
34  * lookup3.c, by Bob Jenkins, May 2006, Public Domain.
35  *
36  * These are functions for producing 32-bit hashes for hash table lookup.
37  * hashword(), hashlittle(), hashlittle2(), hashbig(), mix(), and final()
38  * are externally useful functions. Routines to test the hash are included
39  * if SELF_TEST is defined. You can use this free for any purpose. It's in
40  * the public domain. It has no warranty.
41  *
42  * $FreeBSD$
43  */
44 
45 #define rot(x, k) (((x) << (k)) | ((x) >> (32-(k))))
46 
48 #define __rte_jhash_mix(a, b, c) do { \
49  a -= c; a ^= rot(c, 4); c += b; \
50  b -= a; b ^= rot(a, 6); a += c; \
51  c -= b; c ^= rot(b, 8); b += a; \
52  a -= c; a ^= rot(c, 16); c += b; \
53  b -= a; b ^= rot(a, 19); a += c; \
54  c -= b; c ^= rot(b, 4); b += a; \
55 } while (0)
56 
57 #define __rte_jhash_final(a, b, c) do { \
58  c ^= b; c -= rot(b, 14); \
59  a ^= c; a -= rot(c, 11); \
60  b ^= a; b -= rot(a, 25); \
61  c ^= b; c -= rot(b, 16); \
62  a ^= c; a -= rot(c, 4); \
63  b ^= a; b -= rot(a, 14); \
64  c ^= b; c -= rot(b, 24); \
65 } while (0)
66 
68 #define RTE_JHASH_GOLDEN_RATIO 0xdeadbeef
69 
70 #if RTE_BYTE_ORDER == RTE_LITTLE_ENDIAN
71 #define BIT_SHIFT(x, y, k) (((x) >> (k)) | ((uint64_t)(y) << (32-(k))))
72 #else
73 #define BIT_SHIFT(x, y, k) (((uint64_t)(x) << (k)) | ((y) >> (32-(k))))
74 #endif
75 
76 #define LOWER8b_MASK rte_le_to_cpu_32(0xff)
77 #define LOWER16b_MASK rte_le_to_cpu_32(0xffff)
78 #define LOWER24b_MASK rte_le_to_cpu_32(0xffffff)
79 
80 static inline void
81 __rte_jhash_2hashes(const void *key, uint32_t length, uint32_t *pc,
82  uint32_t *pb, unsigned check_align)
83 {
84  uint32_t a, b, c;
85 
86  /* Set up the internal state */
87  a = b = c = RTE_JHASH_GOLDEN_RATIO + ((uint32_t)length) + *pc;
88  c += *pb;
89 
90  /*
91  * Check key alignment. For x86 architecture, first case is always optimal
92  * If check_align is not set, first case will be used
93  */
94 #if defined(RTE_ARCH_X86)
95  const uint32_t *k = (const uint32_t *)key;
96  const uint32_t s = 0;
97 #else
98  const uint32_t *k = (uint32_t *)((uintptr_t)key & (uintptr_t)~3);
99  const uint32_t s = ((uintptr_t)key & 3) * CHAR_BIT;
100 #endif
101  if (!check_align || s == 0) {
102  while (length > 12) {
103  a += k[0];
104  b += k[1];
105  c += k[2];
106 
107  __rte_jhash_mix(a, b, c);
108 
109  k += 3;
110  length -= 12;
111  }
112 
113  switch (length) {
114  case 12:
115  c += k[2]; b += k[1]; a += k[0]; break;
116  case 11:
117  c += k[2] & LOWER24b_MASK; b += k[1]; a += k[0]; break;
118  case 10:
119  c += k[2] & LOWER16b_MASK; b += k[1]; a += k[0]; break;
120  case 9:
121  c += k[2] & LOWER8b_MASK; b += k[1]; a += k[0]; break;
122  case 8:
123  b += k[1]; a += k[0]; break;
124  case 7:
125  b += k[1] & LOWER24b_MASK; a += k[0]; break;
126  case 6:
127  b += k[1] & LOWER16b_MASK; a += k[0]; break;
128  case 5:
129  b += k[1] & LOWER8b_MASK; a += k[0]; break;
130  case 4:
131  a += k[0]; break;
132  case 3:
133  a += k[0] & LOWER24b_MASK; break;
134  case 2:
135  a += k[0] & LOWER16b_MASK; break;
136  case 1:
137  a += k[0] & LOWER8b_MASK; break;
138  /* zero length strings require no mixing */
139  case 0:
140  *pc = c;
141  *pb = b;
142  return;
143  };
144  } else {
145  /* all but the last block: affect some 32 bits of (a, b, c) */
146  while (length > 12) {
147  a += BIT_SHIFT(k[0], k[1], s);
148  b += BIT_SHIFT(k[1], k[2], s);
149  c += BIT_SHIFT(k[2], k[3], s);
150  __rte_jhash_mix(a, b, c);
151 
152  k += 3;
153  length -= 12;
154  }
155 
156  /* last block: affect all 32 bits of (c) */
157  switch (length) {
158  case 12:
159  a += BIT_SHIFT(k[0], k[1], s);
160  b += BIT_SHIFT(k[1], k[2], s);
161  c += BIT_SHIFT(k[2], k[3], s);
162  break;
163  case 11:
164  a += BIT_SHIFT(k[0], k[1], s);
165  b += BIT_SHIFT(k[1], k[2], s);
166  c += BIT_SHIFT(k[2], k[3], s) & LOWER24b_MASK;
167  break;
168  case 10:
169  a += BIT_SHIFT(k[0], k[1], s);
170  b += BIT_SHIFT(k[1], k[2], s);
171  c += BIT_SHIFT(k[2], k[3], s) & LOWER16b_MASK;
172  break;
173  case 9:
174  a += BIT_SHIFT(k[0], k[1], s);
175  b += BIT_SHIFT(k[1], k[2], s);
176  c += BIT_SHIFT(k[2], k[3], s) & LOWER8b_MASK;
177  break;
178  case 8:
179  a += BIT_SHIFT(k[0], k[1], s);
180  b += BIT_SHIFT(k[1], k[2], s);
181  break;
182  case 7:
183  a += BIT_SHIFT(k[0], k[1], s);
184  b += BIT_SHIFT(k[1], k[2], s) & LOWER24b_MASK;
185  break;
186  case 6:
187  a += BIT_SHIFT(k[0], k[1], s);
188  b += BIT_SHIFT(k[1], k[2], s) & LOWER16b_MASK;
189  break;
190  case 5:
191  a += BIT_SHIFT(k[0], k[1], s);
192  b += BIT_SHIFT(k[1], k[2], s) & LOWER8b_MASK;
193  break;
194  case 4:
195  a += BIT_SHIFT(k[0], k[1], s);
196  break;
197  case 3:
198  a += BIT_SHIFT(k[0], k[1], s) & LOWER24b_MASK;
199  break;
200  case 2:
201  a += BIT_SHIFT(k[0], k[1], s) & LOWER16b_MASK;
202  break;
203  case 1:
204  a += BIT_SHIFT(k[0], k[1], s) & LOWER8b_MASK;
205  break;
206  /* zero length strings require no mixing */
207  case 0:
208  *pc = c;
209  *pb = b;
210  return;
211  }
212  }
213 
214  __rte_jhash_final(a, b, c);
215 
216  *pc = c;
217  *pb = b;
218 }
219 
235 static inline void
236 rte_jhash_2hashes(const void *key, uint32_t length, uint32_t *pc, uint32_t *pb)
237 {
238  __rte_jhash_2hashes(key, length, pc, pb, 1);
239 }
240 
256 static inline void
257 rte_jhash_32b_2hashes(const uint32_t *k, uint32_t length, uint32_t *pc, uint32_t *pb)
258 {
259  __rte_jhash_2hashes((const void *) k, (length << 2), pc, pb, 0);
260 }
261 
279 static inline uint32_t
280 rte_jhash(const void *key, uint32_t length, uint32_t initval)
281 {
282  uint32_t initval2 = 0;
283 
284  rte_jhash_2hashes(key, length, &initval, &initval2);
285 
286  return initval;
287 }
288 
302 static inline uint32_t
303 rte_jhash_32b(const uint32_t *k, uint32_t length, uint32_t initval)
304 {
305  uint32_t initval2 = 0;
306 
307  rte_jhash_32b_2hashes(k, length, &initval, &initval2);
308 
309  return initval;
310 }
311 
312 static inline uint32_t
313 __rte_jhash_3words(uint32_t a, uint32_t b, uint32_t c, uint32_t initval)
314 {
315  a += RTE_JHASH_GOLDEN_RATIO + initval;
316  b += RTE_JHASH_GOLDEN_RATIO + initval;
317  c += RTE_JHASH_GOLDEN_RATIO + initval;
318 
319  __rte_jhash_final(a, b, c);
320 
321  return c;
322 }
323 
339 static inline uint32_t
340 rte_jhash_3words(uint32_t a, uint32_t b, uint32_t c, uint32_t initval)
341 {
342  return __rte_jhash_3words(a + 12, b + 12, c + 12, initval);
343 }
344 
358 static inline uint32_t
359 rte_jhash_2words(uint32_t a, uint32_t b, uint32_t initval)
360 {
361  return __rte_jhash_3words(a + 8, b + 8, 8, initval);
362 }
363 
375 static inline uint32_t
376 rte_jhash_1word(uint32_t a, uint32_t initval)
377 {
378  return __rte_jhash_3words(a + 4, 4, 4, initval);
379 }
380 
381 #ifdef __cplusplus
382 }
383 #endif
384 
385 #endif /* _RTE_JHASH_H */
static void rte_jhash_2hashes(const void *key, uint32_t length, uint32_t *pc, uint32_t *pb)
Definition: rte_jhash.h:236
static uint32_t rte_jhash_3words(uint32_t a, uint32_t b, uint32_t c, uint32_t initval)
Definition: rte_jhash.h:340
static void rte_jhash_32b_2hashes(const uint32_t *k, uint32_t length, uint32_t *pc, uint32_t *pb)
Definition: rte_jhash.h:257
static uint32_t rte_jhash_32b(const uint32_t *k, uint32_t length, uint32_t initval)
Definition: rte_jhash.h:303
static uint32_t rte_jhash_1word(uint32_t a, uint32_t initval)
Definition: rte_jhash.h:376
#define RTE_JHASH_GOLDEN_RATIO
Definition: rte_jhash.h:68
static uint32_t rte_jhash(const void *key, uint32_t length, uint32_t initval)
Definition: rte_jhash.h:280
static uint32_t rte_jhash_2words(uint32_t a, uint32_t b, uint32_t initval)
Definition: rte_jhash.h:359